IFATCA The Controller - January/March 1968

D 20418 F

I FATCA JOU RNA I! OF AIR TRAFFIC CONTROL

In this Issue A Slightly Closer Look

At the SST Terminal IFR Capacity

FRANKFURT AM MA I N

JANUARY / MARCH 1968

VOLUME 7

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New TELEFUNKEN precision approach radars improve landing safety Why? Range inc reased from 10 NM to 12 NM Indica tor sc re ens enlarged from 10 in . to 16 in.

Separat e sc ree ns fo r 4 and 12 NM rang e Modernise d anten nas for co ntrol of appro ach es to diffe rent run ways In co nseq uence landing fac ilities are grea tly improved for p oo r vis ibility c onditions In addition we supply : airways s urve illance rada rs 路 termin al a rea ra d ars . ra dar remo tin g systems 路 da ta processing s y stems . data transmission sys tems

ALLGEMEINE ELEK TRICITA TS-GESELLSC HAFT AEG -TELEFUNKEN Export De pa rtment 路 79 Ulm (D onau) ElisabethenstraBe 3 Germany

Corporation Members of the International Federation of Air Traffic Controllers' Associations The Air Traffic Control Association, Washington D. C., U.S.A. Compagnie Generale de Telegraphie sans Fil Malakoff, Paris, France Cossor Radar and Electronics Limited, Harlow, England The Decca Navigator Company Limited, London ELLIOTT Brothers (London) Limited Borehamwood, Herts., England FERRANTI Limited Bracknell, Berks., England IBM World Trade Europe Corporation, Paris, France ITT Europe Corporation, Brussels, Belgium Jeppesen & Co. GmbH, Frankfurt, Germany The Marconi Company Limited Radar Division Chelmsford, Essex, England N.V. Hollandse Signaalapparaten Hengelo, Netherlands N.V. Philips Telecommunicatie lndustrie Hilversum, Holland The Plessey Company Limited Chessington, Surrey, England Selenia - lndustrie Elettroniche Associate S.p.A. Rome, Italy The Solartron Electronic Group, Ltd. Farnborough, Hants., England Telefunken AG, Ulm/Donau, Germany Texas Instruments Inc., Dallas 22, Texas, USA Whittaker Corporation, North Hollywood, California, USA The International Federation of Air Traffic Controllers' Associations would like to invite all corporations, organizations, and institutions interested in and concerned with the maintenance and promotion of safety in air traffic to join their organization as Corporation Members.

Corporation Members support the aims of the Federation by supplying the Federation with technical information and by means of an annual subscription . The Federation's international journal "Th~ Con troller" is offered as a platform for the discussion of technical and procedural developments rn the field of air traffic control.

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IFATCA JOURNAL OF AIR TRAFFIC CONTROL

THE CONTROLLER Frankfurt am Main, January/March 1967

Volume 7 · No. 1

Publisher: International Federation of Air Traffic Controllers' Associations, 40 Pork House Gardens, East Twickenham, Middlesex, England.

Officers of IFATCA: L. N. Tekstro, President; G. W. Monk, Executive Secretary; J . R. Campbell, First Vice President; Second Vice-President (post vacant); Hon. Secretary (post vacant); Bernhard Ru thy, Treasurer; Walter Endlich, Editor.

Editor: Wolter H. Endlich, 3, rue Roosendoel, Bruxelles-Forest, Belgique Telephone: 456248 Publishing Company, Production and Advertising Soles Office: Verlag W. Krom~r & Co ., 6 Frankfurt am Main N014, Bornheimer Landwehr 57a, Phone 434325,492169, Postscheck Frankfurt (M) 11727. Rate Card Nr. 2.

Printod by: W.Kromer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr 570.

Subscription Rote: DM 8,- per annum (in Germany).

Contrib~t~rs 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).

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

CONTENTS A Slightly Closer Look at the SST .. . ... · · · · · · · · · · · · · · · · · ·

6

IATA Looks at the Terminal Crisis ... . . . · · · · · · · · · · · · · · · · · ·

by Tirey K. Vickers

9

Invitation to Munich

... .. .... · . · · · · · · · · · · · · · · · · · · · · · · · · · .. ...... . ·

15

ICAO's Fifth Air Navigation Conference ... .. . .. . ....... . .

21

Pilot Proficiency and ATC ......... . . . ........ · ... · .. · · . · ·

22

RTCA Meeting Highlights Terminal IFR Capacity c_ontributions ore welcome as ore comments and criti· crsm. No. pa~me~t c~n be made for manuscripts submitted for P_ublrcotron rn The Controller•. The Editor reserves the rrght to make any editorial eh .

• h'ch h . onges rn manuscripts w I . e b~lieves will improve the material withou; altering the intended meaning.

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

14

by Michael V. Huck Area Navigation Techniques in the Terminal Area

by T. G. Angelos

23

V/STOL Navigation in the Terminal Area . . . . . . . . . . . . . . . . . .

27

by E. N. Baur

Advertisers in this Issue: AEG -Telefunken (Inside cover) The Decca . Navigator Company (Back cover), N.v: HoHandse S1.gnoolapparaten (36), Philips Telecommunicot1e lndustrre (4), Selenio S.p.o. (Inside bock cover).

Automatic Position Data Transfer

by G. D. Hadorn

28

The Air Route Interface

31

by R. F. Frakes Potentials for Increased Airport Capability

32

by Harry P. Schmidt Picture Credit: ICAO (21); Jeppen & Co. (26) ; NASA (12); Vickers (6, 7, 8, 10, 11) .

New Eurocontrol Establishment in Luxembourg

35

5

A Slightly Closer Look at the SST

In Seattle on November 14-15, 1967, the Institute of Navigation sponsored a National Air Meeting on Supersonic Navigation. The meeting attracted 170 conferees from 9 countries. The presentations included a couple of encouraging reports which indicated that the SST will be more amenable to ATC restrictions than was originally suspected.

Bill Polhemus described a recent Decca-sponsored simulation study which was aimed at determining the vertical navigation requirements of the Concorde. Using a wide range of high-altitude Met data collected by McGill University, Polhemus made 200 simulation runs on an IBM 7044 computer, to determine the effects of ambient temperature, and ATC constraints, on the fuel consumption and on aircraft performance. He found that temperature in the climb zone will not affect range or fuel requirements very much, although it will make a difference in the time and distance required to reach a given altitude. The higher the ambient temperature, the lower the climb rate.

Polhemus found that errors in forecast temperatures would have the following effects on the performance of the Concorde: Temperature Error

Time to reach cruising altitude Altitude over check point in climb Time over check point in climb Distance to reach assigned flight level

±1 °C

±5°C

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± 3 minutes

minute

± 500 feet

± 2000 feet

± 0.3 minutes ± 1.5 minutes

± 20 miles

± 100 miles

These results infer that on a busy route such as the North Atlantic, where actual temperature reports would be quite frequent and up-to-date, flight estimates and altitude proflles flown by SST aircraft should be highly predictable.

Another phase of the Polhemus study dealt with the time and fuel penalties of off-optimum cruising altitudes Some of the results are shown in Fig. 1. They indicate tha; it will be practical to utilize constant cruising altitudes when traffic prevents the use of drift-up climbs. They als~ indicate that it will be practical to employ altitude separation between SST's.

Not shown in Fig. 1 ~r~ step-climb procedures. Starting out at the optimum cruising level (0 on the left side of Fig. 1), but flying level for 30 minutes, then stepping up 2000 feet-and repeating this process every 30 minut . . f es, produced negligible pena Ities in uel and time, as long as the temperature was no~ ~~ove standard. Similar results were obtained when the 1n1t1al level was held for 60 minutes , followed by. a 4000-foot climb. There would be t·1me for only one 4000-foot step on a transatlantic crossing 1 all cases, the penalties for step climbs, as for all t.h n . . d . h o er off-optimum operations, increase wit an increase · . in air temperature.

It was initially planned that the Concorde's accele t· ra ion . to supersonic speed would start around Fl400, in climbin flight. The Polhemus study found that some fuel . g . h . f savings would result 1f t e aircra t were levelled off temp . orarily around FL400 an d acce Ierate d to above Mach l wh . .

11 level flight. The climb would then be resumed a d e h•n · Id · n t e acceleration wou continue on the way up Th· II d t' . is proce. h . h dure, w 1c 1s ea e op 1mum-energy acceleratio . some strengt h en1ng . . structure n,· Would require o f t he wing d •n or er

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Time and fuel penalties of off-optimum cruising altitudes (Concorde) .

to cope with the higher speed at the lower a ltitude . The use of this procedure would a lso tend to intensify the sonic boom prob lem on the ground.

Polhemus also found that the Concorde cou ld be slowed 150 knots (from Mach 2.05 to Mach 1.8) in cruising Aight, with very little fue l pena lty. All in a ll, the study showed tha t this ai rcraft wil l not be much more difficult to hand le in the enroute ATC system, than any other turbojet aircraft - as long as you don't have to vector it!

V.W. Attwooll of the UK M inistry of Technology presented an interesting paper on North Atlantic (NAT) SST separation cr iteria. The SSTs on this transa tlantic yo-yo run wi ll be schedu led for two round trips per day. The estimated SST peak Aow rates are shown in Fig. 2, together w ith the number of traffic lanes that wi ll be required if 10-minu1e longitudinal separation can be used in each lane. Compared to the prese nt standard, the proposed standard is shorter in time but longer in d istance.

The big question in SST operations is whether or not superson ic Aight wi ll be permitted over land areas. If it is, the NAT SST track system wi ll blanket the present greatcircle route from New York to London. If overland SST operations are outlawed, the NAT SST tracks wi ll have to be moved southward to mi ss Nant ucket, Cape Cod, Nova Scot ia , Newfound land, and Ire land. In this case, the average increase in route mileage (and passenger fares) would be between 30/o and 100/o.

Planners are hoping for 60-mi le spacing between the parallel NAT SST tracks. The reduction from the present 120-mi le late ra l sepa ration standard would be predicated o n th e use of an improved navigation system by th e SSTs. Fig. 3 compares the present and proposed latera l accuracies for NAT SSTs. The UK has investigated two poss ible track-assignment schemes for NAT SSTs: (a) Assign ing each departure to the first available ("most empty") track in turn ; or (b) delaying a d e parture enroute, before e nte ring the oceanic (non-radar) area, lo obtain 1 O mihutes separa tion behind a preceding aircraft, on a shorter track.

The delay wou ld be effected by having the pilot reta rd the start of his superso nic acce leration about 2 minutes (20 m iles) fo r each minute of de la y required to obtain the neces:ary time separation. As shown in Fig . 4, this proce dure_ is ba ~ed on the Concorde's abi lity to cruise 10 miles a minute in subsonic Aig ht or 20 mil es a minute in the superson ic mode. The fuel mileage wi ll be about th e sa me in either case, so th e e nroute delay costs very little in fue l

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Figure 4 (left) Spoce·ti me plot of deloyed-acceleration p rocedu re to o bta in desired lo ngi tudinal seporolion before e ntering Oceon 1c Sector.

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or range - actually about 10% of the penalties associated with the other track-assignment procedure.

The UK study also indicates that it will be practical for the Concorde to absorb a known delay (or meet an assigned time slot) at the destination airport, by advancing the de-bang (deceleration) time about l minute (20 miles) for each minute of delay. This procedure is shown in Fig. 5.

Up to 30 minutes of landing delay could be absorbed in this fashion, with relatively little penalty in fuel. The success of this procedure will depend on the accurate prediction of a irport acceptance time, by ATC, 30 to 60 minutes in advance of the initial ETA, so that the pilot can plan the remainder of his flight profile accordingly.

The ATC prediction will require accurate knowledge of impending traffic loads and airport acceptance rates - a job which ultimately could be assigned to the ATC computer system.

Dr. Karl Karwath of Lufthansa presented a report from the European SST Working Party. He stated that the effects of wind on supersonic operations will be relatively low, for two reasons: (a) cruising speeds are much higher, and (b) wind velocities at SST cruising altitudes are somewhat lower than those encountered at the cruising altitudes of 11

11

the present subsonic jets.

Dr. Karwath reported that actual temperature data, collected during the last three years, show that at the SO-millibar (67,500-foot) level, the air temperature is more than 5 -C warmer than standard, 30% of the time, on the Frankfurt- New York route.

Dr. Karwath isn't sold on the idea of fixed tracks for NAT SSTs Instead, he advocates a so-called "freedom system " where (assuming that navigation is very accurate) an ATC computer would generate a unique collision-free trajectory for each aircraft.

Several presentations at Seattle dealt with the design and operation of self-contained navigation systems for the SST. Sieg Poritzky of the Air Transport Association explained that, while the inertial navigation system (INS) is a very expensive piece of equipment, it provides two byproducts - extremely accurate attitude and heading datawhich are especially important for SST guidance. INS is a self-contained system which is set to the aircraft's known geographical position on the ramp, before takeoff. It then computes and reads out the position of the aircraft con tinuously, throughout the flight.

8

Even th.e best commercial inertial equipments drift two or three miles per hour, however ' so the indicated po SI·t·Ion needs to be updated as the aircraft approache · . . ft I fl. h s its d estrnat1on, a er a ong 1g t. Poritzky suggested th this c.ould be accomplishe~ automatically, with the aid ~; an airborne computer, using VOR/DME information H suggested that VORTAC facilities could be modifl e transmit a digital identification made up of lat~t 1 dto longitude, and elevation data for the VORTAC sit uThe, airborne computer would then process this data e. I e with the rho-theta VOR/ DME information, to de; a ~ng the actual position of the aircraft. The new posit'1 er~me would then be injected into the INS for automatic u ;~ /ta It appears that most SSTs will be equipped ~ mg . combination of self-contained and ground-bas d Wit~ a e naviga. k. h h tion systems, wor mg toget er t rough an airb · h h. h. · orne corn puter. Al ong wit t 1s sop 1st1cated gear ho ' Wever 1 ·t · interesting to note that the prototype Concord ~ is equipped with two ADFs ! e will be

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Ben Mcleod of Pan American Airways . presented progress report on satellite communication . a 0 improvement which should provide dircet p "ls, t coming 1 o -control! · · . commun1cat1ons over oceanic routes Look·1 f h er . · ng art er i t .n the future, NASA representatives advocated th ment of a multi-satellite system to take ove th e est.abl1sh. r e nav19 f and the ATC surveillance functions. It would b a ion electronic Big Brother (ready by 198 42 ) th t e a sort of · a would k . track o f everything that moves. If they name it the . ~ep Universal Tracking System (OUTS), it should be th Orbi~rng successor to INS! e logical

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Although the first generation isn't fl · · yrng yet th craft m~nufacturers are already talking about ' e airgenerat1on SST, a Mach 3 + monster kno the secondwn as the Ad ce d SST (ASST). We suppose the third . vanwill have to be called the Further Adv;:c:e~ahon desig.n one should really be FASST! Incidentally th SFST, as this · TSS ' e rench term f or SST is - a natural result of the F h trail their adjectives after their nou renc tendency to ns.

During the Seattle meeting we noted th t lk · k' · . ' a space -ta is ma mg inroads into aviation An SST fl 1 . ht h ( 'd d · h · . · 9 pat cons1 ere in t ree d1mens1ons) is a "trajectory" d" t '.,rom takeoff is referred to as distance "down' t isk~nce down ra ,, If h" h' rac or . nge . t is t mg goes on, some day you 'll be clearing TWA 700 for a fractional orbit!

--TKV

IATA Looks at the Terminal Crisis

by Tirey K. Vickers

Introduction What are the limitations to airport capacity? How can ATC system capacity be increased? These were some of the vital questions which were probed by the 17th Technical Conference of the International Air Transport Association (IATA) during the week of October 9, 1967. The conference site was Lucerne; the conference subject, "Major Airport and Terminal Area Problems," was of sufficient importance to draw 500 representatives from 40 different countries.

With over 400 new jets on order, the airlines are on the verge of what could be their greatest expansion in history.

Within ten years, passenger demand is expected to increase five-fold, aircraft operations three-fold.

The catch is that many major airports and ATC facilities are already swamped by present traffic peaks. The resulting delays disrupt schedules and greatly increase aircraft operating costs. Unless radical improvements can be made soon, these factors will impose a practical ceiling on aircraft operations, and stifle further expansion of the industry.

General Aviation Particularly in the U.S., the overwhelming portion of the recent growth in traffic demand has been due to the phenomenal growth in general aviation (GA) activities.

