IFATCA - The Controller - November 1975

D 21003 F

JOURNAL OF THE INTERNATIONAL FEDERATION OF AIR TRAFFIC CONTROLLERS ASSOCIATIONS

In this Issue:

Primary Factors affecting ATC System Capacity Japan's Aeronautical Safety College A new Approach to ATC Simulator Control

FRANKFURT AM MA I N

NOVEMBER 19 75

VO L UME 14

IFATCA'76 · 26-30APRIL · IFATCA'76

THE CITY OF IFATCA'S XVth ANNIVERSARY CELEBRATION

IFATCA

JOURNAL

OF

AIR

TRAFFIC CONTROL

THE CONTROllER Frankfurt am Main, November 1975

Volume 14 • No. 4

Publisher: International Federation of Air Traffic Controllers' Associations, P. 0. B. 196, CH-1215 Geneva 15 Airport, Switzerland.

Officers of IFATCA: J-D. Monin, President, 0. H. JOnsson, Vice-President (Technical), R. E. Meyer, VicePresident (Professional), E. Bradshaw, Vice-President (Administration), T. H. Harrison, Executive Secretary, J. Gubelmann, Treasurer.

Editor: G. J. de Boer,

P. 0. B. 8071, Edleen, Kempton Park, Tvl..

1625 South Africa, Telephone: 975-3521 Contributing Editor: V. D. Hopkin (Human Factors) Managing Editor: Horst Guddat, 0·6368 Bad Vilbel 2, Otto-Bussmann-StraBe 7, (Federal Republic of Germany).

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CONTENTS

Subscription Rate: OM 6.- per annum for members of IFATCA OM 10.- per annum for non-members (Postage will be charged extra)

Primary Factors Affecting ATC System Capacity· · · ·

Contributors are expressing their personal points of view and opinions. which must not necessarily coincide with those of the International Federation of Air Traffic Controllers' Associations (IFATCA).

Japan's Aeronautical Safety College · · An Evaluation of Radar Data Processing The Controller's Legal Liability

IFATCA does not assume responsibility for statements made and opinions expressed, it does only accept responsibility for publishing these contributions.

The TC-61 Assault Operation

Contributions are welcome as are comments and criticism. No payment can be made for manuscripts submitted for publication in "The Controller". The Editor reserves the right to make any editorial changes in manuscripts, which he believes will improve the material without altering the intended meaning.

News from the Federation

International Law, Part VII

Comparison of

u. s.

5 13 16 19

21 22

28

ATC Facilities by means of a Stress

28

· · · · · Automation and Training, Part 1

31

IKAT _A new Approach to ATC Simulator Control

35

Around the world in 40 Days, or what kept you, Jules Verne?

38

Fotos: Archiv, Solartron Electronics

News from Member Associations . . . . . . . . . . . . .

41

Cover: Horst Guddat

The AGARD 20th Guidance and Control Panel Meeting/Sym-

Written permission by the Editor is necessary for reprinting any part of this Journal.

Cartoons: Helmut Elsner Advertisers In this Issue: APCA/IFATCA 76, (inside cover), Cossor Electronics (page 2), International Aeradio Limited (page 3), AEG-TELEFUNKEN (page 9), Ferranti Digital Systems (page 26/27), r. P. Sharp Associates Ltd. (page 47). Rohde & Schwarz (inside back cover). Selenia Radar (back cover).

Index

· · · · · · · · · · · · ·

43

OIDS _ Operational Information Display System

46

News from Corporation Members

49

Comments on ATC

51

Publications Review

52

posium, Part I

In 1984 Cossor SSR will still be watching out for you It has been esti mated by the Civi l Aviation A uthority that ai r traffic wi ll increase th reefold by 1984.

It has been estimated by Cossor Electronics that air travel will be three times safer by 1984.

Why? Because airport authorities are increasing ly adopting the almostinfallibl e type of air t raffic control system pioneered by Cossor, based on Secondary Surveillance Radar.

Recent SSA developments by Cossor mean that more aircraft informa-

cossor c».

tion is now available to air traffic controllers much more quickly and accurately than has been possible to date.

Cossor's first experimental SSA was produced in 1950. Continuing development has led to the introduction of the SSA 990, a complete air t raffic control system incorporating advanced data processing and display techniques.

It leads the world in radar technology.

COSSOR ELECTRONICS LIMITED, THE PINNACLES, HARLOW. ESSEX. ENGLAND · TEL. HARLOW 26862

;:-:.,J• "__!.•.. \; .

-

.....~ -~ w:ii ~'i!ll

The first operat ional SSA 990 system is now being installed for the Civil Aviation Department ot the Hong Kong Government

Cossor SSA is serving Australia. Austria. Burma Denmark.

Fr~nce ._ Hong Kong, India, Lebanon, Netherlands. Norway.

Philippines. Sweden, Thailand. Turkey, Un ited Kingdom, Zaire.

Editorial Our Public Relations Effort: What We Are Up Against Possibly the most important single issue wh ich confronts the Federation is the question whether we are succeeding in our efforts to put the controller's case across within and outside the international aviation community. A large part of IFATCA's annual budget is set aside for this purpose, and dedicated officials work ceaselessly to improve our image around the globe. There is no shadow of doubt that if these funds were not allocated for this purpose year after year, the standing of the controller in the international aviation arena would not even be half of what it is today. And yet, we always have been, and we still are, confronted w ith ignorance, misunderstanding and attempts to tone down the important task of the air traltic controll er, by those in the field of aviation publicity who shou ld , of course, kn ow better but who cannot or do not wish to acknowledge the true position. This leads us to two factors: how important is the Air Traffic Control System in the field of aviation, and what are the factors influencing those aviation publicity people who do not see the light of day?

The importance of today's ATC System was probably never more clearly illustrated than in the Report published by Glen A. Gilbert, who was commissioned by ou r U.S. Member Association (PATCO) to do a thorough study on the desirability of rest ructuring t he Federal Aviation Administration , a body which has been much in the news recently and which has come under close scrutiny and criticism. Gilbert, an expert second to none in the aviation consultancy bus iness, explained that since something over 90 O/o of the total workforce of the FAA can be considered as directly or indirectly involved in the ATC System, the conclusion can be drawn that the Air Traffic Services are so important in the FAA's functions that these should be performed in a separate organisational structure, funct ioning outside the Department of Transport, under the name " The United States Air Traffic Services Corporation". Furthermore, since the civil users of the system pay at least SO O/o of its costs ,

Since 1958 we have trained more than 1700 students of 71 nationalities as Air Traffic Controllers for overseas Governments to ICAO standards.

The high standard achieved and maintained by our instructional staff of experienced controllers is one of the many reasons for IAL being selected by these authorities. Flexibility and economy are added attactions. Courses can be tailored to meet individual requirements, incorporat ing national ATC legislation if necessary. At competitive prices. All the courses are approved by the UK Civil Aviation Authority and recognised by ICAO. We offer three standard coursesAerodrome and Approach Control Area (Airways) Control and ¡ Surveil lance Radar Control. We also off<=:r other courses such as an Ab lnit10 course. an AIS course. as well as Special Courses which can be designed to simulate any ATC environ ment.

For further details about the Col lege and course vacancies, please contact The Admin istrator. IAL Co llege of Air Traffic Services. Oxford Ai rport.

Kidl1ngton. Oxford OX5 1SH . England.

Telephone: Kidli ngton 6168

m1

College of Air Traffic Services

3

a business-like approach would afford the best concept on which to base this new organisational structure, hence the derivation of the suggested name. Gilbert further believes that as there is no rhyme nor reason for the number, location or coverage of today's FAA regional offices in the USA, except Alaska, and whereas within the 48 contiguous States, there are 20 areas under the control of what is termed an Area Traffic Control Centre, the establishment of a simplified, streamlined "Area Office" in place of the present regional offices for each of these control areas should not only mean more expeditious and more efficient execution of Washington directives, but should also result in increased safety and economy of operation.

Further proof, if this is still needed, comes from no less a person than U. S. President Gerald Ford, who had this to say in his special message to the 1975 PATCO Convention: "The members of your organisation perform a vital role in our Nation's economy. As we rely more and more on an increasingly sophisticated air transport system for both commercial and recreational activities, the job of the Air Traffic Controller becomes more challenging and complex than ever. In your hands rests much of the safety of air passengers and cargo.

Your skills and successful record in this important task are a comfort to all travellers and they can be a sense of great pride and satisfaction to each of you."

But the national and international aviation magazines which are published today, with one or two exceptions, have never acknowledged nor understood the importance of the ATC System, and in general are doing their readers a gross disservice in keeping them in the dark. May be the mysteries and complexities of ATC are beyond the average aviation journalist's comprehension, but there are some who do make the effort to understand, like David Woolley of AIRPORTS International, in whose magazine ATC does get its proper share of recognition. But what to think of another leading international aviation magazine, which published a lengthy report on IFALPA's 1975 Annual Conference, and rightly so, but curtly rejected reports sent in covering IFATCA's Annual Convention in Melbourne, and totally ignored the event? Some magazines don't even try to hide their absolute ignorance, like a prominent aviation journal which, in an editorial recently, accused radar controllers of giving "vectors to confusion", saying that the poor, forgotten (?) pilot of our times is so over-monitored that his own area of responsibility becomes blurred. This expert asks: "when will the growing bear hug of protective controller guidance stop?", but he obviously doesn't know that if it wasn't for the ease of radar vectoring, pilots would hang around in the stack at least twice as long. It is irresponsible reporting of this kind which keeps the general public in the dark as to the true position.

Let's see editors of aviation periodicals start giving some more due to a vital aviation system which thoroughly deserves it: the Air Traffic Control System. At the Melbourne Conference, the public relations task of IFATCA's Standing Committee II was allocated to the French Association (APCA), and APCA was quick off the mark in arranging the Federation's presence at the last Paris Air Show. Member Associations and individual IFATCA members are urged, for their own good, to throw their weight behind APCA in its uphill assignment.

GdB

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A Look At The Primary Factors Which Affect ATC System Capacity

by Tirey K. Vickers, Senior Vice President, JAMES C. BUCKLEY, Inc., Washington, D. C.

System Elements Air Traffic Control is a vast and highly complex system which controls the flow of air traffic. Figure 1 is a highly simplified diagram of a single air/ground control loop. The elements of this loop are very closely interrelated. As a result, interactions between certain elements can affect other elements of the system, sometimes in indirect ways.

The air traffic control system has evolved slowly over many years. The most important single change was the adoption of primary radar in the early 1950's. Several years later, this was supplemented by the adoption of secondary radar, which solved some of the tracking and identification problems of primary radar, but added several new problems of its own. About this time, computers came into use for printing flight progress strips. These strips are used in air route traffic control centers and air traffic control towers to form a visual display as well as a permanent record of individual air traffic movements.

Only since 1970 has any great progress been made in the implementation of computers for the generation of alphanumeric target displays. This supplements the CRT (Cathode Ray Tube) plan position display of aircraft positions on the controller's radar display, by adding the associated alphanumeric identification, as well as the current altitude and ground speed of individual aircraft targets in the traffic situation.

The most critical constraints in the operation of the present ATC system are airspace capacity, airport capacity, and control workload. These constraints themselves are very closely interrelated.

courses directly to or from VOR stations. Thus, the number of usable routes has been limited by the number of lines of VOR facilities which could be established. The resulting route structure concentrated all aircraft on the radial courses which formed the centerline of the airways. Much of the airspace on both sides of these airways was wasted because of the capability of the airborne equipment to provide guidance only along radial courses.

The recent development of area navigation equipment (RNAV) provides a means of setting up and flying offset courses anywhere within the coverage of the VOR/DME facilities. Aircraft equipped with RNAV will be able to fly parallel courses offset from the centerline of the airway and thus utilize new routes in airspace which could not normally be used before.

Unfortunately, VOR errors plus the lack of slant/range correction in the present airborne equipment require that the width of RNAV tracks be as great as the width of the old VOR airways. Consequently, in many instances there just will not be enough room to fit in the additional RNAV traffic lanes that are needed. Some of the recently established RNAV routes have many points of interference with the underlying VOR airway structure, particularly in the crowded northeast portion of the United States. This has limited the gains which RNAV should theoretically provid~.

Further development of RNAV airborne equipment will provide for three-dimensional guidance along pre-programmed climb and descent paths. The further addition of ground speed control will provide the fourth dimension u~ti­ mately required for complete volumetric navigation. Wit~ airborne equipment providing four dimensions of control, it

Airspace Constraints Airspace capacity is presently limited by the separation standards, which must be large enough to allow for the combined errors and time lags associated with the operation of all the system elements shown in Fig. 1.

During the past few years, the overwhelming proportion of research and development in the U. S. Federal Aviation Administration (FAA) has been concerned with the processing and display of control data. Whatever payoffs will c~me from this effort are now becoming apparent with the wide use of data processing systems in enroute and terminal facilities. Basically, these systems provide a means of tracking and identifying aircraft targets on computer-generated ATC displays. The on-line connection of these systems between different sectors and different ground facilities should greatly improve the coordination functions which are required in clearing aircraft across sector or facility control boundaries.

One of the limiting factors to airspace capacity has been the characteristics of the VOR navigation system, which could furnish positive course guidance only along radial

Figure 1: Elements of a single Air Traffic Control Loop.

5

will be possible for aircraft to navigate within a specified. three-dimensional flight path from take-off to touch-down and to make good predetermined arrival times consistent with guaranteed approach clearances.

Airport Constraints Airport constraints are concerned largely with the number of runways which can be operated simultaneously. However, the construction of new runways or new major airports has become almost impossible in the United States because of current environmental considerations. Therefore, efforts to increase airport capacity must also be concerned with getting the most capacity out of existing runways. In this regard, it may be desirable to review some of the underlying principles. In some respects, the flow of air traffic is analogous to the flow of current in an electrical network. The outbound flow starts out in series (single file on a runway) and subsequently changes to parallel (different routes and altitudes). The inbound flow changes from parallel (different routes and altitudes) back into series (single file on the approach path and landing runway). Traffic density in any lane is analogous to current intensity; any restriction (such as interference with another lane) can reduce the rate of flow on that segment of the circuit.

There is a kind of Ohm's Law which states that the rate of traffic flow in any traffic lane is directly proportional to the speed of the vehicles, and inversely proportional to the amount of separation between them. Applied to ATC, the equation looks like this:

N = V/S, where N = Lane Capacity, in number of aircraft per hour; v = Average Velocity (ground speed) of aircraft in knots; s Average Separation between successive aircraft, in nautical miles.

=

In civil operations, only one aircraft at a time is allowed to use an airport runway. Thus. runways are perhaps the most valuable time-shared facilities in the ATC system •. and the traffic capacity of any airport is inversely ~ropo~t1onal ·me interval between successive aircraft to the average t 1 operations. Because runways handle . take-offs and landings, four types of intervals can occur· A A A A

take-off take-off landing landing

followed followed followed followed

by by by by

a a a a

take-off landing take-off landing

(T-T) (T-L) (L-T) (L-L)

the runway to be cleared before the landing aircraft reaches the point where it is committed to land.

Good airport design will incorporate a number of refinements which can increase airport capacity by reducing the various types of intervals, as shown in the upper portion of Table 1. Because each of the four types of intervals has an almost equal probability of occurring, a reduction in one type of interval reduces the average of all four types only by 1f, as much. For example, if the use of an approach computer some day reduces the average L-L interval only by 8 seconds, it will reduce the average of all intervals by about 2 seconds. It is important to emphasize that in maximizing airport capacity it is just as important to look also at methods of reducing the T-T, T-L and L-T intervals.

Approach Spacing . From the foregoing, it may be apparent that for any g1ve.n set of ~onditions there is a finite limit to the number of aircraft which can be accomodated b . h . . . y a sing 1e approac Iane within a given period of time Th' . . .

1s number can be increased either by raising the approa h . . . c speed (which normally is not desirable for safety reasons) b d . the separation. or Y re ucrng The _Pre~ent 3-mile radar separation standard was chosen arbitrarily many years ago s b' o ar 1trar"I 1Y ·in f act t h a t it was increased 15 o~ . from the statute mile too t:vernig.ht when the U. S. A. went operations the averag e naut!cal mile standard. In actual e separation between . . strument approaches is h successive into a number of factors ~ome.w at longer than 3 miles due . ne is that the control! h little control over the exact arrival f er as very landing threshold after the . ime of the aircraft at the aircraft has passed th gate headed inbound on the glid e approach 1 final approach path, the more time ~h s op_e .. The longer the craft can be affected by variatio ~re 1 ~ rn Which the airns m speeds which will change the actual . wind and a pproach ing threshold. Therefore in order toa~nval time at the landseparation standard will ,not be violat~~sut~e that the 3 mile mally must use an additional ' e controller noramount of separar (b ion uffer) at the start of the approach path to corn spacing errors which might occur f hPensat~ for any r 0 mthe t at Point on · In genera I• th e Ionger the common path, . required. . more buffer 1s

Another factor which complicates th operation and reduces the acceptanc e appr~ach spacing difference between successive aircrafte trate 1s the speed .

YPes on the apstan-. proach path. W h en a fast aircraft is folio · Runway us e 1.5 regulated by prescribed separation . . wing a slower one more separation must be used at the beg· . ' U d ·nstrument weather conditions all aircraft must . mnmg of the approach. When a slow aircraft is following a f t dards. n e~ I b at least 3 miles horizontally or 1,000 feet . . . . as er one, the mm1mum separation established at the be . . be separate Y d r control can be used. Without radar, . . ginning of the vertically when ra a · · approach will gradually increase as the a·ircraft · . must be employed during mstruproceed to much larger separations the runway. In order to avoid extremely large approach inment weather conditions. tervals from the latter cause, the current practice is to atL-T and T-T intervals are governed by runway occutempt to keep the slower aircraft at a speed more compa. the succeeding aircraft cannot pull onto pancy time, as d th run tible with the aircraft it is following until late in the apreceding aircraft has passe e . the runway until the P d" aircraft cannot start proach. The final slowdown to the approach speed must · t and the succee mg be begun in time for the aircraft to become stabilized on way entry porn • . . · off the runway. L-L take-off until the preceding a1r~~f:111~w the Number 1 airthe: glide slope at a safe altitude. intervals must be long enough f the runway before the As the airport runway is one of the most critical and craft to slow down and get cle~r o it is committed to expensive timeshared facilities in the system, the reduction Number 2 aircraf~ reach~s a point wh~:~ding aircraft must of runway occupancy time is an important means of inland. Similarly with T-L intervals, the .

11 ow creasing airport traffic capacity. The runway occupancy . t ke-off 1s started, to a be far enough out at the time a a

6

Higher Capacity

Item

Increased

Type of Intervals Reduced T-T ! T-L I L-T

1.

2.

3.

4.

5.

6.

7.

Airport Improvements Parallel taxiways to ends of runways By-pass taxiways and holding areas High-speed runway exits High-speed runway entries Separate runways for takeoffs/landings Multiple runways for landings Multiple runways for takeoffs

ATC Procedures 8. Segregation of high-speed and low-speed aircraft on different runways 9. Speed Control 10. Selective Sequencing

11.

12.

13.

14.

ATC Equipment Bright radar display in tower Alphanumeric radar displays Approach spacing computer Vortex detector

I I

Flight

L-L

Safety

I

I

i

I

•• • : •• • • • ••• • : •

t

• •

I I

•

Reduced ATC Workload

••• •

•

I I

!

• • I

•

•

I

i

I

I

•

••

•• ••

•

•

•

I

i

•• I

I

•

I

Table I - Effects of various system improvements

time of landing aircraft can be reduced by the installation of highspeed exits strategically placed to allow the aircraft to start a turn off the runway as soon as possible after it has slowed to a speed which is safe for negotiating the turn. Such exits are particularly useful in clearing the runway in order to expedite the take-off of departures on the same runway. For maximum utility, it is important that all exits be adequately marked -and· lighted.

The runway occupancy time of departing aircraft can be reduced by the installation of parallel taxiways so that an aircraft can enter a runway at the end rather than having to taxi out on the runway itself and then turn around before taking off. The design of high-speed runway entries is a further refinement in reducing the lead time required in getting a departure from the runway holding area to the take-off position.

Whenever it is necessary for taxiing aircraft to cross the runway in use, they create a runway occupancy problem which can interrupt the normal flow of take-offs and landings. This situation is characteristic of airports where two active runways are located on the same side of the terminal building. Such crossings can be minimized if the airport terminal is located between the two parallel runways.

Another improvement which can minimize the number of interruptions is to widen the crossover or provide multiple crossovers so that several aircraft can cross together rather than one at a time. . One very serious constraint to the IFR capacity of major airpo~s has been the shadowing and interference effects o~ taxiing or parked aircraft on the localizer and glide slope signals ?f the instrument landing system. These effects ten~ t~ increase with the size of the aircraft. In order to avoid interference with the guidance signals for aircraft on approach, it is necessary for other aircraft to be held outside the zone of interference of the localizer and glide slo~e anten~~s when there is an aircraft on approach during conditions of low ceiling or visibility. This means

that under such conditions other aircraft are forced to hold a long distance away from the end of the approach runway.

Particularly at airports where the same runway must be shared by arrivals and departures, much time can be lost in getting a departure into take-off position after a landing aircraft has crossed 'the threshold. In addition, the long distance between holding position and take-off position can waste considerable airport capacity by preventing a departure from starting out to take-off position if there is another aircraft ready to begin approach during the time it would take the departure to taxi out and take off.

These problems are expected to be greatly reduced with the development of a microwave ILS system. Such development is now underway in several different countries.

When an airport is laid out with two closely-spaced parallel runways on the same side of the terminal apron, runway crossing operations can usually be simplified if the outer runway is instrumented as the primary landing runway, and the inner runway is designed as the primary departure runway. The simplification is possible because less separation is required to clear arrival traffic across a departure runway, rather than departure traffic across an arrival runway. When departures never need to cross the arrival runway, they can operate more freely without interfering with ILS guidance signals for arriving aircraft on the approach path. .

The recent interest in area navigation procedures in the U.S.A. may lead someday to a reduction in comm_unications in busy areas, by the establishment of standard 1~~tru~ent departure and arrival routes which can be sp~c1f1ed. in 3 dimensions and flown accurately by the pilot without mt~r­ vention by the air traffic controller. T~e pot~nt~al benefits of this mode of operation, however, will be hm1ted by the errors present in the existing VOR's which, with DME, form the infrastructure of navigable routes.

From the preceding paragraphs, it may be noted that any increase in the air traffic capacity of a single airport

7

or a group of airports requires either that the time necessary for any series operation be reduced or that additional independent paths be implemented to allow more operat:ons to proceed in parallel (simultaneously). Examples of reducing the time for any single operation include the provision of high speed runway entries and exits to reduce runway occupancy time; the provision of more direct departure routes to get the aircraft out of the area more quickly and thus occupy less of the controller's time; and use of Automat:c Terminal Information Service (ATIS) on a separate radio channel to reduce the controller/pilot communications time required to bring one aircraft through that portion of the system - - and thereby allow the controller to handle more aircraft simultaneously. Examples of the provision of additional independent paths includes the use of divergent runways for multiple take-offs; the provision of parallel runways to allow simultaneous landings and takeoffs; and the shortening of approach patterns to reduce the interference between the traffic patterns of adjacent airports.

The implementation of simultaneous parallel approach systems at U.S. airports had been severely limited by the runway separation standard which required at least 5000 ft. spacing between parallel runways used for simultaneous IFR approaches. This standard was initially calculated as sufficient to provide an acceptable··level of safety without controller intervention. However, it is not contemplated that any dual simultaneous approach system would ever be commissioned without continuous controller monitoring plus the communications capability for instant controller intervention.

Using this premise, a mathematical model has recently been developed, expressing the probability of collis:on of aircraft on parallel final approach tracks. The resultant collision probability figures for this set of conditions are:

30 ...------.-------..---""!"!"'!"'!"!~-------..-------· T

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INCR~ASED SEPA~ATIO~

•~~..&..i-J•-..i--,

BETWEEN HEAVY JETS AND FOLLOWING AIRCRAFT ...,......~...._......!"'!:.+·~""::I-iii: n~·'-''~,J.a·'-''.~"'-!-1.' OF OTHER TYPES ,.,.,-,,-,.

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PERCENTAGE

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80

60 HEAVY

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IN

TRAFFIC

100

10-1 10-a 10-9 10-10

Runway Separation, Feet

2,379 2,559 2,724 2,880

As a result of this and other studies, the U. S. Federal Aviation Administration has finally reduced the lateral spacing criteria for runways used for parallel simultaneous instrument approaches to 4300 feet (1311 meters).

Establishment of parallel runways which are too close to be used for simultaneous instrument approaches can still i~crease airport traffic capacity over that possible with a single runway, by permitting a departure to start take-off on one runway before a landing is completed on the other runway. T~e de~ign of ~irport taxiways to provide independent operation with as little interference as possible between arriving and departing traffic can greatly reduce the amount of controller workload. In some cases, a more streamlined fl~w of ground traffic can also increase airport traffic capacity to some extent by avoiding blockages of ta · t x1 rou es, . . an d th ere by o btaming better runway utilization. .The development of improved surveillance equipment (primary or secondary radar) will tend to increase th _ racy of the aircraft position display. This, together :it~c~~e development of approach spacing compute rs as an addon to the data processing system should all · th . t 1on m e amount of separation required b t ow a reduc. . . e ween aircraft m flight. However, any possible decrease · . . . . m 1ong1tudmal separation between landing aircraft would t'll b . . . . s 1 e hm1ted b Y (a) the time 1t takes a landing aircraft to d ece 1erate and clear the runway for the next aircraft· (b) th .

• e wake turbulence problem, which can be a serious hazard h . . w ere large and small aircraft are usmg a common path.

Every winged aircraft generates vortices . . as a direct spm-off of the process of dynamic lift. These · . . . . vortices spm off the wmg tips forming twin horizontal wh· I · 1r wmds which can be a hazard to following aircraft The inten •t f · s1 Yo these . . . vortices 1s directly proportional to the amount of l"ft b . . .

1 emg generat e d , an d 1s inversely proportional to the · . wing span the airspeed, and the air density The vortex tra·11 d ' · gra ually . . d1ss1pates and normally breaks up within a few · . th t .t . minutes f rom t he time a 1 is generated. Meanwhile, howev . ht er, 1t . can upset a I19 er, smaller aircraft which is followin 9 too closely behind the generating aircraft. The growin danger of this hazard is due mostly to the increased weigh~ of some modern aircraft.

With the introduction of the Boeing 747 in 1968, the FAA established a heavy-jet aircraft category (which included aircraft with a gross take-off weight of 300,000 lbs. or m all and specified that the longitudinal separation betw ore), heavy jet and a following aircraft of the non-heavy-je~~n a Type should be increased to a minimum of 5 nautical mil . d . es. he eff ect of t he increase separation, on runway cap 't . . ac1 y, 1s shown by the lower parabolic area in Fig. 2. About 4 years later, due to the crash of a non-heavy DC-9 aircraft which for some reas?n had less than the required separation behind a DC-10 aircraft, the FAA somewhat irrationally · . increased the separation between heavy jets to 4 nautical m·1 Th . t . t' .

1es. e ~ ff e~t o f th 1s res nc ion 1s shown by the upper shaded area m Figure 2.

MIX

Figure 2· Losses on runway capacity due to increased separation for heavy jets.

