IFATCA The Controller - October 1965

IFATCA JOURNAL OF AIR TRAFFIC CONTROL

...., NO.4

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Safety by means of a closed system of radars Surveillance radars for long-range and termin al area-cove rage Ground secondary radar stations Precision approach radars Data processing systems Radar display and data transmission systems for ce ntral evaluation

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Satco

Efficient transport means prosperity With the SATCO Free-route automatic air traffic control system, pilots at last have the ATC system that is custom-built for them.

Originally designed for military aviation which required an ATC service that would enable pilots to fly any flight path or carry out any manoeuvre with minimum restrictions and maximum safety, the system has now been released for civil use.

SATCO is a ground environment system: no special airborne equipment is required. It is exactly the system general aviation needs.

The system has been ordered

by The Netherlands and German Governments.

The first phase has been in operational use at Amsterdam since 1961 and the second phase has now been installed.

N.V. HOLLANDSE SIGNAALAPPARATEN - HENGELO - NETHERLANDS

Marconi 5264 Mk II 50 cm terminal and approach control radar High perfor111ance, low power, lotN cost

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A target echo area of 3 sq. metres is seen from 80 miles out t o touchdown

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Crystal contro ll ed transmitter with 50-60 kW power o utp ut Built-in paramet ric receiver of high sensitivity Adjustable pulse recurrence frequency ( 500-800 p.p.s.)

Optional p.r.f . stagger Capable of unattended operation for long periods - remote control faci lities are provided Fully coherent and easily maintained MTI system of permanent-echo suppression Conventional or ' broad daylight' display systems

Marconi air traffic contro l systems The Marconi Company Limited, Radar Division, Chelmsford, Essex, England

LTD /554

Marconi Rainbow Radar

This low-priced meteorological radar is completely self-contained. The transmitter /receiver is housed in a specially designed aluminium tower.

Installation, on any site, is simple and inexpensive.

Frequency range Peak power output Aerial Beam width Aerial rotation speed Displays

Display ranges

9415-9475 Mc/s 70 kW nomin al (60 kW minimum) 6' paraboli c dish 1.4° 13 r.p.m.

12" PPI _high brightn ess (incorporati ng electronic bearing indicators which preclude parallax errors) 12 25, 50, 1 00, 150, 200 n. miles

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Marconi meteorological radar The Marconi Company Li mited, Radar Division, Chelm sford, Essex, Eng land

LTO/S8\

A Direct Bearing on the subject

of automatic vhl di equipment

The EKCO VHF/OF equipment gives accurate bearing information on a transmission as short as 3 seconds

OF ra nge About 100 miles for an aircraft flying at 10,000 ft. radiating 5 watts.

Ekco VHF/DF gives clear, fast pre se ntation of bearings, essential for efficient traffic control and avoidance of R/T saturation . High accuracy (maximum syste m error = 2°) is combined with co mplete reliability at remarkably low cost.

The system represents a return t o simplicity, utili sing a continuously rotated Adcoc k ae rial and displaying the received sig nal as a radial trace on a 6 in . diameter C.R.T. Single or two frequency systems ca n be supplied, with up to three local or remote di splay s.

Special features .;, Remarkably high accuracy with low cost.

-:• Instant changeover fro m QDM to QTE. -:• ~ccura~y an.d st ead iness of bearing indication. un1mpa1red by speec h modulation or received tran sm ission. '~ Aut~m~tic bearing indication, without sense amb1gu1ty, by a si ngle radial line on the C.R. tube screen. .;:- Periodi cal setti ng-up procedure unnecessary.

-::- Facilities for remote control from the indicator unit.

-i:- Fully tropica lised constru ction.

The complete system is the indicator unit shown above, a floor-standing rack assembly and an aerial unit.

EKCO

EKCO EL ECTR O NI CS LTD

AVIATION ELECTRONICS AV I AT I O N DI V I S I ON

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S O U T H E N D - ON -S EA

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EN G LAND

IFATCA JOURNAL OF AIR TRAFFIC CONTROL

THE CONTROLLER Volume 4 · No. 4

Frankfurt am Main, October 1965

Publisher: International Federation of Air Traffic Controllers' Associations, Cologne-Wahn Airport, Germany.