Thus, at Lucerne, lengthy discussions were conducted on possible restraints and incentives to get GA traffic moved to satellite airports, or at least keep it out of the "jet stream" of the main airport runways during periods of peak airline traffic. Suggestions included a differential landing fee which would go up during peak airline hours; a~other idea was to charge the same landing fee to all aircraft regardless of size or weight.

Schedule Adiustment In discussing ways of reducing airline delays, the conference brought up a point which many ATC people have advocated for years - the adjustment of airline schedules to spread out the traffic peaks. Example: why should 27 Kennedy departures all be advertised for 1700 hours when it is obvious !hat the last one can't possibly be off before 1745? The highly competitive nature of the airline busi.ness (~obody. wants to be No. 2) is an important reason behind th1~ practice; some airlines have used the argument that there 1s no advantage in advertising capacity at a time when the customer doesn't want it. The airline delegates at Lucerne agreed on one point - they were opposed to the compulsory allocation of schedules by any government regulatory agency.

Sam Higginbotham of Eastern Airlines then introduced some positive thinkin~ into the discussion. He reported that Eastern recently discovered that their on-time performanc~ at Kennedy had. dropped from 65% in 1965, to only 22% in 1967. Responding to the question, "How can we still deliver the most of our product to the customer?"

Eastern is now voluntarily moving a number of Kennedy departures off the even hour, transferring some schedules to other New York airports, and rerouting many overflights completely away from the ~~ew York metropolitan area.

Peak-spreading theoretically reduces airline delays.

However, it doesn't get the passenger to his destination any closer to his desired arrival time. Neither does it solve the real need for increasing terminal area capacity, which can only be attained by (a) increasing the acceptance rate of an individual runway, or (b) establising additional runways which can be operated simultaneously with the previous layout.

Separation Standards There is a kind of Ohm's Law which states that the flow of traffic in any given lane is directly proportional to the average ground speed of the vehicles, and inversely proportional to the average separation (or headway) between them. For any given set of conditions, there is a finite limit to the acceptance rate of a runway. The rate can be increased, either by raising the approach speed (normally not desirable for safety reasons) or by reducing the separation between aircraft.

The present three-nautical-mile radar separation standard came about quite arbitrarily many years ago - so arbitrarily, in fact, that it jumped 150/o overnight when the U.S. adopted nautical mile terminology. (It had previously been 3 statute miles.) Any proposed decrease in the standard would still be affected by (a) runway occupancy time - the time required for an aircraft to decelerate and clear the runway for the next aircraft, and (b) the wake turbulence problem. . .

Exploring the possibility of reducing the long1tud1nal separation standard, the Lucerne conference looked first at runway occupancy time. This can be minimized by the provision of optimally-designed runway entries, exits, and taxi strips. As an example of advanced thinking, the Aeroport de Paris delegates described features ?f the_ new Paris-Nord Airport, which will have runway exits designed for exit speeds of 60 m.p.h.; the high-speed taxi strip system will be designed like a super-highway.

One advantage of the present three-mile separation standard is that it normally provides ample time to get the No. l arrival off the runway before the No. 2 arrival is committed to land. However, the FAA has been toying with the idea of reducing separating to 60 seconds between touchdowns. This would correspond to the distance separations shown in Fig. 1, and probably would be contingent on the use of an approach computer. The 60second standard would occasionally involve double occupancy of the landing runway. Some of the airlines were prepared to accept this situation, as double occupancy is already allowed by some countries under certoin conditions.

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Walt Jensen of ATA suggested that there is no real urgency in decreasing the separation standard, as the average landing interval today is considerably higher than the present standard; controllers have difficulty in closing the excessive gaps which occur periodically in the sequence.

Trailing Vortices A discussion of the trailing vortex hazard revealed an appalling lack of knowledge of the characteristics and effects of this phenomenon, by some of the airline representatives . However, the U.K. Ministry of Technology produced an excellent working paper on the subject, for the Lucerne meeting. Some of the data is graphed in Fig. 2.

The vortex hazard itself forms one of the most important reasons for segregating small aircraft on other runways than those used by the large transports .

term "speed adjustment" was more palatable than "speed control" as far as airline pilots were concerned.

In this connection, other pilots emphasized the need to get all jet transports slowed to approach speed by the time they are over the ILS outer marker, so that the pilot will have enough time to get the aircraft stabilized on the glide slope before reaching the floreout point.

An alternate method of reducing the effects of speed differentials is under study in the U.K. Essentially, it involves reshuffling the landing sequence to reduce the number of fast/slow pairs. As shown in Fig. 3, the slow aircraft would be grouped together instead of being allowed to mix alternately with the fast aircraft. Although this would tend to increase the landing rate, it could produce backtalk from some of the pilots involved, as it would depart from the usual first-come first-served arrangement and thereby produce an unequitable distribution of delays.

Another method of reducing the fast/slow approach interval was suggested at Lucerne, by Walt Jensen of ATA. This method would take advantage of a wide difference in approach speeds, by simply disregarding the 3-mile separation standard and turning the slow aircraft on final approach a mile or so behind the fast one, knowing full well that the separation will increase all the way to touchdown. Probably the greatest objection to this procedure would be the risk of exposing the slow aircraft to the trailing vortices so recently generated by the aircraft ahead . However, as the twin vortices propel each. other

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Figure 2 Theoretical Decoy Time of Vortices in Calm Air Example = A 4000 ft1/sec woke decoys to half-strength in 3 minutes 0

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Speed Differentials One of the factors which reduces runway acceptance rates today is the need to accommodate aircraft having widely different approach speeds. This results in an excessively long approach interval, whenever a slow aircraft follows a fast aircraft down the final approach course . The longer the common path, the longer the interval.

One way to reduce this effect is to ask the pilot of a slower aircraft to remain at a faster airspeed for as long as possible before final deceleration . This is the basis for the so-called streaming, or speed-control, procedures which have been used during the past few years. At Lucerne, Captain J. D. Smith of United Air Lines pointed out that the 10

Fi.gure 3

Space/time graphs

showing

approach

intervals

obtained

with o group of. 6 fast, 3 slow aircraft, using random (first-come first s.erved) sequen~ing'. versus selective sequencing procedures . Dotted lines show oppl1cot1on of J.mile separation standard .

TO AVOID VOR'TICES, NO. 2 A/c ) SHOVLO llVTERCE"PT COMMON PATH NO LOWER THAN ACTUAL PATH FLOWN BY NO.:J. A/C ,/

,,

HEIGHT E)(ACl6ERATEO

Figure 4

It is probable that a number of major airports ultimately will be designed with more than two runways which can be used simultaneously. Indeed, O'Hare could not achieve its present capacity if it did not have two additional runways available for takeoffs during the operation of its dual parallel approach system. The layout of the new Paris-Nord Airport was discussed in detail in Lucerne. This advanced design will have four parallel runways, arranged in two pairs or "doublets." The terminal building will be located between the two doublets which will be 10,000 feet apart. The parallel runways in each doublet will be 1,000 feet apart.

Short turn-on procedure

Controlled Deceleration (CD) downward, the exposure hazard in this case could be minimized by making sure that the slow aircraftwas turned on the common course at least as high as the actual flight track of the aircraft ahead, as shown in Fig. 4.

Arrival/Departure Coordination In day-in day-out ATC operations, the achievement of a high acceptance rate depends on many little things. As the traffic rate goes up, the working tempo increases. At most airports, a departure cannot be released unless the controller knows exactly how far out the next arrival is from the airport. A few seconds delay in getting this information often spells the difference between go and no-go, and a few no-go decisions can greatly increase takeoff delays and airport congestion.

One tool which was recommended at Lucerne for improving arrival/departure coordination in instrument conditions, is a bright radar PPI display in the control tower cab, to give the controller an instant check on the position of the nearest arrival before releasing the departure. This has been tried in several locations, with excellent results.

One American representative pointed out that the simultaneous operation of multiple runways will require multiple approach and departure lanes. The establishment of these additional lanes through the terminal area will tend to reduce the amount of terminal airspace which is presently available to any approach controller, for pathstretching purposes. Therefore, to achieve high runway acceptance rates, some other spacing procedure will have to be used for the precise adjustment of approach intervals.

The controlled-deceleration (CD) procedure was suggested.

In this concept, shown in Fig. 5, ATC uses constantspeed (streaming) procedures to bring the aircraft into the selected approach path, with more speed and more separation than that desired for the final portion of the approach. At an appropriate point on the final approach, the number one aircraft slows down to its final approach speed, at which time the interval behind it starts to contract. The number two aircraft then begins deceleration so

Multiple-Runway Operations Even using all the improvements discussed so far, it will be very difficult to achieve a combined arrival and departure rate of more than 50 IFR operations per hour on a single runway; the only practical way of exceeding this total is to add another runway, preferably one that can be operated independently. Using one runway for landings and a parallel or diverging runway for takeoffs, it is possible to launch one departure for every arrival, at a maximum IFR hourly rate of about 35 in, 35 out. If the demand is higher, a simultaneous approach system is the next logical stage of development.

Present standards require a lateral separation of 5,000 feet between dual parallel runways which are used for simultaneous approach procedures. This standard was arrived at mathematically, with the idea of achieving a satisfactory level of safety without controller intervention.

However, as it appears that no dual approach system would ever be operated without continuous provision for controller monitoring and intervention, it was decided at Lucerne that some reduction of the 5,000-foot separation standard could be tolerated with safety, as long as the use of the system was restricted to "properly equipped" aircraft.

ARROW SHOWS WHERE' l:ACH

AIRCRAFT STARTS C0NTROLL£D

D£C£LERATION DIAGRAM AT LEFT SHOWS' AIRCRAFT POSITIONS AT TIME -t. ( 04- I 40")

Figure S

Space/time grc1ph of c0nt1olled decele1C1t1on :onceot

11

as to arrive at its final approach speed at the time it arrives at its desired spacing behind the number one aircraft. The some process is repeated for each successive aircraft in the landing sequence.

One a ircraft design feature to facilitate CD operations would be a means of varying the drag of the aircraft over a wide range, without inducing aerodynamic buffeting, and without directly changing the trim of the aircraft.

Figs. 6 and 7 show two possible approaches to this problem.

It is quite possib le that on ATC approach computer wi ll be required to determine the desired place for each aircraft to begin CD, in order to achieve optimum separation all the way to touchdown. At Lucerne, it was also mentioned that the provision of a station-keeping feature in the proposed collision avoidance system could en able each pilot to monitor his separation distance behind the aircraft ahead, and control his deceleration accordingly. This would tend to simplify approach operations considerably.

It was recommended that the CD concept be thorough ly investigated by ATC research and development agencies, as a potentially usefu l technique for achieving optimum approach spacing in tomorrow's highly constrained airspace.

comments at Lucerne, the airl ines didn't like it either, for safety reasons, at this stage of the game. However, NASA is about to try out some radically new instrumentation which cou ld change the story by providing much better guidance for the floreout before touchdown. If ultimately successful, the steep approach would not only reduce the noise prob lem; it cou ld open up more low al titude airspace forV/STO Loperotions. It could also simp lify IFR operations at closely-spaced airports such as Nework-Teterboro, by placing the glide s lope of e ither airport for enough higher over the other airport, to clear the way for comp letely independent operations.

\

No ise Abate ment Th e airport noise problem come up for di scussion as a possible lim itation to a irport capacity. Opinions ranged all the way from Dick Brown's (TWA) statement that practically all serious delays at JFK ore caused by noise restrictions, to Lou Achitoff's (Port Authority) statement that noise does not limit capacity at .lfK to any appreciabl e degree. In a review of FAA policy, Bill Morgon said that noise abatement ranks below safety, but above efficiency.

Th e use of steep approaches (g lide path up to 6째) was mentioned as a possible way of reducing approa ch noise.

One of the FAA delegates said that the stee p approach would never be approved, because the Deputy Administrator had tried it and didn 't like it. Judging from the ensuing

Figure 6 Exp crimcntol wing tip drag dev ices on T-33 tel trainer (NASA Photo)

12

Figu re 7

Toil-mounted Speedbrakcs

I LS Shadowing The Lucerne conference discussed another limitation, the fact that whenever an aircraft flies directly over, or nearby, the ILS localizer antenna at low altitude, the localizer beam is shadowed and disturbed momentarily.

As larger aircraft are introduced, the shadowing effects are expected to increase accordingly.

With the advent of Category 111 operations, the possibility of a localizer disturbance at a critical point in the approach looms as a distinct hazard. A possible solution would be to avoid takeoffs on the ILS runway during the latter stages of the instrument approach. This will probably require an increase in instrument takeoff/landing separation, above the present two-mile minimum. The increased separation will tend to lower the runway capacity. The use of another runway for takeoffs (which is desirable anyway if the traffic demand exceeds twenty landings per hour) should eliminate this problem.

heading, and an odometer input for distance, to drive a pictorial display. This type of ground navigation could be especially valuable for airport emergency vehicles.

Controller Workload

One of the airline representatives pointed out that staggering losses in ATC capacity can occur when an airplane wipes out the localizer shack, a radar antenna bearing grinds to a halt, or rain gets into a vital communications cable. In such cases, flight operations may be disrupted for hours, and many aircraft may have to be diverted to some other terminal area. The mere thought of diverting several 500-passenger jumbojets brings nightmares to airline cost-accountants. At Lucerne, the various ATC operating agencies were asked what sort of redundancy was being built into their installations, to protect against such failures.

The FAA representative said that redundancy was very expensive and that it was just not practical to duplicate all the critical items. Alternate power sources didn't help, in the big East Coast Blackout of 1965. Since learning this lesson, the FAA has installed massive emergency generators at major sites. The Canadian representative reported that his agency has installed no-break power facilities at 14 airports, and standby power sources at others.

The capacity of a terminal area can be limited by the capacity of the adjoining air route control sectors; this has occasionally been evident at New York. Conversely, the money spent for improving terminal area capacity can be wasted if the air route sectors cannot handle the increased load. Therefore, the Lucerne conference looked closely at ways of reducing controller workload in air route as well as terminal area ATC facilities.

It was reported that two recent simulation programs, one for the German BFS and one for Eurocontrol 1 have shown the superiority of one-way airways, in reducin g controller workloads by reducing aircraft closure rates. Both programs also showed that the effectiveness of enroute radar control was reduced significantly by the need for controllers to restore procedural separation before handing off traffic to a non-radar sector.

The use of an accurate area-coverage navigation system to permit multiple-line one-way routes which could be navigated by the pilot without controller assistance, was pointed out as a potent method of securing high flow rates with minimum communication!: and control workload per aircraft. U.S. and U.K. delegates described their recent experience with area-coverage navigation techniques.

J. D. Smith of UAL summed it up by saying that area navigation has to come, and the sooner the better.

The need for alleviating the terminal area communications bottleneck was further discussed; FAA described their experiments with digital communications, and United Air Lines reported that they already have six data link equipments airborne in their fleet. SSR was described as an excellent means of securing automatic position, identity, and altitude reports; but the U.K. has already foreseen the day when terminal area traffic density will greatly reduce the validity of SSR coded data - as a result, one of the U.K. working papers contained a number of suggested changes to the SSR system concept. The resulting concept looks suspiciously like a roll-call data link.

ATIS was described as a useful means of unloading routine time-consuming information from control channels.

To secure an immediate reduction of communications congestion, use of the U.S . clearance phraseology "cleared as filed" was recommended to other countries. Using this procedure (in lieu of reading and repeating back the entire departure clearance) should be especially beneficial in Europe, where language difficulties often require additional repeats before the controller finally assumes that the pilot has his clearance straight.

Ground Guidance

Automation

The problem of maintaining normal taxiing operations in Category Ill weather came up for discussion, and an FAA representative said that his agency was groping for answers. The U.K. is still experimenting with buried leader cables, and with this precise electronic guidance has been driving test cars down airport runways "under the hood" at 70 miles an hour. The conference also discussed the use of follow-me trucks equipped with a dead-reckoning navigation system utilizing a flux-gate compass input for

In answer to the ultimate question as to what the various administrations were doing to increase terminal area capacity, an FAA representative described the modular Tracon (Terminal Radar Control) equipmeni with 5 levels of automation, SSR, and collision prediction.

However, he could offer no estimates as to how much all this would increase capacity. J. D. Smith of United Air lines said that the ARTS installation at Atlanta hod increased safety rather than co~acity.

Restricted Areas The IA TA conference discussed a nether widely-prevalent problem which tends to congest traffic flow - the amount of airspace taken up by military restricted areas. It was reported that the U.S. now has a kind of "use it or lose it" policy as far as the military is concerned; the FAA has had considerable success in eliminating some of the least-used restricted areas, and in obtaining agreements to clear traffic through other areas at altitudes and times that do not conflict with military activities.