8

Risk of Collision

On 1 November, 1975 the U. S. FAA plans to increase the separation standards used on the last portion of the final approach path, as follows:

441.015

International Air Traffic :

-SAFETY FIRST Our contribution: ATC radar systems AEG -TELEFUNKEN Fachbereich Hochfrequenztechnik 79 Ulm · PB 830 Federa l Republi c of Germany

£

~~~ ~

Radar equ ipment of AEG -TELEFUNKEN 9

.......

An additional aircraft category of Small Aircraft is established to include all aircraft with a gross takeoff weight up to 12,500 lbs. {5669 kilograms). This category also includes the Learjet. All aircraft in this category are required to have at least four miles final approach separation behind aircraft in the Large category {12,500 to 300,000 lbs.); and 6 miles separation behind aircraft in the Heavy category (over 300,000 lbs. (136,054 kilograms)).

During the last few years, the FAA has directed considerable effort toward the development of wake detection methods to determine the location and relative strength of turbulent wakes in the vicinity of airport runways. One of these methods uses Doppler acoustical techniques, while another utilizes a laser. If such developments prove practical, they could be applied to expedite take-offs of lighter aircraft behind heavy jets. Meanwhile, the National Aeronautics and Space Administration (NASA) has been working on a number of methods to expedite the break-up and the diffusion of vortex patterns behind large aircraft. Some of the methods are: (a) the use of retractable drogues which are deployed from the trailing edges of the wing, near the wingtips to create turbulence; (b) an approach technique for 4-engine jets in which the 2 inboard engines are idled on approach, while power is increased on the 2 outboard engines; (c) redesign of the aircraft to place the 2 outboard engines very close to the wingtips; (d) the use of winglets (small vertical air foils) near the trailing edge of the wingtips to create counter vortices and speed the diffusion of the main vortices; (e) modulation of the wing flaps at a rate which will accentuate the natural instability of the vortices and cause them to cancel each other out within 2 miles or so behind the aircraft.

The FAA is now testing a new concept which is based on the theory that if the wind component near the landing runway threshold exceeds five knots in the forward quadrant, ten knots in the crosswind quadrant, or fifteen knots in the rear quadrant, the wind will either break up, or blow away, the vortices generated by one aircraft, S&'that they will not affect the safety of another aircraft on the same approach path, three miles behind. Should very extensive test of this simple concept prove its validity, it may be possible, with proper ground instrumentation, to some day reduce final approach separations between all aircraft categories, down to three miles when the wind conditions permit. However, initial tests have shown that the wind in the vicinity of the landing threshold can vary considerably from the wind indicated by an anemometer located somewhere else on the airport.Therefore, any implementation of this concept probably will require the installation of additional anemometers near the various landing runway thresholds.

Meanwhile, some relief can be obtained by the use of selective sequencing, which is a technique whereby the normal first-come first-served order of take-off or landing is deliberately changed in order to batch aircraft of different characteristics, and thus decrease the number of times that the present 5-mile separation must be used between a heavy-jet and a following aircraft of the non-heavy-jet category. Another technique is to sequence a non-heavy-jet take-off behind a heavy-jet landing, or a non-heavy-jet landing behind a heavy-jet take-off, on the same runway; better yet, if two runways are available, it is sometimes possible to put all heavy-jet operations on the same runway, and the other aircraft on the other runway.

10

Control Workload Constraints Since the advent of commercial jet transport in 1958, the increased speeds of jet aircraft and the higher density of air traffic has led to the belief that the see-and be-seen concept for jet aircraft is not safe, and that positive control of all aircraft within the airspace used by jet aircraft is necessary. This belief has led to the designation of positive controlled airspace and terminal control airspace around large hub airports. Within such airspace all aircraft are required to be under ATC control and to be equipped with secondary radar transponders.

The trend toward more and more positive controlled airspace will tend to increase even more the proportion of aircraft which will be equipped with transponders, thus increasing the number of aircraft which can be labelled automatically with identification and altitude readouts on the controllers' displays. The ability to obtain continuous altitude information on aircraft will tend to simplify air traffic control procedures and allow more flexibility, particularly in the control of traffic using the satellite airports.

During the past few years there has been a marked increase in the use of speed control around airports, both in having slower aircraft maintain a higher speed in the traffic pattern in order to avoid large speed differentials between successive aircraft, and also to impose maximum speed limits for aircraft at low altitudes in order to increase the time available for visual collision avoidance.

The development of bright displays for control towers is a very useful method of increasing safety and also traffic capacity. Safety can be increased by the fact that the controller in the tower can see other traffic in his vicinity which may not be under his control. Traffic capacity can be increased because the display gives the controller the basis for a go/no go decision with regard to the safe clearance of a departure ahead of the arrival of an aircraft on approach to the same runway. Having this definite knowledge of the existing separation often enables the controller to get the departure on Its way, instead of making it wait until the arrival lands and then clears the runway. The use of bright displays can also be applied to the operation of satellite airports by remoting the radar picture from the major airport, via narrow-band or microwave relay. In this case much greater utilization can be obtained from a single rada; and its benefits can be utilized at a number of nearby airports at relatively low cost.

The ability of secondary radar data processing systems to provide direct altitude readouts, for those aircraft Which are equipped with altitude transponders, ultimately should tend to allow more efficient use of satellite airports, Particularly where such airports are overflown by the flight patterns of the major hub airports in the area. When controllers can have an automatic indication of the altitude of the aircraft involved, they will be more likely to relax the constraints which they would otherwise impose on operations conducted to and from the satellite airports.

The ability of the equipment to provide positive identification of the various aircraft under control tends to alleviate one of the most critical constraints to ATC system capacity - the number of aircraft which a single controller can handle simultaneously. Up to the present time, this number has been extremely low, particularly in those portions of the system in which most of the aircraft are climbing or descending. The development of an approach spacing computer as an add-on function to the present ARTS equipment

is expected to reduce controller workload. It should also provide a more accurate means of compensating for all the variables which enter the approach spacing function, and thus achieve a significant decrease in the average interval between approaches.

Discrete Address Beacon System (DABS), which is expected within 10 years, should remove many of the present disadvantages of secondary radar by eliminating many of the problems connected with over-interrogation, reflection, and mutual interference by nearby transponder-equipped aircraft. However, the ultimate development of this concept will require extensive changes in the airborne transponder equipment.

The amount of communications required for air traffic control tends to increase at an exponential rate, commensurate with the number of pairs of potentially conflicting aircraft in the traffic situation. The time required for such communications can limit the number of aircraft which can be controlled by one sector.

The application of a digital data link is expected to be one of long-range benefits of the discrete address beacon system. In this development, which is expected within the next 15 years, the capabilities of air traffic control computers will be greatly increased to provide collision warning capability and the automatic generation of collision avoidance instructions to the aircraft concerned. In the initial phase, these instructions will be in voice form. Later, if and when enough aircraft become equipped to receive digital data link messages, the instructions will be transmitted in digital form.

The substitution of digital for voice messages is expected to save a large amount of communications time and allow for the control of more aircraft simultaneously. However, the actual effect of these developments on air traffic capacity will not be large, because of the overriding constraints of the other factors previously mentioned in this report.

The development of an airborne collision avoidance system (CAS) has been fostered in recent years by the airlines, mainly as a backup to protect against failure of the ATC system. Unfortunately, the CAS equipment is extremely expensive, both in terms of user equipment, and for the FAA which would have to implement a number of cooperative ground stations. A collision avoidance system which only the airlines could afford would have little social value, as the number of airliner vs. airliner collisions has been extremely small over the entire history of commercial aviation. To produce any significant increase in safety, an airborne collision avoidance system should be affordable and implementable by a vast majority of aircraft owners.

Another concept which is being explored is a pilot warni~g indicator (PWI) system which consists of a small addition. to the beacon transponder. This relatively inexpensive d:vi.ce would detect the presence of nearby aircraft trans~ittmg beacon replies and could filter out a large proportion of false alarms by decoding the altitude data received from th~ nearby aircraft and comparing it with the altitude dat~ bemg transmitted by its own transponder. The PWI device ~ould merely alert the pilot to the presence of a n.earb.y aircraft but would not tell him what to do about the s1tuat1on.

Meanwhile . . â&#x20AC;˘ the re cen t d eve1opment of multi-processing or assoc1ativ.e .~omputers for air traffic control has opened up the poss1b1hty that improvements in the ground-based

air traffic control system may provide sufficient new capability to make the use of an airborne CAS unnecessary. The associative computer can simultaneously perform tracking functions on the transponder replies received from all beacon-equipped aircraft within range of the ground facility.

The computer simultaneously projects the flight path of all aircraft targets 60 seconds into the future, filters this data by altitude, and displays to the controller the positions, tracks, identifications and altitudes of only those aircraft which are on conflicting tracks within a predetermined range of each other.

Probably even more useful than a pure collision avoidance system would be the development of airborne station-keeping (SK) devices for civil use. Such equipment has already been developed for special military applications.

In an advanced ATC system utilizing SK, the ground ATC facility would assign to each aircraft a departure track which could be navigated with a high degree of accuracy.

Adjacent tracks would be as free of mutual interference as possible, and traffic would be segregated by speed class where necessary. Crossing tracks would be separated vertically at crossing points; head-on conflictions would be minimized by the use of laterally separated one-way tracks for opposite direction traffic flow. In such an organized environment, pilots could maintain their own separation in the same stream through the use of an SK display. In climbing and cruising flight the prior segregation by aircraft speed classes in the various lanes would minimize the number of overtake situations or the need for speed adjustments. With an appropriate SK display, however, it would also be possible for a pilot to overtake another aircraft in the same lane. One way would be to divert the aircraft laterally (normally around to the right, as in VFR). The other way would be to."'dfvert the aircraft vertically to pass with altitude rather than lateral separation.

With an adequate SK system, it is anticipated that the separation of aircraft during overtakes would be somewhat less than that allowed in present IFR operations. To preclude a cascading or chain reaction effect in overtake situations, it would be desirable for adjacent traffic lanes to be separated initially by at least twice the minimum allowable separation standard. Using constant. Mach numbers or assigned route speeds, it would usually be possible to maintain any desired amount of separation in trail by adjusting speeds or flight paths to keep one's own aircraft beyond some predetermined radius from the aircraft ahead.

Although ultimately the requirements for guidance and for traffic separation must be met, they often oppose each other. For this reason, it may be desirable for the navigation data and the SK data to be integrated in a single cockpit display, pictorially if possible, so the pilot could s~e where he was in relation to his desired course and to his traffic.

Flight patterns tend to merge around terminal areas.

Arrival paths are inherently convergent as different routes join a common path to a runway. In facilitating the us~ of SK as a primary separation tool, much care should be given to the design of route junctions. Ideally, merging routes should be limited to binary merges, where only two routes merge into one.

Looking toward the future, it is expected that the growing number of simultaneously operated flight paths in future high density terminal areas will constrict noticeably the amount of airspace available for path stretching purposes

11

· spacing aircraft on the final approach path. Therefore, m use of speed control will become even more ·1mpo rt an t the as a technique for spacing aircraft on the final approach path. With an SK display it should be. relatively easy for a pilot to monitor his spacing and also his rate of closure behind the aircraft ahead, so that he can gradually reduce his headway to obtain the desired approach interval.

Comments on Air Traffic Control by Aviation Spokesman Across the World David e. Johnson, Allied Pilots Association, on "Severe Weather Avoidance": .

"Airline pilots have their own separ~t1on standards. I The name am spea k .1n g now of severe weather avoidance. , in itself will bring a wince to a controller.s face ~nd add a crease t o a P·11ot's brow· It has been with us . since the · · of t·ime and is here to stay. Many times I have b egmnmg . marvelled at the way controller and pilot as a team .devise a satisfactory method to circumnavigate or detour. this phenomenon, pav ·1ng the way for others to follow m safety. and M es h .mg the pilot's required separation from weather ff · the controller's required separation from known tra 1c 1s a difficult chore, to say the least. It is here that ~e have need for flexibility, necessity, sympathy, and som~t1mes empat~y w1•th each other. At times we differ - each with safety •on his • · d eh with his own convictions. The contro 11 er s pnmm , ea .

Th ·1 t' mary concern is separation between aircraft. .. e P• o s concern is separation from thunderstorm ce 11 s.

And on the subject of "The Holding Pattern": "The holding pattern is the safety valve of motion, the vent for time. Holding patterns are avoided many times by speed control, routeing changes, and sometimes ch~n~es in destination. If one is looking for a colourful description of a holding pattern, some of our seasoned air travellers would be more than happy to furnish the adjectives! In terminal areas, holding patterns are sometimes avoided by vectoring. There is pro and con for this manoeuvre. To some, to be going somewhere - anywhere - is better than going around in circles. It is the beginning of their approach, the final separation for landing. To others, it is a never-ending congo line or daisy chain at ever reducing speeds and increasing deck angles. Aircraft response is sluggish, and increased vigilance is a necessity. Couple this with the questionable reliability of airborne and ground radio equipment and a lack of procedures in the event of their failure, and you will understand why leaving the confines of the holding pattern with its insured safe separation is, to some, a risk. If one does not know how the traffic signals are regulated, he will have trouble all the way. In the event of radio failure, flight crews would not know how the signals were regulated in the daisy chain vectoring.

We have all been lucky so far, but luck, fate or faith are all poor substitutes for professional planning and programming."

To go back to the subject of "Weather Avoidance", now read what a controller has to say about it:

c.

Martin Coddington, ATC Team Supervisor Minneapo-

lis Intern. Airport: "For many years there has been some speculation that pilots are deviators. After much study, it seems that only

12

pilots who have weather avoidance radar are deviators.

The other pilots are pretty straight. Weather avoidance has mushroomed into a real serious problem in the ATC system. May be it's because there are more aircraft in the system. May be it's the pilots' attitudes. Or may be it's true what the doomsday people say: the weather really is getting worse. Whatever it is, from the control position on the ground it is an agonizing affair. While the controller tries to be understanding and help in any way he can, he cannot overlook the fact that he has lost his frequency to the non-stop congestion of various requests and has lost control of the traffic as it continues on in chaotic manoeuvres around the suspected dangers. We sometimes curse the person who thought of putting radar in airplanes, but actually our gripe is with the people who fail to train aircrews in the proper use of this equipment. One crew will say, 'Sure, climb on course looks good to us', and the next minute proclaim the only way for them is a deviation to the left of about 15 miles. They are shortly followed by a crew who insists on going to the right. By this time the first crew is reporting back that deviations aren't necessary at all, the ride is very smooth in moderate rain. Subsequent crews aren't easily convinced of this report, and it starts all over again. The planes are now scattered all over the sky and wander about at will, sometimes requesting to deviate, sometimes advising they are deviating, and sometimes saying nothing but doing as they please.

~bout this time, all the other sectors are screaming and telling the controller to get his airplanes back into his own airspace, as they have problems of their own. That makes sense, but his instructions get varied responses. The first guy says, 0. K., he'll get back on course. The second says '~ike hell I ~ill'. Th~ controller meets this profanity with ~ little profanity of his own and firmly repeats h" · t • 1s ins ruc. tions. Th~ following moments of tension are broken by another pilot, who keys his mike to ask if anyb d k . o y nows how to spell FCC. This bit of humour is lost on the controller as he remembers flow restrictions. He ask f s or 25 m1·1 es ·m t ra1·1 un t"I1 f urther notice.

I would make the observation that there seem t b . . s o e an ever increasing theory among radar equipped ·1 t . p1 o s that they must deviate around anything that shows on the scope.

At. the controls of the aircraft there seems to be merit to this theory, but at the controller's radar scope, this may not make sense at all, considering the six planes that just penetrated the area with no problems. Nevertheless, th controller will permit the deviation to the best of his resou~ ces and start slowing down subsequent flights. Back at the runway, the pilot that had been about five minutes frorn take-off suddenly realises that he is 30 minutes from takeoff. Behind him are another crew who not only are shocked at the thought of a one-hour delay, but are already Callin their dispatcher to discuss an unplanned fuel stop en ro t 9

u e.

1 would ask pilots to do a little studying and soul search-

ing on the use of thei.r radar. If a deviation does not look absolutely necessary, 1t should not be requested in mod _ ate or heavy traffic conditions. When they do ask and after .

• er discussion the contro IIer 1s adamant against the deviation, they must understand that he has no choice, that they must comply or ask to reverse course for a landing. It is of the utmost importance that IFR airplanes be separated. When a deviation will result in a loss of separation from other IFR aircraft, the deviation will be and must be denied."

Japan's Aeronautical Safety College

llHI.

-.,

Student's Gateway to ATC Japan, the Aeronautical Safety College, Haneda Airport, Tokyo, Japan.

History Japan's first "College of Air Traffic Control " - now called the Aeronautical Safety College - was set up in one room in the old wooden Civil Aviatio n Bureau building at 1-1, Ohtemachi, Chiyoda Ward, Tokyo, in 1952. Seven years later, in 1959, the Co ll ege moved to a two-storey wooden building called T-5 at Haneda International A irport, Ohta Ward, Tokyo.

In 1964, the College - then cal led the Train ing Centre for Air Traffic Control and Maintenance Personnel - was housed in the building cal led T-202 at Haneda International Airport. Its purpose was to train air traffic controllers and maintenance personnel of the Civil Aviation Bureau, Ministry of Transport. The Training Centre was subsequently renamed the Aeronautical Safety Institute in 1967 and moved to the new feroconcrete building at 1-6-4, Haned a Airport. It was eventually given its present title and status of " Th e Aeronautical Safety College" in 1971. Since 1971, the courses of instruction have been constantly revised to keep pace with the ever-changing techniques brought about ~Y the introduction and development of turbo-prop and iet aircraft, with their associated problems for the controller. In 1974, the modern branch school at Sendai City located on the northeastern part of the island of Honsh u was taken into use. This branch college is equipped with up-to-date computer and radar systems in o rder to meet the training requirements of the fast growing technology of ai r traffic control in Japan .

Organisation The organisation of today's College is as follows : T he President of the Co ll ege is responsible to the Director of the Japanese Civi l Aviation Bureau for the basic training of all air traffic controllers, communicators and maintenance personnel. Within the College there are f ive sections, namely, three training section s (Air Traffic Control , Communi cations, and Electronics - under the corn-

mand of a Chi ef Instru ctor who is responsible to the President for the instructional cou rses); a General Affairs Section; and an Instruction Affairs Section. The five sections are directly supervised by the Vice President of the College. The modern branch school at Sendai City is organised on the same lines: here also are five sections, namely, the same three training sections as at the main Colleg e, and a General Affairs Section and an Engineering Section . Many advanced courses are offered at the branch school ; they are normally open to, experienced ai r t raffic cont ro llers, communicators and electronics maintenance personnel.

The College instructors are usually volunteers selected for their operational experience and qualifications. They have op portunities to visit operational stations during recess to keep in touch with the latest procedures. Visiting lecturers cover special subjects and also matters of general in terest in aviation. Each year, a few instructors are given the opportunity of making a study tou r to some fo reign countries.

The College is equipped with all the latest visual and aural training aids, which are used extensively. Among these are conventional black, white, green magnetic boards ; various types of projectors - overhead, sl ide and film ; video and aural tapes ; aerodrome, approach, analog approach radar ; digital processing analog approach and area radar control simu lators. Practical and t heoretical instruction is given in all aspects of the air traffic services to enable air traffic controllers to sit for the exam inations which are conducted by the Air Traffic Control Examination Board of the Civil Aviation Bureau, for the Ai r Traffic Cont roller's Licence and the appropriate rat ings.

Entry Requirements Although there is a channel for an extra ad ult entry. the main sources of rec ruitment are through t he regula r co urse stud ent scheme and the special ATC course student scheme. Th e difference between these two schemes is that

13

I!

'I

'!

., Students at the controls in the Tower Lab. It won't be their last sweat.

regula r course students are juniors st raight from hig h schoo l who enro l! a t the College for a two-year course of inst ru ction in A TC (or in Communications or El ectronics) , w hile th e ATC spec ia l course - w hich lasts s ix months _ is o pen to c olleg e graduates w ho are older and w ho have received a higher education. The regular c o urse stude nt can be descr ibed as a typica l appre ntice. On ly ma les are admitted to t he C o ll ege.

The types of co u rses offered a re: Regular cou r ses Number of yea rs

Nu mbe r of students

ATC Course

2

40 for each year

E lectronics

2

30 fo r each year

Comm unicatio ns

2

20 fo r each year

Special ATC cou rse -

6 mo nths

50 for each ye a r

The entry requirements a re : for the regular cou rses

high schoo l graduate un der

21 years o ld ; for t he ATC special course - junior college graduate or t he e quiva lent under 26 years o ld . No previo us ae ron aut ical experie nce is essential i n ord e r to be accepted for the two types of co urses. successful applicants are admitted to the College after passi ng the entrance exam ination which is set by the Person nel Agency . Regular cou rse students are graded init ially as G.S. 8-2 with a salary of 63,900 yen a mo nth, whi le special ATC course students a re g raded init ia lly as G.S. 8-5 thro ugh 8-7 wi th a salary of 67,500 ye n t hrough 72,700 yen a m onth. A ll st udents a re , o f co urse , pub li c service e mployees. The competitive entrance examinatio ns set for both the regular and specia l AT C co urses co nsist o f ge neral know ledge, apti tude, Eng li sh , mathematics and phys ics.

However, th e contents vary from course to course. The app l ica nts must a lso meet the requirem ents for medical an d phys ical standards which apply t o profess ional pilots.

The College year is divided into three terms. A ll the students of the regu lar cou rses are required to live-i n and are accomodated i n the College dormi tory free of ch a rge except for a nominal charge for mea ls .

14

Syllabus of the ATC Two-Year Training Course General Subjects First Year 30 hou rs 30 hours 60 hours 30 hours 60 hours 60 hours

Second Year

Foreign Language English

120 hours

90 hours

Athletics Physical Traini ng

60 hours

45 hours

Ethi cs Psychology Law Descriptive Geography Mathematics Physical Science

Special Subjects Outline of Air Traffic Control Aeronautical Communications Fl ight Assistance Services Aerodromes Flight Operations Services (1) Flight Operations Services (2) Air Navigation Facilities Domestic Aviation Law International Aviation Law Domestic and International Communications Law Air Navigation Meterology & Aviation Weather General Aviation Aircraft Characteristics Radio Eng ineering Ai r-route Traffic Control Aerodrome Traffic Control

30 30 30 30 30

hours hours hours hours hours

70 hours 100 hours 75 hours 60 130 60 30 140 76

45 hours

hours hours hours hours hours hours

90 hours 90 60 90 75 30 30 30

Approach Control Radar Air Traffic Control Establ ishment 0 f A. ATC A irspace Systems utomation Radar Fund amental and ATC Radar .

Outl T ines of Electronic Computer ypology (Teleprinter) Special Lectures Extra Curric~lar Lessons

Practical Instruction Weather Codes Teletype Communications Air Navigation Air-route Traffic Control Aerodrome Traffic Control Approach Control Radar Air Traffic Control Combined ATC Train ing Operation of Automation System

30 hou rs

15 hours 30 hours 90 hours

hours hours hours hours hours hours hours

30 hours 90 hours

35 hours 60 hours 30 hours

Total 1650 hours

135 hours 135 hours 135 hours 135 hours 135 hours 135 hours 1650 hours

Everything under control, students at Radar simulator positions.

Syllabus of the Special ATC Course Familiarisation Electronics Rules of the Air Communications Law Radio Aids Aircraft Characteristics Meteorology Air Navigation English Air-route Co~trol Aerodrome Control Approach Control Radar Control Air-rou te Control (on simulator) Aerodrome Control (on simulator) Approach Control (on simulator) Radar Control (on si mul ator)

30 hours 60 h ours 70 hours 55 hours 35 hours 50 hours 45 hours 40 hours 40 hours 50 hours 45 hours 30 h ours 45 hours 50 hours 50 hours 50 hours 50 hours

This is foll owed by 6 month s practical training at the aerodrome or ATC Centre to which trainees are posted after their successful completion of training at the College.

Footnote The above detail s were suppl ied to IFATCA by the President of the J apanese Air Traffic Controllers' Association , Mr. Tan Hayashi, who attend ed the Federation's.14th Annu al Conference in Melbourne, Australia, 14-18 April, 1975. Mr. Hayash i took the oppo rtunity to discuss hi s Association 's intenti on to join IFATCA with J ean-Daniel Manin and other Offi cers of the Board and we confidently expect that this very well fun ctioning Association w ill shortly join the ranks of the international co ntrollers' community.

The Associat ion was founded in 1962, and its growth has been remarkable by any standard, not only in t~~ .stead ily increasing number of members but also in its act1v 1t1es. T he o rganisati on's head office is located at T okyo International Airpo rt and is manned by a full-time secretary to the Secretary General, w ho takes care of routine matters. All other staff of the office are ai r traffic contro llers, and ~II . d t an h onorary basis. tasks and projects are came ou on ...

Management of the Association is the responsibility. of 16 representative Directors, who undertake their share in the activities of the Standing Committees (numbering five).

The Association had 1,100 individual members as of January, 1975.

Comments on Air Traffic Control Heard Around The World U. S. Senator Hubert Humphrey, Guest Speaker at PATCO 's 1975 Minneapolis Convention : Your Organisati on is an outstanding legitimate union.

You are professional people as wel l as what they call the wo rking family. Profess io nal people are finding out that it is important to organise.

I was one of the first to come out in 1950 for the right of federal unions to have col lective bargaining. Your present contract with the FAA is forward looking , progressive, and possi bly one of t ~e best yet negotiated on behalf of federal employees.

I was also solidly behind PATCO when you had your troubles in 1970. The govern ment has been negligent over the years in providing all of the safety features that might be at our airports.

I'm interested; I fly a lot, and pray to God you know what you are doing . There needs to be greater attention to the problem of air congestion. Sometimes an accident happened because we just didn't have t he facili ties.

An Ode to an Air Traffic Controller To him wh o sits up in his tower, Gazing on the assorted shower Of intrepid aviator s old and young , Cool. or calm or highly strung.

They try his patience , test his skill Give him hell if something fails And even though it's zero-zero There's always on e idiotic hero.

Who wants to fly and can't see wh y The m.a n up there won 't let him try.

And discovers wi th much elation He' s narrowly missed a vi ol ation .

To many he's just a voice on R. T .

A voice that many don 't wish to see For on seeing him they kno w for fact He'll say what he thinks of their last silly act.

In remembering his patien ce. frustration and skill Why can 't he on ce just say "Something-Uniform". Bil l.

Now I wi l l end this unusual rhyme, Or ode. to the fellow who spends all his time Helping all fl yers where-air they might be Providing they have the correct fr equency.

(Ray Middleton. Mechanic. Spitfire Inc .. Windsor Airport. On tario .

Canada)

15

An Evaluation Of Radar Data Processing

by Jon R. Sharpe, Chicago ARTCC

Introduction Chicago Center controllers have used computerized radar for almost two years. They have grown accustomed to its alphanumeric face, and seem quite willing to use it in preference to broadband radar. An Operational Readiness Demonstration (ORD) was completed conditionally, however, with problem areas carefully outlined.

The difficulties were not of great enough significance to FAA management to delay or deny operational changeover to Radar Data Processing (RDP), and it is now the primary system. From my vantage point as a low altitude wing controller, I sense that the problems outlined in ORD, plus other unmentioned difficulties, demand a critical look at RDP capabilities. Is the system safe, efficient, reliable, usable? In what significant ways does it improve broadband radar presentation and Air Traffic Control capabilities? This evaluation will include System Features, Computer/Controller Interface, and Recommendations.

System Features Has information available on broadband radar been successfully digitized?

Secondary Radar information has been transformed most successfully. The digitized transponder target is more uniform in size than its broadband counterpart and is also closer to the exact position of the aircraft. Discrete beacon code readout, altitude reporting information, and automatic tracking capabilities are features new to enroute radar systems and offer sophisticated aid to controllers.

With the availability of more detailed information have come attendant difficulties. Discrete codes are often set incorrectly by pilots, resulting in failure of automatic tracking and code display on the PVD until the proper code is set. Additional communications between pilot and controller are necessary to correct such conditions, affecting frequency congestion and workload unfavourably. When certain amendments are made to active flight plans, a new discrete transponder code is assigned, resulting in mistracking by the computer until the proper code is selected by the pilot. Because of increased electronic sensitivity, transponders that give normal returns on broadband radar are sometimes not displayed on RDP. It has become apparent that some modern transponders are incompatible with RDP requirements and will not provide targets on the PVD. These transponders, and others that malfunction seem at times to block a normal radar return from the aircraft too, even though a transponder return is not displayed. Aircraft with such transponders are excluded from the RDP system.

Primary (normal) radar information has so far successfully resisted consistently acceptable c~nver~ion to digitized information. The goals of RDP m this area are laudable: 1) eliminating clutter from ground returns, inversion, AP; 2) displaying only radar returns fr~m only nontransponder equipped aircraft; 3) presenting precise weather information. The RDP program has b~en unable to achieve these goals possibly_ b~~ause of an. incomp~ete understanding of the infinite vanab1~1ty of radar mforma~1on.

Radar controllers know from experience that many ad1ust-

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me~ts have to be made throughout the day to obtain optimum raw radar aircraft target and weather displays.

The RDP program requires specific sensitivity settings for e~ch radar function it seeks to present or eliminate.

Applying a "hard" rule to a situation that varies due to electronic and atmospheric changes gives inconsistent results. Raw radar target returns visible on the broadband system ~re often not presented on RDP or are presented t~o erra~1cally f~r successful tracking. The transponderless a1rcra!t is practically excluded from RDP system service. ~ typical example of this situation was a Convair 580 with inoperable tran.sponder flying at 8000 feet within 35 miles of the radar site which never presented a normal radar retu_rn on RDP. The aircraft was displayable on b db d equipment. roa an

While that Convair seo was not d' 1 • • t .

1sp ayed, inversion re urns were appearing as + and b 1 • • • • sym ols on RDP. nvers1on 1s sometimes displayed as we th . . b a er information on RDP It h . as een impossible to differentiate inversion and weather returns on broadband radar· . t d t f' • P• 1o reports are ~:e . o con m~ or deny controller suspicions. RDP makes e interpretative decision for control! ers now - often ~rroneous Iy. The RDP system often fails to . . f1cant weather reported by .1 t . present s1gm. p1 o s and displayed on broadband radar. Such failure seriously affects th e controller's ability to prepare for weather avoid ·1 · . ance requests from p1 ots and aid aircraft without weather r d a ar aboard Clutter on broadband radar means false t . molous propagation, electronic jamming and i.:get_s, anaRDP clutter means alphanumerics: symbolo ers~on. On become numerous enough to confuse rath gy which has etr than help the controller. Utilizing the full system pr esen ation pro 'd full data blocks with 3 lines of informatio f vi es aircraft, 2 lines of data for each a1·r n ftor each tracked . . era target hav· t• mg altitude reporting capabilities lists of inf . . . ' orma ion for holding, inbound and departing aircraft weath ' er symbology and radar return symbology. Data blocks overl ' ap each other and other symbology, causing the information t b readable until the controller can manually sepao te un. ra e the data or 1t moves apart as the aircraft moves. Doubl d blocks (full plus limited) appear on aircraft with a~r ata . . h h 1tude repo rt mg equipment t at ave been pointed out d .

• a ding I I d c utter. n mo erate to heavy traffic situations it .

1 ~ n~t only impossible to find places to move data whe stay in the clear but it is also impossible to take ~~~t .will to make the moves. Automatic data block sepa t· time . ra ion may not be feasible. Most of the alphanumeric s b presented on the PVD through only two .Ym ols are 9 allowing the controller little choice or select~'" controls, · •on of infor• mation that can be de-emphasized without a1so losing necessary sym bo Is. Th e RDP scope picture . · requires significantly more controller concentration to d . db ec1pher than b roab and radar..The cause is probably the plethora of 1 sym o s representing and tagged onto radar returns False radar targets, always a part f d · . .. o ra ar, have become a mor~ s1g~1f1~~nt problem, thanks to attached data blocks showing f1cht1ous code and alt't d . .

1 u e information. . .

This can cause unnecessary excitement . th m e mmd of a controller when one of his aircraft conv ·h erges wit a false

target materializing suddenly at the same altitude.

The sheer volume of information requiring processing has possibly not been reckoned with, for, when traffic is heavy the computer takes longer to accept messages and may even fail from overloading. Failure obviously cuts controller efficiency, but slow acceptance also hurts, for a controller has to wait for acceptance before doing something else or he may be distracted from catching an entry error.

Computer/Controller Interface "This facility has adequately trained personnel to assume control of air traffic using the A3D2.0 RDP program." (Chicago Center Operational Readiness Demonstration, 30 Sep '74, p. 2) "During periods of moderate to heavy traffic volumes it is impossible to make all required entries into the computer system."

(Chicago Center Operational Readiness Demonstration, 30 Sep '74, p. 9)

The above statements have been regarded as contradictory, and illustrate that a viable man/machine interface has not been successfully developed. Before making recommendations for improvement we should consider the capabilities and capacities of both man and machine once again, and possibly revise the theory behind the RDP system.

A basic element in RDP theory is the belief that a controller can easily assume the added tasks of a computer operator because the program is going to save him lots of time doing menial chores. In practice - over two years of practice -I find that not many menial chores have been removed and, in fact, the job of entering required information in the computer has become an oppresive, distracting, and at times impossible requirement. The controller now must wear two hats: controller of aircraft and computer operator. The two jobs vie for his attention, and the expense of this conflict is measured in safety, or loss of it.

Replacement of the plastic "pip" by an electronic data block full of information is. an: impressive accomplishment, but it has eliminated an important eye/brain/hand function which helped the controller establish and keep the necessary 'picture' in his mind. Pushing those "pips" seems to have been a more effective way of keeping track of an aircraft than scanning a scope and reading data blocks.

The incidence of aircraft not being given a frequency change after handoff was completed via RDP has significantly increased. Possibly because a hand is not kept busy pushing "pips" messages indicating acceptance of handoff go unheeded and the data block drops from the scope before a frequency change is effected.

The ability of the controller to develop an advance picture of traffic about to enter his sector has also been affected adversely by not being required to make "pips".

When a Chicago Center controller made a "pip" he would mark the appropriate strips with a slash. Besides cutting d~wn on duplicate "pip" making, that slash also helped him detect new strips placed in the bays, and he could add the necessary information to his mind picture more quickly. I found myself looking at every strip whenever I wanted to update my picture, a much more time-consuming ~rocess than the old .. adding" method. It seems a good idea to still slash the strips when you read them initially to . make new strips more noticeable. The data entry requirements of RDP have also distracted the controller from r~viewing strips properly. Many controllers find that the first they know about an aircraft is when a handoff flashes at them, although a strip has been in place for at least

30 minutes. They have been too busy entering required data into the machine, and have failed to keep a necessary picture and plan - a dangerous situation.

Automatic handoff is at best semi-automatic, in the environment I work in. Less than half of all handoffs are automatic, and many of these still require voice communicat:on to release control, relay assigned headings or pilot requests, or obtain proper frequency information. Many handoffs must be made manually because receiving facilities are not RDP or ARTS-equipped, or because the aircraft has been disqualified from auto-handoff by slipping out of flat track mode or being unexplainably "caratized".

There have been little savings in controller-to-controller communication time.

The point-out feature of RDP is used frequently by Chicago Center controllers for saving aircraft frequency changes when transitioning from high altitude to low altitude sectors and vice versa, and when desiring to use a bit of adjacent sector airspace without transferring communications. Once the point-out is made on the PVD it must still be verified by voice and approval obtained for the planned operation. No saving in communication time between sectors is realized, and extra time is required to depress the proper keyboard buttons.

The requirements for entry of data into the computer are complicated and time-consuming. A handoff or pointout requires that eight keys in four different locations be depressed, unless the cumbersome trackball is used, cutting the key depressions to four. The hand movements require eye contact to complete, and the eight required key depresslons multiply chances for error. Precious time is used doing the menial task of data entry, time that was previously used for thinking out and making control decisions. For the controller to do successful control work during periods of moderate to heavy traffic, he must ignore many of the required data entries, which destroys the currency and accuracy¡ of the information on his scope.

Once the information is out-of-date and erroneous it cannot be relied upon and thus is useless; the controller has to rely completely on information recorded on flight progress strips. As long as the computer display cannot be updated correctly during peak traffic periods, the system cannot be evaluated properly.

Duplicate data-recording systems also place a greater burden on the controller. To complete revisions, they must be both written on flight progress strips and entered into the computer. The computer offers distinct advantages in disseminating revised information, but the dual entry requirements double previous workload requirements.

The theory that the alphanumeric data presented on the controller's scope with RDP positively assist him with his job is open for some discussion. At first, it seemed that all the data presented would be of great benefit located with the targets on the scope. Symbolic presentation of radar information (types of targets and weather) also seemed an improvement. In themselves, each feature is an advantage over broadband presentation. But once all the information appears on a scope it can become confusing and difficult to read even when data does not overlap. The comprehension powers of man seem to have been exceeded. The reading of so many symbols and letters and numbers each time the controller looks at the scope may be too detailed a task. Much that is extraneous also appears on the scope to distract, such as Mode C intruder information on aircraft outside the sector airspace. false 17

targets with code and altitude information, false weather and clutter returns. This unnecessary information attracts the attention of the controller uselessly, and at times merges with and obliterates data which the controller needs.

Near major terminals like O'Hare Airport data blocks can get literally lost in the irrelevant clutter of limited data blocks and weather. By changing altitude limits and deselecting many available RDP features the display can be "cleaned up" enough to be comprehensible, but then many of the boons of RDP are lost. It is ironic that the busier a controller is the less RDP can aid him.

The different message entry formats on manual and radar positions adds to controller confusion and encourages mistakes. Mistakes mean doubling the time required for message entry. Some features of the manual position computer equipment that increase confusion and reduce efficiency are: 1) failure to cancel an entered message automatically once it has been accepted correctly by the computer, and 2) update messages received on aircraft that have already left sector airspace, have just had strips printed which are not yet in place before the controller, or will never enter the sector.

The growth of the RDP program can be illustrated by the development of the Quick Reference Card (illustrating features of the program which can be used by the controller) from 4 - 3 1 /2 x 8" columns to the Reference Card with 7 - 31/2 x 8" columns of small print. The word "quick" was dropped from the title for obvious reasons.

The altitude-reporting equipment has appeared to be quite accurate, when the delay in receiving information from an aircraft is accounted for during climb or descent.

The only real problem encountered is when an aircraft outruns the acceptable limits the system places on altitude variation allowed between updates. Lear Jets and military fighters consistently outrun the parameters, and altitude readout is cancelled by the "XXXX" symbology until a manual report can be entered by the controller and accepted by the computer.

The altitude-reporting feature has yet to save much communication time, for it must be verified verbally. When a controller is busy and needs a vacating altitude report he usually has to ask for it or he will miss it and delay further climb or descent clearances. Too much data on the scope face restricts his ability to read altitude reports.

In summary, the relationship of the computer with the controller is not as beneficial as was promised, and in fact affects the controller's ability to safely control aircraft adversely by distracting him from his primary function.

Recommendations More will have to be learned about raw radar returns before better presentation of the various types of information available can be digitized adequately. Until research is completed and an effective program implemented controllers will need a broadband picture at their position to see weather and normal radar returns, plus transponder returns from aircraft incompatible with RDP requirements. Thought should be given to developing a closer relationship between the controller and the equipment - a way for him to either adjust equipment sensitivity himself or to talk directly with the technician at the radar si~e to explain a roblem and observe improvement of the display. Controliers often have information on exact conditions which the technician needs to know in order to be sure the display

18

is correct. The infinite variability of radar should be given a more significant place in the factor list controlling program development.

A study should be made of controller capability to read and comprehend data presented on the PVD. Results of that study should be used to establish guidelines for development of a presentation that will not exceed normal controller comprehension capacity, and will provide efficiently usable information enhancing the safety of the ATC system.

Emphasis should be placed on completely automatic features to remove many data entry requirements. The present "automatic" features should be improved so as to work effectively more of the time, and new automatic data entry programs should be developed quickly. A voiceactivated entry device seems quite feasible, especially because of standardized phraseology used in ATC communications. "Trigger" words for a voice system are already in place. A different transponder system, sending the aircraft callsign, would eliminate the need to identify aircraft with discrete numbers that make no sense to the pilot and often get set incorrectly. Air carrier aircraft could have variable selection capabilities for changing trip numbers and itinerant aircraft might have a simpler, permanently-set identification circuit. A simple IFR/VFR mode switch would sensitize or desensitize the transponder for presentation on the controller's display. Altitude reporting could still be an optional feature.

Such a transponder would eliminate one unnecessary number from the controller's display. Simpler message entry procedures might also allow for deletion of a computer number in the data block. The ideal data block should contain a minimum amount of completely accurate information. Subsequent computer program developments should strive to achieve this ideal.

Elimination of many number identifications by making sector dial codes the same as sector computer numbers is in the development stage at the Chicago Center and promises to ease the problem of remembering several sets of number codes. This system should be extended systemwide.

Limited data block information can be invaluable to a controller but sometimes clutters the scope with useless information. Partial correction without loss of the feature could be gained by selectable presentation of transponder code and/or altitude information.

Control of Mode C readout information via the sort box grid should be changed to limit presentation of such data ~o no more than 2 1/2 miles beyond the sector boundary, m order to eliminate extraneous information from distracting a controller.

Replace the time parameter from dropping data blocks after handoff by retaining the data block until the aircraft departs the sector laterally or vertically.

Point-outs sent to other sectors should inhibit display of a limited data block on the target at the receiving sector.

Seeing two data blocks on the target can cause unnecessary confusion.

Allow data block information updates to be made by controllers during and after handoff to ARTS facilities, and send pertinent information to ARTS. Speedup movement of the trackball on the PVD and increase the target area so that fewer misses and concomitant re-entry attempts will occur.

Increase parameters for acceptable altitude reports so that small jets will not exceed the limits on climb and descent. Make deletion of the "XXXX" symbology easier so that return to Mode C information readout is instantaneous.

In conclusion, although it is apparent that the present RDP system is not completely successful in doing what it

is supposed to do, I trust that further developments will be implemented which w i ll make digitized radar a more viable tool for the controller. These observations are the thoughts which come from experience in using the RDP system.

I hope they are considered carefully by deve lopers of the Air Traffic Control System.

The Controller's Legal Liability

by Andreas Avgoustis, LL. B. (Lond), Chairman IFATCA SC VII, Legal Matters

Foreword Following Maitre Boullez's explanation of aspects of the Controller's legal liability in our February 1975 issue, the subject is thought to be important enough to warrant further examination. The writer's aim is to enlighten the Controller to a greater extent regarding hi s legal liabilities and obligations to the air space user, and to acquaint the reader w ith some Court precedents in which the Air Traffic Control factor was alleged to have been the main cause of the aircraft accidents, or had contributed to them.

Following this article, there will be two opinion articles in later issues on the Controller's liability during the various phases of an assumed flight, viz. the take-off, en-route and landing.

General Responsibility Before going into a detailed description of a Controller's liability, it is essential to distinguish civil from crimi nal liability. The Controller's liabi lity during the course of his duti es may be both civil and criminal. His civil liability w ill most certainly be concurrent w ith his employer's, i. e. the Government Authority, but his criminal liability wi ll not be shared with anyone else.

To injure a person without intention to do so - and, of course, without recklessness which amounts to intent - is no crime. The careless infliction of injury to another is no offence; nor is damage to property without intention to do so and without recklessness. So carelessness on its own cannot be classed as a criminal offence.

It may seem strange that negligence, which plays such an important part on the "stage" of the Civil Court should but rarely make its appearance before the Criminal Court.

The Courts have developed one crime of negligence only, viz. manslaughter. For non-fatal injuries the injured person relies for the reimbursement of the expenses incurred in the treatment of his injuries on the Civil Court. Nevertheless, if through gross negligen ce, i.e. carelessness, one knocks out the eye of another with his umbrella, no crime has been committed. In the eyes of the law this is merely a dispute between two persons. Naturally the question which comes up is : when would a Controller be held guilty of criminal negligence? and the obvi ous answer is that he will be guilty if through gross negligence or carelessness he causes the death of any person on board an aircraft in an air?raft accident. To render him , however, criminally negligent it must be proved before the Court that his negligence was gross neg ligence.

Andreas Avgoustis

The law as regards the Controller's crim in al liability in such other circumstances where no loss of life occurred cannot be determined with absolute certainty as there are no legal precedents which one may rely upon, but it w ill be rational at this stage to assess any such liabi li ty by studying the li ability of other skilled professions wh ich the Courts have been called upon to decide under simi lar circumstances.

A man who p ractices a profession is bound to exercise it with the skill and competence of an ordinary worker of that profession. Every one who enters into a skilled profession undertakes to exercise it w ith a reasonable degree of care and skill. Most Control lers are Government Servants trained to carry out a skilled profess ion and are subject, in addition to the general law of the land, to Civil Service Rules and Regulations. In other words : they are l iable to additional burdens wh ich may conflict with the ordinary 19

"Rule of Law" which says every one is equal under the law and no one is above the law. This could determine the position of a Controller who has the misfortune to face a criminal charge with a sentence of imprisonment and forceful expulsion from office with catastrophic consequences of financial ruin both for himself and his family.

Since the standard of care and skill is take:i to be that possessed by men of ordinary competence exercising the particular profession, it naturally follows tho.t th3 opin:ons of these persons as to the conduct of a reasonably skilful man under a certain set of circumstances are admissible in evidence. Each particular case will of course be treated in accordance with its merits. The main point to be determined is not whether the person concerned did or did not exercise reasonable and proper care, skill and judgment.

Whether other persons exercising the same profession and being men of experience and skill would or would not have done as the person concerned, is a matter which must be examined and determined during the inquiry. It may be argued in cases other than those concerning the control of aircraft that the person who faces the charge was not under an obligation to perform his duties with an extraordinary degree of skill but only to a reasonable and ordinary extent.

The extent of this principle is somewhat uncertain as regards the Controller. The principle may reasonably be accepted that the Controller is under a definite obligation to his employer to carry out duties with an utmost degree of care and skill. It will be discovered that this contention bears some truth when one reads the reasoning delivered by judges in suits before the Courts where the responsibili~y of the Air Traffic Controller was at stake. The greater his experience and knowledge of the profession, the greater would be the requirements expected of him. To expect such extreme responsibilities is to suggest that the Controller is superhuman and his decisions sometimes taken under strain and in split seconds must be those of a man of extraordinary skill. At this stage, however, it will be saf~~ to assume that the most satisfactory method of determmmg this question is by proving that the majority of Controllers, say nine out of ten, would have acted similarly under .the same circumstances. We may then resolve with certainty that a reasonable degree of care and skill had been exercised. . ·i ·t The Controller may find himself named in a c1v1 su.1 . as co-defendant with his employer, the Governmen.t. Pract:smg lawyers find this a more convenient method ~h1ch ~orks to the advantage of the complainant in proving his cas~.

Should he be found liable for negligence, the c.ontroller in t cases will not pay any compensation, but his employer ;e~~g vicariously liable (liable for the acts of his employees) will be called upon to pay.

Trends Courts have until recently adopted the contenti~n that . ept under special circumstances, are ultimately Pilots, exc . · ft Th' ·bi for the safe operation of their a1rcra .

1s respons1 e .

FR e today to a large extent in the case of V may even b e tru . . u s courts - the main source of informaflights. B ut now · · I . f th. series of articles - have almost complete Y t1on or is ·b·1·t f m reversed the situation by taking respons1 ' I y aw~y r~ the Pilot and are expecting instead from th~ Contr~ ler t at xtraordinary skill for taking spht-oecond he displays an e Th u s Government has strongly defended the . . dec1s1ons. e · · . . .· f the Controller by introducing the defence of pos1t1on o . . h discretionary powers in the prov1s1on of ATC, or by emp a-

20

s1smg that the Controller was under no obligation to do more than what was expected of him as prescribed by the ATC manuals.

The "no obligation" defence has repeatedly been raised when the Controller had done everything that his manuals required of him or had not acted because no provision existed in these manuals for any act:on. The manuals, as we all know, outline what the Controller must do under certaln circumstances. This defence, that the Controller had acted in accordance with his manuals and that he was under no further obligation has been weakened by the U. S. Courts and they now impose upon the Controller the additional task to assist the Pilot to effect a safe flight even if he (the Controller) is required to go beyond the rcgulat:ons.

They impose this duty upon him and oblige him to do more than what is required of him by the manual. It must, nevertheless, be emphasised that the "no obligation" defence is still a strong one.

On the other hand, the defence of "discretion" by a Government Authority has been overruled by the u. s.

Courts where the negligent acts or omisslons by the Controller contributed to the accident. In the case of u. s. v.

Union Trust, where the Controller issued a landing clearance to two aircraft at approximately the same time on the same runway, the Government attempted to shelter beh:nd the defence of "Government discretionary powers". The Court held that the Government has discretion on whether or not to esta~lish. a C~ntrol Tower once the airfield is operating; once this d1.sc~et1on is exercised, the Controller's negligent acts or om1ss1ons are not discretionary and the Government is therefore responsible. Furthermore, the Appeal Court compared the Controller's action in this case with that of a driver of a mail truck exercising discretion wh · · h en d nv!ng t. rough a red traffic light. This is very logical reasoning smce the Controller like the driver of the mail truck made a wrong decision and was negligent during the performan~e of his duties. The Government, of course, in this case did not attempt to excuse the negligent act of the Controller, but merely attempted to relieve itself from liability. Obviously, the Controller had caused the accid anty en.

Other avenues of defence, such as an act of God or . . an abso Iute IY inevitable accident, etc., can be used in cases of negligence by a Controller, but I shall not try, at this stage, to visualise situations which could fall under these categories.

Disciplinary Action As mentioned above, the Controller being a Governm Servant - the situation of course will be different in :hnt cases of Controllers being employed by a commercial bode or a private agency - is subject to Civil Service Rules a ~ Regulations. This section of the law is completely separa~e from the general law of the land to which all other citiz . ens of the State are su bJect to. Therefore, it is an addition 1 burden placed upon civil servants only. An act or omissio~ by a Controller need not be a subject matter for a Court action. His act or omission may be such, e. g. an airmiss incident, that no grounds exist upon which a civil or criminal action may be based. Usually, inquiries into incidents of that nature are carried out by persons or Boards appointed ad hoe. Any disciplinary measures taken against the Controller will not be followed by a civil or criminal Court action. However, the Controller if he is dissatisfied with a decision of such a tribunal, will be free to seek justice before a proper Court of Law.

The TC-61 Assault Operation

by Comodore Athos Arturo Gandolfi,* Director de Transito Aero, Buenos Aires

In 1951, the Argentine Air Force (AAF) started its initial penetrations onto the ice-covered Sixth Continent with the Avro Lincolns which had been taken into service towards the end of World War II. Their powerful Rolls Royce engines could be heard thundering through the Antartic sky, exploring the ever-lasting ice, with a flying range originating from the purpose for which the aircraft were built, namely, strategic bombing. These flights marked the beginning of a long, steady and strong effort in search of a suitable spot for ai rplan es to land on with wheels, instead of ski-equipped aircraft.

Following those initial penetrations, the Linco ln ai rplanes were replaced in 1960 by others more appropriate and more suitable for operation in that area. The search became easier when HC-47, Beaver and Otter aircraft com'.11enced to land on areas se lected befo rehand, thus carrying out an aptitude and feasibility plan carefully developed

by Argentinian Antartic specialists. All these operative studies and background work helped to locate a well-defined area. called Vcom . Marambio Island (formerly Seymour) considered to be the most adequate for landing on wheels.

At the beginning of the 1968/69 campaign, a UH-1 H helicopter landed on the island and its c rew explored the north-eastern part of the pl ateau, removing soi l samples for analy~is and classification according to its consistency, cohesion, etc. Th is evaluation brought about the settlement of a camp whose members, with the help of picks, spades and explosives, shaped a runway which on reaching 2.600 ft. length, made it poss ible for an AAF F-27 to land on October 29th, 1969. In th is way, the runway was offici ally inaugurated.

Early in 1970 the runway reach ed a length of 3.900 ft.

Now it was judged ready to receive high loading capacity planes, such as the C-130 "Hercules", in its special tactica l delivery operations. At the same time, the llnd Transport Grou.p c rew began training for the operationa l flight pattern required for landing at Vcom . Marambio.

The Air Assault operation is a techniqu e which has been th~roughly studied and has been eval uated as the most suitable operation ; as a matter of fact, it has been largely ~ried out in actu al combat operation s and as a result was Judged the best possible method of landing on an unprepared runway. Air assault thro ugh landi ng requ ires a thoug htful use of the elements invo lved. The fundamental f eatures of th · . . . is technique which became necessary at Maramb10 involved . .ons such as: flying . . 't cons1derat1 the aircraft t o 1s maxim um aerodynamic perform ance; the glid e attit d . u e on touchdown ; the subsequent r un ; and braking withint anTehxtremely sho rt distan ce within its operatio nal weight, e c. ·d erat1ons · d " . ese con s1 were necessary because of soil con itio.ns (snow and ice) , as well as the length of the run~ay :hich does not allow further extension since one of 1 sdetnh s originates in the plateau facing the Weddel Sea an e other end · "bi t s in a deep, rocky ditch, virtually imposs1 e o 1evel off in line with the runway.

Everything was studied, evalu ated and carried out to th e smallest detail. .The fue l pattern and weight which the airc raft has upon arrival and land ing on the Island were simulated during an

Comodoro Athos Arturo Gandolfi, Director de Tnlnsito A6reo.

intensive training period carried out on a concrete r unway which did not exceed 2.300 ft. This was deliberately selected with a view to deman ding the crew's best skill , a consideration that wo uld not have been necessary if a longer runway had been available on the ice. From the ground, combat control equipment of the First Air Brigade was used to help in the t raining , and many reels were fi lmed while the plane was approaching fo r tou chdown unti l a fu llstop landing, and th is helped to detect erro rs and brush up the techniques being used.

In April 1970 everything was ready fo r starting operations and the most austral AAF Base on the Continent, situated in Rio Gallegos, was selected as a suppo rt base.

The severe Antartic conditions made worse by deep low pressure centers and by fog surrounding the plateau which caused both the ceiling and the v isibility to come down to zero, th ree t imes doomed the operation to fai lure, after an equal amount of penetrations made over the Drake Sea. On April the 11th, when the isobaric gradient had attain ed its lowest val ue over a long period of time and when conditions indi cated that a land ing could not possibly take place that day, upon the fourt h penetration made over the Drake Sea, the plane succeeded in arriving over the Isla nd • Comodore Gandolfi is the Director of Services. and in this story describes the landing of the first C-130 on the Antartic Comodoro Gandolfi was the Commander of

the Argentine Air T ra ffi c events which led to the ice at Marambio Island . the aircraft involved

21

\\llHI< \ IH.I.

c

So ended a historic enterprise which took place not so long ago and which had called for a lot of sacrifice, teamwork and achievement, all of them forming part of the tremendous spirit which had always distinguished the AAF mission. Ever since that historic occasion, AAF "Hercules" aircraft have landed frequently at Marambio. The work undertaken there is fruitful and continuous, and covers operations such as logistic support to the evacuation of the sick, both Argentine and foreign, to other Antartic units.

Future plans go far beyond a mere military operation. It is hoped to use Marambio as a support base to transarctic commercial flights. An aluminium runway of 7.200 feet with radioelectric facilities and infrastructure will in the near future enable a specialized unit - which will include air traffic controllers - to render the necessary support to aircraft flying over the white continent, which will mean that they will fly a much shorter distance than is the case at present, and which will join the American continent with remote Oceania. The AAF are striving to attain that objective which is not confined to our country alone, but is intended to unite nations and promote the welfare of a large number of people all over the world.

Base Aerea Vcom Marambio in Antartica.

The importance of Marambio as a support base has been proved only very recently when Argentine Air Force C-130's and F-28's evacuated part of the crew of USS "Glacier" trapped on the Weddel Sea by the ice. It is also envisaged to build an hotel on the Island in order to give tourists from all over the world the fascination of the Antartic.

This Turistic Hotel could come about in the not too distant future.

under a cloudless sky. The C-130 "Hercules" TC-61 successfully assaulted the frozen runway for the first time, a runway half covered with snow and swept by the Antartic wind of Marambio Island.

The TC-61 Air Assault Operation on the 11th April, 1970, to the runway swept by the frozen wind of the Antartic at Marambio represents the starting point for the development of international civil aviation in that part of the world.