Backup Facilities

13

The FAA representative said that tests of an approach spacing computer at JFK had shown a possible increase of about 3 landings per hour, but that the controllers were not enthusiastic about it because of the large additional workload required to operate the computer. Stan Seltzer of American Airlines pointed out that 3 landings per hour represented a 10% increase, and that therefore the further development of approach computer techniques should be encouraged.

Joe Conerly of FAA said that the J FK tests showed that a successful approach spacing computer will require automatic tracking, a better man-machine interface, and controller acceptance. Jacques Villiers, who pioneered ATC automation in France with his CAUTRA system at Orly Center, stated significantly that the installation of ATC automation inevitably increases controller workload, as the controller must serve the computer; the payoff comes only if the automation system can increase performance or reduce workload in other areas, to more than make up for the increase in manipulative workload.

Collision Avoidance Systems (CAS) CAS was discussed only briefly at Lucerne, possibly because this was a terminal area meeting and nobody was quite sure how the present airline CAS concept could ever be applied in terminal area operations. TWA's Dick Brown stated that CAS was not intended as a primary separation tool, but "strictly an emergency supplement to the system." Some European airline personnel stated privately that CAS would be a fantastically expensive patch to put on anybody's system, and that its cost (S 30-50 thousand per aircraft} could be better spent by improving the basic ground system .

Aircraft Design By the time the conference was nearly over, it appeared that the main gain in airline passenger capacity during the next few years would come through the use of larger

The Seventh Annual Conference of the International Federation of Air Traffic Controllers' Associations will be held from 22nd to 26th Apri I, 1968, at the Regina Pa last Hotel, Munich, FRG. The Conference will be under the patronage of the Hon. Georg Leber, Fed era I Minister of Tran sport, and the Opening Ceremony will take place on the evening of the 22nd April, in the Plenary Ha II of the Bavarian Parliament.

The Regino Polast Hotel, venue of the Conference, will provide omple space for conference sessions and corn-

14

aircraft, rather than from any radical improvements A TC capacity.

in

~h.e Boeing man stated that the 747 may still grow an add1t1onal 50 feet (16 m.) in length, and that subsonic transports may ~row ultimately to 800-passenger doubledeck configurations. However landing gear de · · sign 1s I d · ' a rea y serrously. complicated by runway bearing strength and the latter 1s rather difficuli· to assess 0 d" r pre 1ct accurately. . Although there w~s considerable interest in V/STOL aircraft at the meeting, the present lack of fl · demonstrator capable of meeting airline pe f a ying . . r ormance capacity, and economic requirements kept the d" . ' . .

1scuss1on largely on the academic side. It may be along in f 0 years, however. ew We noticed what appeared to be a general 1· f . r h . f h coo ing-off oh aCir ine ednt us1a~m or t. e SST. The weight and cost of t e oncor. e continue to increase, and although the BAC representative assured the conference that th k performance wouldn't suffer because the eng· e ta eoff ine power · · d was b eing increase too, runway bearing st h begun to loom as a critical factor. A Qantas reprengt has resentotiv said he d ou b te d t h at t h e Concorde could be u d . e Asian region because of this factor alone The B se. in the stated that the SST would generate man.y new oeing man but that the travail would all be worthwhile be problems, ability of the resulting aircraft to shrink c~use of the However, if many more countries legislate e. World. sonic boom, our guess 1s that the SST will sh ~g~inst the but not continents. rrn oceans

Conclusion Although the conference didn't settle 0 b. .

1 it certainly gave them a good airing On ny 9 issues, d e man su · up the meeting by stating that he hod frnoll mrne 1earned h . .

Y d h vast Iy comp I 1cote t e terminal area probl ow This may mean that the Lucerne meeting hem .really is. . .fl1can tl y t h e wor Id -wi d e population of AT as •ncrea se d s1gni Don't say we didn't warn you!

C Experts.

fortable accomodation for delegates and b I h o servers It w·ll 1 a so ouse an exhibition of modern ATC : sponsored by leading avionics industries. equipment, Various federal, municipal, private and ·i·t . m1 I ary organ1. d h . . sa t ions an out orrt1es are taking an act" · . ive interest in the . . .

C f d on erence an are ass1st1ng rn its preparation .

The Organising Committee are confident that the Seventh Annual IFATCA Conference will be an eff . and successful meeting, taking place in an . ect1ve which will long be remembered by the ·t · .environment par 1c1pants.

P-t

RTCA Meeting Highlights Terminal I FR Capacity The Radio Technical Commission for Aeronautics (RTCA) is an extensive organization of airspace users, pilots and controllers, industry and government officers, and both civil and military contractors, which works cooperatively to focus attention on much needed improvements in ATC, navigation and communications. Through frequent re-analysis and continual appraisals of all available and potential research, it seeks out guidance and direction for electronic development for aviation. Through RTCA's endevours, a co-ordinated program for resolving mutual technical problems and forwarding recommendations, which can be incorporated in the manual and procedures of airspace users, as well as federal regulations, is available to all utilizing the airspace of the United States. Many RTCA proposals, developed by Special Committees composed of its members, and occasionally non-member experts, who are invited to assist, are evenlual ly adopted internationally as standards and practices.

RTCA has now undertaken, at the request of the European Organization for Civil Aviation Electronics (EUROCAE), a joint endeavour to establish an international standardinzation of requirements for both manufacturers and users of avionic equipment. Financed by U.S. Government agencies and corporations, the RTCA gathers together a wealth of talent, which could never be purchased, to study the technical problems facing air transport to-day and well into the future.

The theme of the 1967 Annual Assembly Meeting of the RTCA, held at the Statler-Hilton Hotel in Washington, D.C.

from September l 9-20th, focused attention on "Upgrading the Terminal Area".

For years the problems posed by the explosive growth of air traffic, the increasing number of IFR flights, the introduction of high-speed and numerous smaller new aircraft, along with the ability of the terminal area and airports to handle the ever increasing loads and requirements, have been readily evident. The RTCA Assembly, in four separate panel sessions, undertook to discuss the solutions what can be done, what should be done, immediately to upgrade the capabilities of large and small terminals to move more traffic, more reliably and more efficirntly in all types of weather.

Following the Opening Address by Alexander W. Wuerker, the Chairman of RTCA, a Keynote Address was given

by Joseph T. Geuting Jr., Manager, Utility Airplane Aerospace Industries Association of America. He emphasized the impact which general aviation aircraft operations even now, and well into the foreseeable future, have placed on present ATC systems. The ability to depart and arrive whenever and wherever the business men wish, will necessitate vast improvements in terminal procedures and equipment if the economy of not only large countries but newly developed nations are to continue flourishing. The great demands being required from an almost already overburdened ATC system will dictate increased technical assistance, and development of navigation and communication facilities, and these problem areas must be tackled to-day by both industry and government.

Improving IFR Capability The first session, moderated by Maj.Gen. Francis J. Taylor, Jr. (USAF) Ret., dealt with "Improving IFR Capability".

Three papers were presented on subjects related to these items. Mike Huck of AOPA talked about pilot proficiency, William Gracey of NASA read a paper on "Operational Aspects of Steep VTOL Approaches as determined from Helicopter Tests under Simulated IFR Conditions", and Richard Wasicko, also of NASA, presented a study on "Aircraft Flight Characteristics" and their resultant effect on terminal operation.

An extract of the "Pilot Proficiency" paper by Mike Huck is reprinted elsewhere in this journal.

In his study on the operational aspects of steep VTOL approaches, William Gracey indicated that by using a continuous aircraft course line/moving map display, permitting speeds up to 56 kts., a course path of 卤 3 degrees, and a corridor length of two miles, special high-angle (6 degrees) approach corridors were considered to be satisfactory. A breakout altitude of 100 ft. was considered

the minimum for 60 kt. approaches, 50 ft. could safely be employed if the touchdown point was approximately 500 ft. from the glideslope origin, since slow down and "flare-out" to hover could result in overshooting, if the origin and touchdown were co-located when such a low altitude minimum is used.

A constant width path for the final l .500 ft. of the approach was demonstrated in the simulation to be required, with visibility therefore l .500 ft. for a 50-ft. breakout and 2.000 ft. for a 100-ft. breakout. Time to fly either the 60 kt./ 2 mile approach and the 30 kt. l 1h mile approach averaged about three minutes.

Richard Wasicko's paper centered around the results of a NASA study on aircraft flight characteristics, utilizing seven different types of aircraft and 23 pilots from government and industry, as well as from resear路ch organizations.

In this study, it was established that: 1. The ILS approach phase under conditions of atmospheric turbulence is the most demanding flight phase for general aviation aircraft.

15

2. The aircraft's handling qualities and stability have a significant effect on the pilot's workload and his rating for IFR terminal area operations.

Simulated tests with five types of jet aircraft to reduce noise resulted in the conclusions that: 1. Steepened approach profiles utilizing a single segment glide slope from 3 to 6 degrees was satisfactory and less workload and effort than a two segment glide slope approach letting down from a 6 degree slope down onto a final 3 degree slope for a 200 ft. VFR breakout.

2. The piloting task would be eased and confidence increased in performing the steeper type approaches if the engine response time at the lower power settings could be reduced.

3. The lower power settings and utilization of thrust for controlling the aircraft during the approach had more of a significant effect on the ground-level noise than the steepened approaches, if utilized in small adjustments such as an autothrottle. Steepened approach paths are technically feasible to achieve noise abatement, but considerably more research is required in the design of aircraft and power plants to offset the need for strong or large throttle variations to maintain stable flight characteristics which "drown out" any gains the higher approach paths have in reducing noise at ground level.

4. Tests utilizing hydraulically actuated spoilers connected by a servo motor to a thumb control on the pilot's control wheel responding to control column and/or throttle changes to provide increased or decreased lift during a glide-slope capture to touchdown particularly

in the flare and touchdown phases were significant in easing control and precise flight path adherence.

5. Utilizing a Direct Lift Control (DLC) system in an F-8C with a spring-loaded control on the column to command variable gain flap-to-elevator interconnect in order to alter the aircraft's longitudinal response, and employing an autothrottle to compensate for selected and actual airspeeds, simulated ILS approaches were flown to a 100 ft. breakout with the pilot then guiding the aircraft to a target touchdown point on the runway, similar to a carrier landing at sea, resulted in promising concepts which could greatly assure increased landings at busy terminals during adverse weather conditions.

Further research is therefore considered warranted on this system.

Flight tests conducted with STOL aircraft (NC-1308 and 8reguet 941) both indicated that good handling qualities are fundamental to attain acceptable IFR terminal operations. The NC-1308 required a stability augmentation system to improve the performance when utilizing blowing boundary layer control, while the Breguet 941 without stability augmentation was sufficiently acceptable to permit tests of steepened ILS approaches up to 7.5 degrees under actual IFR weather conditions.

The fourth paper of the morning session presented by Alphonso J. Barr of the FAA's Airports Service placed emphasis on the standardization of lighting systems so that a small airport's lighting of a taxiway is the same, identifiably but not necessarily as elaborate, as that of a major terminal. The layout of Category 11 approach and runway centreline lights was later discussed with pictorial displays.

Easing Terminal Weather Problems The Moderator for this session was Newton A. Lieurance Director Office of Aviation Affairs of the Environm~ntal Scie~ce Services Administration (ESSA).

Charles Roberts of the ESSA started off with a paper emphasizing the difficulties of Terminal Weather Forecasting in view of the fact that aviation forecasts were probably the most difficult to prepare, in that the elements of prime concern (fog, cloud, etc.) were most variable, and often related local phenomena and complex causes such as factories, escarpments and large bodies of water or marshlands being adjacent to the airports.

Terminal forecasts are currently issued every six hours for about 400 locations in the U.S., covering a period of twelve hours. Some 130 international airport terminals have 24-hour forecasts prepared for long range flights.

In such forecasts the cloud cover must be specified within 150/o 1olerances as to height; visibility is only prepared for term ina I forecasts when it is expected to be restricted to less than eight miles, and if less than six miles some obscuring phenomena must also be specified. Surface wind direction and speed in excess of ten knots only is included.

Significant changes requiring amended forecasts include a lowering ceiling of 1.000 ft. or below; no ceiling forecast but a 3.000 ft. or lower "deck" moving in; a 1.000 ft. ceiling is forecast but varies by more than 500 feet; visibility is forecast to be between 3 and 5 miles but drops

16

to less than 2 miles or varies by more than 1 mile if previously forecast to be 3 miles or less; and if no thunderstorm activity was forecast, yet a heavy Cb is now forming.

Consequently, due to these rapidly fluctuating changes, the forecaster often cannot keep up to date when forecasting for 15 or more stations.

The accuracy and credibility of forecasts have been statistically proven for "good flying weather" to be within 5% of remaining above VFR limits. Only by automating the observer's functions to prepare immediate prognosis based on current information can accuracy be improved.

Matthew Lefkowitz, Chief of the Observations and Methods Branch of ESSA at NAFEC in his paper pointed to the "MESONET" program where photoelectric detectors from 14 observing stations within 50 miles of Atlantic City, N . J., continually determine cloud height every 6 sec. on the approach end of the major instrument runways. This is automatically presented to the terminal forecaster to assist him in analyzing the situation and thereby more accurately predict future changes quickly. However, wide variations are often observed from adjacent stations on the MESONET and further studies as to siting, observation cycles and variables will result.

Runway Visual Range (RVR), measured by a transmissometer is often misleading for the pilot executing an instrument approach, for visibility as well as fog layers are

often moving. However, further research into vertical and slant range visibility may yield possible positive trends.

Inaugurated at Newark in 1957 from experimental research commenced during world war 11, the RVR contemporary system was re-evaluated by the FAA and Weather Bureau in 1965. An observer program utilizing a moving vehicle along a runway resulted in 3.100 instantaneous observations, varying occasionally with individuals up to 1.000 feet under identical conditions. Nevertheless, 67% of the observers under night time conditions sighted further than the RVR, while in daytime 92% saw further.

The human factor, therefore, appears to be the greatest obstacle to standardization and interpretation of observations in the terminal areas. Just as a drop of rain falling on one observer standing beside another observer from an overcast sky provides physical proof it is raining, the other may argue because he didn't see or feel it. At that moment, he is not yet convinced it is raining until another drop hits him in the eye. It is, however encouraging to note that pilots are capable of probably seeing farther down the runway upon landing than the RVR states.

With his paper on "Countering the Vortex Problem", ex-Controller Walter S. Luffsey, representing the FAA, showed an excellent colour film on the vortex "flow field".

Utilizing artificially coloured smoke emitted from a high tower under the influence of a 10 kt. wind, and an aircraft flying at 230 kts. about 300 feet above the "smoke towers", the tornadolike funnelling of trailing vortices was graphically illustrated. In general the size of the wake generated by the "disturbing aircraft" is based on the aircraft's speed, wing span, lift, wing geometry and air density.

Formation of vortices is based on the concept that the wing sheds a sheet of vorticity along its entire trailing edge which quickly rolls up and off the tips as a pair of whirling vortices. The downward and tangential velocities can be mathematically calculated on the aforementioned parameters. After generation the downward displacement and lateral spreading, which are usually equal, are normally only dispersed by ground or object contact until the wind can dissipate them. It is possible for an upwind vortex to remain almost stationary in light crosswind conditions.

The turbulent wake generated by the "disturbing aircraft" and/or other aircraft along with the air's viscosity, atmospheric temperature and pressure gradient have pronounced effects upon dissipation. For an aircraft flying into trailing vortices: Across track or at right angles to the "generating aircraft" severe gust loads approaching design limits may be encountered in which an upward pitch immediately followed by a downward component (the centre wake), then a second upward pitch occurs; A Ion g track within a trailing vortex immediately following the "generating aircraft" where one wing is in a downward vortex component and the other an upward, a complete roll can be induced, even with full opposing aileron applied; Along track directly between the t r a i I i n g vortices where the downward components are affecting both wings, the rate of climb and lift may be significantly reduced to the extent it could cause the aircraft to settle even with power being applied.

Future research will be directed at measuring the velocity of the flow field existing within the vortex core and high altitude (FL350) studies will be undertaken to determine possibilites of "chop" generation affecting enroute jets in the low atmosphere density regions. Controlled wind tunnel tests with aircraft models will provide additional scientific data to develop aircraft equations of motion.

Solutions to cope with this wake turbulence phenomenon are essentially impractical for the efficient and expeditious control of aircraft. Increased lateral and longitudinal separation with "ATC to pilot" reminders or warnings with radar vectors based on computer generated vortex matrices can presently assist, if conditions for the formation of vortices and their persistence are known.