International Law

by E. McCluskey

Part VII The Freedom of the Seas In an earlier article in this series we discussed the territorial seas and now we return to the principles of International Law to discuss the freedom of the seas. This principle probably more than all the others had a great effect on the development of the Law of the Air. The High Seas by definition are all the salt water on the surface of the earth which is not completely cut off from the general area of salt water by the Caspi~n a.nd the appro~ch to which is navigable by ships and which is open to .shi~s of all nations, except that part of the salt water which is part of the territorial seas of any State. We already sa~ that various States laid claim to complete oceans as their territorial seas and how sense eventually prevailed. By the beginning of the 19th Century the principle of the freedom of the High Seas had been established. It was summed up in a court case in the United States in 1826 as follo~s: .

II possess an entire "Upon the ocean in time of peace, a . ' . f 11 appropriated to equality. It is the common highway o a â&#x20AC;˘ . the use of all, and none can vindicate to himself a superior

22

or exclusive prerogative there". These words should be remembered when we come to discuss the question of the Continental Shelf.

As the High Seas cannot come under the sovereignty of any State, there is the implication that there is freedom of navigation for all ships, merchant ships and warships alike of any nationality. There is also freedom to lay submarine cables, freedom to fish and freedom of aerial circulation over the High Seas. Oceanic controllers may raise their eyebrows at the last statement but it is defined in the Geneva Convention on the High Seas 1958. The USSR made full use of this freedom over the North Atlantic until on becoming a member of ICAO she recognised the Chicago Convention and with it Oceanic Control Areas.

One might be tempted to ask why it is of interest to air traffic controllers who belong to IFATCA to have some understanding of the High Seas. The answer is simple in that only five of our Member Associations, Austria, Hungary, Luxembourg, Rhodesia and Switzerland cannot under any circumstances find themselves controlling over the High Seas.

Once it was established that everyone had Freedom of the Seas it meant that all States could use the High Seas without exception right to the limit of the territorial sea of any State. No priority existed for the nearest State, with the result that the most profitable fishing grounds were often far distant from the home ports of the fishermen. The seas of Iceland and Newfoundland as well as parts of the North Sea attracted fisher men from distant States. The fishing fleets of Iceland and Denmark made long voyages to the Arctic Ocean. Whaling and sealing had the same lucrative attraction and the ships of the United Kingdom and Norway among others were to be found in the South Atlantic.

Vested interests were built up in many areas.

Jurisdiction was not altogether lacking but each State was limited to its own ships and its own nationals. This is the first limitation of complete freedom on the High Seas since the law of the home State applies aboard snip and the ship is under the exclusive control of the State whose flag she flies and of that State's warships. These rules were established in English and American Courts in the Le Louis and The Antelope cases. A treaty for the abolition of the slave trade could not justify arrest of a vessel of another State unless the treaty conferred the right of arrest and both States were parties to the treaty. Finally the Ant:Slavery Conventions gave such powers and complete freedom was limited still further. Piracy jure gentium as we saw in the last article was considered an International crime and custom demanded that freedom of the seas for pirates be not only limited but eliminated.

As we can see two principles were being established side by side. First of all each State had free use of the seas and the:r resources and exclusive jurisdiction over its own ships. So there was a conflict of interests in trying to conserve natural resources. In the Behring Sea Fur Seal Arbitrations the Court rejected the right of the USA to arrest Canadian sealers in order to conserve the seals in Alaska.

Similarly the Courts refused to consider legal the arrest of a United States' sealer by Russia on the grounds of conserving Russian seals. However, in the Araunah Case, a British ship was seized 16 miles from the Russian coast.

Even the British officials on the spot did not intervene since some of the crew were sealing in small boats half a mile from the coast and it was defined in this case that a ship can be constructed to be in territorial waters or the contiguous zone by means of its boats. This type of problem led the interested nations to draw up conservation treaties which of course were only applicable to those States which signed them. Much of this was codified into the Geneva Convention of 1958 on the Regime of the High Seas. Where this Convention defines the freedoms it states that these freedoms and any others recognised by the general principles of International Law must be exercised with reasonable regard to the interests of other States in the exercise of their freedoms. Thus freedom of aerial navigation must take into account the practice of other States recognising control areas under the Chicago Convention.

Clearly a free for all on the High Seas would not be possible especially in the busier shipping lanes. The lea_di.ng maritime States therefore had to try find common policies since one set of rules for avoidance of collision might contradict another. No International Law existed until 1910.

Each nation enacted its own law but there was a tendency to follow the United Kingdom very closely. The first step was "Regulations for Preventing Collisions at Sea" included in the Merchant Shipping Amendment Act 1862 and further

Acts in 1873 and 1894. The "Commercial Code of Signals for the Use of all Nations" was published in England in 1857 and adopted by all maritime States. A Conference in Washington in 1889 revised these rules and most States had enacted the new rules between 1890 and 1900. The pioneers in aviation adopted many of these rules for aircraft since they knew no others. With the advent of rad!o more rules had to be drawn up and the Washington Radiotelegraph Conference 1927 charged the United Kingdom Board of Trade with keeping the Codes up to date. The League of Nations got agreement on standardisation of buoyage by 1936 and the Convention on Manned Lightships not on Station was concluded in 1930. The buoyage agreement was equally applicable to flying boats and the Lightship Conventions apply today to Ocean Weather Vessels operated under the aegis of ICAO. As a result of the Titanic disaster in 1912 the Convention for the Safety of Life at Sea was signed in London in 1914.

This is one of the Treaties which remains applicable in wartime. The very detail of ship's construction was gone into in the update of this Convention in 1948. The International Load Line Convention was signed in 1930. The Loadline and Safety of Life at Sea Conventions gave States whose ports were visited by foreign vessels the chance to inspect the ship and ensure that safety standards were adequate. These Conventions were the forerunners of Airworthiness Certificates, Maintenance Log Books etc. for aircraft. Clearly there were some rules which were restrictive to ships not employed on long distance voyages. Traffic was quickly divided into three groups, coasting trade, home trade and foreign trade. Home trade for the United Kingdom became all trade with Ireland and the Continent of Europe between the Elbe and Brest. Other States put on similar limits. Then within these fixed limits they started to apply the rule of cabotage covering rights for foreign vessels to trade between two ports in the same country. These rules were developed in the five freedoms of the Chicago Convention.

It is interesting to note how some rules for aircraft developed from the rules of the Sea. When Bleriot made the first cross-Channel flight, the United Kingdom Customs Officer was faced with a problem. He decided that as an airship was treated as a ship, an aeroplane should be treated as a yacht and he issued a yacht storebook. The Customs papers for aircraft today are still based on the yacht storebook.

So now the freedom of the High Seas had become subject to many rules and regulations mostly involving safety.

But the principles of International Law apply equally to all States and it became necessary to consider the case of landlocked nations. Rules were developed to permit landlocked States access to the sea either by Treaties on the use of rivers such as the Danube and the Rhine or by treaty to facilitate use of ports to the merchant ships of landlocked States. Austria consistently used Venice, Switzerland Genoa etc. The development of these rules facilitated the development of rights for these same States for _overflights in the aviation field and also at times even for airport facilities. Basle airport is situated in France and Geneva airport is used for internal flights in the French system.

Jurisdiction as we saw is a matter for the flag State on the High Seas and policing is done by their warshi~s just as it is in general for piracy. A warship has the right to approach a merchant ship to verify its flag and may seize a vessel for flying the flag of its own State without authority.

23

The 1958 Geneva Convention states that there must be a genuine link with the State which must effectively exercise its jurisdiction and control over ships under its flag in administrative, technical and social matters. This was aimed at States such as Panama, Honduras, Liberia, Costa Rica etc. permitting the use of flags of convenience. The flag may not be changed during a voyage. Clearly this type of policing could not be developed for aviation over the High Seas but the "flag of convenience" was seldom used in aviation.

In wartime the High Seas round enemy ports may be closed by blockade and warships have the right to visit, search for and seize contraband. This may also be used in conjunction with self-defence. In 1873 the Spanish navy captured the Virginia, an American ship, on the High Seas on its way to aid insurgents in Cuba. Some of the ~eop~e on board were British and they were executed on arrival in Cuba. The United Kingdom government protested about the executions while accepting that capture and detention was justified.

Allied to blockade is "hot pursuit". This means that a sel may be pursued on the High Seas and seized if a ~~i~e has been committed within territorial waters. Offences against customs, fiscal, immigra~ion or health law~ permit hot pursuit also from the contiguous zone. Pursuit ust be immediate and continuous and must start not later ~an the contiguous zone for an indefinite distance but if the fugitive ship enters another State's territorial . d en d s waters. This poses problems even in. wartime an th~ British Navy was in breach of International Law whe~ 1t d the prison ship "Altmark" in neutral Norwegian cap t ure d h "h t ... waters in 1940. Ireland has recently use t e o pu~~u1t Cod I e ff ec tively against Russian trawlers. TheI recent rue d h" hi" h war" in disputed waters off the coas~ of Ice an 19 f et that International Law 1s an ever changing te d th e a · · system with continuous development of prin~1p 1es and customary law. In deciding the is~Ye the lnternat1~nal Co~rt of Justice was faced with judging a case on its merits immediately before a United Nations Conference on the Law of the sea. A wrong pronouncement could have · serious . . agreement.

1y a ff ec ted the chances of multilateral was reaffirmed in the separate opinion of Judge Th e o Id Iaw {U 't d K' Fitzmaurice in the Fisheries Jurisdiction Case me ing"Clearly therefore the Geneva Condom v. 1ce Ian d) 1973. · vent1on rese rved nothing to the coastal .State by way of . · exc I us1ve f'1sh e ry r"ights . except in what might be called m dentary fisheries. It afforded no ground genera I t erms, Se . . . of exclusive fishery rights in waters that for the asse rt ion . .. were outside the territorial sea, and therefore High_ Sea~ . ·1ateral action to conserve her fisheries Iceland's case f or u n 1 . . and at the same time aim at wider conservat1_0.n 1s not the ·1 teral action and the authorities are now only case o f uni a . th' k the whole concept of the High Seas. We . having to re in will be more interested to see what develops as regards

'? -

airspace over these Seas. rguments which have caused the In fact some o f the a . quandary are the result of long standing Law which _was established in the days of European Overs~as Empires.

One freedom which has not been challe.nged is. that of the subsoil. The subsoil of the sea is territorium null1~s c~pab~e . saw in Article 3. Occupation in this of occupation as we . . b . context 1s y mines or tunnels so long as 1t does not. endan. eas above For communications ger the f ree d om o f the S · . . there is freedom to lay submarine cables and pipelines may also be laid again provided there is no interference of free24

dom of the seas above. Damage to such cables is regulated by the Paris Convention 1884.

Another freedom which has gone undisputed is that of naval manoeuvres on the High Seas. These are permitted provided they do not interfere with the normal use of sea lanes and fisheries. Our interest in this is when the air forces decide to carry out aerial manoeuvres using the same freedom and the presence of firing ranges and danger areas which if they do not interfere with shipping can often create chaos in the civil system of Air Traffic Control and many of these are clearly outside territorial waters. This aspect we will return to under aviation law.

Under the principles of Freedom of the Seas there grew up certain prescriptive rights for the use of the seabed notably the pearl fisheries off the coast of Ceylon (now Sri Lanka) and in the Persian Gulf which were deemed British through immemorial usage and effective occupation. Strangely enough immemorial usage in English Law must date from before Richard I or the beginning of the 12th Century.

Other States sought to establish similar rights and a natural claim seemed to be the Continental Shelf. The Continental Shelf as a term was borrowed from geology and modified. Off most continental coasts the seabed shelves downwards for varying distances before falling steeply to the ocean depths. This is usually at about 100 fathoms or 200 metres. Some are submerged parts of the Continent such as the Baltic Sea, the North Sea or the Persian Gulf. The attraction was, in 1945, oil and is even more the attraction today. The whole problem was set in motion by President Truman's declaration in 1945 of United States' rights to exploit the Gulf of Mexico. "The United States regards the natural resources of the seabed and subsoil of the Continental Shelf beneath the High Seas but contiguous to the coasts of the United States as appertaining to the United States, subject to its jurisdiction and control, and, if the territory of another State abuts on areas contiguous to the United States, the submarine boundary between them should be agreed on equitable principles." This was in no way to impede free navigation on the High Seas above.

This declaration had a snowball effect. British protected States in the Persian Gulf put forward a similar claim; the United Kingdom claimed areas off the Bahamas; Australia followed; and then the expected chaos arrived. Ecuador.

Panama, Brazil and Peru claimed the "epicontinental seas" based on the Continental Shelf theory. Some States having no Continental Shelf decided to join with a claim of 200 nautical miles zone "for protection and control". These were Chili, Costa Rica and El Salvador. Bolivia and Paraguay which were landlocked opposed as did the major maritime nations including the United Kingdom and the United States. Brazil, Peru, Panama, Nicaragua and Ecuador opposed even the principle of complete freedom of navigation for ships and of overflight of aircraft. In Lima in 1970 the Declaration of Latin American States on the Law of the Sea was adopted. Argentina, Chili and El Salvador had strong reservations. Colombia, Bolivia and Paraguay were opposed, and still uphold the doctrine of free navigation and overflight. However strong support for the Latin American ideas was forthcoming not only from Iceland but from the States of West Africa and South East Asia. The West African States had begun to build fishing fleets but others without such resources found distant fishing fleets catching fish off their coasts, using none of the facilities ashore, and exporting fish to these States. One of the exporters was Iceland. The South East Asia case also inclu-

ded the problems of the Archipelago. Ecuador had treated the Galapagos as a unit with territorial waters extending outward from baselines drawn between and on the outer islands of the archipelago, the longest baseline between islands being 147 miles though it is not known whether the waters inside were national waters or territorial sea. This was contrary to the Law on Straits as we saw in Article 3.

Indonesia made a similar claim, straight baselines being drawn to include all the islands and the waters being considered internal. The Philippines and Iceland made similar claims. Iceland however excluded islands far out to sea from the system. (The United Kingdom declared that she did not apply the principle to the Bermudas nor Fiji and the United States made a similar declaration for the Hawaiian Islands). Again there was protest from the maritime States.

We will touch again on this type of problem in aviation law but if we take a look at the map of South East Asia we can easily see the legal problem for an air traffic controller in the event of an accident. Taking the case of an air traffic controller for example in Singapore, he might be talking to an aircraft in Indonesian airspace over water, when an accident occurs. In the subsequent Court Case in Singapore, which uses Anglo-Saxon Law, if the accident is considered to be over the High Seas the judge uses a legal fiction to give himself jurisdiction and then applies the Singapore law. If however these "High Seas" are to be considered internal to Indonesia he must apply the law of the country where the accident occurred applying the law as he supposes the judge in Indonesia would apply it and in effect a Roman-Dutch system. Clearly this could cause long legal wrangles as to which law to apply and the air traffic controller would be under strain all through the proceedings.

This is just another example why IFATCA's Standing Committee Vil is putting so much effort into the eventual achievement of International Legal Limitations on the Civil Liability of the controller.

Now the States are having to look for compromise and Venezuela raised the idea of the "patrimonial sea". This was included in the Declaration of Santo Domingo 1972.

"The coastal State has sovereign rights over the renewable and non-renewable natural resources which are found in the waters, in the seabed and in the subsoil of an area adjacent to the territorial sea called the patrimonial sea. The whole of the area of both the territorial sea and the patrimonial sea taking into account geographical circumstances should not exceed 200 nautical miles". This idea favours a regional solution to certain problems of the sea, since it considers geographical, economic and biological circumstances and could not be uniform. The only uniform part would be a 12 mile limit to the territorial sea. Bolivia being landlocked did not favour the Santo Domingo Declaration and tended to follow the Kenyan Draft Articles for applying this type of idea by economic region so that "The Coastal State shall permit exploitation of the living resources within its zone to neighbouring developing landlocked and nearlandlocked States, and States with a small Continental Shelf provided that the enterprises of those States desiring to exploit these resources are effectively controlled by their national capital and personnel". It is submitted that such solutions must be tied by International agreement to ensure that those who have rights in such areas also discharge certain duties for the world community.

Meanwhile using the basic Geneva Convention on the Continental Shelf 1958 and without reference to the ideas being propounded in South America and Africa, economics

have pushed the States bordering on the North Sea and elsewhere to partitioning the seabed for oil and natural gas exploration. Among these are some of the same maritime powers which protested so vigorously when others for their own economic reasons tried to rewrite the principle of Freedom of the Seas. Again we see that power politics and nonrecognition of the principles of International Law are good for some and not for others. The hope for the future does not appear to lie with the individual States. The hope must therefore be that wiibin~¡the International Organisations, staffed by people of many nations thinking out problems internationally and not nationally, the States will eventually drop their petty jealousies and work within the International Organisations in the regions and throughout the World to apply and improve International Law. The International Organisations will be the subject of the next and subsequent Articles.

For further study: International Law: Chambers: Sweet & Maxwell Chapter 3. The Law of Nations: Brierly: 0. U. P. Part VI Chapter 8.

Oppenheim's International Law: Lauterpracht: Longmans Vol. I Part 2 Chapter II. International Law: Schwarzenberger: Stevens Chapter 20.

The Patrimonial Sea: Nelson: International and Comparative Law Quarterly Vol. 22 Part 4. The Problem of Archlpelagoes in the International Law of the Sea: Amerasinghe: ICLQ Vol. 23 Part 3. The Fisheries Jurisdiction Cases: Churchill: ICLQ Vol. 24 Part 1. Issues arising in the Icelandic Fisheries Case: Katz: ICLO Vol. 22 Part 1¡ The International Seabed Area: Auburn: ICLO Vol. 20 Part 2. Water Pollution and the Future Law of the Sea: Petaccio: ICLO Vol. 21 Part 1. Die Freiheit der Meere und das Volkerrecht: Meurer. La L!berta del Mare o lo stato chiuso moderno: Varadi: Guggenheim. Regime of the High Seas: United Nations Organisation.

Comments on Air Traffic by Aviation Spokesmen Across the World J. M. Ramsden, Editor of FLIGHT International, on a topic which confronts controllers daily In their minute-tomlnute decisions, "Aviation Safety": "Our job is disclosure, and I argue that more should be published to increase professional and public understanding of what is happening. Information improves the product, and that goes for air safety. The more you publish about it the more likely it is that aviation, thanks to better communications, will be safer.

There is also the intellectual discipline of having to explain what it is you are trying to achieve. The obligation to explain one's plans and policies results in better plans and policies. This does not only apply to industry's public relations, it also applies to the Civil Service. I regret very much that Civil Servants do not agree with the argument that they should fully explain what they are doing and carry people along with them.

So, as I said, the more you publish about safety, the more safety there will be. In my experience safety is the most reader-motivating subject in aviation journalism everyone is concerned with it. I am very proud of the two awards that FLIGHT received in 1974 for its air safety writing. You may be worried that publishing too much about safety frightens people off aviation; that is certainly a point of view. 1 wonder if people notice that FLIGHT never publishes photographs of aircraft crashes? We never have, but we do publish everything we can get our hands on about incidents _ other peoples' lessons and experience. You never know what accidents they may prevent."

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Ferranti simulators put years on your student controllers

I

J ···· :-·. .

Our A TC training simulators give controllers the experience they need to do their job - before they start doing it.

This is due to the detailed and comprehensive realism of Ferranti digital simulator systems.

The trainee controller's radar displays are identical with those used operationally, and simulated RT and intercom are provided. With this equipment the trainee learns how to cope with aircraft identification, separation, sequencing, the allocation of levels, routing, stacking, and other problems.

Ferranti have studied air traffic control in depth and have an understanding of current and future needs as realistic as the simulators themselves. We know the economic importance of

handling heavy air traffic with minimum delays.

It's hardly surprising therefore that Ferranti ATC simulators have been chosen for the largest and smallest requirements and are currently in service or on order for London Heathrow, Amsterdam Schiphol, Rome Ciampino, Copenhagen Kastrup, Taiwan Taipei, Sydney Australia, and at the College of Air Traffic Control at Hurn. And a Ferranti simulator is used at the CAA ATC Evaluation Unit for their real time traffic control studies.

Ferranti Limited, Digital Systems Division, Western Road, Bracknell, Berkshire, RG 12 IRA. Telephone: 03443232. Telex: 848117.

FERRANTI The real thing in simulation

News from the Federation The International Labour Office and IFATCA The news that the Governing Body of the I.LO., at its 195th session last March, was unable to see its way clear to include a specialised meeting in the program of industrial meetings for the biennium 1976-77, to cons'.der the urgent problems concerning air traffic controllers, was received with dismay at the Federation's 14th Annual Conference in Melbourne, Australia (see the special Conference report in our August 1975 issue). The decision was presumably taken for financial reasons.

In a personal letter to IFATCA President J.D. Monin, Mr. H. A. Dunning, Chief of the Workers' Relations Branch of the I.LO., has advised the Federation, however, that the Tripartite Technical Meeting for Civil Aviation, which is included in the 1976-1977 programme, should provide a good opportunity to discuss the social and labour problems of all categories of personnel in civil aviation including those of air traffic controllers. Mr. Dunning adds, that, in any case, the Governing Body will take into account the recommendation to convene a specialised meeting for air traffic controllers when the programme of industrial meetings for the biennium 1978-79 is next brought up for discussion.

The Federation regrets this turn of events, for as long as the unsatisfactory status of controllers world-wide is left as it is, the safeguarding of aviation is not enhanced.

Our Relations with the International Air Transport Association Controllers throughout the world have long been frustrated by their inability to persuade IATA to accord to the profession the¡ privileges of free or reduced air transportation which IATA makes available to other professional and non-professional members of the aviation community.

The interest of IFATCA members in this matter have been repeatedly expressed at the Federation's Annual Conferences. Most thinking aircrew and aviation administrations acknowledge the Controller as the third crew member on the flight deck and this fact will become more apparent in the future when automation of the Air Traffic Control System places an even greater responsibility for safety in his hands. IFATCA's cooperation with ICAO grows daily on technical matters as our acceptance of their invitation to sit on the recently formed MODATS and SMGCS Groups illustrates. Such an understanding move by ICAO is bound to be beneficial to all airspace users.

If it were not for controllers' efforts around the world, the high runway utilisation rates achieved to date - especially now the need has arisen to conserve fuel - would never have occurred. This effort is matched by the combined discipline and skill of the aircrews who work so closely with us. IATA, with other Groups and Companies have thereby profited, but members of the Executive Board of the Federation have so far laboured in vain to achieve the desired change in IATA policy.

As indicated in the report of IFATCA '75 which was published in our August issue, the Federation has at last become frustrated by the failure of conventional approaches to IATA and has concluded that a more impressive form of appeal is necessary if anything is to be achieved. The delegates to IFATCA '75 accordingly approved unanimously a co-ordinated world-wide campaign in which all controllers have been asked to participate. The first phase of this campaign was focused on the IATA meeting which took place earlier this autumn and while it remained a persuasive approach, it was hoped that, with the co-operation of individual controllers, it would prove more effective in forcing the subject on IATA's attention than have been the representations made in the past.

Comparison Of U. S. Air Traffic Control Facilities By Means Of A Stress Index

by Carlton E. Melton, Ph.D., Stress Physiology

Research Unit, Aviation Physiology Laboratory, Civil Aeromedlcal Institute (FAA), Oklahoma City.

American editor and essayist Charles Dudley Warner once observed, "Everyone talks about the weather, but no one does anything about it". The same might be said about stress: we spend a great deal of time and effort measuring the consequences of stress and discussing it, but we seemingly do little to alleviate it. This indictment may be too severe, however, because an understanding of stress is a prerequisite to doing something about it, and we can reach that level of understanding only if we talk freely with each other. At times Oppenheimer's remark, "What we don't understand, we explain to each other", seems appropriate.

The very word "stress" is confusing. It is borrowed from engineers, who use the word to describe a force applied to a structure, such as a beam or bridge member. The resistance of the structure to the applied stress is called strain.

Strain gauges were developed for the purpose of quanti-

28

tating the structure's response to the stress. Hans Selye, a physiologist, took the engineering term "stress" and used it to describe the living body's response to disturbing conditions, such as injury, sickness, exposure to extremes of heat or cold, intense physical effort, etc. These disturbing conditions themselves Selye called stressors. When the stressors are severe, the presence of stress is obvious because the individual's departure from normal is great enough to be appreciated by any observer.

Selye described the common reaction of the individual to these disturbing conditions in terms of hormone output from the adrenal gland and called the time course of that response the General Adaption Syndrome (GAS). Selye proposed that this response was nonspecific; i. e., it was the same regardless of the stressor. The GAS encompasses an initial defensive response (alarm reaction): a long-term

intermediate adaptive response (phase of resistance), when the individual successfully copes with the stressor; and a terminal stage (phase of exhaustion), when illness or death occurs because of the duration and strength of the stressor.

This concept of stress is easy to understand in the context of only two conditions, unstressed (normal) and stressed (pathological).

The tendency has grown to the point of general acceptance to refer to the day-to-day "rigors of life" as stress.

In short, the GAS has been extrapolated into the range of normality so that one must think of degrees or levels of stress that are prepathological or, in behavioral terms, that lead to deterioration of the quality of performance.

One is led inescapably to grapple with several assumptions implicit in the concept of stress within the range of normal. First, there is the assumption that stress will ultimately be harmful. Since everyone eventually dies, this assumption is difficult to refute; it is also difficult to confirm if one subassumes that stress will only hasten a person's demise, predispose him to disease, or degrade the quality of his performance. The term "stress-related diseases" has been applied to a large collection of disorders.

Some of these stress-related conditions are ulceration of the gastro-intestinal tract, emotional illness, rheumatoid arthritis, and suicide. Though the relationship between these conditions and the work an individual does can be described only in actuarial terms, it has led to the identification of certain professions as having a high stress content; e. g., Air Traffic Control. The exact relationship, on an individual basis, between objective estimates of stress and disease has not been established.

The concept implies that there is a threshold of stress above which the potential for disease is increased. Such a value is not to be found in the published literature. The values of the various stress indicators given for normal populations of humans have such a wide range as to exclude only those given for persons suffering from diseases characterised either by the production of large quantities of the stress hormones or by the lack of them.

Second, quantitative stress assessment is complicated by a bewildering array of physiological, biochemical, and psychological indicators. Physiological measurements in common use include electrocardiogram, electrical resistance of the skin, eye movements, electroencephalogram, respiratory rate, and many others. Because of the large number of individual observations that is possible when such measurements are used, statistically significant differences are commonly revealed for physiologically unimportant changes. Often, interferences about stress are drawn when the changes merely represent the difference between the resting and active states. There are no criteria by which these measurements can be related to stress, and interpretations are further complicated by a number of extraneous activities - physical activity, smoking, coffee drinking, a~d eating - that act upon such things as heart rate and skin resistance.

Psychologists have been no better than physiologi$ts.at defining stress. All psychological stressors contain eleme~ts of conflict or threat. The stressed individual responds with fear, anxiety, or frustration. In all cases, however, the psychological approach involves assessments of abnormal behaviour, affect, or attitude.

Products of metabolism in blood and urine are probably the most widely used and accepted of all stress measure-

ments. The most important of these indicators are the hormones - the steroids and epinephrine from the adrenal gland and the norepinephrine released from certain nerve endings. These substances are secreted into the bloodstream and excreted in the urine. Measurements of steroids, epinephrine, and norepinephrine are commonly supplemented by measurements of potassium, sodium, calcium, and magnesium.

Arguments have occurred over which of the above biochemical entities are the best stress indicators. One reason for the arguments is that there is a differential response to various stressors. Anxiety, and anything else that stimulates metabolism, causes increased epinephrine output that is out of proportion to increases in steroid or norepinephrine output. Excitement or activity causes a disproportionately high rate of excretion of norepinephrine; injury causes an outpouring of steroids. Thus, if a researcher is to appraise total stress resulting from a mixture of stressors, he must cover all bets and employ a battery of measurements. However, when this is done, the researcher finds he has abandoned the frying pan's uncertain safety for a sure fate in the fire because now several values must be interpreted that oft~n do not agree in either direction or amplitude of change.

The investigator's dilemma is deepened when he tries to draw conclusions about stress from the level of excretion of a substance without regard to a baseline, because he has no way of knowing the direction of change. If, on the other hand, he considers the amplitude and direction of change from the baseline, he may be further bemused to find that his preconception about stressors is wrong, for the "baseline" level may be higher than the work (stressed) value.

The problem of stress quantitation can be skirted if one employs a comparative approach and ranks- differ.ent groups according to levels of the various indicators of stress. However, one still has to deal with the annoying problem of interpretation when the rankings for the several indicators do not agree, as is commonly the case; then one does not know on which indicator to rely.

Though it falls short of universal application, a biochemical stress index (one that integrates the various indicators into a single expression) has been devised in the Aviation Physiology Laboratory of the FAA Civil Aeromedical Institute. This index is useful within a given population that is homogeneous with respect to stressor; e. g., the Air Traffic Controller population.

The index (Cs) is calculated from the amounts in the urine of steroids (st), epinephrine (e), and norepinephrine (ne). Because the three compounds occur in urine in the approximate ratios of 500 st:10 ne:1 e, some weighting procedure is necessary to prevent st from being the sole determinant of the index. Weighting is accomplished by dividing the individual resting (baseline) and work (response) values of each metabolite by the average of all the values for each metabolite in the entire population. This weighting factor is referred to as the "grand mean". It is calculated for each metabolite and has the effect of bringing each value to the neighbourhood of unity. In our laboratory, the "grand mean" is derived from more than 2,000 values for each of the three metabolites.

For reasons outlined earlier it is desirable to integrate the baseline and response val~es. This procedure is carried out simply by obtaining the product of the weighted baseline and weighted response values for each metabolite.

29

This product, or individual index, is referred to as "c". Thus, there are three c-values: Cst• Ce, and Cne· The final composite index, Cs, is obtained from the average Of Cst• Ce• and c ne· The average is used so that the. index can be expanded to include other measurements. Smee Cs is dimensionless, any other measurement for whi~h there are baseline and response values can be averaged mto Cs. Cs is an expression of the total amount of stress; i. e., as stress increases, Cs gets larger.

Cs can be computed for individuals, for facilities, for various work positions, for shifts, or for most any other condition. The requirements are that there be baseline and response data and sufficient data from which a grand mean can be computed. Cs has been computed for each controller who participated in the nine studies carried out at eight u. S. Air Traffic Control facilities. The chart shows the ranking of ATC facilities by Cs and shows the contributions of Cst• Ce, and Cne to C 5 for each facility.

The Streng triangle is a diagrammatic way of showing total stress (Cs) and the relative contributions of Cst• Ce, and c (see the chart for the key to the three-letter identifiers). l;ethe Streng triangle, the individual c-values are shown as lines emanating from a common point and diverging at angles of 120°. The lengths of the divergent lines represent the magnitudes of c 51 , Ce, and Cne (see the triangle for ORD in the figure). Lines drawn perpendicular to the ends of the c-value lines form an equilateral triangle, the altitude of which is equal to the sum of the c-value lines.

Since the area of the equilateral triangle is proportional to its altitude and since Cs equals one-third of the altitude, the size of the triangle is directly proportional to Cs. The ranking by size, similarities, and internal differences of the triangles are immediately apparent.

We can conclude several things from these figures.

O'Hare Airport, Chicago, Illinois, is the busiest airport in the world, and the tower controllers there ranked highest in stress. Some of the reasons for the high level of stress among O'Hare Tower controllers were apparent in the summer of 1968 when the study was carried out. The massive "slowdown" was in effect at several major U.S. terminals and centers. Although O'Hare controllers were not direct participants in the slowdown, the result at O'Hare was the same as though they were. More than 100 jet airliners were commonly on the ground at O'Hare at one time; there were 6-hour delays for departure. A major runway was closed for rebuilding. The tower was staffed at 45 percent of its authorized strength, and controllers were working 6 days per week. The high level of stress was apparent even to a casual observer. and our objective measures bore out that impression. O'Hare ranked high in all three individual cvalues; thus. it was high in total stress (Cs>· Opa Locka Airport in Miami, Florida, is one of several u. s. high-density general aviation airports. For several years Opa Locka, with more than 600,000 operations per y~ar, was the second busiest U. S. tower. However, ~t the t:me of the stress study, Opa Locka ranked 10th nationally bee much of the training activity that had accounted for caus d' h · the large volume of traffic had been 1spersed to ot er a1rNonetheless. the tower was still an extremely busy po rt·i·t s. . in good weather. ra d'10 t raff'1c was v1'rt ua IIy con t'1f aci 1Y• · Th e ch ronic · stressors th at wer frequencies. nuous on the to were so apparent at O'Hare were not observed at Opa The objective stress measurements bore out that Lock a. . . t b ut t he . n the c and Cne Imes were prommen e . . o b servat 10 c line was short. Thus. it appears that C5 t 1s an index of st

30

chronic stress commonly associated with unresolved conflict and frustration whereas ce and Cne are indicative of workload and activity stress.

Houston Intercontinental Airport Tower in 1970 was on a straight 5-day shift rotation. The controllers preferred the 2-2-1 (2 evenings, 2 days, 1 midshift) because of the long weekend associated with it and were dissatisfied with the rotation that had been established. Controllers at Houston Intercontinental had just concluded a "sick-out" when the stress study began, and disciplinary actions were pending against several of them. In short, conditions at Houston Intercontinental were qualitatively similar to those at O'Hare, with the exception that the traffic was much lighter at Houston than at O'Hare. The Houston ('70) Streng triangle reflects this similarity in its internal configuration. The short ce line in the triangle reflects the fact that Houston's traffic volume was lower than O'Hare's.

In 1971 Houston Intercontinental returned the 2-2-1 shift schedule. The same group of controllers was restudied in 1971, and the triangle shows a fairly symmetrical internal arrangement with a noticeably shortened est line. At the time of the 1971 study, most of the conflicts had been resolved at Houston; however, the workload had been increased somewhat, which perhaps accounts for the lengthened Ce line. Also, it is apparent from inspection of the triangles for Houston that total stress was about the same in 1970 and 1971. In fact, the 1971 triangle is slightly smaller than the 1970 triangle. Thus, one would conclude that the 2-2-1 rotation pattern in itself was not more stressful physiologically than was the 5-day pattern. Management has alleged that shift compression on the 2-2-1 pattern does not allow sufficient time for adequate rest between watches. Documentation of the amount of sleep of controllers on these two shift schedules showed that these controllers did, indeed, sleep significantly longer in association with a week of the 5-day schedule. However, the single midshift on the 2-2-1 pattern substantially lowered the average amount of sleep because the controllers normally took only a short nap prior to work.

When the single midshift is not considered in the comparison, the controllers slept an average of 18 minutes more when on the 2-2-1 schedule than they did a year earlier when on the 5-day schedule. It was concluded from these studies that strong managerial reasons may lead to the selection of one or the other of these shift schedules, but preference could not be established for either of them on physiological grounds.

The comparative stressfulness of different shift schedules was re-examined at Atlanta Center (straight 5-day rotation) and Fort Worth Center (2-2-1 rotation). Again, as can be seen by the Streng triangles, the 2-2-1 facility was less stressful than was the 5-day facility. The difference in stress levels at the two facilities may, of course, be due to multiple causes. However, the assumed stressfulness of the 2-2-1 schedule was not severe enough to override those causes.

The studies at Oakland and Los Angeles Terminal Radar Approach Control Facilities (TRACON) were carried out in 1972 before the installation of ARTS-Ill equipment. It is noteworthy that total stress at the two facilities is equal (Cs = 0.60), though the internal configuration of the Streng triangles differ. Studies at Oakland and Los Angeles have not long ago been completed - when the ARTS-Ill equipment became fully operational. When the data are analyzed, it will be interesting to see how automation affects the nature and amount of stress at these facilities.

Cs, Csff ce, and Cne for each ATC facillty studied (ranked by Cs)

Facility FTW ARTCC (Fort Worth Center) LAX {Los Angeles TRACON) OAK (Oakland TRACON) IAH ('71) (Houston Intercontinental Tower) IAH ('70) MIA ARTCC {Miami Center) ATL ARTCC (Atlanta Center) OPF (Opa Locka Tower) ORD (O'Hare Tower)

Cs 0.34 0.60 0.60

Cst

Ce

Cne

0.22 0.66 0.62

0.58 0.34 0.76

0.20 0.81 0.43

0.68 0.74 0.76 0.82 0.84 1.05

0.89 1.27 0.61 0.76 0.64 1.41

0.62 0.29 0.71 0.34 0.74 0.75

0.52 0.65 0.96 1.37 1.15 0.98

One advantage of this stress index is that it does not matter whether the baseline value is greater or less than the response value. Occasionally, a controller will show a decrease in excretion of steroids and catecholamines while on duty, which simply shows that work represents an escape from some greater off-the-job stressor. By using the product of the weighted baseline and response values, one estimates total stress. Sometimes the baseline derived from off-duty resting values is the prime determinant of total stress.

Workload as represented by total communication time is not significantly correlated with c 51 , is weakly correlated with c 5 and Cne• and is strongly correlated with c 8 • These observations emphasize that there is some specificity to the stress response.

In summary, we feel that any appraisal of stress must rely on a battery of tests rather than a single indicator, such

RELATIONSHIP OF Cst, C8 , Cne REPRESENTED ON THE STRENG TRIANGLE

c& ffi & Cne ORD

IAH ('70)

OPF

IAH ('71)

ffi

ATL

OAK

MIA

LAX

FTW

as the amount of adrenal steroid excreted in the urine. Several indicators can be integrated into a single expression by very simple calculations, thus facilitating the comparison of ATC facilities and individuals. We recognize the shortcomings of this index, but we feel it has usefulness in the appraisal of stress in air traffic controllers. We hope this method can be used in the future to define the limits of work for individuals, to identify individuals in whom pathological processes are imminent, and to evaluate the effect of changes in the Air Traffic Control system.

Automation and ATC Training Staff Report, Part 1 The very timely subject AUTOMATION AND TRAINING was the theme of an International Seminar held by EUROCONTROL from 14th till 18th October, 1974, at its Institute of Air Navigation Services at Luxembourg. Some eighty participants from thirteen countries gathered there for a week and discussed how automation and other advanced methods and media could be used to make ATC training more efficient.

The organisers of this interesting meeting had set their goals high and attempted to cover a wide range of subjects, which were subdivided under the following headings: Introduction and Review of Psychological Aspects of Teaching.

Analysis of the Problem of Training Air Traffic Services Personnel in Consideration of the Evolution of Tools put at their Disposal, and notably of the Introduction of Autom~ted Data Processing in Air Traffic Control.

Computerise~ Traini~g Simulators as Pedagogical Aids for th~ Practical Training of Air Traffic Controllers.

Teach'.ng Machines and Computer-Assisted Training Techniques, and the possible Utilisation of these aids in Air Traffic Control Training.

These topics were treated in sixteen papers, presented

by International experts in education and ATC training, and vividly discussed in ensuing panel sessions.

G. E. Krug, the Director of the Institute and very able chairman of the Seminar, was assisted by top-level speakers from universities, national ATC academies, aviation administrations and ATC field units, and last but not least from industry. Their vast experience in a variety of subjectrelated faculties established the basis for a sound approach to the many problems associated with ATC training.

ATC Training and Learning Psychology Professor Dr. C. F. van Parreren of the Rijksuniversiteit Utrecht, Netherlands, opened the scene with an analysis of Air Traffic Controller Training from the standpoint of the psychology of learning. He defined ATC tasks as "action tasks", where the emphasis is on the performance of actions aimed at precisely defined objectives, rather .t~~n reflection on general problems. Consequently. the Tram• ~ of Air Traffic Controllers should be concentrated on acquisition of the required action patterns. Because of the highly diverse working situations encountered in the ATC environment the patterns of actions which have to be learned must possess the requisite flexibility.

31

A good solution towards such flexibility is to train the student for a certain group of concrete working situations occurring within a specific existing system, in such a way that the learning of actions required within this system is linked to the full understanding of the general principles on which it is based.

In ATC training we are concerned with the acquisition of skills. On-the-job (OJT) training, therefore, seems to be an appropriate training method. The trainee is immed:ately confronted with a working situation and the actions to be performed. However, the on-the-job training must be preceded by a period of extensive pre-training outside of the live ATC environment. The pre-training, usually conducted at an ATC academy or institute, provides the general basis for efficient specialization training on the job. Because of an increasing shortage of training capacity in the live environment, there is an increasing demand for shortening the on-the-job training. The question is whether a reduction in OJT can be compensated by longer, more efficient, or differently organised theoretical and simulator training.

Care must be taken here that theory and practice are not divorced. The complaint is often made that trainees are having difficulties to apply the knowledge acquired in theoretical lessons when they require it in the working situation. The knowledge is non-functional.

Algorithmic Structure of ATC Tasks In order to determine how "functional knowledge" can be acquired, Professor van Parreren referred to studies by Sperandio and Bisseret and proposed that the hierarchical scheme of ATC actions should be investigated in greater detail. This would allow Controller actions to be described in the form of flow charts or algorithms (what is meant here is not only the external, physical action of a Controller but also his mental activity).

F I o w c h a rt s are generally in the form of trees: they reproduce the system of interlinked actions ("branches") in diagram form.

To illustrate the structure of an a Igor it h m and a sequence of actions controlled by an algorithm a method developed by Russian scientists (Ljapunow and Landa) is particularly" instructive. A relevant notation looks like this: 1 2 2 1 ABa t Cb t . -l- E. -l- DC. It should be read as follows: Do A, then B. Check whether condition a occurs. If so, do C and check whether condition b occurs.

If so. stop; otherwise follow arrow 2, i. e. do E and stop.

If condition a does n o t occur, follow arrow 1 etc.

This diagram shows that two kinds of variables must be distinguished, namely "operators" (capitals) and logical conditions (small letters). The value of a logical condition indicates which operator must be used. Conversely, the use of an operator can produce a particular value for a logical condition for another operator. An es_sential ch_a_racteristic of action algorithms is that the logical. cond1t1ons must be capable of being determined unambiguously by the acting person, and that for him the operators must be elementary actions. He must be able to perform them faultlessly and without hesitation. Consequently, ~hether a set of instructions is in the nature of an algorithm does not solely depend upon its form (i. e. an interconnected sequence of operators and logical conditions), but also on the knowledge and skill of the person who has to carry it out. What is an elementary action for one person need

32

not be so for another. Furthermore, in the course of a training programme some actions become elementary which initially were not. This is closely connected with the abbreviation of actions which occurs in any learning process.

Professor van Parreren then put the question whether it is in fact true that ATC tasks, or at least major sub-tasks among the overall task of an Air Traffic Controller possess an algorithmic structure. He compared the Controller's work with the activity of a chess player: Both are controlling movable units (chessmen and aircraft) in relation to a fixed reference system (the sixty-four squares of the chess board and the airspace structure). So far it has not been possible to represent the thought processes of a chess player by means of a system of algorithms, although certain phases in these processes show approximately an algorithmic structure. Similarly, the ATC task does not seem to render itself suitable for complete algorithmic treatment. Intuitive elements also come into play, for instance in the choice of alternative solutions.

Nevertheless, Professor van Parreren demonstrated that the work of an Air Traffic Controller is suitable for algorithmic treatment to a much greater extent than that of the chess player. The chess player's final goal (mate) is a very remote one, and it can be achieved by following an immense number of different routes, while in addition his opponent can provide a great many more unsuspected surprises than the Controller has to face (e. g. unexpected behaviour of aircraft, weather, etc.). The Air Traffic Controller was said to operate within a "narrow manoeuvring area", and the chess player on an open field.

ATC-<Training as Teaching of Algorithms The speaker went on to suggest that in the training of Air Traffic Controllers the teaching of the algorithms which correspond to the various sub-tasks must take pride of place. In this way future Controllers would not only be properly trained for the tasks which they have to perform, but also the problem of acquiring functional knowledge would become manageable. The structure of any algorithm shows what knowledge is required for action in accordance with the algorithm; the relevant logical conditions must be known as well as the values which they may assume. This pre-supposes the learning of concepts, their symbolic representation, the values which may occur for them, and also the way in which the value can be determined.

So the requisite knowledge and the form in which it is required are precisely determined by writing out the actions of Air Traffic Controllers in the form of algorithms. Those who are taught an algorithm come to know when they must actualise this or that piece of knowledge. All this together constitutes the description of knowledge to which we refer as "functional".

Learning Hierarchies A fully written out algorithm for a sub-task (such as procedural conflict detection) makes very heavy demands on the person who has to operate it in accordance with the algorithm, since numerous identification algorithms, with the logical conditions required for these, occur in its hierarchical structure. Furthermore we must remember that the algorithms which an experienced Controller follows are frequently shorter than those which we have to teach in training.

Which method should, hence, be applied; the immediate introduction of all knowledge in the complete realistic algorithm, or the presentation of knowledge separated from an algorithmic context? Professor van Parreren suggested that there is another, far more suitable alternative: imparting knowledge in the framework of reduced, simplified action algorithms which have been obtained by eliminating a number of variables from the genuine working situation.

A training course organised on this basis would be built up from a series of algorithms which gradually become more complicated and, hence, increasingly more realistic.

A number of advantages of such a teaching strategy were alleged by the speaker: Commencing with very simple act:on situations at the beginning of the course, the trainee immediately appreciates the "rational". As a result of the gradual build-up of the series of algorithms, he can keep abreast with the course; each successive algorithm is a meaningful, readily grasped development of the preceding algorithm. Consequently, the trainee retains the rational basis of what he learns throughout the course. Flex:bility is therefore guaranteed. As a second advantage the acquisition of "functional knowledge" was quoted: no superfluous baggage is conveyed and the subject matter immediately fulfils an "action" function. A third advantage of the proposed teaching strategy would be that knowledge was acquired in the framework of a (simple) action, with the knowledge being necessary for that action: it was learned "en passant" from the motivational point of view.

A process of incidental learning and not of memorising, as the learning psychologist would put it. Cramming would be unnecessary, with the required elements of knowledge being learned just by applying the algorithm.

In this strategy, Professor van Parreren explained, he had combined Landa's ideas algorithmisation in teaching with the basic idea of the American Gagne, namely the construct:on of learning hierarchies.

Three Fundamental Principles of the Proposed Teaching Strategy summarising key points of the strategy referred to above, the speaker highlighted the following: The principle of incidental learning The requisite knowledge is acquired in performing actions for which the knowledge is essential, thus dispensing with tedious memorising. Newly acquired knowledge is readily applied, forming the basis for the next, more complicated step in the learning process.

A relevant exercise programme must be composed in such a manner that the various elements of knowledge all occur with the requ!site number of repetitions and at well chosen intervals. Visual aids are needed for initial "prompting" of students.

(This method is also used by GAL'PERIN) The principle of the abbreviation of actions As in the previous "Principle of incidental learning", Professor van Parreren here also referred to the scientist GAL'PERIN. While an action is being lean:ie.d. on the basis of an algorithm, the initially very detailed action is abbreviated step by step: action components drop out. It is only through this characteristic of the human learning process that we learn complicated action patterns such as those required for chess playing, the solution of mathematical problems or Air Traffic Control.

Abbreviation of the actions achieves both a reduction in "cognitive strain" and a saving in time. It is noteworthy that the high speed of a trained person (including the trained Air Traffic Controller) depends not so much on an acceleration of the original processes as on a change in the structure of the action: it is abbreviated action which makes the high speed possible. Abbreviation of the Air Traffic Controller's action is consequently essential for the ability to act in real t:me.

Again referring to GAL'PERIN, the speaker explained that, although occurring spontaneously in learning processes, abbreviations should not be left to chance in an optimum teaching process. The teaching programme must make provision for c o n t r o I of the abbreviations.

The principle of complete orientation This principle of GAL'PERIN was considered to be of cardinal importance in any instruction process in which algorithms are used. It implies that in each phase of the learning process the trainee must be supplied with the relevant "cues" on which he is to base his action, so that essentially he is able to perform the action faultlessly - even if slowly, elaborately and with the use of external aids. Incomplete orientation of the trainee results in trial-and-error behaviour and teaching results which are not sufficiently flexible.

Programmed and Computer-Assisted Instruction At the end of his presentation, Professor van Parreren outlined his views on P. I. and C. A. I.: "The advantages of programmed instruction and computer-assisted instruction are well known. I see great scope particularly in the combination of textual and visual data in a computerised set-up for the training of Air Traffic Controllers. However, the principles of instruction on which the teaching programme is based are ultimately more important than the equipment!"

GdB (To be continued)

ATC: A Morale-Oriented Service Air Traffic Control is a morale-oriented service - it is an important and responsible function wh!ch carries with it a higher degree of public accountability than found in any other Government service. The functions of ATC require the application of dedication, alertness, attent:veness. concentration, initiative and the very necessary team work.

Emot:onal disturbances which may be generated by low morale have, in the long run, a detrimental effect on the safety of air operations.

(CAOOAA Newsletter)

Cheap At The Price A passenger boarding a Boeing 747 at Nandi Airport. Fiji, asked the stewardess about the cost of hiring a headset for listening to the recorded music during the long haul across the Pacific.

"Two dollars" came the courteous reply.

A fellow traveller across the aisle. leaned over and was heard to remark: "You can have mine for one dollar. mate It's only done 5000 miles!"

(World Airnewsl

33

Comments on Air Traffic Control by Aviation Spokesmen Across the World N. Shlnderman, Bureau of Recruiting and Examining, U.S. Civil Service Commission, on "Controller Selection Criteria In the U.S.A.": "As for other positions in the Executive Branch of the Federal Service, positions of Air Traffic Controller (grades GS s, 7 and 9) are filled by open competitive examination.

However, because of the importance of these positions, a separate examination program is in operation for filling these positions.

The announcement for the vacancies is a very attractive multicolour publication which also serves as recruiting literature, and about 25,000 copies are distributed throughout the country to schools, State employment offices, veterans organizations, community organizations, Congressional offices, Government offices, and special groups likely to be interested in this occupation. In 1971, to meet a rapidly expanded need for applicants, the FAA developed two motion picture features for recruiting purposes. Spot radio and television advertisements were used by the media periodically nationwide, to publicize the examination. Special articles were placed in national magazines and other issuances. The result was a list of eligibles containing the names of more than 20,000 candidates.

A maximum age limit of 30 at the time of appointment has been established for all entrants. The qualifications requirements for Air Traffic Controller positions are as follows: GS-5: Pass a written test plus 3 years general experience or 4 years of college or combination of both; GS-7: Pass a written test plus 3 years general experience or 4 years of college or combination of both and 1 year of specialized experience or 1 year graduate work or superior academic achievement; OR: Pass written test with very high scores plus 3 years general experience or 4 years of college or combination of both; OR: Pass a written test plus one of the following: civilian or military facility rating in Air Traffic Control involving active control of air traffic in center or terminal; past or present FAA air carrier dispatcher certificate; past or present instrument flight rating; past or present FAA navigator/bombardier; past or present co-pilot or pilot rating or equivalent military rating with 350 hours of flight time; past or present rating as an Aerospace Defense Command intercepter director; GS-9: No written test - 3 years general experience or 4 years of college and 2 years specialized experience or 1 year specialized experience combined with 1 year graduate work.

(Positions in grade GS-9 are now no longer filled from this examination - Ed.) General experience is progressively responsible work which demonstrates potential for learning and performing Air Traffic Control work. The work could be administrative, technical, or other types of employment. Education may be substituted tor experience - up to 4 years of college for 3 years of experience. Specialized experience is experience in military or civilian Air Traffic Control or comparable experience (for example. military activities involving direct

34

control of aircraft and missiles) which shows that the candidate has the knowledge, skills, and abilities required to perform ATC work at the grade level for which application is made.

The written test consists of five parts as follows: 1. 60 questions on arithmetical computations; 2. 35 questions on spacial perception; 3. 50 questions on letter series (abstract reasoning); 4. 35 questions on following oral instructions; 5. 60 questions on simple reasoning problems.

Final numerical scores are derived as follows: GS-5 Ratings are based on the written tests and extent of education; GS-7 Ratings are based on the written tests and the extent of education and experience related to the job; GS-9 Ratings are based on an evaluation of the kind, amount, and pertinence of qualifying specialized experience.

Prior to appointment, candidates are required to demonstrate in an interview that they possess the personal qualities necessary for successful performance in the position, including the following: ability in oral expression; poise and self-confidence; resourcefulness; practical intelligence and judgment; alertness; decisiveness.

Candidates who are found to be deficient in these qualities may be passed over for selection for the position. In the interview the determination of eligibility or ineligibility may be based on the evaluation of the qualities listed above only. The Civil Service Commission certifying offices review ineligible evaluations. Candidates who successfully meet the requirements in the interview are scheduled tor a physical examination with a physician in or near their home towns selected from a list approved by the FAA at no cost to the candidates. The physical standards which must be met are rigorous. In addition to the medical exa~ination candidates are required to complete a personality inventory. The results of the medical examination and the inventory are sent to the FAA Medical Division for final evaluation. Candidates who may have psychological disorders as revealed by the personality inventory are referred for a psychological examination.

A. preliminary check of investigative files is made for candidates tentatively selected for appointment. Subsequently, a full field investigation is conducted for each candidate appointed."

Jail for Japanese Piiots . Two Japanese military pilots, held responsible for the

m1d-~ir collision with an All Nippon Airways B 727 in 1971 causing 162 deaths, have been sentenced to four years,

~nd two years and eight months' jail respectively. The JU~~e criticised Japanese aviation policy which permits military practice flights near civil air routes where pilots take responsibility for spotting and avoiding civil aircraft.

The two convicted pilots were practising formation flying and the instructor (sentenced to four years) in lead aircraft failed to see the 727 because his attention was diverted to watching formation.

(Aviation News Digest)

IKAT: A New Approach To ATC Simulator Control Using a simplified input/output device to feed the digital processor of a training simulator, instructor training time can be reduced from weeks to only a few hours for proficiency ...

by D. Canfield, Chief Engineer-Special Projects and T. Redford, Senior Systems Analyst, Systems Division, Solartron Electronic Group Ltd.

A typical Training System Configura¡ tion of Aircraft Control Units for a 16 target ATC simul ator. Units include (left to r ight) three Interactive Keyboard Terminals (IKAT), an ASA 33 Teleprinter for exercise initial i~ation . and a Plan Position Indicator Display.

Simulation has been accepted as an essential medium in aviation trai ning for many years. It is inconceivable today, for example, that an airlin e pi lot wou ld complete his training without many hours spent in a flight si mulator. But, what of the need s of air traffic controllers - an area of training for which simulation gives the same benefits and is just as critical to safety?

In a simulated environment, the pilot can be safely stressed and tested under any emergency condition that he is likely to encounter in the air, such as engine, electronics or hydrauli cs failure. Through simulation, he is trained to deal with situations that he might never encounter in rea l life. Here, it is relatively easy to justify the need for simulat.ron , because at least three benefits are indis::iutable: comprehensive training , cost saving~ and .the total ab_sence of risk to man or machine. Yet, arr traffic control simulators have not achieved the same universal importance as flight simu lators. This situation surely could be improved to a point where all authorities obtain the same benefits from ATC simulation.

For the trained controller, new equipment is helping him to cope with the increasing density .of. air traffic .. Radar manufacturers are providing more sophtstrcated equipment to meet new demands; information presented to controllers now can be correlated to remove extraneous responses. filtered to remove ground returns and selected in altitude or by coding. Convent ional controls are being r~pl~~ed by keyboards or touch devices. Accuracy and relrabrl1ty are being improved by progressive change from analog to digital techniques.

25 years of experience In parallel, companies producing ATC simulators are also advancing rapi dly to keep abreast with developments in live radar eq uipment and to take advantage of new techniques. Our firm . for example, has specialised in all major types of area and term inal radar simu lation for many years.

The first ATC simulators were produced in the 1950s.

The early simulators were analog devices, but now digital design is used almost entirely. Digital techniques have removed the analog system 's disadvantages of limited accuracy, difficulty in setting up and temperature drift. In recent years, the advent of the mini-computer has brought new skills to the simulator manufacturer and hence more benefits to t he user. A cost benefit also has occurred more recently with the declining price of minicomputers as such equipment is increasingly miniaturised. The result is that more frequently we now f ind a minicomputer at the heart of an ATC simulator, controlling simulated aircraft manoeuvres and generating displayed data to the trainees.