Dissipation of vortices could be assisted by installation of non-powered counter fans at the wing tips and saw tooth or stepped flaps which would generate separate "flap vortices" to counceract upon the wing-tip vortices.

On the ground, hedges or small Christmas trees as used to outline runways in Canada during the winter and bursts of compressed air generated to "sterilize" the landing or take-off areas might be employed.

A turbulence caution indicator suggesting the presence of hazardous turbulence may be developed in the future, utilizing laser techniques.

Segregation of large and smal I aircraft, and pilot procedures of remaining above the flight path of a preceding aircraft, touching down further down the runway than the preceding aircraft and lifting off at a point before the preceding aircraft, are methods which will permit the pilot to avoid vortices in the terminal area.

The red and white path of the VASI (Visual Approach Slope Indicator) could be changed to a red and green (internationally STOP and GO) indicator to advise that a previous aircraft had touched down or was still flying (hence creating vortices) at or beyond the VASI touchdown point. The problems of vortices are presently known and will only be magnified by the jumbo jets and SSTs so that caution by pilots and controllers in respecting these dynamic forces is the best method of avoiding their disastrous effect.

During the ensuing discussion, the panelists were rather critical of the lack of up-to-date and accurate weather information and posed several searching questions.

Leading the discussion was Clifford Burton, Executive Director of the ATCA, who questioned the legal responsibilities of ATC personnel providing RVR information, in the light of recent court decisions concerning li?bility.

Also when borderline weather conditions exist, the importance of accurate and easy to read weather data is an absolute necessity as the Controller must use his ~est judgment in advising pilots of possibilities and rapidly deteriorating conditions.

Robert E. Commerce, a United Air Lines Dispatcher representing the Air Line Dispatchers Association,. a~~ed for a speed up in the transmission of ATIS data by l1m1t~ng it to weather only and pertinent information for landing flights with reference to the type of approach in progres.s.

Also, would it soon be possible to forecast RVR as 1t wil I be the basis of limitations for category 11 operations? He also questioned the high percentage of accuracy stated in forecasting weather based on "revised forecasts" and not on the ,,initial forecast" as this was not a true picture of accuracy, really.

17

Captain Lee Hines of Eastern Air Lines, representing the ALPA, asked that weather at alternate airports for flights diverting from original destinations be more readily available such as on the ATIS when the airport is "closed".

Also, pilot proficiency does not warrant the lowering of the 200 ft. minimum to 100 ft. on category 11 approaches, as it is not practical for the risks involved, whereas fully automated approaches to zero-zero is more realistic and hence funds should be directed to such programs. He also emphasized that the B-747 and C-5 would require greater runway/sequence spacing, or an immediate solution to the vortex problem.

Robert E. Monroe, Policy and Technical Chairman of the AOPA, questioned "What is a terminal area?"

The average general aviation flight is less than 2 hours duration and AOPA pilots consider actual observations more accurate than forecasts, as these are issued more frequently. He pointed to the fact that many pilots do "self-briefing" from local broadcast station information which is a dangerous practice, but it is almost impossible to get a telephone line to the forecaster. Hence possibly a "Pilot to Forecaster" RT frequency might be more useful.

"The need for accurate and factual information is obvious, but everyone is talking about the weather, who can do something about it", he chided.

Lt.Col. Johnson of the USAF Operations and Training Division at Andrews Air Force Base was not too impressed

with the "razzle dazzle of (weather) charts" and pointed out that more time should be spent in putting out observations and factual current data rather than suppositions.

He asked whether it would be possible to "multiplex" weather information on broadcast channels, or have national TV broadcasts of weather maps instead of TV test patterns. He pointed out that in the Southwestern States stations break into regular programming to provide tornado and hurricane advice to the general public for safety.

However, only public requests for it will dictate such policy implementation. In the meantime, he wholeheartedly encouraged pilots to utilize the Flight Service Stations readily available with such information service.

Other comments expressed that sate I lite power restrictions limited the transmission of information, and voice not digital information was required so that any and all receivers could participate.

It was noted that Prestwick has a ground-to-air weather forecasting link with NOTAM information from . about 20 stations readily available for overseas flights.

Low frequency was utilised 20 to 25 years ago weather broadcasting, why not so much now? Or, at least until voice transmission is completely obsolete and data links to aircraft with channel switching, like the preset Decca channel selectors, or TV national weather maps makes it uneconomical.

Terminal Area Navigation

and Communications Crocker Snow, Director of the Massachusetts Aeronautics Commission indicated in his paper "Getting the Most from Present Navaids" that whoever chose this subject obviously "thought we weren't". He then procee~ed to point out that this assumption was indeed _correct 1~ that many runways were remaining idle immediately ad1acent to major international terminals. Utilization of th~se coul? alleviai路e much of the present congestion at ma1or terminals, but because they are military or municipally operated, the problem is a political one. Consequently, to handle the situation utilization of non-intersecting runways, parts of runways' and short parallels are the only answer immediately available to the Controllers.

With regard to electronic navaids he stat~d, "It seems obvious that the less accurate the electronic path to the runway ;h;eshold, the greater the need for li~hts, and vice versa. However, notional policy seems to be 1ust the opposite; i. e., 3.000 ft. of approach lights required for hig~ly precise category II !LS, and nothing for AD~ app;,ooc es on a homer usually several miles from the airport 路 Inexpensive xenon flash approach lights ore readily available and are being used by the military in Vietnam, "but they sti II hove to clear the twin hurdles of R & D and flight standorcls", for use in the continental USA. The archaic incaclescent rotating beacon atop the tower is still being installed whereas xenon flash which is more

18

conspicuous, has greater coverage, costs no more to install and even less to run, is still THE standard.

Several ILS back course localizers are not utilized because they do not quite meet FIDO standards for minimum t~lerances for the required percentage of times in operation, yet often never exceed the maximum tolerance Pilots executing ADF or VOR approaches to such often ~iss their approaches whereas locally based operators, using these back courses as a "monitor" for their ADF ~ppro~ch, al~ost never ove_rshoot. Even state operated experimental runway localizers, which cost about 1/5 as much as a cat~gory I localizer, and appear to be just as accurate, provide much better runway guidance than a TVOR. However, they cannot be used for other than test purpose: until federally approved. Experience suggests a long wait and con_s~quent raise in costs. "Here is a typical c~se of where striving for perfection should not be permitted to foreclose early use of something which seems to be much better than any other existing low cost electronic approach aid".

runwa:~

In general, simple and worthwhile improvements should not be neglected just because they are not 100% ideal, but put to work if nothing substantially better is readily available.

"Area Navigation in ihe Terminal Area" was the topic of a paper by T. G. Angelos, Manager, Navigational Aids United Airlines. It is reprinted elsewhere in this Journal'.

Increasing Terminal Traffic Capacity

~

I

The Moderator for this discussion was Mortin A. Warskow of the Aviation Systems Research Airborne Instruments Laboratory.

Frank W. Kolk of American Airlines, lnc.'s Engineering Research and Development "broke the silence" with his paper on "The Noise Problem".

"The increased growth (of air transportation) in recent years", he stated, "has resulted in congestion now in every facet of airport and air space operations ... it is safe to conclude that the industry's growth wil I be even more spectacular in the next ten years. The situation is indeed critical!"

During the next three to four years the scheduled airline fleets will double their pure jet aircraft inventory over 1964 figures. Since they will be basically the same as those flying today, as far as noise is concerned, communities had best look to improvements in terminal procedures and engine design for any relief.

Noise abatement procedures will certainly not increase capacity. Airlines follow circuitous routes to avoid noise sensitive areas and accept imposed or voluntary restrictions of throttling back. The fan ahead of the rotors causes the greatest noise and siren whine. Utilization of new techniques will reduce such noise but the price of development is six to eight-thousand dollars per engine.

Although many aircraft engines are nearing "economic and maintenance retirement" retrofitting an entire fleet would be "economic suicide". A new aircraft and engine is therefore required to circumnavigate the noise problems.

With current four-engined aircraft, operating costs exceed S 600 per hour and therefore the impact of even 2 minutes of delay, on the ground or added flying time soon becomes economically intolerable for any carrier.

A heavily loaded long-range jet taking off from John F. Kennedy airport can easily violate the maximum noise limit of 112 PNdb if forced to take off on a runway which has a noise measuring device installed. Consequently, rather than run the risk of violating the limits, the pilot may elect to take off on another less desirable runway which causes a reduction in airport capacity and traffic flow, particularly if the primary "landing runway" is the one which has to be used for takeoff.

Thrust reduction or increased rates of climb are practical and effective methods of reducing aircraft noise but both are not operationally possible at the same time for the benefit of municipalities infringing on airport property.

Industrial zoning and temporary housing, plus a public awareness of the need to control zoning regulations could alleviate many complaints arising today from taxpayers.

There is no short term solution to the problems of noise and only long term planning for the next decade is going to ease the situation at most major airports.

The next speaker, John C. Mercer, spoke on "Terminal Automation", pointing to the three major elements that offset the capacity and efficiency of terminal areas: Airports, Airspace and ATC Equipment/Procedures. ~day's airports vary greatly in design and in their individual capability to handle current traffic and the heavy increases in air traffic forecasted. Airport runway layout and associated navigational aids do not guarantee similar capacities at all airports. Obstructions, and particularly anti-noise procedures, are significant constraints.

. !

Effective use of the airspace is also constrained by a multiplicity of cross paths to adjacent airports, and traffic peaking that causes holding, and the need for excessive radar vectors.

Terminal radar has been a system smoother and a most significant ATC tool in the inventory today.

But what about tomorrow?

Automation Our plan for air traffic control automation in the terminal area is based on progressive steps to add automation to the existing radar system.

The introductory level of automation will be beacon tracking at 62 of the 118 terminal radar facilities now handling approximately 740/o of the IFR traffic in the United States. This is expected to increase safety and capacity by: -

Simplifying the maintenance of radar identity Display of Mode C altitude data Minimizing controller and pilot workload Improving airspace and airport utilization.

It is possible to add planning, metering and final approach spacing to an already established basic computational capability. Targets are tracked; computer assists in metering traffic from the outer fixes, and final approach spacing techniqLâ&#x20AC;˘ias are initiated to get maximum airport capacity.

Other features are: electronic tabular displays, conflict prediction techniques, and the all important transition/terminal flow control between the en route and terminal areas.

Where are we now?

ARTS - The Advanced Radar Traffic Control System with modified tracking logic, faster methods to address the computer and rearranged display of control data will help smooth Atlanta's operation.

New York Com m on I FR Room - This plan for combining the approach control facilities at LaGuardia, Newark and Kennedy into a common control facility allows removal of artificial airspace barriers, enhances coordination, and in addition to the safety aspects, allows more efficient use of all the terminal airspace at all times.

TRACON Modular Automation Enroute Interface

and

the

Needless to say, the design of the terminal system is dependent on the enroute automation program automatically passing required flight data to facilities equipped with a terminal computer.

The Beacon Tracking Level program is well underway.

The system description and engineering requirement have been completed, and the initial system will be installed in the early part of 1969.

In the meantime, a continuing progrom of radar improvements is being implemented. Modifications include side lobe suppression and solid state components. New techniques elimina~e radar outages. With automation, mosaic displays of several radars and the capability for rapid reconfiguration will make less critical the loss of a single radar source. A reduction in the workload imposed on the controller to accomplish required man-machine communications, is necessary for full benefits of outo mation. Work in this area has a high priority.

19

Evaluating Future

Improvements

Conclusions:

What will automation do for capacity?

-

Airport improvements provide the means greatest increases in terminal capacity.

How does system capability compare to the traffic forecasts?

-

Significant increases can be achieved by automation and procedural improvements. These have by far the greatest benefits in comparison to cost.

-

A combination of these alternatives will probably be required at many terminals to match the forecast demand.

How much of the activity must be absorbed by new or improved airports?

What is the benefit/cost of the various add-on levels of automation?

For increasing terminal area capacity, some of the alternatives are: -

Computer Aided Approach Spacing (CAAS) Considerable confidence can be placed in the ultimate feasibility of this due to the results from system trials at both NAFEC and John F. Kennedy International.

-

Speed Class Sequencing (SCS) - Aircraft of similar performance capability are grouped in the approach sequence so as to reduce the number of large interval_s.

This technique has been successfully demonstrated in s:mulation.

Reducing Separation - This assumes that it is !e.chnically feasible to do so without increasing coll1s1on risk. These studies consider the average accuracy and variability of radar and display systems, maintena_nc~ of flight path, and controller assessment of separation.

?Y

Distributing traffic more evenly throughout the day reducing the peaking factor (percentage of daily operations occurring during peak hours).

-

The entire realm of airport improvements, i. e. long~r runways additional runways, additional exits and taxiways, m~re ramp space and added approach aids.

It is generally conceded that automation _will be required to achieve any of the first three alternatives.

Gains in IFR hourly capacity of 5 to 150/o due to Computer Aided Approach Spacing are shown. Additi~nal gains of 4 to 25% for 60 second spacing appear possible.

Speed class sequencing shows further increases of 5 to 7%. In a system combining 60 seconds separation, speed class sequencing, and CAAS, total gains up to 450/o (depending on runway configuration) could be expected.

On an annual basis, an average delay per aircraft in excess of two minutes or peak hour average delays in excess of about thirty minutes, are considered unacceptable to users. Beyond this, the system begins to deteriorate very rapidly and delays quickly approach infinity.

JFK delays are averaging better than 2 mins/acft now.

The addition of automation and procedural improvements would significantly reduce delay; however, the improvements would not provide acceptable capacity (peak hour average delays less than 30 mins./acft.) for more than a yeor or two. A modified airport layout would probably provide acceptable capacii"y of this runway configuration.

Redistributing or flattening the traffic peaks (to a 6% peaking factor) would closely approximate the delay saving accrued by automation and procedural improverneni路s. Addition of a new airport should provide combined capacities ot acceptable levels through at least 1985.

20

for

the

Richard F. Frakes of the FAA was the afternoon's third speaker. His paper "The Air Route Interface", and the final paper of the session "Potentials for Increased Airport Capability", which was prepared by H. Schmidt and read

by Dave Little of R. Dixon Speas Associates, are reprinted elsewhere in this Journal.

The panelists added considerable information and thought provoking comments during the discussion which followed.

Thomas M. Sullivan from the Port of New York Authority advised that there was already a Bill before the House to permit the FAA to certify aircraft with respect to engine noise for operations from certain airports. At present, he stated, there are 17 scheduled air carrier flights departing from JFK between 5 p.m. and 5:03 p.m. weekdays. Also, access to passenger terminals and baggage needs to be improved if an airport's capacity for handling aircraft and the size of jets are increased. He indicated that some airline co-operation is required to alleviate these problems.

In the immediate New York area, S 460 million for 3 airports had been recentl~ appr~ved and projects were now underway. Teterboro Airport 1s to become Pon-American's major base for training and a general aviation airport, as a special bus service to central Manhattan will be subsidized to encourage its utilization, rather than Newark LaGuardia and Kennedy. ' Walter Buechler of the FAA doubted if the noise abatement problem area could ever be solved, and quoted the complicated departure procedure for aircraft using Runway 04R at JFK, which has to be utilized approximately 50% of the time due to local wind conditions.

Frank A. Cirino of American Airlines reflected that some noise complaints received are often not valid and questioned the use of "curfew times" if one is to solve "peak period" problems. With regard to ATC, he called for an immediate elimination of the routine or clerical functions of the Controllers, and for closer liaison with the military and general aviation agencies. A computer link to the major airlines' dispatchers for scheduling of the arriving aircraft might assist in "gate utilization" congestion. Signs to indicate taxiways and a low cost VASI would assist pilots arriving for the first time at strange airports, and not hamper the ground control frequency.

He also requested that federal authorities as soon as possible commence studies on the time and pressures asserted on ATC personnel with regard to continued efficiency.

Capt. A.E. Smith of Piedmont Airlines and a representative of 1he ALPA openly commented that during the entire session the word "safety" had only been heard twice. He queried whether there was a general assumption be formulated that the improvements mentioned will also increase safety, and if so this was creating an illusion of false protection, as the collision factor is still the greatest

problem, particularly in the areas of VFR traffic. The regulations governing VFR in high density traffic areas, he suggested should be raised, "as it was sometimes like Russian roulette to approach a busy facility during the diminishing daylight hours!" He also questioned the 60sec. computer spacing of flights as possibly delineating safety and increasing the vortex problem.

sed three distinct possibilit ies for al l pa rt icipan ts to consider before next yea r 's meeting.

1. Development of lateral thrust deflectors on the downwind side of runways to permit cros swind landings and takeoffs and to b reak-up vortices .