The number of aircraft that must be simulated simultaneously has increased steadily over the years, as dictated by the increase in live traffic. Fo rtunately. the digital computer has allowed this capability increase to occur without severe cost penalties. Fo r example, it would be prohibitive to construct an analog simulator for 100 tracks, but quite practical using digital techniques. A resultan t problem. however , has been how to determine a method of ''flying¡¡ large numbers of simulated aircraft. For analog systems, one " pilot" would fly two simulated aircraft. but suffic ient training school staff cou ld not be made available to co ntrol 100 aircraft in this ratio .

35

IKAT, Step 1 : Four step sequence shows the d isplays invo lved in carrying ou t the assignment by a student controller of a change in aircr aft fli ght level.

IKAT, Step 2

Simulator control simplified

ing before he ca n fulfil his task, and thi s typically req uires up to six weeks duration. Th is training prob lem is quite common with a function key and al phanum eric keyboa rd.

(Brit:sh Ai rways discovered this prob lem with the term:nal entry to its BOADICEA reservation system and now provides a simulator for the sole training of keyboard operato rs.)

But it must be remembered that the ATC simulator is intended to train the controll er, not the SPO.

Fo rtunately, computer prog ramm ers provided the solution. By feeding flight plan data into the simulator minicompu ter at the start of the exercise, it is possible to programme the system to fly the si mulated aircraft a ut ~mati ­ cal ly accord ing to thei r ind ividual fli ght plans, without manua l interventio n.

T he ro le of the simulator pilot operato r (SPO), sometimes referred to as a "Blip Driver ", is now considerably reduced to the following t asks: reporting on airc raft positions w hen required and manuall y co ntrolling the simulated aircraft on ly when deviation s to the planned fli ght are req uired.

It has now been found pract ical for one SPO to handle up to ten s imulated air c raft.

When SPO th e pla n ned keyboard

manu al contro l of an ai rc raft track is necessary, must inform the computer of the alteratio n to the ·d flig ht. Most simulator manufacturers p rov1 e a for t hi s purpose , this bei~g _the m ost conven ient har d ware read ily available and. easi ly interfaced . to a com operatio na l req uirements of t his keyboard , puter. Th e tremely stringent.

The SPO, who controls ex however . are . several track s. l·s requi red to input .messages very rapidly ith directions received from the student to keep pace W . . controlle r. M os t keyboards • therefo re, co ntain function keys for co mmon IY use d e ntries (e. g. HEAD ING , SPEED,. FLI GHT LEVE L) toget h e r w i'th numeral keys and a lphabeti cal keys ' genera I en tries · And · large numbe rs of keys must for more be

rovided. Th e messages typed thereon are accepted by P . the co mputer program me and · if "valid " , must be acc urate in format and data content. With th is t_ype of ~e~board ,_ it has bee n found th at th e S PO mu st be given su ffi c ient train-

36

Better input/output control It was this facet of the ATC simul ator system that our eng ineers felt required improvement. Thus, they concentrated their efforts on developing w hat we now call the In terac tive Keyboard And Terminal (IKAT) system, shown publicly for the first time at Farnborough Internatio nal , 1974.

This device has similarities to the touch display technique id en tifying disp layed items, but retai n s the e rgo nomically convenient keyboard positi on for the operato r's use.

IKAT consists of a bl ank, solid-state keyplate con taining a matrix of 48 touch-sensitive elements assoc iated with a visual d isplay unit (VDU). The display shows a corresponding matrix of 48 rectang les, and in each is written the function , or data content, of the associated keyplate elemen t. When the operator touches a key, the corres ponding rectang le on the VDU is in dicated by inversion of the v ideo - that is, it lights up. Therefore, the operator can readi ly slid e his finger to a chose n position on the keyplate to select the required function. To make an ent ry, he presses his finger down o n the keyplate to engage a microswi tch, an action co m pa rable to normal typing .

In th is mann er, the SPO uses the keyp late to select an item, such as HEA DING or FLIGHT LEVEL, and mak e an entry. He is then autom atically presented with another page

IKAT, Step 3

IKAT, Step 4

of data on his VDU, such as num erals to co ntinue the message entry. It can be considered that th e VDU data presentation is analogous to the sequential pages in a book of referen ce data : When an item on a page is selec ted, the next page in the message format sequence is introdu ced for an other item se lection. Thu s, the message format is determined automatically and cannot be subject to operator errors. Furthermore, at each step, th e operator is presented with a limited choice of items, all of which are valid selections at that stage in the message entry, un like a conventi o nal keyboard where all keys are available at all times and many of which cou ld be invalid if typed.

this key, the VDU disp lay is changed to that shown in the third photograph, which contains the necessary data fo r the revised f light leve l to be input into the training system.

Step 3. Note that the aircraft at th is stage is still on the same bearing and speed, but its altitude has been increased to FL 096 (9,600 ft.) - it is still climbing. The revised altitud e f ig ures are at this p o int keyed into the terminal. The new flight level is to be FL 120 ; this photo shows that the figures 12 have been assigned and t he remaining digit. 0, is about to be.

The most effective way of describing how the So lartron JKAT has simp lified aircraft control in an ATC simulator exercise is b y illustration. The acco mpanying seq uence of photog raphs shows the steps invo lved in assig ning a new fl ight level to one of the airc raft und er the SPO co ntro l. In this case, the c leared alt itud e of "Air India 278" is alte red from 15,000 feet to 12.000 feet, according to inst ruct ions issued by the trainee controller who is seated in front of a plan position indicator display: Step 1. At th is stage, the SPO, who ha~ four ai rc~af t un der his co ntrol has identified Al -278 by li ghtly running his fin ger across' th e non-designated keyboard until th e Al-278 panel on the VDU lights up. Having checked that the co rrect airc raft has been chosen. the pilot app lies extra pressu re to the key, and the page display on the VDU changes to that s hown in the next photograph.

Step 2. This display reveals that Al-278, over the B rookmans Park beacon (BCN BPK), is flying on a bearing of 221 (BRG 221) at an altitude of 8,900 ft . (FL 089) , and is climbing to 15,000 ft. (C 150) at a speed of 500 knots (500 KTS). The FLI GHT LEVEL panel is shown i lluminated , in dicating th at the SPO has located the appropri ate key and is app lying very light f inger pressure. After he appl ies extra pressure to

Step 4. The flight level has been keyed in, and th e final stage before executing the message is this check on the new in st ruction. The revised flight level is shown in the upper left hand co rner of the matrix with the alternative in structions EXECUTE o r DELETE in 't he upper right hand co rn er. Pressing the EXECUTE key enters the message of t he flight level change. The DELETE fac ility allows for errors in the data to be rectified . (If, for example, 11 o had been in advertently keyed in instead of 120 as the flight level, the ins tructions would be cancelled before execut ion so that the operation could be performed again , this time with the correct data.) N ot shown is the final stage in the sequence. where, having executed the revised flight level, the display presented to the SPO reverts to that shown in Step 1, where he is kept info rmed of exerc ise t ime. aircraft under his co ntrol , and so on , whi le a wait ing fresh ATC instruc tions.

Thus, the complete operation of altering the flight level of Al-278 according to the trainee control ler's instructions has been carried o ut in a matter of five or so seconds. It shoul d also be rec ognized th at the display in Step 2 sh ows th at any of the flight profil e parameters c ould have been altered , such as bearing or speed , as well as additio nal data so li cited, s uch as range from beacon. It has been proved that by using th is method of track control. si mulator pi lots can become proficient in a matter of hours. rather th an weeks.

37

Around The World in Forty Days, Or What Kept You Jules Verne?

by E. McCluskey, Eurocontrol Bretigny

From 1964 I hadn't missed an IFATCA Conference so it was not without some trepidation that I heard of the decision to hold IFATCA '75 in Melbourne, Australia. Impossible, I thought, but so were so many other things, so what about doing the "impossible" several times over. The Conference had to be tied to a long leave. So once Qantas had announced the days when certain flights were impossible, it was a question of arranging to arrive in Melbourne the day before the Conference, to leave Brisbane either on a Thursday or a Sunday and to leave home and arrive back on a weekend.

So armed with a ticket which was more like an accordeon than anything I've seen, passport, visas, health certificates, case, camera and overnight bag on the 22nd March 1975, the journey into the unknown began and without the aid of M. Passepartout. Having been assured that heavy clothes were not necessary for the West of Canada, imagine my astonishment when the great day dawned with snow on the ground. The unknown started immediately since the flight left from Charles de Gaulle Airport, Paris, which is an adventure in itself and not at all easy to negotiate.

Air France announced a delay of one hour on departure and as I had a forecast four hours to wait at Montreal, the delay could quite conveniently be used to find one's way around the complicated duty free shop system and find the gate for departure. Finally we were off over the Channel, S. W. England, Ireland and out on to the Atlantic. This was an Air France new to me since I am used to their short flights. The service and the cuisine was France at her best and the film just as un-understandable in French as in English. Newfoundland passed below, the Saint Lawrence river, and we were touching down at Montreal Airport having caught up the hour lost and with the prospect of the dreaded four hours wait.

On time to the minute, we boarded the Air Canada "direct'' Vancouver but with the temperature at 4 degrees below there was a delay while the aircraft was sprayed with de-icing fluid. Now for the first time of many occasions I was to fall foul of this word "direct" which is used by the airlines much as the Italian Railways use "rapide" or "diretto". It means exactly the opposite. The stewardesses dressed in blue jeans and checked blouses gave the impression that temporary staff had been taken on but I suppose looking back this "uniform" must be considered as national costume. It was early afternoon and we were asked if we would like dinner. Not yet fully recovered from a surfeit of French cuisine. I was in two minds but thankfully I accepted. The "direct" flight now spent an hour on the ground at Winnipeg. Airborne again, it was announced that dinner would be served to those who boarded at Winnipeg who by local time had probably just got up from the table, but those who boarded at Montreal would be served with coffee and peanuts. At last I had discovered why we controllers used to call Trans Canada "tin can". It was true and with another hour at Edmonton with similar treatment after getting airborne yet again, many were wondering whether malnutrition would set in before Vancouver and some

38

had to go further. Through the gathering dusk the Rockies passed below and at 8 p. m. local time the welcome lights of Vancouver were seen below.

When one meets Irish cousins one has not seen for twenty years, the boat just has to be pushed out. All very well if your body believes that it is 8 p. m. Mine was not entirely convinced, but the "longest" journey was already over or at least so I thought. Naturally the family laid on visits and right from the start illusions began to be shattered. Spectacular as the Rockies are, they are not more so than the Alps and the mighty Fraser river famous for its rapids could have been crossed on foot without getting one's knees wet, if one could stand the temperature. Vancouver Island looks tiny on the page of an atlas. In fact it is as big as Ireland and the ferry from Vancouver to Nanaimo is bigger, and the journey longer, than the equivalent Dover-Calais. However, pricewise, the Canadians can take over the cross-channel run any day they like. Their charges are approximately 8 per cent of those of the crosschannel monopoly between England and the Continent.

The big surprise both in Canada and the States was the difficulty in changing Deutsch Marks. Small banks were willing to change with three days notice. Suddenly a week had passed and it was off to the airport for the Canadian Pacific flight to San Francisco. If Charles de Gaulle is difficult ior finding duty free shops, Vancouver is easy. One hour before flight time, you are too late. As in Montreal, security checks were done with an x-ray machine which shows the whole world how badly you 've packed your bag.

The flight departed one hour late and fortunately duty-free supplies were available. I say fortunately, since although a certain brand may be the international passport to smoking pleasure, it and its equivalents do not seem to have received a visa for the west of the U.S. A. Apart f ram one evening visit across the border from Vancouver, the arrival in San Francisco was another first and it is highly recommended as a gateway to the U. S. A. Never before in such a large city have I found people so friendly. And of course there are all the wonders of the Golden Gate Bridge, the Cable Cars, Telegraph Hill, the Redwoods, Chinatown, Fisherman's Wharf (although I prefer the old name of Barbary Coast), the Mission Dolores and many more. It is small wonder that people leave their hearts in San Francisco. But time was again catching up and I now met Qantas for the first time, not on R/T. After years of complaints, the companies got rid of the iniquitous airport taxes into the price of the ticket. These are back under many different guises, but a "leaving the mainland tax?"

The State of Hawaii should do something about that. Leave the mainland we did in a 747 which had almost as many cabin crew as passengers most of whom were cabin crew on discount tickets. They also seem to rate first class treatment at the expense of the fare paying public and it took exactly four hours and numerous requests before finally I could smoke "nontoasted" tobacco once again. The holiday mood was now established so it was with a little dis-

appointment that there was no Hawaiian music no hula girls and no welcoming leis at Honolulu Airport.' That like everything else must be paid for, but nevertheless the friendly "Aloha" everywhere soon repaired the damage and I was shortly installed in my hotel on the beach at Waikiki.

This was the time to relax, enjoy the sun, the beach, the pool and the fantastic Hawaiian cocktails. Nevertheless one had to see something and the trip around the island of Oahu via Pearl Harbour, the sugar and pineapple plantations, the northern beaches with the enormous surf the Mormon Temple and the upside down waterfalls upwards by the wind, Diamond Head and the Church of Father Damien are memories not easily forgotten. The guide on the tour had everyone enthralled with his stories of Hawaii's history but fortunately he did not look up the valley that morning and see 300 Zeros flying down towards Pearl Harbour and order his passengers out into the ditches, as he had done several years ago, only to discover that they were filming "Tora, Tora, Tora".

The last day arrived and with the prospect of a 2359 hrs take-off, it was decided to retain the hotel room until 8 p. m. A fortunate decision, since had I checked out at midday as others had, Qantas could not have contacted me to inform me that the flight was delayed eight hours. Others were not so fortunate and slept in the open since the airport buildings are closed for security at night. My hotel was paid by the company and the hotel at the next stopover informed and so at 8.45 a. m. it was off across the dateline and the Equator to Fiji. The Qantas system had worked so efficiently that the hotel construed the message that I would not be arriving at all, and now the panic to find another. on the dateline it had become Sunday and there was the interesting experience of going to Church in a little Mission school and of being the only European apart from the Missioners themselves. It had been my intention to contact the Fijian Air Traffic Controller's Association and now the ATC Mafia system began to work. After interesting discussions on IFATCA and the difficulties of control and SAR in the area, Mr. Patel - the Fijian observe~ to .Melbourne _ very kindly showed me around. Another 1llus1on was shattered when 1 discovered that it takes three days to go around that island. So much for the tiny d~t on the map marked Fiji.

In the early evening I was staring at the sky for my first sight of the Southern Cross. And later tasting the local brew called "Nice Bolos" (or "Nice Nice" for those of you who are not fluent in the Fijian language.) It consists of white rum, sweet Italian wine, ice, pineaple and orange juice. Very refreshing and two hours later the top of your head blows off. But the tropical beauty of Fiji had also to be left behind and I boarded the Air New Zealand flight for

blow~

Auckland.

For service, Air New Zealand went immediately to the top of the league and was not to be surpassed for some time. Although the flight arrived on schedule, the hotel had let my room as I was considered late, despite the Qantas guarantee of payment so again it was "look around". Certainly the Auckland hotel was the worst of the trip and with the attitude found in Auckland I was beginning to regret going to New Zealand. The "porns" seemed to have brought their attitudes with them. The New Zealand Airways flight to Wellington was on time but otherwise was reminiscent of British internal flights. My impressions of New Zealand were rapidly changed when Peter McDermott - who was to lead the New Zealand delegation to IFATCA '75 - turned up to greet me at the airport and from then on the red

carpet was laid out from the Chief ATCO all the way down and the hospitality knew no bounds. I was fortunate also i~ meeting again Keith Naisbitt this time with his family. Keith was the first ever New Zealander to come to a Conference way back in Vienna. So there were plenty of reminiscences of .eveni.ngs in the Vienna Woods drinking half pints of white wine. Not only did attitudes change but also the weather for instead of the windy city of Wellington, the sun shone, the air was calm and the beauty of the city and the surrounding area could be appreciated. Then came the flight to "next door" Australia. A distance almost equal to Canada-Ireland and again with the excellent service of Air New Zealand. And so at Kingsford Smith Airport Sydney the Australian adventure had come true. Installed in the hotel, I decided to get my bearings and was rather shattered to hear from across the street "Bon jour, Ted comment ra ' v va.?" T he French delegates had arrived the other way round and had already found a discount souvenir shop. At least the lady of the shop had offered discount but her husband was Dutch, and so it took some good-natur-ed haggling to achieve that discount. (Yeah, trust the Dutch - Ed.) It must be the bridges, but here in Sydney was all the welcoming ~tmosphere of San Francisco. And Sydney has no less tourist attractions than the California city. Certainly the new ?per~ House with the backcloth of the Sydney harbour bridge is a sight well worth seeing and no less impressive are the "colonial" buildings with their "Sydney lace" the beach at Bon d"1, the surf at Bronte, the parks and gardens ' which seem to cut the city into several parts and, so far from Athens, the seco~d . largest Greek speaking city in the World. The h~spitahty and the organisation of our Australian colleagues will .be mentioned elsewhere so for the visit to Melbourne it suffices to give p ure 1Y personal remm1scences.

• • • was a This great IFATCA Conference because it showed that the Federation has co me o f age albeit . six . years early. There ~as an extremely high standard of technical debate both m Committee and 0 ut s1"d e. The dangerous rapids of politics .· were once again negot·1ated with · extreme prec1s1on · · by t he E xecutive Board and the innate goodwill of the controllers present. And it was with great personal satisfaction that I watched the c on f erence take the necessary steps to give · IFATCA a n e ff ect1ve · . at the same . legal personality while time, after a long and at times difficult series of negotiatio~s: the Eurocontrol Guild finally became a Member Association and I had the pleasure of receiving the scroll from the hands of the President. 1 must be slipping but it took me until Saturday to find the Australian brand of Conference committee in committee D. Who will forget the Australian ~olklore at Emu Bottom? After watching the efforts at throwing the boomerang, I'm convinced that the Swiss should 39

stick to cross-bows and I'm equally convinced that a certain Swedish delegate got his back,. by some. conjuring trick.

The city of Melbourne also had its attractions not least of which the art gallery where the windows permanently need to be washed and the Yarrow river which "flows upside down", the cottage of Captain Cook smuggled out of England by some far sighted Aussie and of course the fantastic Fitzroy Gardens.

The Melbourne hospitality did not stop there, as I found out when I arrived at Cairns after another "direct" flight from Melbourne which took in Sydney, Brisbane and Townsville on the way. At least TAA turn round in an average of fourteen minutes. A signal had gone ahead and at Cairns Australian hospitality continued uninterrupted. one event .was as outstanding as the next, but who would refuse the chance in Australia to fly with an ambulance flight? Off through the Baron Gorge along the Barrier Reef to Cooktown and then up to Weipa, a bauxite town on the Cape York Peninsula. But alas, not one pati~nt but !our ~o 1 am offloaded! I thought of Phi leas Fogg without his tram in the middle of the prairies, but here was no railway line.

In one hour the panic was over and FIS had arranged a lift back to Cairns. Aviation in Australia is just like that. Next day at the unearthly hour of 6 a. m. I had seen my first Australian dawn and was off to take part i~ another trip arranged by the airport staff at ~airns, this time b~ speedboat to the Great Barrier reef. This day had everyt~ng from catching coral trout, to swimming from a sand island in the to the sail along the Coral reef to Green Island, . .

C ora I Sea , with its underwater observatory and its crocodiles well enclosed. Of course by now I was beginning to forget which day it was and literally turned up early by 24 hours for my flight. The thought of another early start was not appealing I pressed on to Brisbane and was fortunate to be able so h bi .. to see the ANZAC Day parade. Then t e memora e v1s1t to Australia had to end. There was no bet on the time taken b t ne had to consider other stops still to be made. So on b~a~ the Qantas 747 yet again illusions were shattered.

Leaving Brisbane at 2 p. m. it was only four and a half hours later that we left the Australian coast finally behind and the flight was nicely timed to see Bali in the sunset, unfortunately only from the air. I~ was on over the Flore~ Sea to th~ spectacular sight of Singapore harbour by night. Here 1t was that the system seemed to break down. The next page of my accordeon ticket had not been recorded in the Malay Airways computer and now I was on standby. It was in Singapore that one noticed the influenc~ of London Airport.

Arriving from a foreign country and going to another, one

40

is forced to go through customs with the inevitable security check because one has been out in the main concourse, and still with a customs and immigration check at destination. The intervention of the Qantas station manager ensured a seat on the flight and one hour after takeoff we landed at Kuala Lumpur where the hospitality again rivalled that of Australia. A meeting arranged by Claude Oliveiro~ who had been many years ago training at Prestwick, allowed all facets of IFATCA to be discussed with Malaysian controllers. I believe that it will not be too long before Malaysia joins the Federation. Here one had to be impressed with the development which has gone on in the country since independence. But again regretfully the visit was all too short and Bangkok was the next stop. The highspot of all the flights must surely be the service on Thai International and what is more their stewardesses in national costume must be the prettiest in airline service anywhere.

As if that was not plenty, imagine my surprise when I was given vouchers for taxis and my hotel by the clerk with whom I confirmed my onward flight. "We are different from other airlines, we look after our passengers. Welcome to Thailand" he said. What a pity Thai don't fly all around Europe! Bangkok of course is a fabulous city with its palaces and temples and its famous floating market. It was a wonder to watch the skill of the gem-cutters and the embroidery workers. Time did not permit a trip to the renamed Mekong to see the "Bridge on the River Kwai" but on the military note one could not help noticing the smartness of the Thai army and the precision flying of the Air Force. Thai also have "direct" flights and the Delhi flight routed¡ via Dacca but the high standard of service was, if anything, surpassed.

Delhi is a city of contrasts between the old and the new.

Perhaps the main interest was the Red Fort with its palace ancient site of the peacock throne before it was taken by the Persians. But Delhi was not the object of the visit to India so it was off to Agra by Indian Airways with a rather aptly named Captain "Hurree Hurree". Of all the monuments visited surely the last was by far the most memorable.

In seeing the Taj Mahal one cannot be disappointed. It is far and away more magnificent than words and pictures can portray it. Satisfied that the journey had gone according to plan, there was now only the flight home to think of, but 1_had not counted on Indian weather. Just prior to flight time, the sky blackened with a sandstorm and the aircraft prom~tly overflew. By the time Indian Airways got semiorganised and put the passengers into a tour bus with some Japanese tourists, there was no chance of catching the scheduled Japanair flight from Delhi. Five hours for a journey of 175 km in a standstorm was not my idea of an ideal way to end a holiday, but more was yet to come. The bus delivered all the tourists to their hotels (Air India was now gone also) and finally dropped the connecting passengers a~ the Indian Airways office in the centre of the city. And did we come as a complete surprise to the duty officer!

After two hours of argument as to why we should not pay our own way to the airport and arrange our own onward flights, they finally conceded the taxi fare and phoned the duty officer at the airport. But the taxi ride was not to be direct since the police were holding up traffic because of the arrival of the Prime Minister. The Japanair flight had been another of these all stops to Paris so the prospect of an actual true direct flight to Frankfurt by Lufthansa looked as if lost time could be recovered. Unfortunately, half of India had the same idea and the flight was grossly

o0verbooked. If one can be amused at such a time in the morning, it was rather amusing, looking back on it, to find an airline steward trying to talk farepaying passengers off 1he flight as this was his only possibility to use a ten percent ticket for his parents. No wonder Committee A had such hard words to say about IATA! Offloaded, everyone was on to the inevitable Clipper One. By this stage, I was beginning to wonder how the dear old lady who knows nothing of airlines ever copes. For now Pan American could not accept a ticket made out to Japanair

by Qantas unless one of these airlines made it over to PanAm, but their representatives were no longer there. So back to Indian Airways to ask if be:ng members of IATA meant nothing and finally the PanAm station manager came 1o an agreement that the ticket would be guaranteed. Airborne at last with the prospect of a flight via Karachi, Beirut and Istanbul to Frankfurt and then make my own arrangements on an open ticket to Paris. Breakfast arrived: two sandwiches on a serviette and coffee in a cardboard cup but after 17 hours without anything it was like nectar and ambrosia. It was only later that I realised that the service was not in the top half of the league. However, Philias Fogg had crossed half of India on an elephant, so at least my Jumbo was faster.

Ah, but surprise, surprise, the aircraft went unserviceable at Beirut and some passengers were offered a night-

stop at Holiday Inn. But alas! - last year's Conference had been in Israel and there was no question of passing passport control. Arrangements were being made by PanAm for Frankfurt and London passengers, but Paris is not on their route so it was off to negotiate with Middle East Airlines.

This time direct Paris was possible in twenty minutes, if only I could get a PanAm representative to drop his negotiations for the London flight in four hours t!me. Finally somebody signed and Cedarjet promptly upgraded the ticket to first class. However, their 707 was also unserviceable and there was another wait until another was found.

Touchdown at Orly was at 5.30 p. m. instead of the scheduled 7.50 a. m. at Charles de Gaulle, less than ten hours late after all the Odyssey, but with all the places not yet seen, perhaps the more leisurely pace of Jules Verne has something to say for it. I must seriously think of that when IFATCA goes back to Australia as surely we must one day.

But now with the adherence of Sierra Leone, Africa has become our second region numerically speaking. I wonder how long Jules Verne would have taken on that trip? Oh, well, next year the Conference is only a couple of tankfu!s of petrol away and as usual Lyon will become the most memorable Conference ever. It always happens. Just ask any of those who've been. Nevertheless, I will not be greeted at the office next year with "Welcome back Christopher Columbus" as happened on May Sth last.

News from Member Associations Argentina Like their U.S., French and German colleagues before them, the air traffic controllers of Argentina are going through a trying period, with 6 controllers still dismissed and other punitive measures still in force as a result of the industrial ATC dispute in that country. But their spirit is unbroken, and the ties between ATEPSA and IFATCA have been strengthened through the solidarity displayed and preoccupation shown by the worldwide community of controllers.

Following the efforts by the President of IFATCA in trying to establish a climate of reconciliation, the Swiss Association have taken the initiative to collect funds to help ATEPSA pay the salaries of the dismissed controllers, a gesture which our friends in Argentina are much appreciating. ATEPSA and IFATCA will both continue their efforts, in close cooperation and in the interests of air safety, to steer the situation to normal circumstances.

Australia compensation One of the members of the Australian Association who worked for 18 years in a control tower has made a successful claim under the Compensation (Commonwealth Employees) Act for skin cancers upon his arms and hands. It was determined that he had "contacted a disease, namely solar damaged skin, arising out of or in the course of his employment."

Belgium The Guild has conducted an opinion poll among its members, the outcome of which will serve as a guide to the Executive when it comes to assessing the priorities of tasks in hand and the kind of action members would like to see taken.

Belgian controllers attach most importance to factors which directly affect the job of controlling air traffic itself, grouped generally under the heading "common professional interests". Immediately following are, in this order: equipment, ATC procedures, automation, management, flightreducing facilities, work-coordination, legal aspects, etc.

Less importance is attached to factors which concern the safeguarding and consolidation of the profession itself, such as public relations work, publicity and allied matters. At the bottom of the list come subjects which facilitate the work of the controller, as design of control rooms, restroom facilities, canteen service and individual interests.

The full survey, the results of which the Guild would no doubt supply to interested parties on request, makes interesting reading, but may well be disputed by controllers working in other environments, especially where recognition of the controllers' profession has not reached the level attained in Belgium.

Canada A New Motto for CATCA The suitability of CATCA's present motto was questioned at the 1975 Convention and the delegates directed the

41

National Council to consider devising a more appropriate one. The council subsequently accepted a suggestion from the Quebec Region that "The Guiding Hand" would succinctly express the controller function and would correspond to the CATCA logo which appears on the Association's letterhead. The council further agreed that the new motto should be rendered in Latin. The classics departments of two universities were ~~nsult~d a~d bo~h recommended the phrase "Manus Dmgens , which will begin to appear on CATCA's stationery as new stocks are ordered.

United Kingdom Medical News The Guild reports that its Medical Advisory Committee, under the Chairmanship of Dr. N. C. Brown, are planning to repeat their past success by holding another Medical Symposium, in Manchester, 10th & 11th April 1976. Once again the Symposium will discuss 'Stress in ATC' and, once again, it will enjoy and benefit from the generous sponsorship of Geigy Pharmaceuticals Ltd. IFATCA's Member Associations will recall the event that made such an impact on the Guild's reputation, namely the Medical Symposium that was successfully organised in Manchester in 1973. Members and Non-Members alike applauded the efforts that brought about that unique opportunity of introducing the general medical profession to the singularly peculiar problems of the Air Traffic Controller. The Doctors listened and posed a number of questions; they showed great interest in the controllers' problems - particularly the stress factor - but all made the same comment "when are you going to do this again".

As to the subject of stress: at the 1973 Symposium, a number of questions remained unanswered and it is hoped that the subject will be covered in much greater depth at the 1976 meeting. A distinguished panel of medical and scientific speakers of international reputation has been encompassed, and SATCRA have offered their considerable facilities and experience into their research into stress factors and will be contributing in full. The Guild itself will be presenting forceful arguments in favour of a reappraisal of existing situations. The full facilities of the post-graduate department of Manchester University and Messrs. Geigy Pharmaceuticals have been offered for the venue.

Alpha-numeric Callsign Trial The European Division of British Airways have been carrying out a trial to determine whether the use of Alphanumeric callsigns reduces the likelihood of callsigns confusion and confusion of callsigns with flight levels and headings. A meeting of the interested parties was called to discuss the results.

Very few pilots had commented on the scheme and the majority of those who had were opposed to it. It had been determined from several operational controllers that they were not enthusiastic about it either, and from this it was concluded that in view of general opposition to the scheme in its present form it would be discontinued and emphasis placed on the need for good R/T discipline_ by both pilots and controllers. Any changes in the allocation and use of callsigns would have to be agreed internationally to be really effective and would have to be compatible with the stored flight plan system.

42

The Guild believes that a problem does exist and that further thought should be given to the subject. In the meantime good R/T discipline offers the best protection against error.

United States The PATCO Scene After 14 months of bargaining, PATCO and the FAA reached agreement on a new labour contract for controllers.

Both Acting FAA Administrator James Dow, himself a former controller, and PATCO President John Leyden praised the return to labour stability that approval of the contract would bring.

In testimony before the Transportation Subcommittee of the U. S. House of Representatives' Appropriation Committee, PATCO has asked for more controllers and more money for ATC. President Leyden said that although the new automated ~~uipment can be of substantial help to controllers, no add1t1onal controller productivity can result. The President detailed the various increased workload elements controllers now face.

After an interval of several years, the PATCO Journal has reappeared, and the long-awaited pilot issue contained 52 pages, with a 4-colour cover of RDP at Chicago Centre an~. the same highest quality layout and paperstock and wntmg as in the past. IFATCA congratulates our u. s. Member Organisation on an excellent production and wishes PATCO every further success in this field. ' Alth?ugh held now quite some time ago, the results of :ATCO s 1975 Convention in Minneapolis continue to draw mtere~t.. At the Convention, Mr. C. O. Miller, former Director 0 ~ Aviation Safety for the NTSB, outlined the new PATCO Air Safety Program. The stated purpose of this program is to develop daily safety consciousness, by continuously en路 路 larging and man i t ammg an air safety program among the cont~ollers which will not only contribute to accident preve~ti~n but also enhance the role of the controller in the aviation community. The program will include operational hazard analysis, to resolve hazards "before the fact" an ATC Safety Information Center to develop a knowiedge base ~f known precedent in ATC safety matters, safety education and training to foster safety awareness, and the encouragement of participation by the membership in ~rou~s and activities where controller impact can be effecti~e m the furtherance of air safety. As to accident investigation: the Organisation has now structured its efforts on a 路 more w路 . organised footing. A three-man PATCO "go-team" ill 1~ future be sent to the crash site; one field investigator spec1a!IY trained for the task, one member of the Safety C~mm1ttee, and one representative from the National Office.

Wit~ the ~elp of the NTSB, PATCO has developed an ATC accident investigation course for its field people which is hope~ w.ill produce a more knowledgeable and efficient contribution to the investigation.

The Convention proved one of the best attended, with over 800. attendees. Robert Meyer, IFATCA's Vice President (Professional) was re-elected unopposed for a further threeyear term as PATCO Vice President (Great Lakes Region).

Attendees were also given details of the PATCO/FAA agreeme~t on the structure and composition of a new Classification system for determining controller grade levels. The Cl~ssification Report recommends the adoption of a factorpomt method which considers the total work environment

and responsibilities of controllers - particularly job complexities - as well as the volume of traffic.

Misgivings have been expressed regarding the division of responsibility between pilot and controller for terrain separation. In the wake of recent crashes, the FAA has placed more responsibility on the controller for terrain avoidance by having him read the approach plate profile to the pilot and by additional altitude monitoring. The controllers accept these duties but lack the resources to make these activities practical. Reading the profiles back and forth ties up already crowded radio frequencies, distracts the controller

from his other separation duties, and accomplishes very little. Additional monitoring of altitude with reference to terrain forces the controller to hold the aircraft for a longer period of time and allows him to concentrate on fewer planes. Both of these "safety" procedures have the result of slowing down traffic by reducing the number of flights a controller can safely "work" at any given time. The additional tasks are especially burdensome to those terminals which are understaffed such as O'Hare, Miami and others; the procedures call for extra staff for which the FAA has made no provision.

The AGARD 20th Guidance and Control Panel Meeting/Symposium, Part I

by V. D. Hopkin Royal Air Force Institute of Aviation Medicine, Farnborough, U. K.

Introduction From 20 to 23 May 1975 at the Transportation Systems Centre in Cambridge, Massachusetts, the 20th Guidance and Control Panel Meeting of AGARD was held on the topic of 'Plans and Developments for Air Traffic Systems'. About 250 delegates attended. The current status and future plans for much of Air Traffic Control were covered in the proceedings, which consisted. of two k~ynote addresses, thirty-seven papers, a symposium over-view and ¡summary, .. and visits to the Lincoln Laboratories and to the Boston ARTCC En Route facility. The symposium was divided into seven sessions; there were no parallel sessions. The seven sessions covered respectively navigation, surveillance, automation, airports, approach and landing, advanced concepts, and system performance measures. Each paper or group of papers was followed by a discussion period.

Following the formal welcome and Chairman's introductory remarks, the first keynote address was given by Mr. e. McLeod of Pan American World Airways. Viewing the theme of the conference from the point of view of airline management problems, he emphasised that at a time when airlines were fighting for survival because of high costs and fewer passengers there was a need to be more critical in adopting highly complex sy~tems an~ to pr~fer cheap~r, simpler systems which functioned satisfactorily and which needed less costly avionics since these costs had in turn to be covered by increased charges. In considering DABS (Discrete Address Beacon System) and IPC (ln.ter~ittent Positive Control), the airlines would have no ob1ect1on to these in principle but wished to be reassured that less costly alternatives had been as thoroughly evaluated. An evolutionary process of ATC development was advocated.

Existing system capacity may be actually reduced wh~n new aids are introduced because of greater concern with the limits associated with factors such as turbulence.

The second keynote address was given by Mr. J. Dow, the acting administrator of the Federal Aviation Administration. His cautionary tone was similar to that of Mr. Mcleod.

He foresaw the need to reduce the manpower intensiveness

in air traffic control in the future as a means of limiting the ever-increasing costs incurred. He emphasised that at the present time while new aids and developments must be thoroughly explored and evaluated the need for careful costing was most important. Both these keynote addresses were of interest in making it clear that future developments in ATC must not only be technically reliable and innovative but financially acceptable and not overcomplex.

Navigation The first session included papers on radio navigation, on strategic control and new systems. The first paper, by K. Watling and R. C. Rawlings of the Royal Aircraft Establishment Farnborough, described studies of automatic navigation systems to improve the utilisation of controlled airspace. They thought that technology already can provide a planning and operational capability well beyond that to which the navigational system can respond. They believed that the use of improved navigation in controlled airspace in the future could produce useful savings in time and money within a short time. This conclusion was based on the optimum use of VORIVMA and relied on reducing lateral and longitudinal separations by providing accurate statistically predictable performance. The most useful first steps in the provision and use of improved navigation systems would be to examine a spectrum of modern navigation systems and their associated laws in order to assess their ex~ected performance, and to study and develop systems which would permit smooth automatic coupling and would attempt to learn the magnitude and direction of existing wind in order to allow for it.

The second paper, by M. Pelegrin of the Ecole Nationale Superieure de l'Aeronautique et de L'Espace, described four dimensional navigation in terminal zones considered as an automation problem. He described a method using a combination of real time and fast time simulation.

Precisely controlled descent profiles could lead to substantial improvement in descent times if they could gain pilot

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0

acceptance. In a more automated system, it _should become possible to follow such precise descent profiles.

Mr. R. L. Erwin of the Boeing Company presented a r on the strategic control of terminal air traffic. In his pape d f" d f d" · I concept also, the air traffic system ~me our. 1mens1on~ tracks for all arrivals, leading to optimum spacing of traffic for landing on the runway. These tracks relied on using four . nsional navigation and guidance equipment to fly the d 1me · d assigned paths. Encouraging _results have ~een obtame . ·ng a fast time simulation of strategic control as 1n USI • . lied to arriving traffic at Los Angeles International A1rapp h · · d t r · ort. At this stage further researc 1s require o op 1m1se fhe algorithm, to test it in an ai~borne e_nvir~nment, and to find an evolutionary method for introducing 1t. or. H. Neumann of Messerschmitt-Bolkow-Blohm described Air Traffic Control concepts with extensive utilisation of automatic data processing. He thought that automated data processing alone was likely to increase controller workload, and envisaged a need for better co-operation between the controller and the computer. He believed that the computer should be used for support in real time which would lead to some small gains in controller capacity, that certain executive tasks should be assigned to the computer which would lead to a dialogue between the controller and the computer, that the computer should relieve manual support tasks and share the executive control with the controller, and that the computer must be part of a system into which data were entered by others apart from the controller in order to keep the interface between the computer and the controller himself reasonable for message dialogue. His paper was based on the notion that eight aircraft could be controlJect simultaneously by each controller. He distinguished various computer roles, a strategic long term planning role including flow planning, an intermediate role including flight progress adjustments and determining clearances, and a more tactical role dealing with actual flight data and flight progress control.

Lt. Col. J. F. Beran of the Wright-Patterson Air Force Base described a programme to equip approximately 700 United States Air Force aircraft with OMEGA navigation equipment. This programme is the first large scale competitive procurement of airborne OMEGA navigation sets. The emphasis is on obtaining low cost automatic equipment which satisfies en route navigation performance requ:rements. The paper described essential equipment characteristics and concluded that results from recent data collection flight tests demonstrate that an adequate technology exists to satisfy US Air Force requirements. or. R. S. Cooper of the US Department of Defence described a global positioning system in the NAVSTAR Program. This System is based on 24 satellites and would provide continuous coverage anywhere because at any point at least six satellites would be available from which the best four would be selected to provide the data. Very high standards of accuracy in position and velocity information could be computed and the data fed to numerous classes of land, sea, and air users. In drawing up specifications, emphasis was placed upon the maximum commonality of equipment and on ease of maintenance. This programme is now at the concept validation stage and soon transmitters will be installed on the ground and in airborne prototypes. The first satellite to start the evaluation is due to be launched in 1976 and a programme is envisaged in which further satellites will gradually replace existing ground transmitters.

Surveillance The second session, on surveillance, was concerned with both primary and secondary radar and with the requirements for military tactical surveillance. It began with a paper by Mr. K. Milne of the Plessey Radar Company surveying primary radars for air traffic systems. This described problems facing designers of radars such as the minimisation of ground clutter, of precipitation clutter and of angel echoes, combined with high reliability and with the need for an adequate data rate. Examples were drawn from current systems of the kinds of solution to these problems which are available or which can be foreseen.

Recent advances in automation and signalling processing techniques were interpreted in terms of their probable influence on future primary radars. It was thought that in the near future the main changes will be to make today's radars more compatible with automated control systems. More radical longer term changes were envisaged including the introduction of three dimensional radars to assist in achieving area navigation, and the development of adaptive multifunction radars to provide fadeless gap-free cover with improved system reliability.

Mr. M. Natchipolsky of the Federal Aviation Administration gave a paper on the improvement programme for air traffic control radar beacon systems (ATCRBS), also known as secondary surveillance radar (SSA). Current problems which degrade the presentation of targets were described, some of which, though tolerable to the air traffic controller, would not remain tolerable with automated equipment. Most current problems were attributed to poor antennas, difficulties of interrogator management, inadequate reply target detection and processing criteria, or inadequate airborne transponder performance. He argued that the monopulse processing and detection system has inherent advantages which can be realised and which should resolve most of the operational problems with beacons. He emphasised that the improvements which he described are practical and workable and have been demonstrated.

Mr. R. c. Bowes of the Royal Radar Establishment and Mr. P. R. Drouilhet of the Massachusetts Institute of Technology presented a paper on the ADSEL/DABS secondary radar selective address systems. ADSELIDABS refers to an address selective discrete address beacon system and can be thought of as a selective addressed secondary radar system which is an extension of the present day secondary surveillance radar. It provides the usual surveillance data of identity, height and position, and also a data link communication facility with signals between air and ground in both directions. It is proposed in the United States to link this device to the intermittent positive control form of air traffic control. The paper gave an overall description of the system and the results of some experimental work. The principal envisaged application is to provide enhanced surveillance and communication capability in support of the increased automation of air traffic control. A high inherent flexibility and growth capacity is claimed for the system.

Mr. R.R. Wilz of the Naval Electronics Systems Command described a marine air traffic control unit which permits an expansion of capacity of expeditionary airfields. Existing marine air traffic control units fulfil a tactical role and rely completely on manual operation. They can become saturated with air traffic and they rely on raw video, old equipment and no data link. The future MATCALS system is based on existing proven hardware and software and will be adapted to United States Marine Corps needs. It no

longer has the deficiencies of raw video, no data link and old equipment but will include automated conflict prediction and some conflict resolution by computer. The system is seen as a major advance in the sophistication and value of mobile air traffic control systems.

Automation The third session, on automation, included papers on human factors, on flow control, on conflict detection and resolution, on intermittent positive control and on an integrated multifunction system for navigation, collision avoidance and communication.

The first human factors paper was given by Mr. R. A. Rutter of the Mitre Corporation who considered the role of the human in a 'fully automated' system. Starting from the economic need to reduce the labour intensiveness of the ATC system while maintaining or improving safety and the utilisation of airways, he contended that it appeared to be technically feasible to achieve significant increases in air traffic control productivity, in the form of the ratio of flights handled to the number of staff needed, by means of the automation of the more routine IFR traffic, planning and control processes. One approach to the problem of formulating and evaluating an experimental model for automating routine en route sector control was described in the paper; having identified the basic design concepts and discussed the automated control tasks performed by a digital computer simulation he then envisaged the roles and responsibilities of the air traffic controller in such an environment and the future evolution of the controller's role. The size of the potential long term saving could be used to estimate the magnitude of the research effort which should be devoted to try and achieve these savings.

Mr. v. o. Hopkin of the RAF Institute of Aviation Medicine presented a second human factors paper, on the provision and use of information on air traffic control displays. His theme was that it is not sufficient merely to provide information for the controller but that this must be in a form which is compatible with his abilities, his skills, and his experience. Several kinds of mismatch can occur at the man machine interface in air traffic control systems, one of which is that the relevant information provided is not in a form which the man can use. A technological advance need not necessarily convey human factors benefits and novel display techniques may embody relatively obscure human factors problems which emerge only at a late stage in display development. Evaluations of innovations can be biased by concentrating on their known merits and failing to measure or reveal hidden inadequacies. The traditional reliance on the man's strengths of adaptability and flexibility, in order to match the man and the machine in the system, is thwarted if the man cannot use the information presented to him. Problems of ensuring that the displayed information has been adapted successfully and can still be used occur with changes from qualitative to quantitative information with incomplete automation, and with apparent retention of decision making roles when these have in fact been greatly modified. System changes may inadvertently affect the roles of human memory and attention, and design changes may therefore have to be introduced to aid and supplement these human functions in new ways.

Dr. R. s. Ratner of the Stanford Research Institute described the automation of local flow control metering operations in the en route/transition environment. His paper related a first step in the process of developing coordinated

local flow control. The development has been tested only in simulation and preliminary results suggest that capacity and controller productivity can be improved by introducing automation into local flow control without incurring any increase in traffic delays. Peak traffic surges would be regulated and smoothed by flow control processes and sector workloads could be limited to standard values. It is believed that this form of automation is inherently more tolerant of faults than is the automation of control processes more directly related to the maintenance of separation, because flow control deals with future rather than current traffic.

A paper by Mr. V. W. Attwooll of the Royal Aircraft Establishment dealt with the optimisation of traffic flow around a network. Two distinct types of study were described, those taking a simple situation and establishing the optimum balance between the penalties arising from rescheduling and delays due to actual congestion, and those in more complex situations with a network of routes concerned with the optimum distribution of planned flow rates among various routes and hence the desirable amount of rescheduling at each of the traffic generating airports.

The paper concluded with specifications for the application of the principles, envisaging firstly the establishment of planned flow rates on individual routes and secondly the preparation of optimum airline schedules to conform with target flow rates. The increasing complexity of routes may make it impossible for the controller unaided to reach an effective solution of such traffic flow problems in a network.

Two papers were concerned with conflict detection and resolution. One by Dr. A. Benoit and his colleagues from Eurocontrol considered some of the effects of the introduction of accurate aircraft trajectory predictions in Air Traffic Control. The development of a short term trajectory prediction module should evolve through a simple phase compatible with the present state of automation in air traffic control and then develop to a more elaborate phase compatible with a concept of air traffic control based upon long term accurate aircraft trajectory predictions. Existing aircraft data available at the control centre, mainly air routes, cleared cruising altitudes and radar information, are supplemented by simple processing techniques to extrapolate the trajectory of the aircraft for a short period. A prediction may then be made a few minutes after take-off for the rest of the trajectory with reasonably good accuracy. No additional data are involved at that stage. A second stage utilises additional data which does not require additional on-line communications. Examples would be the performance data of individual aircraft, and several levels of elaboration for data of this kind could be introduced successively. In a third stage, data not presently available could be generated or collated and introduced to the computer trajectory module. This would lead to a complete trajectory prediction system for use either on line or off line for traffic management purposes. The paper described some of the mathematical methodes and algorithms involved at the various stages in this process and related the theoretical findings to data from actual climbs of aircraft out of major airports.

This last aspect was developed by Mr. R. G. Ball and his colleagues from the Royal Radar Establishment. Their paper outlined a technique for improving the controller's ability to visualise by using computer assistance to provide a predictive display showing aircraft positions and configurations at a designated time in advance. The technique could also be used to help the controller with conflict detection 45

and resolution. The controller can conduct a dialogue with the computer and try out various options, the outcome of which can be displayed to him to enable him to assess the consequences of a proposed action before he actually takes it. The computer can also help to monitor the aircraft to ensure that they remain on conflict-free trajectories.

Mr. M. Perie of the Federal Aviation Administration described intermittent positive control (IPC), a totally automated ground based collision avoidance system. It functions by taking positive control of VFR and IFR aircraft whenever this is needed to avoid hazardous encounters. It also provides pilots with continuous information on the location of nearby aircraft and is intended to lead to safety in controlled mixed and uncontrolled airspace for all types of users in both the IFR and VFR flight conditions while retaining the freedom of action associated with VFR flight.

The paper included a description of the design concept of intermittent positive control, and presented the analytical simulation and experimental results obtained hitherto.

Simulation programmes are currently underway and a flight

test programme is also in progress with the aim of trying the IPC concept in an actual flight environment.

M. L. Milosevic of Thompsons, France, presented a paper on an integrated multifunction system for navigation, collision avoidance and communications. The intention was to seek a widely flexible system design, based on modules and extendable, accepting very flexible and rational procedures, permitting the autonomous operation of various stations, and allowing considerable initiative in communications both on the ground and in the air. Such a design provides navigation capabilites, surveillance with identification, and data link of individual standard messages, and also envisages digitally transmitted voice communications.

The anti-collision and landing functions are also facilitated.

The transition between current systems and an integrated multi-function system with all these facilities may be achieved either by introducing the new system as an entity or by adapting one of the current systems through several intermediate stages. Which is the better method can be determined only after a complete analysis of all the implications. (to be concluded)

OIDS: Operational Information Display System

by John Gaffney*)

Introduction The Electronic Systems Master Plan for Montreal's new airport at Mirabel identified a need to consolidate the display of information required by air traffic controllers. A system was 11eeded which would collect this information and present it on a television type display. Organised into "pages", according to type or control position requirement, different data would be selected by the controller only as he needed it. The myriad of dials, readouts, teletype printouts, overhead projections and scribbled notes would no longer plague the operational environment.

An engineering model was developed by TERC, Computer Systems, T & E Branch of the Canadian Ministry of Transport, to determine the feasibility of such a system and evaluate the effect of its introduction to ATS operations.

This model system was built around a minicomputer and incorporated only two display channels. When installed in the ACC at Dorval for testing and evaluation, the controllers were instructed not to rely on the displayed information but merely try to evaluate its effectiveness and usefulness. Responses to a questionnaire indicated an overwhelming acceptance and an immediate flood of suggestions for additions and improvements. The major concern at the time was the quality of the display. It was felt that some more work was needed to improve legibility and to cope more adequately with the high ambient light conditions during daytime operation in the control tower cab.

*) John Gaffney received his Master's degree in Electrical Engineering in 1971 and joined the Telecommunications Branch of the Canadian Ministry of Transport the same year. Specialising in digital circuit design and technology he worked in automation on both the secondary and primary radar digitiser programs. He became involved in the preparation of the OIDS specification in 1972 and is now the project engineer.

46

Confident that these problems could be resolved, a joint team from ATS and T & E prepared a final specification and issued an invitation to tender. The initial phase of the program had been so successful that the decision had been taken to expand the procurement to supply each of the Area Control Centres in Canada as well as Mirabal with a system. On this basis, a contract was let in September 1974 to I. P. Sharp Associates Limited to build the OIDS.

System Description The development of the final equipment specification for the OIDS resulted in the definition of a system that is somewhat more complex than the engineering model. The physical differences are mainly that the computer subsystem is now composed of duplexed processors which will run in a main/standby mode providing instant switchover in the event of failure, and that the display sub-system will supply thirty display channels initially and is capable of further expansion. Additionally, all data paths will be totally duplicated or at least backed up to provide failsoft operation. Even in the event of a total processing subsystem failure, a manual mode of operation will exist to permit updating certain vital data items. As a further protection against a total system failure, one set of conventional displays for wind and altimeter will be retained in each operational area, i. e., tower cab, TCU and ACC. Data inputs to the OIDS are considered to be of two types, automatic and manual. Automatic inputs are those which are fed into the system by being polled under computer control. They include wind direction and speed, current altimeter setting, RVR, weather reports, field lighting settings and navaid unserviceability status. The data is processed and formatted for display without manual intervention. Facility is also provided, however, for manual input to modify existing data, add new data, or delete old

By a control signal issued by the master, the display subsystem is instructed as to which output to accept for display. The standby processor monitors the operat ion of the master while conti nuing to process data itself. In this way, the standby is instantly ready, shou ld the master fa il, to assume the role of master and continue to provide the required output w ithout interruption to th e user. When such a switch-over occurs, the now-failed master is p revented from regaining contro l of the system wi thout manua l intervention to clear t he fault. Should the second processor fail before the first is repaired, the system can be reconfigured to continue operat ion on a l imited bas is w ith all inputs provided manually. When one o r both computers are repaired, the operationa l program can be restarted and, after a short time to allow the data base to be regenerated to current values , t he system can be returned to norm al operation.

In the degraded or totally manual mode of operati on. the user will have only a limited info rmation dis play ava i lable to him. Since the d isplay of such things as AVA and wind are dependent on the computer to p rocess the ana log inputs and provide a digital display, th is data would be lost if the comp uters failed. To p rovide the most critically required information i n t his case , two th i ngs are done. Firstly, one set of ana log readouts for wind is retained whe re possible, in each operational area; i. e., towe r, TCU, ACC. Secondly, a special data page is p repared whi le t he computers are operating. Th is page contai ns data wh ich can be updated manually, and is stored in a memo ry in t he d ispl ay su b-system. When requ ired , then a si mple switching ope ration will p rovid e this d ispl ay pag e to all posit ions and all ow the collator position to up date it manually through his keyboard. During any s uch time of manual or

information which is no longer required. Manual input is effected by the use of keyboards and a set of commands which are recognised and acted upon by the compu ter.

The display of information at the controller positions will be on a CRT monitor. The data is preformatted by the computer into "pages", the size of which is limited to the amount of information that can be displayed i n a legible manner on the monitor. Pages are of two basic types, general purpose or "primary", and single purpose or "secondary". All pages can be selected for viewing at any display position by simply entering the page number via a push-button keypack. In this manner, the controller can retrieve specific information when he wants it without having to sort it out from reams of paper or a myriad of displays.

The Hardware The heart of the OID System is a pair of lnterdata Model 70 minicomputers. Each contains a fully-configured 64 K-bytes of core memory and necessary interfaces for interconnection with other parts of the system. An ASR-33 teletypewriter and a dual drive cassette unit are provided as peripherals, one of each for each computer. All data inputs, either automatic or manual, are provided to both computers where they are processed for d isplay. The machi nes run on the same operational program , at the same time, though not in perfect synchronisation. Output is available fro m both. The selection of which wi ll be displayed is made in the display sub-system according to which co mpu ter is the master at the time.

During normal operat ion, with both computers operating, one is designated "master" and the other "standby".

I. P. SHARP ASSOCIATES LTD. ADVANCED ATC SYSTEMS I. P. S harp Associates (IPSA) succeeds in consolidation of its role in A ir T raff i c C o n tro l rel ated prog rams with two major contract awards in 1975.

• •

OID S INFO 75 -

Th e Operational Information Display System for Canad a-wi de use.

A management information sys tem for Schipol Airpo rt in A m st erd am.

OID S is a multi-channel, computer-b ased vid eo dis pl ay used by ai r co n tro llers to ret rieve essen t ial data instantly upon request. Some examples are: runway vi s ibilit.y, we a.ther cond itions, al ti mete r sett ings , time, runway in us e and many o ther types of d ata for his own a 1rpo r.t incl udi n g _ o t~er ai rports th ro ug hou! the world. The central ization o f data will simpli fy th e c o ntro ll ers duti es b y e l1 mmatmg the need fo r c heck ing a variety of indiv idual senso rs and printouts.

INFO 75 provid es for an Airport D ata Display System usi ng vari o us inpu ts f rom other ai r t raff ic control systems sui:: h as SARP and SATCO. · t Ltd ·1s one of the largest Can ad ian -owned c ompanies spec ial izing in c om puting s y sI . P . S h arp A ssoc1 a es ., . .d t 1 d t · ·· · The co ntinuing aim of IPSA 1s to prov1 e proc ess con r o , a a acqu 1s 1t1on , au tom ated tern s an d se rvices . . . "th th I · Id d T h. analytica l systems and computer comn:unications tn kee ping w 1 e evo v 1ng wo r nee s . o ac 1eve this a im, IPSA offers s ig nifi cant content 1n : • •

System Engin eering and Management H ardware Design and Production

•

S o ftware Design an d Product ion

•

System Tes t a nd Integ ration

· t es L·im·ited , Bo x 1900 • 150 Rosamond Stree t , Carleton Pl ace, O n tario KOA 1JO I . P. Sh arp A ssoc1a

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emergency operation, the user would have no page selection capability beyond this special page.