2. Designing "indexing la nding gear" simi lar to t he B-52's for civil jets.

John P. Woods of the National Business Aircraft Association, inc. (NBAA), stated that the solutio n to noise abatement must not disregard safety, and the enti re picture must be viewed, as only the pilot manipulating the throttles can produce an immediate solut ion of any measurable degree. H e suggested a more ba lan ced use of runways and airport facilities, and that safety must be correlated with airport capacity. Too often the re is too much delay by authorities in acting on a problem area even after it has been recognized, aired and action planned. He indicated that the NBAA was also actively participating in the northeastern U.S. navigation aids evaluation. He, too, commented on the great pressures that ATC personnel encounter during Cb activity and the peak traffic periods by stating, "It's just fantastic".

To summa rize this 1967 RTCA Meeting, a member of the audience stated, "This year, we have hea rd the problems discussed by experts, now let's get out and in form t he public about these airspace p robl ems so that we can get something done about them before next year's meeting!"

In conclusion, Program Chairman Tirey Vickers expres-

JRC

3. Plan that runways at adjacent a irpo rts be buil t para llel to those at the ma jor terminal in orde r to avoid conflict ing traffic patterns.

In his closing remarks, W il liam C. Fuchs, Vice-Chai rman of the RTCA commented that the concept of "l ooking out of the window to avoid traffic has to come to a g rinding stop as soon as possib le by p rovid ing some form of sepa ration ".

ICAO's Fifth Air Navigation Conference ICAO's Fifth Air Navigation Conference was held at !CAO Headquarters in Montreal from l 4th November till l Sth December, 1967. Three hundred and nine delegates and observers from 62 countries and six international organizations were in attendence.

The Conference elected Thomas E. Went of Barbados as its Chairman, and Walter A. Dwyer of Australia and Sever Sripcaru of Roumania as Vice-Chairman.

Mr. Dwyer is a lso President of the World M eteorological Organization's Commissio n for Aeronautica l Meteorological Organization's Commission for Aeronautical M eteorology, which was meeti ng jointly with the Air

Navigation

Conference

for

two

agenda

items

w ith

meteorological aspects.

Mr. Scripcaru wil l be well remembe red by IFATCA Members from his part icipation in the 1965 Annual IFATCA Conference at Vienna.

The Conference was designed to improve the safety and efficiency o f the approach, landing and take-off pha ses of fligh t. The agenda included the follow ing: approach and take-off; movement o f aircraft and vehicles on the ground; categories and cha racteristics of land aerodromes; aerod rome services; information for the approach, landing, take-off and g round movement of ai rcraft; noise in the vicin ity of aerodromes.

ICAO

21

Pilot Proficiency and ATC¥

by Michael V. Huck AOPA

PILOT PROFICIENCY can be divided into three parts, all of which are essential if the term is to mean anything in terms of results: (1) the need to know what to do, (2) the ability to make the airplane do what must be done, (3) the ability to assess how well the pilot performs whatever mancuver or set of maneuvers is being evaluated.

Back in the days of the silk scarf, proficiency wasn't so complicated . If a pilot was alive, he was proficient. It was as simple as that. But things have changed! Nowadays Joe Pilot not only has to keep his aircraft right side up and miss mountains but he has to learn procedures what they are, how to talk his way through them - and how to push his vehicle through the necessary maneuvers to duplicate the sometimes complicated lines drawn on a printed page.

Some procedures are complicated; some are simple.

Some ere essc:ntial to the safe expeditious movement of air traffic, and some are the obvious and asinine result of an attempt to keep bureaucratic minds busy. Assuming the pilot has the ability to adequately control his aircraft, the real proficiency problem in the terminal area occurs when someone screws up a procedure. The hairy chested superman type pilot or controller can then be expected to take the attitude that, "If he can't hack it, he shouldn't come in here." The thing these folks forget is that the primary purpose of an aircraft is transportation, and if he "doesn't go in there" his airplane hasn't fulfilled its mission .

What I advocate is a thorough analysis of the existing procedures, with the thought of eliminating those that do not serve any useful purpose. One which comes to mind immediately is the holding pattern entry. In order to figure out how to properly enter a holding pattern, a pilot must go through quite a bit of mathematical gymnastics, or twirl another plastic computer while his aircraft is eating up sky.

It should be remembered that the average General Aviation pilot is not a full-time professional. He uses his airplane to get from point A to point B in much the same way as he uses his automobile. He uses the aircraft because he can cover more ground in a given per iod of time than by using surface transportation. Another thing; most of us are flying by ourselves, with only one head to fly, communicate and compute. Every time that one head is loaded down with an unessential task, performance suffers in those tasks that are essential. We must do away with the nonessentials to get the needed optimum performance in the essentials .

Some procedures are necessary so that pilots and controllers can anticipate to some degree what the o:·her is about to do. This benefits the controller far more than the pilot, because the controller is aware of all the procedures tor his particular terminal; but these procedures vary considerably from one terminal to another .

Besides simplifying procedures whenever possible, it is just as important to standardize them, so the transient pilot wn expect the same thing to happen to him whether he is at his home field or clear across the country. This means •

22

From a paper presented at the 1967 RTCA Annual Assembly.

the end of such things as the "River Approach," VFR landmarks such as the Temple, and other similar hocus-pocus, but the result can't help but be a smoother operation.

In fiscal year 1966, General Aviation conducted 25 percent of the instrument approaches recorded by FAA. However, in the last five years, General Aviation approaches doubled in number while air carrier approaches remained almost the same. If this trend continues, by 1980 General Aviation will conduct over 70 percent of the civil instrument approaches in the United States.

The new private pilot of today doesn't feel as though he has made it. More and more pilots are writing AOPA and saying, "I just got my private pilot certificate. I want to get my instrument rating as quickly as possible. How do I go about it?" It won't do to simply sit back and say that all these guys have to be more proficient. Sure, they have to learn whatever is necessary and learn it well. Our job is to simplify things so they can concentrate on what is really necessary and don't have to spend a lot of time on the unessential frills. This is no time to shout, "I had to learn all that garbage; he should too."

Today's aircraft owner has more money to spend on his aircraft than his predecessors had in the past. As a result, he will have more electronic equipment which will give him greater capability in the terminal area. However, we must constantly keep in mind the need to keep things simple, and remember that e.ach new. ~ie~e of eq uipment, while possibly improving basic capability in today s system, is another knob to turn or another switch to throw.

1

This is not to say that a single super-homer is the ideal piece of gear to tackle the system at O'Hare or Kennedy; but most of us are alone up there and any requirement to identify some obscure intersection or report crossing radials involves looking up the fix on the chart and tuning from one to three radios-during which time we are expected to steer a precise course, maintain altitude, and think ahead of the airplane. Radar has improved the situation, the single-frequency approach will help (if we ever actually get it), and we can expect further innovations that will reduce cockpit workload to a point where we can concen1rate on precise navigation of the aircraft, and be ready for the tighter system that must come when the terminal traffic situation is called upon to handle double and triple the present traffic loads.

TERPS* is now with us, and will allow virtually thousands of little hamlets to have their own instrument approach and thereby become a part of the nationwide IFR system. Minima probably won't be very low for the majority of these airports due to their distance from the approach facility; but this will surely beat the current practice of shooting an approach at a larger airport and then scudrunning to the outlying field. This increase in capability will make an instrument rating even more useful to the majority of General Aviation pilots and will further speed the growth of General Aviation instrument approaches.

•

Standard Terminal Instrument Procedures .

Category II capability is just around the corner for the General Aviation pilot without the requirement for all the exotic equipment that costs more than the plane itself. The ability to land in these low weather minima will mean greater reliability. It will increase the usefulness of an airplane and generate further need for a higher degree of precision in flying the aircraft. That brings us to the key to solving the terminal area problem in the future: we must unload the pilot to the point that he can put the vast majority of his effort into flying with extreme precision.

Why do we need such precision? For one thing, the use of parallel ILS approaches is being hailed as a tremendous tool for moving more traffic. The present standard allows simultaneous parallel approaches if the runways are separated by at least 5000 feet. We are beginning to tighten this up. At Atlanta, staggered parallel approaches are being conducted with less than 5000 feet separation between runways, and this is only the beginning. While parallel runways are partial solution to the terminal problem, they won't completely solve it. There will always be a limit to how many parallel runways can be placed on a given airport. There aren't enough airports in our metropolitan centers, and those we have are rapidly becoming saturated under our present concepts. The number of airports cannot be increased very much, simply because of the lack of available real estate. Therefore, we must learn how to improve the capability of our present sites.

What we will really need in the near future is a method of conducting simultaneous approaches to converging runways. I'm sure a suggestion like this will bring forth all sorts of reasons why it can't be done. I can think of a number myself: this is not what we need, however. We need some deep thinking that will come up with the solution as to how it can be done. It may take some exotic approach sequencing computers and a close degree of speed control to do the job. Maybe it will just take some darn good controllers. One thing it will definitely require is precise flying. Given the precision required, our airports can have an IFR acceptance rate almost equal to that which they now have under VFR conditions.

How do we get the required precision? It won't come

overnight. It all starts with the first flying lesson. If a student pilot is taught that the only way to fly is precisely, and no other way is acceptable, he will adopt tighter standards for himself and his goal will be perfection, rather than just good enough to get by. Once this goal is established, the pilot will be his own best monitor and check pilot. He will continue to press to improve his technique, and will eventually become a pilot with truly professional capability.

One of the best efforts on the part of FAA toward encouraging instrument pilots to gain the necessary "live" experience to gain proficiency is the SIP program which is presently active in the Southern Region. The tender loving care which is dealt out in this program helps to build confidence in the fledgling instrument pilot and will pay off when the chips are down. Minor mistakes can be straightened out, and the pilot soon becomes competent because he is not afraid to get experience in the system.

As he is led by the hand, he acquires confidence in his ability to operate in the system. He also gets an opportunity to refine his skills, which in turn gives him more confidence. The whole thing snowballs until he suddenly has the ability to operate with a considerable degree of professionalism.

Of course, all the training and tender loving care in the world won't mean a thing if the pilot eventually becomes complacent. Complacency is the replacement of confidence with cockiness. The only way to fight it is to continue to strive for perfection during every minute of every flight. We can't improve the terminal situation without tightening up on our flying techniques, and we can't do that if we are complacent.

The only way for instrument pilots to maintain a level of proficiency sufficient to allow improvement in the terminal area is to constantly strive for the utmost in precise flying all the time. This is just as important for the 10,000hour pilots as it is for the man who has a brand new fog ticked. When really precise flying becomes the rule rather than the exception, when instrument pilots will accept nothing less from themselves - that is when we can expe~t major breakthroughs to solve the congestion problem in our terminal area.

Area Navigation Techniques in the Terminal Area-ÂĽ

by T. G. Angelos Manager, Navigational Aids United Air Lines

Introduction In busy terminal areas, at present, ground-controlled radar vectoring has, to a large extent, displaced conventional pilot initiated navigation. A part of any consideration of area navigation techniques to attain significant benefits for the ATC system is the requirement that the navigation function be accomplished from the cockpit.

RTCA Speyial Committee 104, "Long Range Planning for the Air Traffic System" subscribed to this view by stating:

the reduction in pilot and controller workload.

Such requirements should be predicated upon a proper a !location of functions between those done by automatic means and those requiring human judgment. For example, the responsibility for the navigation of an aircraft must lie with the pilot, and the responsibility for expediting traffic, particularly in the terminal area, must rest with the controller."

"In developing requirements for the improvement of the ATC System, emphasis should be placed upon both system capacity and system safety, along with

In the terminal area situation, the outbound traffic flow srarts out at intervals from a runway rapidly transitions, with ground radar assistance, to divergent routes and altitudes. Radar guidance by means of heading vectors,

â&#x20AC;˘

Paper presented at the 1967 RTCA Annual Assembly.

23

in conjunction with speed control, comprises the terminal area controllers major tool. His skill in interpreting the radar data displayed permits integrating traffic of varying speeds and performance into proper sequence to achieve a consistent traffic flow to the runway (or runways) in use.

In some areas, path stretching and traffic segregation is accomplished in the Center's radar arrival control sector to facilitate the approach control function. When the traffic demand approaches or exceeds the airport acceptance rate, employment of radar in order to achieve on orderly flow has proved effective as opposed to holding aircraft, en masse near the airport.

Pilot I Controller Workload The present terminal area traffic control concept is based almost exclusively on the use of radar with no advantage taken of the area navigation capability inherent in the system that can be made available to the pilot. In effect, the radar controller temporarily takes over the navigation guidance of the individual aircraft to provide spacing and lateral separation. This concept imposes added workload on the pilot as well as the controller, which increases with the number of potential conflicts, and this number goes up as the square of the traffic density.

The resultant communications workload upon the flight crew and controller alike is extremely heavy when traffic volume is a factor during the critical approach and departure phases. A significant part of the pilot's activity is devoted to handling radio contacts or interpreting instructions - too often it is difficult for the pilot or ATC to relay information when timeliness is a factor.

The foregoing outlines the heavy reliance on surveillance radar equipment and procedures to meet today's traffic flow demands in the terminal area. It further points up that present radar control, in view of performance limitations, controller mental stress and demanding communications load, has reached the point of diminishing returns. The number of aircraft that can be handled individually at a radar sector limits system capacity. To quote SC-104 again, one of the Special Committee's recommendations under the heading of Airspace Utilization Requirements is: "Investigate and implement techniques and methods which will assure the safe separation of traffic in congested terminal areas without imposing penalties of increased delays or time consuming circuitous routing and communications exchanges."

Air Carrier Interest To provide the flexibility for navigation in all of the volume about a navigation facility, supplementary equipment and instrumentation is required. The pilot should be equipped to navigate on an area basis with at least the equivalent accuracy and ease with which he is able to navigate presently on airways. The need for more efficient use of the airspace and of expensive ground facilities (and their frequencies) plus the potential of direct flight without flying VOR radials has inspired a renewed ai~lin.e interest in area navigation . Traffic increase forecasts indicate that the enroute use of "flexible routes" will be an operational requirement in the early 1970's.

United Air Lines tested a Bendix Course Line Computer system in a DC-BF in 1964. This equipment utilized the phantom station principle and also provided a parallel

24

mode of operation to permit flying offset from selected airways. Our limited study of potential savings by flying direct routes as compared to airways, indicated o sizable annual saving, for the two direct routes flown during this test.

Recently Pan American Airways evaluated the Butler Vector Analog Computer (VAC) system in a B-727 in the Berlin Corridor. This system displays command guidance on a cockpit indicator which is used in much the same manner as the conventional course deviation indicator.

Area navigation devices being developed for civil use range from simple parallel track computers, several types of Course Line Computers (CLC), through the more sophisticated (and more costly) Pictorial Displays (PD).

Pictorial computer displays with capability for continuous position, instantaneous orientation and use of map slewing for the interface between pilot and computer, makes this design especially attractive for terminal area applications.

Two basic types of pictorial moving map displays that utilize VOR/DME inputs have been developed - the roller map and those employing film strip for projection on a display screen.

Representative systems are to be flown in a cooperative test program developed by an ATA/FAA Operations/ Procedures Working Group. The objective of this evaluation program is to define the operational benefits attainable, to the flight crew and the ATC system, with equipped aircraft in the present airspace environment. Chosen for the initial test was the Washington-New York-Boston enroute and terminal area (northeast corridor) environment. Eastern and American Airlines have elected to participate in this program and four aircraft are to be involved: General Precision/Decca Omnigraph 1) EAL DC-9 Collins CLC System 2) EAL DC-9 Butler National Corp. VAC 3) AAL BAC-111 (Vector Analog Computer) 4) AAL BAC-111 Bendix Parallel Track System.

The program involves four progressive phases: using existing Phase A - 50 flights/10 days/10 crews terminal procedures and airways.

Phase 8 - 100 flights/30 days/l 0 crews - using specific terminal routes and offset tracks based on phantom stations.

Phase C - 100 flights/30 days/l 0 crews extension of Phase 8 with reduced route widths.

The Working Group agreed that radar separation and tracking will be required for all phases and ATC will provide radar separation in accordance with present standards. The successful completion of the evaluation of Phases A through C would lead to the implementation of Phase D which is the same as C, but without mandatory radar separation.

Cockpit Space Limitations A major hurdle to positive consideration of pictorial map disp.lays for terminal area use has been the problem of cockpit space for a suitable installation. A proposed B-~27 installation for a system incorporates a unique track guidance feature which makes the projection type of display suitable for instrument panel installation as a horizontal navigation situation indicator. This display, in addition to providing answers to the basic question "In which direction" and "How far" also provides steering

information (deviation indicator) and thus is considered a flight instrument, mounted on the panel within the pilot's normal scan pattern for maximum utility.