The collator position mentioned here is an important part of the OIDS. The position consists of a keyboard, CRT monitor, stand-alone video generator and refresh memory and manual switches for system reconfiguration in the event of sub-system failures. The functions of the collator include verification and correction of displayed data, entry of NOTAM's and messages, the routing of particular information to the position or positions primarily concerned, and the assumption of system control in the event of total computer sub-system failure as previously described.

Production of a highly legible and reliable display is probably the most important aspect of any display system.

The display sub-system of the OIDS has been designed to provide these features in the simplest manner possible.

There are two video controller chassis, each supplying half the video channels required, plus one extra channel which acts as a back-up to the channels in the other chassis. Both chassis are interfaced to both computers so that both can receive data from the master computer.

Each video channel has a dedicated video generator and refresh memory. A video generator failure, then, causes loss of display at only a single position. During the time needed for repair, the controller can switch his monitor to the standby channel. The information on this channel is essentially a duplicate of his normal primary page and is continuously updated by the computer. While in this configuration, page selection is not possible from the affected position. Repairs and restoration to normal operation will usually be very rapid, requiring only the replacement of the printed circuit board for that channel.

The CRT monitors to be used in the OIDS are of high quality manufacture. Supplied in two sizes, 9-inch and 14-inch, they will have a P-31 phosphor (green) and a nonglare etched face plate. The non-glare feature is required to combat the high ambient lighting conditions of daytime tower operations and has also been found to yield an excellent picture in the normal and darkened conditions of the ACC/TCU. The monitor chassis is designed to permit mounting in consoles or stand-alone cabinets so that the monitor can be positioned for the greatest convenience of the controller. In order to provide even better .,isibility by each individual in a multiperson sector operation, slave monitors can be added to a display channel and positioned as required. tn such a configuration, although the same information appears on all monitors in response to requests from a single keypack, everyone can be afforded an

or at least by manual reconfiguration causing only minor interruptions.

All is not milk and honey, however. Computers are only as smart as the people who program and feed them with data. Occasionally, errors occur and these must be corrected. Thus, the "man-in-the-loop", the collator, is required to keep an eye on the machine and be ready to tend a hand if the going gets tough. This is not to imply that the machine cannot be trusted to get the job done. Indeed, the predicted system availability for the OIDS is better than 98.5 %, and it is the fervent hope of the designers that the one and one-half percent of the time that the OIDS might be in-operative will occur when the airport is closed because of weather.

Summary The delivery schedule for the OIDS is in full swing, and the system has been installed, or will be installed, at Mirabel; the Development Certification Centre in Ottawa; the Telecommunications and Electronics Training Centre; Dorval; Winnipeg; Vancouver; the new ACC at Dorval; Moncton; Edmonton; Toronto; and Gander.

The OIDS forms part of the Canadian ATC automation program. Together with the JETS, ICCS and other computer based systems such as FIDS and GAATS, it is another step in the development of a system which must grow to meet the needs of a rapidly expanding air traffic control operation. As such, it has been designed to meet a number of requirements today to improve the operational environment of the air traffic controller, and to be able to expand to serve more and varied needs tomorrow.

As the system will exist initially, it operates on a standalone basis, independent of other systems. It is foreseen, however, that in time, links will be established with the previously mentioned systems and perhaps with others not yet conceived. It should also be noted that while the OIDS is capable of expansion, it is also capable of contraction.

Scaled-down versions could be supplied to serve the needs of smaller operations consisting of a tower and TCU or a tower only.

The key to such expansion/contraction capability is a modularly designed system, the modules of which can be assembled in the required configurations or can be modified or even replaced entirely as new or better designs are created. The OIDS is such a system. (first published In the Spring, 1975 edition of the CATCA Journal)

unrestricted view.

Airmiss

The Controller's Viewpoint To the air traffic controller engaged in vectoring an aircraft onto final for 06L at Montreal, OIOS is merely a name for the push-button keypack and CRT monitor he has before him. He need not concern himself with the why's and wherefore's of the data collection and display process. And this is precisely what the system was intended to accomplish. By merely pressing two numeric keys on a keypack, the search process. which could involve leafing through a clipboard full of messages or craning to read an overhead display at the end of the room, is accomplished in milli-seconds and the requested information is presented.

Failures within the system are countered in some instances by sophisticated and imperceptible switchover to good units

48

"Airmiss" - the dreaded word crackled around the control tower as the captain of a Boeing 727 approaching a South African airport reported narrowly missing converging traffic early on Christmas morning. Frantically the unhappy controller scanned his movements board in search of the offending traffic while grabbing for the microphone.

"No traffic on the board; must be some hamfisted pilot who hasn't bothered to file a flight plan", the controller thought to himself. "Can you identify the other aircraft?"

ATC asked the Boeing skipper.

"Affirmative". came the reply. "He was a funny little man with a large beard sitting in a sleigh and being pulled by reindeer ... " (World Airnews)

News from Corporation Members Cossor Radar and Electronics Limited Eurocontrol has placed a contract worth almost 20 million Belgian Francs with Cossor Electronics for the installation of a dual secondary surveillance system (SSR), and related ancillary equipment, on Mount Gabriel, near Cork, Ireland. The radar station will comprise two buildings each housing a SSR 700 equipment enclosed under a Radome.

The duplication is to obtain the essential reliability since the station will be remoting data to both the Eurocontrol Upper Area Control Centre at Shannon and to the London Air Traffic Control Centre at West Drayton. When operational in early 1976, this station will give upper airspace coverage in the S. W. Atlantic approaches to Europe (particularly the supersonic transport routes) and give dual coverage of the Eurocontrol SSR station at Shannon.

This station will be a practical example of Eurocontrol's role in rationalising the air traffic system of Western Europe and in providing Air Traffic Control facilities covering more than one State in the interests of both economy and operational efficiency.

International Air Carrier Association IACA recently held its Sth Annual General Assembly in Geneva. The membership unanimously re-elected Anders Helgstrand (Sterling Airways) as head of the Ass~ciation confirmed Edward J. Driscoll (NACA) as 1st V1ce-Prean d sident and Leoncio Salazar (Spantax) as 2nd v·ice- Pres1'd ent.

During the course of the meetings, ~. complet~ review was made on worldwide air transport policies, practices and procedures, with particular emphasis o~ discriminatory and restrictive practices by governments with respect to charters and their effect on consumers' access to this lowcost mode of transport. Resolutions were ado.pt.ad opp~­ sing the establishment of artificially pegged, minimum .prices by governments and the extension of part-charters into markets. It was concluded that both of these actions would undermine the basic air transport structure. . . .

IACA re-affirmed its adherence to the following prmc1~­ les: a) equality of treatment of all consumers; b! .competition in a free-market as the proper method of pricing charters; c) elimination of restrictions which preclude the freeflow of traffic between countries which restricts consumer access.

Marconi Radar Systems Ltd. A Marconi-developed system of Computerised Mo~ular • .

• . d nd under operational Monitoring (CMM) 1s now insta 11 e a . evaluation by Britain's Civil Aviation Authority. CMM is designed to ease the problems of systems management a~d this installation the first of its kind to be tested operatio• 't · of the nally, is carrying out remote control and moni oring en route ATC radar station at Raith Hill in Scotland.

CMM modules implanted in the equipment at Raith Hill collect data which is digitised and transmitted over a normal telephone channel to a control centre at Gailes, seven miles away. By this means the Raith Hill station can be continuously monitored from Gailes, and if its performance is seen to be degraded preventive action can be taken. The

control facilities of CMM can operate over the same network as that used for data gathering and can be used to bring a standby unit into service or, during maintenance, to institute marginal testing.

The company has also completed a study and prepared a draft specification for the inclusion of CMM in the new Scottish Air Traffic Control system scheduled to start in December 1976. Marconi CMM is designed to gather and process information from a selected number of key points in almost any group of electronic or electromechanical equipment. It gives a rapid assessment of the extent of any failure and helps to optimise the performance of the equipment. The system provides constant automatic checks at every level of operation, detects the development of faults as they happen and gives valuable warning time which enables immediate remedial steps to be taken. The detailed sensing is carried out by data selector units which, because of their small size and interfacing characteristics. can be implanted in either new or established equipment to sample digital or analogue quantities - for example, voltage, frequency, time, events, temperatures and pressure. The resulting data is passed in analogue form to a digitising and control unit and from there in digital form to a central processor, where the final assessment and analysis takes place. The final link in the chain is the operator's console unit. If required, the interface between the operator and the computer can take the form of a control panel and electronic display unit so that the operator can take immediate remedial action.

The Plessey Company Limited Bahrein International Airport is to be equipped with a Plessey AR-5 primary radar and a Series 200 automatic secondary radar under a contract announced earlier this year. The AR-5 is an L-band (23 cm) radar, first introduced in 1971.

Plessey Navaids has a £ 30,000 ($ 72,000) contract from the British CAA for a Type 1020 DME for Edinburgh. The DME is to be integrated with a STAN 37/38 ILS, the first such use of DME in the U. K. It will serve an over-water approach where marker beacons cannot be installed. Cat. 3 operations are planned. The Type 1020 was developed by Butler National Corp., USA, with whom Plessey has a Manufacturing and Marketing Agreement. Plessey Navaids is also installing a PLAN 17/18 ILS at the Hawker Siddeley airfields at Hatfield and Woodford in England. Total value of these two systems exceeds £ 100,000 ($ 240.000).

Racal-Thermionic Limited Racal-Thermionic Limited have added Spain and Holland to the list of European countries into which their International Communications Recorder has been sold. Launched approximately two years ago, this range of recorders is now in service in more than forty countries. The orders received from the Spanish Air Ministry and the Dutch Fire Brigade are in addition to recent sales into Norway. Belgium. Italy and France.

Used for non-stop monitoring of communications circuits, the recorder is specifically designed for ultra thin triple-play tapes. enabling sufficient tape for more than 24

49

hours continous working to be packed into a spool only eight inches in diameter, and will monitor up to 32 channels simultaneously.

Software Sciences Limited Software Sciences has been awarded contracts to evaluate the capacity of Portela Airport and airspace under various conditions for the Portuguese Government, and to evaluate the capacities of Dusseldorf and Cologne/Bonn Airports and their terminal control areas for the North Rhein/Westphalia Ministry of Transport.

The Portela study forms part of the Portuguese Government's review of its future capital investment programme which includes provision for a new international airport at Lisbon to replace Portela. A special Government committee has been set up to review this requirement and Software Sciences will be evaluating the capacity of the existing airport and its airspace to assist the committee in determining if and when a new airport is necessary. The company will carry out a fast-time simulation of the Lisbon FIR to evaluate its capacity against forecast future requirements. The Portela study confirms an international trend towards optimisation of existing airport capacities as a means to at least delaying capital expenditure on new airports.

The contracts for Dusseldorf and Cologne-Bonn form part of an overall study, involving an evaluation of the present and planned runway/taxiway configurations at both airports and of the capacities of the present route structures within the associated terminal control areas. Constraints and critical areas affecting the achievement of optimum capacities are to be identified and the interaction between the two airports evaluated. The contracts also involve two German consultancies who are investigating the implications of a combined airport and forecasting air traffic volume.

Software Sciences have now won over eighty contracts in the airspace field in twenty countries. The company's strenght in this area derives from its combination of ATC experience (six of its consultants are former air traffic controllers) and management sciences skills.

The SATS system, incorporated in the Swedish ATC College at Malmo, provides co-ordinated civil and military ATC training using a flexible computer system. Facilities available include the simulation of more than one radar stati~~· the display of u~ to 90 aircraft of 30 different types, prov1s1on for up to 13 ~1mult~neous exercises, and a library of ATC procedures including standard arrival/departure routes and ILS approaches. As in the TAST system data may be frozen or replayed as required. The simulator has 39 positions, including 12 16in radar PPls and 14 pilot positions. The system h~s storage for 4,000 simulated flight plans and 500 exercise plans. The simulation speed can be varied from two-thirds to five times real time. on associated electronic data displays (EDD) information regardin aircraft movements and meteorological data can be dis~ played. The EDD is . used by the student both to rece·1ve information an d to input data into the system via a keyboard. The computer can display on the EDD predicted aircraft tracks up to nine minutes ahead. The pilot can input aircraft flight parameters and initiate R/T frequency changes, tra~sponder co~es or pre-programmed flight programmes. Simulated radio transmissions can be relayed around up to 34 of the 39 positions.

Thomson-CSF, France In a company reorganisation, Thomson-CSF has concentrate_d respon~i~ility for its airport and Air Traffic Control equ~pme~t within one company, T-VT. The Department of Landing Aids (Depa.rtment d'Aides l'Aterrissage), formerly a part of the Microwave Division of Thomson-CSF has ~~en transferred to T-VT. The latter, a Thomson-CSF subs1d1ary based at Meudon near Paris, is responsible for radar and ATC systems. With the addition of ILS, VOR, DME and Sydac (the portable C-band microwave landing system), T-VT offers a range of airport and airspac · _ .th' . e equip men t f ~om w1 . '". ~ts own. organisation, a point felt to be of particular s1gm!1cance in international marketing.

Another move m the reorganisation is the incorporation of Thomson-CSF Audiovisual (TAV) into T-VT. TAV I d r II t eIev1s1on . . area Y sup~ 1es a screens used by T-VT in its information systems.

a

T-V~r.s capital has been doubled to fr 50.4 million (about

Stansaab Elektronic AB Stansaab of Sweden has specialised in the field of simulation of Air Traffic Control systems and is a leader in real-time simulation techniques. The company has many years of research and development experience in data systems and design and production of all equipment except standard computer peripherals is carried out in-house, as is the continued development of software. Turnover exceeds £ 10 million annually and Stansaab has 800 employees at its factory near Stockholm.

Two of Stansaab's major projects are the TAST training simulator for the Royal Swedish Air Force and the SATS Air Traffic Control simulator for the Swedish Board of Civil Aviation. TAST provides training facilities for radar trackers, observers. height operators and interception controllers. The system provides fully computerised radar simulation for seventy consoles interfaced with graphic and alphanumeric data displays. The software system includes inputs which provide such detail as ECM simulation, clutter display and a facility for recording and replaying exercises, and .. freezing" displays for analysis. Fast-time (i. e. quicker than real time) simulation is also possible.

50

$ 10 m1lh~~). The company anticipates a turnover of about

fr ~00 m1ll1on ($ 100 million) this year. Radio-Suisse the Swiss ATC authority, has placed a fr 10 million ($ 2 miilion) c~ntract f~r. automation of radar data at the Geneva-Cointnn and Zunch-Kloten regional Control Centres . Th e equip· ment will consist of double 720 systems for processing · . of radar and flight data, with T-VT 570 consoles eq · d ·th 16 · th t• uippe w1 -m syn e 1c radar displays and electronic data d.1 _ plays. Equipment earlier installed by T-VT will now be all ~­ cated to approach control, and the new facilities will be used for en-route control.

All Traffic is Traffic to Controllers "I'm a bit worried about that world seminar on air traffic control that got under way in town today.

About 400 air traffic controllers from all over th Id tt d" Th , e wor are ~ en. mg. e~ ~e the lads with the complex and responsible Job of guiding the big jets safely into airpo t That's why I'm puzzled by part of the ad . . r s. · ·t · h vice given to v1s1 ors m t e conference hand-book. It tells them the satest way to cross the road!"

(Columnist David Brunton in the Melbourne .. Herald... 14 April 1975)

Comments on Air Traffic Control Heard Around The World U. S. Radio Commentator Earl Nightingale, in a commentary on the stresses and obligations to which controllers are subjected: On our last program, we were discussing ulcers, and the research that indicates they are produced from a feeling of helplessness to cope with stressful situations, and the most ulcer-prone job in the world appears to be that of the air traffic controller, the man who uses radar to guide the landings and take-offs of planes at busy airports, and their position in the skies.

The air crews are unaffected, passengers are unconcerned, but the poor air traffic controllers seem to work and labour in a state of vicarious horror. A study of 111 controllers in the Chicago area by Dr. Richard R. Grayson of St. Charles, Illinois, disclosed that one-third have peptic ulcers and another third were on their way to develop!ng them. Controllers work under enormous pressure, which they often can't control. Airplanes keep coming, especially at Chicago's O'Hare Airport where the test was conducted.

A plane lands or takes off about every thirty seconds, and at peak traffic times they are coming in and going out in bunches. Controllers live in constant fear of a mid-air collision. That is a terrible responsibility to rest upon a human being. After a near-miss, a controller said, "I just felt as if I had been in a bad automobile accident, and came out of it unscathed. I was nauseated, felt weak, my heart was racing, and my hands were sweating."

Or. Grayson said that a narrowly averted mid-air collision caused by one of these conscientious, intelligent, punctilious young men, has the same effect on him as he himself had just escaped death by a hairsbreath. The symptoms that follow, such as anxiety, insomnia, inability to eat, and irritability, plus their spin-off effects of marital discord, inter-personal animosities, and efforts of peergroup support, all become stresses in their own right. On a day on which weather conditions are bad, at the rush hour in the late afternoon, with hundreds of jets from all over the country and all over the world converging on one small patch of real estate, each plane with its precious load of human beings, and which each having to be held in an area of safe air, so it can be vectored in to land, why, it must be like juggling a dozen vials of nitroglycerin, standing in a hammock, in a schoolyard. But they do such an outstanding job, making air travel safer than any other form of transportation, including walking - a testimonial to their skills and dedication.

Squadron-Leader B. C. Jones, SATCO, RAF Gutersloh, Germany, in a commentary on IFATCA '75, Melbourne 14-18 April, 1975: Nearly 500 delegates and observes, from 37 nations, attended the 14th Annual Conference of IFATCA. That so many travelled so far is an indication of the growth and success of the Federation since its foundation in Amsterdam in 1961. The acceptance of Sierra Leone, Sri Lanka and Eurocontrol this year brought the number of Member Associations to 41, supported by some 23 of the world's leading aviation industries as Corporate Members.

There are several reasons for this growth but possibly the most valid is the realisation by the individual controller that nobody understands his problems, or appreciates his

worth, like another controller, whatever his nationality, colour, language or political alignment. At the 1973 Conference in Reykjavik, Iceland, a senior observer from the International Labour Office of the United Nations, a veteran of 20 years attendance at meetings of all persuasions, stated that he had never before met such rapport between delegates. "Argue they may", he said, "but never with rancour and never losing sight of the aims of their profession and their Federation."

These aims were well summarised by the Australian Minister of Transport, the Hon. C. K. Jones, in his welcoming address to the Conference at the Melbourne Hilton " . . . the role of the Air Traffic Controller is vital to the safe, orderly and expeditous flow of air traffic. It is a role demanding continued dedication, deep concentration and a high degree of alertness and expertise." Despite these demands, th.e 1.ast two years have seen controllers imprisoned for wishing to form an Association; controllers suspended, then fired, for seeking professional status; and controllers forced to take additional jobs to obtain a living wage. Ho~ever, dedication and expertise were certainly apparent in the scope and depth of material presented in th~ three committees of the Melbourne Conference: Committee "A" Administration, Committee "B" Technical, and c.ommittee "C" Professional, whose members worked, despite the temptations of the host country and the incredible hospitality, a solid ten-hour day. Subjects varied from the re~orts of the Regional Councillors, through Area Navigation Systems, Simultaneous Use of Parallel Runways and Automated Interchange of Air-Ground Data, to Hi-jacking and the Legal Liability of the controller.

The President of IFATCA, Monsieur Jean-Daniel Monin, Supervisor at Geneva Centre and legendary figure among the world's air traffic controllers was ever-present and indispensable. Probably no-one c~uld have brought about agreement between the Cypriot and Turkish representatives on the differences.- around the Cyprus ATC situation. The President's annual work programme reads like that of a captain of industry, with a trouble shooting trip to South America, trips to the U.S.A. and Southern Africa TV interviews and hard-hitting speeches to internationai congresses. ~et all this is undertaken in leave and off-duty time and his technique is charm, logical argument and persistence. Another IFATCA veteran, John Saker, currently Watch Supervisor at London Air Traffic Control Centre functionned as Chairman of Committee "B" a truly for~ ' m1"d a bi e JOb, but the endurance record must have gone to Ray Soden, the Conference Organiser, also Chairman of Committee "A". How he managed this, only Ray will know.

I

One of the President's tasks in 1974 had been to present a paper to an ILO meeting entitled "ATC - A Profess_ion Still Without Status", indicating a world-wide conviction among controllers that they were being taken for granted, and at the Final Plenary a resolution was announced of Committee "A" aimed at settling a long-standing grouch ~f co~trollers - lack of concessionary air travel rights. It is the'.r belief that the pilot/controller relationship is special, and vital to the safety of air navigation, and that this is best fostered by contr~llers flying whenever possible. Under present IATA regulations - the infamous (to the world's controllers) _Resolution 200 - controllers are denied the ticket concessions afforded to airline employees and are obliged to pa~ full fare to travel w:th IATA carriers. The subsequent adoption of the Committee "A" resolution meant that the 51

Federation is now committed to take positive action to right what is considered a serio~s wrong. . . . ·1 Air Operations Officers Assoc1at1on of AustraTh e C IVI • • f . t have worried future contenders for the pos1t1on o I 1a mus . · W'th host association by the magnitude of the!r expe~1se.. 1 ous help from the hotel and an 1mpress1ve hst of t remen d · d' sponsors it was organisation par excellence,. me 1u mg a · I post-mark at the Conference Post Office, sumptuspec1a · f ·1· ous receptions and dinners, immaculate committee ac11ties, secretarial agency back-up and even lessons on Australian lore and language · · ·

Publications Review The United States Air Traffic Services Corporation

by Glen A. Gilbert, Glen A. Gilbert Associates, Suite 1002, 2650 Virginia Avenue N. W., Washington D. C. 20037.

The PATCO commissioned study on the need to re-structure t.he Federal Aviation Administration has turn.ad into ~ "bes~-seller" with calls from many quarters for more copies. Published m two ~olus Volume No. 1 presents the basic elements of the study m a ;~OOO word document, including 10 tables and organlsat.ion cha~s, while Volume No. 2 contains comprehensive background information and references on which Volume 1 is based. . .

The study explains that over 90 °/o of FAA's personnel 1s d~rectly or indirectly involved in the . ATC Syste~, and .as the Air T ffic service is so predominant m the FAA s functions, these s~~uld be performed in a separate organisational s~ructure, fu~~­ tioning outside the Department of Transport/FAA. Smee _the c~v1I users of the service pay at least 50 O/a of its costs, a busine.ss-llke oach would afford the best concept on which to base this new atppcr tu re hence the name "The U. S. Air Traffic Services Corporas ru • · · · ·11m1'l'tary tion".

However, the service would continue the 1oint c1v1 1 use of the airspace in the "common system". Gilbert stresse~ t~at his proposed new concept of government organisatlo~ ~or av1a11on is based on a solid study of the b~st features ~f existing government agencies, as well as those of private companies. .

The Corporation would have a nine member Board of Directors. reporting directly to the U. S. Congress, and appointed by. the U ..s.

President, subject to confirmation by the Senate. The en~ctmg legislation will establish the broad categories representing all shaof aviation activity including the user element (users of air d tr:~sportation) - from which the Board members will be selected ithout regard to political affiliation but based solely on character :nd ability. The report describes in detail proposed internal rules f the Board and the functions of each of the units under the Board.

0 Gilbert believes that FAA's Regional Offices in the USA shou~d rouped. With 20 areas under the control of Air Route Traffic ~e ~e~I centres, a simplified, streamlined "Area Office" for each of hon r control areas should result in more efficiency, increased safety, t eds~ economies, in contrast to maintaining the present extensively an in . f' . f om ff d nine regional offices. A long list of bane its accruing r sta e at·ion of the new corporation is listed. There is no doubt that the ere .

Gilbert's arguments are convincing and carry sound reasoning ..

The end goal of this study is, of course, the enactment of implementing legislation. To this end. copies have been .w.idely. distribut~d H se and Senate members. departmental offlc1als involved m to. t~u i'ndustry and news media. Gilbert's study proves one factor av1a 1on. th above all: the immense role. but. o~ten toned down, played by e ATC System in today's world of av1at1on.

GdB

The ICAO Annual Report, 1974 published by the International Civil Aviation Organisation, 1080 University Street, Montreal 101, P. Q. Canada.

In its customary Annual Report, which was rele~sed i~ May 1975, ICAO reports that efforts to improve the over~ll air traff'.c managenationally, regionally and Co ntinued on a broad front. t ment sys . . 'd emin 1974 The need for optimum e ff'1c1ency o f A'ir T ra ff'1c worldwi e. · 1 ·1 bTt f d' t ATS outes was Services (ATS) and for genera ava1 a 1 1 y o 1rec . r accentuated during the year by the need for special measures to

52

conserve aviation fuel due to restricted availability and increased costs. The need to extend the provision of Air Traffic Control service to routes or areas where flight information service or air traffic advisory service had so far been considered adequate or acceptable continued to be emphasized. The requirement that SST aircraft, when introduced into commercial service, must be provided with ATC service at all times during transonic and supersonic flight aa· ded a new dimension to this question.

In high traffic density areas, the need for better utilization of airspace and greater air traffic handling capacity was a matter of continuing concern. Increasing attention was given to the accuracy and reliability required or aircraft navigation systems as a basis ror reduction of current horizontal separation minirr.a; and, \he aeva1opment of internationally agreed minimum performance specifications for navigation systems used on oceanic and other long-haul routes was advocated. The potentials of area navigation techniques were further explored, as was the role of ground-based monitoring systems in the separation of aircraft. The feasibility of reducing vertical separation above flight level 290 was given renewed attention, and the practicability of introducing composite separation also for flights between the United States' mainland and Hawaii was examined.

Measures to regulate the air traffic flow along heavily travelled air routes or to limit the number of flights into particularly congested aerodromes, to eliminate or to reduce excessive delays, continued to be applied and refined, pending Increases in the capacity of aerodromes and the air traffic management system. In Western Europe, a number of temporary ATS routes were created to reduce the traffic density on the regular routes or to bypass areas of frequent congestion.

The application of primary and secondary surveillance radar continued to expand with particular emphasis on the latter. In the highly technically developed States, the use of automation for the processing and displaying ot fllght-plan and flight-progress information and ror the interchange of data between adjacent Air Traffic Control units or between control positions within such units was steadily expanded and refined.

In the U. S., a programme for the introduction of an Automated Radar Terminal System (ARTS) at 61 high-to-medium density airports was completed. And, a plan for equipping airports having a lower traffic density with a less sophisticated ARTS system was being pursued, as was a programme aimed at introducing by mid-1975 automated radar data processing in all of the 20 Air Traffic Control Centres. Major ATC automation progrnmmes were also in progress in Canada, Japan and Western Europe.

Airborne collision avoidance or proximity warning devices continued to be the subject of research and development. Flight tests performed with one system indicated the feasibility of combining the functions of an airborne collision avoidance/proximity warning device with those of an airborne transponder and data link. However, no specific type or system had been selected for standardization, nationally or internationally, by the end of the year.

During the year a new programme was agreed upon by a group of States. Known as the "Aerosat Programme", it has as its goal the launch in 1978 of two satellites bearing a test. evaluation and demonstration system for aeronautical and Air Traffic Control communications and surveillance, primarily over oceanic areas. If the results are technically adequate and their cost effectiveness favourable, this programme could lead to an operational aeronautical satellite system in the middle-to-late 1990s.

(ICAO Bulletin}

The Golden Wingnut of the Month This award goes to the seasoned Arrivals controller who crossed microphones with the VFR Private one very busy Monday morning not so long ago.

He couldn't have arrived at a worse time - the flow had reached. no. 38 in the sequence, and someone was threatening a go-around, while the STAG was secretly negotiating a quick runway change. The Omni was out, the localiser was dropping off, someone was talking about a displaced threshold on 07 and the tea was cold.

"ABC, due to congestion in the terminal area. orbit in your present position until advised".

"ABC, Roger, how many orbits do you require?"

"ABC, you do the orbits, and I'll do the counting."

(Cocodooledoo. Sydney)

ATC ground-to-air equipment

for frequency ranges 100to162 and 225to 400 MHz Safety in aviation is only possible with precise electronic instruments and communications syst ems, such as those Rohd e&Schwarz has been d eveloping , producing and bettering f or th e past forty years. Rohde & Schwarz also offers you perfect service, from planning right down t o maintenance and training .

Receiver - transmitter - transceiver fo r rad iotelephony, soli d-state and of fl exible modular design: VHF/ UHF simultaneous receiving equipments EU 25 . . . /ED 21 ... w ith several channel receivers operatin g on one antenna. Along w ith this go preamplifi ers and multicouplers.

VHF-AM 50-W transm itter SU 151 (1 c han nel) o r SU 156 (6 c hann els) , broadband design, no time-consumingtun in g w hen changing crystal. VH F transmit-

ting system NU 156 (next to operator) , with six pri mary transm itters SU 151, two st andby transmitters SU 156 and aut omatic switc hover un it. UHF-AM 30-W t ransmitter SO 131 (1 chan nel) of broadband design.

VHF-AM 10-W transmitter/receiver NU 001/2502 w ith transm itter SU 116 (6 c hannels). VHF-UHF 10-W t ransceiver XT 3039 - multi channel equ ipment particularly suitabl e for emergency status.

VHF/UHF antenna systems Th e multiple-utility omnidirectional antennas of the series HA 53 (above left) are particularly suitable tor transmission and reception in ATC applications.

Splitters and f ilters available for switching several transm itters or receivers to one antenna.

~DE

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