Terminal Area Techniques With this background, a review of some promising terminal area techniques and potential benefits to both the pilot and controller follows: Designated arrival/departure tracks - The establishment of additional terminal tracks, including curved paths, to be flown without guidance from the controller, offers the advantage of reduced radar vectoring communications, by-passing of slow traffic, and a reduction in the number of VOR/DME channel changes in the terminal area. More efficient A TC system operation results from the improved pilot ability to anticipate and perform altitude and heading changes. Additional tracks would facilitate control problems such as descending and/or climbing arrivals and departures through other traffic. To introduce this concept a system of discrete tracks could be patterned after the "normalized" or median radar tracks customarily used in transitioning aircraft to the final approach course. Predesignated tracks based on normal flow experience would limit controller intervention to those times when it become necessary or desirable for the aircraft to depart from the designated track.

Approach spacing computer/PD computer integration Future ATC system design indicates that designated paths will become items of computer information. Procedures for spacing arriving aircraft could be accomplished by comparing the actual position of an aircraft with the optimum position on a given path. Depiction of the extended final approach path with increments of distance on the pilot's terminal display would permit a choice of shortened or lengthened paths for assignment.

Instead of guiding the aircraft from feeder fix to the outer marker area by radar, the equipped aircraft could intercept the localizer at the desired distance beyond th~ marker for final approach with a minimum of communications contacts.

Simplified holding procedures - With PD e~uipme~t pilots can enter holding pattern, position the aircraft in the pattern, and depart the pattern . with improved efficiency and accuracy. The effects of. wind can. b~ compensated for readily so as to remain well w1th1n the boundaries of the allocated airspace.

Eliminate circling approaches to unequipped runways - When weather conditions require operation on runways not served by landing aids, the display wi.11 direct the aircraft to a straight-in approach to the desired runway.

Suitable terminal charts will depict mileage from touchdown along the runway centerline extension wi~h recommended let-down altitudes. Less flight maneuvering in the immediate terminal area is required and where radar is utilized a reduction in the controller/pilot communications load should result.

Assist in vertical flight path control - One criterion for future ATC system development is that the system must allow flights to climb, cruise and descend within the normal best performance ranges of the various aircraft types.

Continuous position information along with computed readout of elapsed time-to-go to the feeder fix or clearance limit offers attractive possibilities to the pilot and the controller. Equipping the pilot to navigate and predetermine arrival time to any designated point, within

very close tolerance, should assist approach control in organizing traffic into an orderly landing sequence.

Assist in noise abatement procedures - Many noise abatement procedures require circuitous routing . Probably the best example is the visual river approach to Washington National which requires the aircraft to follow the river to the airport. The ability to fly curved paths and to lead turns accurately will definitely assist the pilot in the performance of such procedures.

Pictorial Display Equipment and the SST Dynamic simulation studies conducted jointly by FAA and NASA are described in FAA Report No. RD-66-62.

"ATC Concepts for Supersonic Vehicles". This study included an investigation of PD navigation routes in various air traffic situations. Terminal procedures were designed to test arrival and departure operations, representative of present-day traffic at both the John F. Kennedy and San Francisco airports. PD flight paths were used in the terminal complex to determine the value of PD in integrating the SST in the ATC system, and also to determine the capability of the system to accept this operational concept in a terminal control area with high density traffic. Controllers did not vector SST aircraft. They were assigned PD routes, to and from the airport, and were completely responsible for their own navigation. Present-day separation standards, altitude and/or radar, were provided SST aircraft assigned PD routes.

Subjective opinion indicated that PD routes were advantageous to the ATC system. The following discussion 1s based solely on this subjective opinion: PD routes were established within the framework of existing airspace allocations. It was obvious that with prudently designated PD routes, the vectoring area was reduced to a minimum, and maximum utilization was made of the airspace. Parallel routes were also possible without additional navigational aids or complex vectors. When aircraft used the PD, fewer vectors were necessary and there was a decrease in communications workload. It was also possible to establish an arrival sequence and the desired interval long before aircraft reached the final approach course . By positioning aircraft on a given track and adjusting airspeeds of these aircraft to be compatible with each other, it was sometimes only necessary to monitor the traffic all the way to the runway. When SST aircraft were using PD there were no violations of holding pattern airspace, and the controllers' task of monitoring the holding pattern was minimized. The use of PD routes thus decreased controller workload and gave him more time in which to provide better service.

The study concluded, in part, that an effective means of providing segregated routing to SST aircraft is through the use of PD equipment. It was recommended that pictorial display equipment b2 considered as an aid to navigation to permit maximum utilization of a irspace without the addition of ground navigation facilities .

Pictorial Chart Format Techniques Our joint effort with Jeppessen & Co. in chart format design has led to some interesting experiments involving terrain depiction. The objective here is a presentation of safe clearance altitude while maneuvering or when a

25

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series of radar vectors are issued in the terminal area.

Figure l is a sample Denver terminal area chart. Scal_e factor is 5 NM to the inch. 1/15 of the total chart frame 1s viewed here as the film travels under the lens at a rote proportional to ground speed. The circular area indicated would be displayed when over the Denver YOR. Figure 2 is the Denver area with a minimum altitude grid superimposed. The purpose of this experimental chart is to depict the area maneuvering safe altitude. The grid is similar to that used by radar controllers. Minimum safe terrain clearance altitude is shown in each grid area.

Figure 3 is the same area with natural relief superimposed.

The addition of natural relief to this chart helps simulate the actual appearance of terrain.

Flight Information Retrieval It is expected that chart frame capacity will provide room for static displays (position and guidance function removed) to permit information retrieval and display, such as, emergency procedures, check lists, etc. Similar static display possibilities have been investigated in the experiments. For instance to include the minima box on the pictorial display of approach charts, or to display on the airport diagram typical airport and runway data. This latter information is presented in a similar manner as on present flight manual pages.

Complementary Considerations In advocating area navigation techniques to improve terminal airspace uitilzation it should be realized that any resulting increase in traffic capacity requires an effective increase in airport acceptance rate. To be realistic, terminal area applications of area navigation devices should be viewed as one part of the overall systems approach leading to improvements in the terminal area and the airport complex. Also, optimum efficiency of pilot/ controller procedures in the terminal area requires that other complementary actions should continue to be pursued:

1. The development and implementation of improved VOR accuracy capabilities from ground facilities and in the airborne equipment.

2. Terminal area automation in the form of final approach computer sequencing to assist the controller in spacing aircraft to optimize the acceptance rate of the runway.

3. High volume terminal areas will require adoption of a designated system of tracks for use by the pilot and controller.

Conclusion Area navigation, pictorial display techniques offer the most potential for optimum pilot/controller applications in the terminal area. Much industry activity is rightfully concerned with airport acceptance rates and runway acceptance rates. However, there is also a need, in the terminal area, for an improvement in "controllers acceptance rate". The industry goal of pilot initiated area navigation from the cockpit will help achieve this objective by changing the emphasis and allowing the radar controller to perform more of the monitoring function .

26

V /STOL Navigation in the Terminal Areaic

by E. N. Baur Vice President, Flight Operations New York Airways, Inc.

The introduction of the new family of twin turbine engine helicopters accompanied with recent developments in navigation and instrumentation have made full instrument flight operations possible for the first time in scheduled helicopter service. The long-run commercial implications are significant. This development is a major advance which will bring the same kind of schedule regularity to helicopter services which the air traveler has come to expect from today's fixed wing jet services.

Improved regularity will be an important factor in attracting more passengers and commercial revenues. A completion of a higher percentage of scheduled flights will also permit the more effective utilization of equipment, personnel and ground facilities.

Because of these developments, we now know that with the next generation of helicopters and V/STOL aircraft, we can provide city center to city center service with maximum schedule regularity employing air space not now fully utilized by any other aircraft.

A considerable period of experience with a low frequency hyperbolic navigation system h~s assured th.e Federal Aviation Agency and New York Airways that this system will provide the primary navigation function. This hyperbolic system fulfils the pilot's need for ~~owing precisely his relative position in space. The mixing. of V/STOL and fixed wing air traffic in a congested terminal area like New York under instrument flight conditions using the COMON System, is impractical as well c;is ~ostly.

As early as 1951 New York Airways .realized t~at the co-mingling of V/STOL and fixed wing. 01r~raf! during. !FR operations, as well as line-of-sight nav1gat1on installa.t1ons such as VOR systems, were unsuitable for low a.lt1t.ude V/STOL operations, especially in cities where tall budd1~gs interfered with the line-of-sight signal. The usual shadowing of the VHF signal from the VOR or TACAN facility does not always assure adequate guidance throughout the route structure. As a matter of necessity therefor, New ~ork Airways began to work on the development o~ a navigation system where the signals would not be ~1sturbed by buildings or other obstructions, and that was independent of the present COMON IFR Navigation System.

Early investigations revealed that the Decca. Navi~~tor System, then in extensive use for marine navi.ga~1on, u!d1zed principles which were capable of establishing a.1rcraft location without the use of very high frequency line-ofsight signals or present COMON Syste~ navi~ation.

However, at that time, the Decca electronic equipment and instrumentation were not only far too large and heavy for helicopter installation, but als~ there had. b~~n no hard operating experience demonstrating th~ feasib1~1ty of their use. A Decca Navigator System ground inst~llat1on (Decca Chain) was installed in the New York area 1n 1957 under a contract between New York Airways, the Decca â&#x20AC;˘

Paper presented at the 1967 RTCA Annual Assembly.

Navigator Company and the Airways Modernization Board. Airborne Instrument Laboratory carried out the technical measurement portion of the program. Following the termination of this contract, New York Airways continued to work closely with the Decca Navigator Company in the development of a navigation system with airborne equipment especially suitable for use of transport helicopters and V/STOL aircraft employed in a daily air eerier service. The New York Airways' installation was utilized under visual flight conditions to monitor enroute flight tracks and the airborne system was appropriately called Flight Track Monitor. New York Airways commenced an intensive testing program of the prototype equipment, logging over 40,000 operational flight hours.

The flight program provided sustained controlled experience with the operation of the equipment and a scientific measure of the performance of the system within a terminal area independent of fixed wing IFR traffic.

On February 16, 1965, New York Airways received authority from the FAA to utilize the Decca Navigator System to conduct full instrument operations both enroute and at the terminal area. With the complete implementation of this approval, it is estimated that flight schedule cancellations for weather reasons will be reduced by about 100/o.

The FAA-NYA metropolitan area instrument flight air traffic control concept provides, to the maximum degree possible, for the segregation of helicopters operating under instrument flight conditions. It is expected that helicopter traffic will thus be expedited over extremely short stage lengths with little or no adverse impact on the normal flow of fixed wing aircraft. The IFR flights conducted to date, have borne this out.

New York Airways Boeing V-107 helicopters are equipped with the following navigational and communications equipment: 1.

2.

3.

4.

5.

6.

7.

Dual Mark VIII Decca Navigator System Transponder Single VOR system Dual VHF transmitter and receiver Instrument landing system glide slope receiver Dynascience electrostatic discharge system Marker beacon receiver

The Decca Navigator System shows the pilot visually the geographical location of his helicopter with a stylus inscribing on a local area map the exact path being flown, thus enabling him to fly directly to his destination much as a motorist follows a road map. A pictorial display of the navigational data in the cockpit is essential to provide for accurate trackkeeping and orientation, particularly unde:¡ strong cross-wind conditions. The pictorial display also minimizes the pilot workload involved in almost ontinuous take-offs and landings at high density airports.

27

The Air Traffic Division of the FAA in finalizing instrument flight approval with the Decca Navigator System as 0 primary navigation aid, established a route width of 1.5 nm on either side of the track center line; o minimum vertical separation from other aircraft of 1,000 feet; a holding pattern air space area of 2.6 nm width and 3.9 nm length, provided a hook-type entry is mode into the holding area; a radar separation of 3 miles; and o 500 foot minimum obstruction clearance altitude above the surface.

Complete segregation of helicopter instrument traffic from the fixed wing traffic was the project goal in the early stages of the program. After o lengthy and careful study, however, it was conceded that a completely independent operation was not feasible in the New York area, one airport control zone practically abuts the other.

The air traffic control pion which was adopted provides for the maximum independence of helicopter instrument traffic through the use of procedural segregation. The helicopter routes, holding patterns and altitudes are depicted visually.

There is a tremendous market existing today in the metropolitan area and city center to city center transportation market. This market will increase with the rise in population and in urban living while the great cities of the world continue to strangle themselves on traffic. The helicopter and VTOL family of aircraft require no highways, no tunnels under the streets, no unsightly structures above the road, and no vast areas of land for parking or terminal areas. Today's helicopters lift people above the ground congestion and utilize air space that is below the intermediate approach altitudes for fixed wing traffic operating under instrument conditions and yet high enough to reduce noise nuisance and attain safe terrain clearance.

The virtues and the benefits to be derived by the public from the helicopter and VTOL aircraft are as closely dependent upon flight operations during instrument conditions as the fixed wing aircraft. The public acceptance of VTOL transportation assumes instrument operation into restricted and limited landing areas with equivalent regularity and other features that ore already common with surface and fixed wing air transportation. The operational environment in which air traffic control would be exercised must certainly accommodate full instrument operation conducted on the basis of accurate and flexible navigation at all enroute altitudes down to ground level.

Essentially air traffic control information is either airderived or ground-derived and certain data which is now air-derived is capable of being obtained from ground sources. Aircraft position con be established by primary radar when this is available. Secondary radar is effectively utilized to supply data with respect to identity, position and altitude. The role of a data link in an air traffic control system must be determined.

A proper balance must be achieved between information obtained by air traffic control, on the one hand from the aircraft, and on the other hand from its own ground resources. In this connection the relationship between the air traffic control and navigation system must be considered. The quality of the navigational data must be high. Air traffic control and navigation form two closely related elements. Just as a pilot needs to know his precise position at all times and the action he must take to maintain his desired route and flight level, so must air traffic control have precise knowledge of the position, flight level and identity of aircraft under its jurisdiction so that safe separation can be preserved.

Automatic Position Data Transfer楼

by G. D. Hadorn Federal Aviation Administration

There is a rising volume of concern among aviation authorities for major improvements in handling air traffic at the U.S .' terminals . It has been apparent for a number of years that only the introduction of automation could provide the capability needed by air traffic controllers to handle expanded operations around the country.

Several of our major terminals - Chicago, Los Angeles, Washington - already ore being taxed to capacity, and with the air travel "explosion", more will be in the near future. Based on this, we are proceeding with a program aimed at providing varying degrees of automation at all radar terminals, depending on their volume of traffic.

At the same time. there will be built in an inherent growth capability. Facilities with less than full automation will have odd-on-capacity to provide additional functions if and when needed.

Major high-density Terminal Radar Control (TRACON) facilities are planned to have full primary radar and 路

28

Paper presented at the 1967 RTCA Annual Assembly .

radar b~acon alphanumeric displays. Lower density TRACON s and smaller category locations, such as FAAoperated military approach control facilities, will have at least the capability of displaying actual altitude and beacon c~de _informati~n in numeric form directly on the controllers display. This feature will give him constant thre_e-dimensional position information on all transponderequ1pped controlled targets. Selection of specific hardware to meet these requirements has not yet been made pending completion of a test program with several experi~ mental systems. _The nor~al plan position indicator (PPI) radar presentation on airport surveillance radar-type displays (nonscan converted) presently in use may continue to be used a~gmented with either alphanumeric or only numeri~ display of data, depending on facility requirements.

Included will be identity and calculated ground speed on transpond~r-equipped aircraft, plus actual (computer corrected) altitude readouts from aircraft replying to Mode C transponder interrogations.

Experience gained from our field trials of the Advanced Radar Traffic Control System (ARTS) conducted in 1965 at the Atlanta (Georgia) terminal will provide the initial base of departure for future terminal automation. That experience demonstrated that a number of benefits can be realized by providing either alphanumeric or simply numeric capability to existing facilities. Some of the more important ones are: - Simplified maintenance of target identity - Direct readout of altitude data via Mode C - Reduced controller coordination and communications workload, and - Provision for on evolutionary transition to terminal automation.

Our experience gained from developing the radar and beacon digitizer (Common Digitizer) for the en route NAS Stage A facilities will be applied to the experimentation program for terminal areas. The first effort underway is to identify the problems of radar and beacon digitizing peculiar to the terminal operational environment. This effort will provide data from which performance specifications can be completed for a Terminal Video Digitizer (TVD) for use in highdensity TRACON's, where the full automation is expected to be needed.

We believe the TVD functional requirements will be much the same as those for the en route Common Digitizer (CD). Functionally, the CD accepts video inputs from search radar returns and beacon replies, detects the presence of valid radar and beacon targets, computes the target center azimuth, validates beacon altitude and identity replies, and furnishes one message per target per antenna scan. Messages are formatted and transmitted at 2400 BPS over voice bandwidth data channels to the associated ARTCC facility for further processing prior to display.

Some of the important differences between en route and terminal operational environments which we believe will affect the functional requirements for the terminal digitizer are: Much higher concentration of aircraft by sector Higher pulse repetition frequency of search radar, the need to "see" all aircraft at close-in ranges and at tbe lower altitudes, together with increased "groun~ a.nd angel" clutter, all of which can contribute to a significant increase in the false target output rote from the digitizer, and .

More stringent requirements on allowable delay wh1~h affects the real-time positional error on the controllers display. Maximum in-process delay for the TVD must be limited to 0.3 seconds, while the CD in-process delay can be as high as 5 seconds.

Traffic projections for major terminal areas indic?te that the number of aircraft during peak operation periods will double in ten years. (The average peak at Chicago O'Hare today is over 300 aircraft in the area of coverage.)

We are planning to modify one o_f the NAFEC .~ado; Video Dato Processors (RVDP) to provide the capability. 0 manipulating the sensitivity of the sliding window dete.ctio.n process. This scheme involves controlling the quantizers sensitivity in discrete zones of coverage of the antenna scan as a function of the system thermal noise pi.us ~he prevailing level of the clutter in each zone. Th~ ~b1ectiv~ of our experimentation is to determine whether it is technically feasible to reduce the data load input to the

TRACON computer to an acceptable level of false targets and, at the same time, assure that the sensitivity of the statistical detector in the TVD is at the maximum useful level for each discrete zone in the area of radar coverage.

We hope that our experimentation with the RVDP in simulated and real life terminal environments during the next year will provide us with some answers on the magnitude of the problems that have to be resolved before a TVD can be operated successfully in major and highdensity terminal areas.

The TRACON computer will be provided with mediumspeed modems to interchange data at 1200 or 2400 BPS over a duplex voice-bandwidth data channel connecting the en route computer at the ARTCC with the associated TRACON facility. These modems will be identical to those provided for interfacility data transfer between en route computers. A summary of interfacility data transfer subsystems characteristics are: -

-

Subsystems availability - 0.9980 minimum Bit error rate (exclusive of parity) - Average 1o-s, or less Data channels separate geographical routing between centers when required to improve overall system availability, and Alternate channels access - use of dial-switched networks to permit data transfer over an alternate channel when a discrete channel has failed.

All of the functional requirements for data transfer associated with the TVD have not been defined. We do know, however, that the increased number of aircraft targets in a sector, in conjunction with a 0.3 second limitation on processing of target messages by the TVD, could result in a data transfer rate as high as 24,000 BPS. In the event that the digitizer equipment is located at a radar site which is beyond cable distance and broadband re;moting is not employed (no PPI presentation), we believe multiple 4800 or 7200 BPS voice-bandwidth data channels should be employed since they would provide the required redundancy (not available from the conventional 19.2 or 40.8 K/BPS data channel currently tariffed by the common carriers).

Experimentation is planned with several high-speed voice-bandwidth modems to determine state-of-the-art performance. This effort, in conjunction with the RVDP experimentation to define the TVD performance requirements, will assist in defining the terminal radar data transfer system configuration and functional requirements.

Based on the life-cost program benefits of using broadband versus multiple voice-bandwith channels, the highspeed data transfer system will then be developed for timely implementation with the TVD. Some of the high-activity terminal facilities will have the capability of operating "on line" with the Central Computer Complex (CCC) at the center (ARTCC) by means of "Flight Data Entry and Printout Equipment (FDEP)."

This will enable these facilities to file and receive data via a direct computer link. Three basic equipment items located at the remote facility will interface with the Peripheral Adapter Module (PAM) of the central computer.

They consist of a Data Communications Control Unit, one or two Alphanumeric Keyboards, and one or two Flight Strip Printers.

Communication between a remote facility and the CCC will normally be via leased, half-duplex, telegraph circuits at a signalling speed of 8.33 characters per second . IBM

29

Tilt-Rotate, and EBCDIC or ASCII codes are to be used.

Code conversion and error checking functions are accomplished in the Data Communications Control Unit and the Peripheral Adapter Module of the central computer.

Major features of the equipment include: -

Odd parity checking of all transmitted characters and control information Bit-by-bit checking of each character to be printed Automatic "good or bad" response from receiving device to sending device for each message Polling from the Central Computer Complex Automatic time-out and computer interrupt for lack of response to polling Printing on either or both printers and in two colors and two character sizes, and Data entry from either keyboard.

Another advancement - somewhat further down the road - which can be expected to expedite traffic flow in the terminal area is the automation of a considerable portion of the communications between pilot and controller.

In particular, vectoring and frequency-change instructions to the pilot, and acknowledgements and automatic transfer of critical aircraft status items to the controller are well suited for transmission via a data link to a display, or to an air traffic control computer. Pilots and controllers, freed of routine communication functions, could then concentrate more effectively on the serious business of getting the airplane safely and expeditiously into and out of the terminal. Voice backup would, of course, be instantly available for unusual or emergency situations.

Unfortunately, we have not as yet been able to obtain anything approaching universal agreement on just how such a system would be operationally employed. Until such an agreement can be reached, it will be extremely difficult to synthesize and describe a practical system which would be developed and implemented. There seems to be a general opinion - probably quite valid - that although an automated ground-air-ground data link will ultimately be required, it will not be operationally practical until the automated ground ATC environment of the National Airspace System has become operational. We are well aware, however, that new systems do not spring forth full grown and that much spade work over a long period of time is required. Looking forward to the day of implementation, we are at present involved in this spadework.

We are,. and have been for some years, active in the RTCA s~ec1~l committees concerned with digital data communication systems including SC-11 and 111. We are repres~nte~ on the ICAO {International Civil Aviation Organization) groups which are studyin th 1路 t. . . h . g e opp 1ca ion 1 tee n1ques to air traffic control o. f d 1g1ta 路 . . commun1ca t"ions, including those in the terminal areas of 路 t t.

I 路 in erna 1ona a1rpo.rt~. And wear~ closel.y mo.nitoring activities of the AEEC (A'.rl1nes Electronic Engineering Committee) such as AIDS (Airborne Integrated Data System) and BITS (B" I .

1nary nformation Transfer System), etc. We are of co I ' urse, a so working to establish a meaningful, and fully-acceptable set of operational requirements for a data link. To thi~ end, we have conducted a number of simulation experiments at NAFEC. Presently, we are preparing plans and establishing an environment at NAFEC which will permit simulation involving the computer display channel and other elements of the NAS which will most likely interface with a ground-air-ground data link.

We have also conducted laboratory and flight experi-

o

30

ments which will assist us in defining system standards, and are planning additional experimentation for the near future. Present plans envisage a modular approach to the implementation of the data link in the ground-air-ground environment. A possible first step, which might be practical at a fairly early date, would be the initiation of an automatic ground-to-air terminal information service.

Rapid and radical advances have been made within the past few years in the quality and reliability of portable and transportable time and frequency standards. In addition, techniques which permit remote slaving of moderate accuracy standards to a master standard have also been developed. As a consequence of these developments, a large number of system concepts which depend critically upon the ready availability of very precise standards of time and frequency are now becoming practical.

These concepts, generally grouped under the generic term "time/frequency systems", show promise not only of improving many types of avionics equipment, but possibly even providing entirely new capabilities. The FAA, under a comprehensive study contract, is presently examining and evaluating the possible utility of these improvements and capabilities to the air traffic control system. In this pap~r, however, I will touch only upon that specific class of t1m:/frequency systems which are probably closest to operational status, and which may prove useful in alleviating terminal traffic problems: collision avoidance time/ frequency systems.

A number of system concepts have been proposed, and, over the years, some have been reduced to hardware.

Presently, two systems are under serious consideration.

While differing in detail, both perform the following basic functions.

1) Cooperative range and range-rate measurement, based on a ~ri~ri estimates of the time and frequency of tran~m1.ss10~ of a signal from an intruding aircraft. (The a priori estimates, of course, are supplied by the time and frequency standard).

2) Som: degree ~f data communication capability to provide for the interchange of any additional variables required to assess collision threats, and 3) Decision logic to assess the threat imposed by the intruding aircraft and, if required, to select and display an escape maneuver.

Unfortunately, these systems require that all of the aircraft population carry at least a minimum installation to provide fully-effective system operation.

A very searching operational analysis will first have to be conducted to determine if such a system (which is, in effect, an electronic VFR or "see and be seen" technique) is or can be made compatible with the rather rigid ground control exercised by the ATC system in crowded terminal areas. A possible operational technique which might be evaluated would be the use of a two-step warning system - an early or advisory warning of possible conflict, which would be presented only to the controller, over some sort of data link, to warn him of the necessity for immediate control action, followed (if this is not effective) by the standard maneuver command presented to the pilot on a cockpit indicator.

In the presently proposed system, there is a limited communication capability which could be adapted to telemetering useful information from the aircraft to the

controller (or computer). We are investigating the possibilities of an integrated system of collision avoidance and data link which would increase safety and minimize delays, while at the same time reducing pilot and controller workload.

In summary, then, to help alleviate the terminal area problem we plan to initially introduce numeric or alphanumeric display capability in the terminal areas to simplify maintenance of target identity, provide direct readout of altitude data, and reduce coordination and communications workload.

We are installing "Flight Data Entry and Printout Equipment (FDEP)" at remote facilities such as TRACON's

RAPCON's and RATCC's which will have capability to file and receive flight data via a direct link to NAS Central Computer Complex (CCC).

Our work on ground-air-ground data link is proceeding at a slower pace, but we hope to have the technology and system standards well defined by the time they are needed for implementation.

We are expending considerable effort on collision avoidance systems. Here, as in the case of data link, the major problems are operational - how to ensure that a majority of aircraft are properly equipped. The technical problems (as is usually the case) are comparatively simple.

The Air Route InterfaceÂĽ

by R. F. Frakes Federal Aviation Administration

En Route air traffic control in the continental United States is accomplished today in 21 Air Route Traffic Control Centers (ARTCC's). The Federal Aviation Administration plans to automate each ARTCC with a system called En Route Stage A. Each Center will be interconnected with adjacent Centers and with associated automated Terminals by high speed data transmission links and the entire system will function as a nationwide, real-time, automated air traffic control system.

The broad objective of En Route Stage A is to increase the traffic handling capability of the air traffic control system while maintaining or increasing system safety. The following are specific goals: 1. Provide automation aids for establishing and maintaining radar identification of aircraft in the system.

2. Provide automatic display of altitude or flight level information with aircraft position.

3. Provide automation features for easy transfer and accurate processing and updating of flight information.

4. Provide a computer processing capability to serve as a base for subsequent automation improvements.

The attainment of these goals will assure that the en route air traffic controllers will be relieved of those tasks that can be performed faster and more accurately with computer assistance. .

The following are the significant automated operationa I features of the system:

1. Automatically and manually initiated computer program tracking.

2. Bright display of alphanumeric and radar ~ata.

3. Entry and processing of flight plan information.

4. Flight progress strips printed at the appropriate sector positions.

5. Provision for entering and rece1v1ng updated flight data at all operating positions. lntersector coordination through computer generated alphanumeric displays, both plan-view and tabular.

7. lnterfacility coordination through the use of computer transmitted data.

8. Computer generated displays of geographic and 6.

weather data.

9. Provision for automatic computer initiated handoff capability. â&#x20AC;˘

Paper presented at the 1967 RTCA Annual Assembly.

The automated en route system is divided into four functional capabilities; namely input, output, data processing and monitoring-recording.

INPUT - Remote and local data entry devices are used to input flight plans, flight plan amendments, weather data and other messages for processing and routing by the computer. Aircraft position, identity, and altitude are determined by a collocated radar/beacon system for all beacon transponder equipped aircraft. For aircraft with no transponder, only radar position is determined. The radar/beacon data are digitized at the radar site by a device called the Common Digitizer and transmitted over narrowband transmission facilities to the Air Route Traffic Control Center. There, the radar data are accepted by the computer for processing.

DATA PROCESSING - The data processing functions validate the input messages, process and store the data base, perform required calculations of both flight and radar data base, perform required calculations of both flight and radar data, generate and route output messages and provide control of the real-time program.

OUTPUT Flight progress strips are printed and distributed at the appropriate control positions. Presented on display consoles is the current air situation consisting of processed radar and beacon data, tabular data, map data and certain weather data. Where required, input messages are acknowledged if found to be acceptable or an appropriate error message is sent to the message source.

MONITOR-RECORDING - The system has the capability to monitor status, configuration and performance of each subsystem. Recording capabilities are provided to enable specific data to be periodically transferred to magnetic tape for both legal recording and system analysis purposes.

SYSTEM INTERFACES - When the En Route and Terminal facility automation programs are completed, there will be a nationwide system with the facilities interconnected by high speed duplex data transmission links operating computer-to-computer at a data rate of 2400 bits per second. Each En Route Air Route Traffic Control Center will be interconnected to other Centers with which it has a common boundary. Each computer equipped Terminal facility within an En Route Air Traffic Control Cente1"s boundary will interconnect to the Center.

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At certain high density automated terminals, the Flight Service Stations, Airport Traffic Control Towers, Air Carrier Operations Offices and ~1il.ita~y. Oper.ations Offices within that terminal's area of 1umd1ct1on will connect online to the high density terminal computer. If they are not within the high density terminal boundary, they will interconnect directly with the En Route Traffic Control Computer utilizing equipment called Flight Data Entry and Printout Equipment operating at teletype speed of 100 words per minute.

In addition, the Air Force and Navy terminal facilities will also be interconnected on-line to the En Route Traffic Control Center's computer.

DATA TRANSFER AND HANDOFF The Terminal facilities will receive flight plan data for controlled aircraft, both arrival and departure, on-line from the En Route Traffic Control Center's computer. For automated facilities, this transfer of data will be accomplished approximately five minutes before the aircraft is estimated to arrive at a designated fix or is estimated to depart.

The minimum flight transferred will be that required to establish computer files; i. e., aircraft identity, assigned beacon code, destination airport, entry fix or departure route fix, and in the case of arrivals, an estimated time of arrival at the entry fix. The data is arranged in the proper format by En Route computer prior to transmission to the Terminal facility . Additional interfacility flight and track data transfer necessary to effect a handoff between facilities will be accomplished automatically.

IMPLEMENTATION The first automated en route facility will be the Jacksonville Air Route Traffic Control

Center. Functionally it will be a full En Route Stage A facility when completed. Considering the equipment used, it will be a "one-of-a-kind" facility in that some prototype and modified equipments are utilized. The FAA plans to retrofit this facility with production equipment as part of the total en route automation program. Equipment installation at Jacksonville is nearing completion and considerable equipment testing has been accomplished.

Following the completion of individual equipment testing, we plan to configure the equipment into subsystems, to accomplish individual subsystem tests and then to integrate the subsystems in an orderly method, into the total system configuration for final system hardware tests.

The operational computer program will then be installed and a period of testing called Program Shakedown will begin. Upon completion of this phase of testing, the system will be ready for the operators and controllers and is said to have an initial operational capability. Program Shakedown is presently scheduled for completion in December of 1968. Following program shakedown will be a period of operational testing called System Shakedown which involves the total system, hardware, software, controllers and operators. Following the successful completion of System Shakedown will be the final phase called Operations Changeover in which the system will actually be used for air traffic control.

For the follow-on implementation, nearly all of the equipment contracts have been let and production is under way. Equipment delivery will begin early next year.

It is the goal of FAA to complete this first step of en route automation, Stage A, in all Air Route Traffic Control Centers by 1972.

Potentials for Increased Airport Capability~

by Harry P. Schmidt Vice President R. Dixon Speas Associates

It is interesting to reflect upon how technology, sociology, and public acceptance of air transportation has changed the perspective with which we consider airport planning. Not too many years ago we were struggling with the problem of how to operate aircraft under minimum weather conditions at all our airports. Today we have essentially solved that problem, and at the larger airports are interested in keeping runways operable in the face of potential noise restrictions with an increasingly compelling motivation for substantial inc;eases to airport capacity. At many smaller airports we are involved in economic justifications for the first (the weather) problem, recognizing that the second problem is just around the corner.

This panel is quite properly composed of people representing several different specialities, since the airport capacity problem concerns each element. The final actual operating capacity is going to be determined by the weakest link in the system, and not governed by the strongest. With regard to specifically the airport proplem, we intend to cover the following: l) Effect of noise 2) Requirements for general aviation 路

32

Paper presented at the 1967 RTCA Annual Assembly .

3) Runway development: (a) Number and configuration (b) Dimensions (c) Terminal area (d) Turnoffs (e) Runway ends 4) Navigations and communication aids Most of these elements are not new. However in our airport p!anning work we find that so often one is ;empted to lose sight of long term requirements in the interest of short term solutions. Consequently, it is always desirable to be able to back off completely and look at the full spectrum of problems and apparent solutions.

1) One

serious compromise to airport operating capability can arise from noise restrictions which impose ineffic~ent "preferential runway" criteria on aircraft operations.

This problem is really so basic that often it is over-

l~oke~ until it is too late, and at that point in time the

s.1tuat1on becomes so complex, involving political, operational, economic, and psychological factors that clear-cut solutions are never available.

Airport configuration should therefore be the result of pre-planning, and less the subject of too late compromise.

In many instances planning is the subject of short term solutions which seldom yield sufficient options in the long run. This is the natural result of the young airport characteristics no capacity problem, little traffic, no noise problem, little money to spend for additional land acquisition, and too little local support for comprehensive zoning for compatible land use. When noise does become a problem, all the other factors have moved in an opposite direction and the solution is difficult to achieve.

For the young airport, therefore, the handwriting on the wall is clear - you will get jets, and more jets; - traffic will grow; - land around the airport will become developed, and then problems will multiply rapidly.

So while the airport is small and has vacant land around - do something to protect its future through a joint program of land acquisition and zoning. The land will always be a good investment financially (industr'.al parks, etc.) and in years to come the throngs of humanity will not be massed at the field's boundaries .

For the older airports, the problem may already be well developed, and cheap solutions are impossible.

In such an instance there are various alternatives change the principal runway orientation, or develop compatible land use through purchase, zoning, or highway construction in approach and departure paths.

These solutions are obviously expensive, but so is the alternative of substantial reductions to capacity, or, relocation to a more distant airport site. One thing is certain, however, that the cost of an alternative will be more at a later date than it is now.

In either case, whether considering the young or older airport the decision must be based upon a reasonable plan of development. Whatever funds are committed for such a purpose must be efficiently applied - pref~ra~ly utilizing some form of costbenefit analysis !o dete.rmine which is, for operational as well as economic considerations, the most prudent plan for future development.

2) A i r p o r t p I a n n i n g , p a r t i c ~ I a r I Y i n t e r minal areas, must consider accommodations of small aircraft on other than air carrier runways.

The theme of this paper is how to get the most from 路 t - and generally speaking this means to make your airpor . the most effective and efficient use of economic res~urces.

Thus, the idea is not recessarily to maximize total aircraft operations on a particular runw~y, but rather to get the ractical utility from a given amount of money. mos t P 路 f Conversely, this can mean satisfying the m~st aircra t (and passengers) for the minimum total expenditure.

This clarification is believed desirable to put the total airport planning requirement~ on a positiv~ basis . Implicit in this statement is the ultimate necessity of . forwa.rd thinking to satisfy two dissimilar elements - air comer and general aviation. They both need runways - but not of the same lenght; they both need airspace.' but can be handled more efficiently if not the same airspace; and they both want to be as close as possi.ble to the center of town, but not necessarily at the same airport. ~e:erthele.ss, there are certain elements of general av1at1on which

should remain at the air carrier airport, although not necessarily on the same runways that the air carriers generally utilize.

Planning for a progression of airport maturity might take the following form: -

-

-

Initially the airport can reasonably handle all air carrier and general aviation aircraft.

As future requirements for additional runways and facilities are forecast, evaluate the nature and characteristics of the general aviation activity to determine what portion could reasonably be relocated to satisfactory general aviation facilities at an alternate location.

The remainder of general aviation will remain at the air carrier airport for this portion, evaluate the potential for accommodation on short runways removed from the main stream of air carrier traffic.

Develop a system of general aviation airports which will surround the metropolitan area. Certain of these airports to have full IFR capability including runway lengths of 5000 ft. and more, as may be required for the more sophisticated general aviation aircraft. The other airports to be VFR airports, with runway lengths of 2500 ft. to 4000 ft. All airports to operate independently of air traffic patterns serving the principal airport.

3a) R u n w a y d e v e I o p m e n t p I a n n i n g s h o u I d consider the future potential for a parallel runway system, at least in the principal operating direction.

The objective of runway development programs must be to maximize an airport's operational capacity within the geographic area available for development. The means of accomplishing this will vary with different circumstances as to the importance of IFR capacity (as differentiated from VFR capacity) and the make of aircraft (large aircraft versus smaller general aviation aircraft).

The magnitude of improvements achieved with additional runways will vary quite substantially depending upon the specific conditions, and so, rather than attempting to quantify these improvements, we will discuss them qualitatively. But first a word about capacity. Our organization in conjunction with United Aircraft Corporate Systems Center and Tirey Vickers developed a couple of years ago a computer simulation model of airport (and terminal airspace) operators. From this model, which can consider every possible combination of runways, operating rules and weather conditions, we have been able to see what affects capacity, and how much improvement can be attributed to various factors. However, the randomness with which demand (operations) occur is in itself a contributor to variations in the capacity - demand - delay relationships.

Thus, we feel that being highly exact about the definition of an airport's capacity (in terms of movements per hour) is overstating the mathematical probability that such capacity will, in fact, be achieved . We do not say this because we feel that the computer simulation is less exact than some other method - but rather we say this because the computer has been a tool by which we could look at the entire workings more accurately than by other methods, and thus we have come to appreciate the full ramifications of airport capacity.

33

However, although the total number of movements (related to on overage delay) may hove significant variations, the relationship between alternative plans can be minutely appraised by simulation. Thus, relatively modest differences between configurations can be explored within the framework of present and future operating rules and aircraft mixes.

Getting bock to broad guidelines, however, the following is meant to be guidelines for general planning purposes: (a)

Most airports will start out with a two-runway configuration for wind coverage. Under light wind conditions both runways can be used to substantially increase capacity. (b) A parallel runway in the principal runway direction will offer the potential for substantial increases in capacity over a single runway configuration. (c) Parallel runways separated by 5000 ft. or more offer the potential for simultaneous IFR operations. For major air carrier airports this capability will eventually be required. Although this 5000 ft. standard may be reduced at some time in the future, prudent planning would suggest that this 5000 ft. separation be developed if at all possible. (d) Runways separated by less than 5000 ft. offer, under today's rules, substantially less IFR capacity than the wider spread runways. It is recommended that additional effort be devoted towards operational criteria which will increase the capacity of such a system. (e) (f)

A parallel runway for general aviation should be considered to assist the VFR capacity.

With regard to closely spaced parallels, attempt to obtain as much distance between them as possible if heavy aircraft ore operated alongside small aircraft in order to minimize the wing-tip vortex problem.

3b) T h e u t i I i t y o f r u n w a y s u n d e r c r o s s wind conditions may be improved by wider and longer runways than currently used.

Invariably it is desirable to maximize the utility (~en~ent of time that a given direction con be used) of the principal runway direction. To do this, you must either increase the aircraft's crosswind tolerance, or the pilot's tolerance.

Since in most all cases it is the pilot's tolerance which is the limiting factor, treating this item woul? app~or desirable. We have discussed the prospect of mcreas1~g crosswind tolerances by wider and longer runways with a number of operational personnel, and have r~ceived their individual opinions that such runways would, in fact, substantially increase crosswind tolerances. They (and ":e) believe that both wet and dry runways may be used with substantially greater crosswinds if they were 250 ft. to 300 ft. wide, and at least 1OOO to 2000 longer than presently considered standards.

We present this not as proven fact, but rather a.s a proposition that deserves consideration and evaluation.

The ability to utilize one runway (two directions) for a vast majority of oil times would rather significantly change our airport planning criteria, and in most ca.ses greatly eas: a possible noise problem. Other efforts to 1m~rove crossw1~d capability such as runway grooving to assist the we~ .(with puddles) runway problems are recognized as add1t1onal items which will assist the overall problem.

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3c) T h e t e r m i n a I a r e a s h o u I d b e d e v e I oped in the middle of a parallel runway configuration.

Any use of an active runway for crossing aircraft traffic subtracts from the runway's basic capacity. In most cases, any substantial amount of runway crossing traffic stems from the fact that the terminal is on one side of the field, and all runways ore on the other side. This is often the case when the basic airport pion was not modified when additional runways were added.

This decision is justified on the basis of minimum investment in additional airport modification; however, it may well affect long time utility of the airport. Should long range forecasts show substantial increases in demand, and there is an inherent interest in remaining at the present site, it may well be desirable to alter the basic configuration to put the terminal in the middle "now", rather than the more expensive solution of doing it "later".

3d) T h e I o c a t i o n a n d c o n f i g u r a t i o n o f turnoffs should be related to present and future aircraft mix.

Runway capacity is essentially related to average runway occupancy time. To increase airport (runway) capacity, it is necessary to reduce runway occupancy time to a minimum. For landing aircraft this is done by placing exits in accordance with the deceleration characteristics of the particular aircraft mix. However, certain generalities can be made: (a) Angular turnoffs (20째-30째) are much better than rightangle turns. (b) The throat of the turn should be as wide as possible to give pilot the broadest "target" to aim at, and to reduce the critical need for highly accurate tracking during the turn. This will give the pilot more confidence for maneuvering through the turn at higher speeds. (c) The turnoff should not be a "dead-end" where a full stop will be required soon after leaving the runway. (d) Wet runways require longer stopping distances. Therefore, a dry runway turnoff and a wet runway alternate turnoff must be considered for each major aircraft classification. (e)

On long runways the touchdown point will tend to be further down the runway than on a short runway. (f) Deceleration will be influenced by terminal location. (g) Provide a means of getting general aviation aircraft off the runway as soon as possible.

Turnoffs have properly received considerable attention in airport capacity discussions. Our studies have indicated that turnoffs con affect a runway's capacity by up to approximately 25%. Although the average runway is not that bad, most runways can use improved turnoffs that may affect capacity in the order of 10% under certain conditions.

3e) R u n w a y A c c e ss Ro u t e s a I s o a f f ect runway capacity and should be carefully considered.

In the same way that turnoffs affect runway occupancy, so do runway entrance points affect occupancy and, therefore, capacity. The most common fault is when the entrance taxiway is not at the end of the runway. Since most pilots will taxi to the very end of the runway, they, therefore, are

required to taxi a short distance in the wrong direction and then make a 180째 turn. This consumes many precious seconds which substantially affect the runway's efficiency of operation.

Secondly, the runway access taxiway should have sufficient space for taxiing aircraft around the first two or three aircraft in line for the action . This will permit the tower controller to hold a couple of aircraft which are encountering a route or center delay and bypass them with other aircraft which do not have such restrictions .

4) Modern g round e q u i pm en t a n d pro c e dures can assist in expediting runway traffic. Th i s includes lighting, surveillance radar, alternate communication capability and division of con trol personnel responsibilities .

The capability to handle increasing numbers of aircraft on runways is also directly related to the efficiency with which pilots can control their aircraft, particularly on the runway, and the efficiency of tower control personnel to direct their movements. These would include the following: (a)

(b)

During IFR and nighttime operations, a center line inrunway lighting system which outlines high speed turnoffs assist the pilot in leaving the runway at higher speeds.

Under the same restricted visibility conditions (as above) radar aids in the tower will assist control personnel in directing aircraft. Surface detection (ASDE) and surveillance radar, including bright displays of both radar sets, will assist in this respect.

(c)

Under certain conditions the total airport capacity may be determined by the ability of one controller (the live runway controller) to talk to all aircraft under his jurisdiction . A division of responsibility between two men may be practical - particularly when there are parallel runways with the tower in the middle

(d)

We would envision that more sophisticated communication devices that direct aircraft taxiing will be adopted in the future.

(e)

Central location of the tower to permit controller to see all runway ends, will improve their direction capability.

(f)

With airports of greatly increased dimensions, there is a substantial reduction to the ability of controllers stationed in one central location to see distinctly all runway ends. Under such circumstances, either much greater reliance on radar control and other electronic signaling devices, even for line runway operations, or multiple tower installations - each with its own area of responsibility - would appear needed .

In summary, we have mentioned several items which must be considered in airport planning - altthough most of them are not new. In retrospect, it would appear that the greatest single item of importance to future airport operations lies in the area of planning for the long term future, recognizing that there are cost-benefit implications in long range planning. Secondly, we suggest that an airport is not sufficient by itself, but must be considered in the light of regional demands by air carriers and general aviation aircraft.

New EUROCONTROL Establishment in Luxembourg A number of important decisions for the future of EUROCONTROL, the European Organisation for the Safety of Air Navigation, were take~ by_ its Permanent Commission of Ministers at a meeting 1n Brussels on 7th December, held under the chairmanship of Mr. Albert BOUSSER, the Luxembourg Minister of Transport.

In addition to providing specialized, advanced and standardised training in accordance with jointly agreed principles, the Institute will be equipped to offer basic training, if desired, and contain the nucleus of a documentation centre for international technical publications relating to the security of air navigation .

The Commission decided to set up a new joint establish ent in addition to the EUROCONTROL Experimental m Centre at Bretigny (France), inaugurated early t h'1s year, and the first EUROCONTROL International Air Traffic Control Centre at Maastricht (Netherlands), now in the

Construction work on a site of several acres wh ich Luxembourg is offering to EUROCONTROL free of charge , will begin in 1968 and classes are scheduled to start by the end of 1969.

course of construction.

This new establishment will be the EUROCONTROL Institute of Air Navigation, which is designed to meet the growing requirement for th~ specialised training of Air Traffic Services personnel dictated by the pace of tech nical developments in the Air Traffic Control _fields . The Institute is to be built in Luxembourg and will be open not only to ATS personnel in the Eurocontr~I area but a_lso to those serving in other countries both in and outside Europe.

A further major decision taken by the Ministers on the Agency's recommendation was to centralise all upper airspace Air Traffic Control services for the Benelux/Germany Region in the Eurocontrol Centre at Maastricht. That this is now possible is due to technical developments, particularly in the field of radar data transmiss ion. The Organisation will thus be able to realise a saving of several hundred million Belgian francs as compared with the previously contemplated solution, which was to build two Control Centres in this region.

EURO

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AIR TRAFFIC CONTROL DATA PROCESSING SYSTEMS now largely being 路realised in /

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With SM R- 124, Signaal's high -speed micro - min rea ltim e general purpose computer in corporated in your ATC data processi ng system you wil l have at your disposa l a highly modern processor.

Signaal's expe ri ence accompan ies all elements of ATC systems, for example the mi cro -m in digital d isplay subsystem for radar v ideo, synthetic dynamic and electronic tabu lar data di spl ay.

Signaal also produ ces primary and seco ndary radar video ext ractors.

Signaal's system covers the entire range - hardware and software.

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SIGNAAL radar, weapon control, data handling and air traffic control systems.

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â&#x20AC;˘ The answer to increasing air traffic con fu sion 1s an accu rate, comprehensive. automatic and reliable Nav/ATC system incorporating a Data Link.

Decca-Harco 1s the only system that can meet the navigation and ATC demands of both sub- and supersonic air traffic. And only Decca-Harco can provide the flexibility and accuracy that permits close lateral separation of aircraft throughout the route structure.

At the control centre the Decca Data Link provides the controller with accurate displays of the identity. altitude and precise pos1t1on of all co-operating aircraft. using the common reference of a high accuracy. area coverage system . The necessity for R/T communication 1s reduced by the use of two -way Alpha-Numeric messages and routine reports are eliminated. reducing the work load and 1n creas1ng the rel1ab1l1ty of the ATC system.

On the fl ight- decl< Decca Om111trac-the world 's most advanced l1 ghtwe1ght d1g1tal computer-provides the pilot wi th undistorted pictorial presentation and automatic chart changing The 'ghost beacon' facility gives him bearing and distance to any point. Omn1trac also provides auto-pilot coupling and automa tic altitude control which maintain respectively any required flight path and fli ght profile The ETA meter 1nd1cates either time to destination or ETA.

It 1s only through an integrated system. operating from a common reference. such as Decca Harco. that a great many aircraft of different types flying at various speeds and altitudes can be eff1c1enlly co-ordinated into a single d1sc1plined traffic pattern.

DECCA-HARCO The comprehensive Nav/ATC system The Decca Navigator Company Limited ¡ London