Officers of IFATCA: L. N. Tekstra, President; G. W. Monk, Executive Secretary; Maurice Cerf, First Vice President; Roger Sadet, Second Vice-President; Ernest Mahieu, Hon. Secretary; Henning Throne, Treasurer; Walter Endlich, Editor.

Editor: Walter H. Endlich, 3, rue Roosendael, Bruxelles-Forest, Belgique Telephone: 456248 Production and Advertising Sales Office: W.Kramer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr 57a, Phone 44325, Postscheckkonto Frankfurt am Main 11727.

Rate Card Nr. 2.

Printed by: W.Kramer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr 57a.

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

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

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

CONTENTS The United States Supersonic Transport ..................

Lessons learnt in nine Years SATCO ......................

cism. No payment can be made for manuscripts submitted for publicaf . ion ·in •Th e Controller•. The Editor reserves . th e right to mak d' . . . h'ch h . e any e 1torial changes in manuscripts, 1 w . e believes will improve the material without altering the intended meaning.

Bright Radar Displays ...................... · · · · · · · · · · ·

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G. N. S. Taylor

Air Traffic Services at the IVA ......... · · · · · · · · · · · · · · · · · ATC Transponder Performance Pre-Flight Test Set .. · · · · · ·

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19

Tirey K. Vickers and Edward M. Hunter The SRT Philosophy on ATC Automation

W_ritt_en permission by the Ed'1tor i·s necessary for reprinting any port of this Journal.

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J. S. Smit

Secondary Radar Implementation Dates in Europe .. · · · · · · ~ontributions are welcome as are comments and criti-

6

Raymond B. Maloy

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J. Edwards General Purpose Computers and CRT Displays in Air Traffic Control ......................................... · · · ·

Ad vertrsers · ·rn ~his Issue: Cossor Electronics, Ltd. (15); The Dec~o Navigator Company, Ltd. (Back Cover'. Ekco Electronics, Ltd. _(4); N. V. Hollandse Signoolop~~raten (l);. The Marconi Company, Ltd. (2, 3); Selenia S.p.A. (Inside ~ack Cover); SODFLUG GmbH (36); Telefunken AG (Inside Cover); Wilcox (36).

R. Arnolds IFATCA Corporation Members .............. .

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The International Federation of Air Traffic Controllers Asso-

ciations ....... · · · · · · · · · · · · · · · · · · · Picture Credit: Bundesanstalt fur Flugsicherung (16, 17); EUROCONTROL Agency (18); Hazeltine Corporation (19, 20, 21); Solartron Electronic Group Ltd (13); Standard Radio and Telefon AB (23, 24, 25, 26); Telefunken AG (27, 28, 29, 30).

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33

Altimetry at High Altitudes with a View to the Vertical Separation of Aircraft

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Dr. Ing. Frhr. v. Villiez

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The United States Supersonic Transport

The following paper was presented by FAA Assistant Administrator Raymond B. Malloy at the Annual Conference of the Arbeitsgemeinschaft Deutscher Verkehrsflughofen, Munich, lOth September 1965.

It is a great pleasure to be with you here today to discuss the next great step forward in civil aviation, the supersonic transport.

As you know, four manufacturers are conducting design work on the supersonic transport, or SST, in the United States. Two are airframe companies - Boeing and Lockheed. Two are engine companies - General Electric and Pratt & Whitney. Federal Aviation Agency design contracts with these four companies began on June 1, 1964. As President Johnson stated recently in announcing a further detailed design and testing phase, a good deal of progress has been achieved in this design program in the direction of a safe, economical SST with excellent performance characteristics.

The present phase of design work is directed specifically at enabling construction and test of preproduction prototypes to begin at the earliest possible time consistent with these objectives for a fine commercial airliner. The development philosophy has been built on the principle that the detailed design and test phase is of the greatest importance in developing a sound aircraft. Part of this process is continuing technical, economic, and market analysis, of course, to determine and establish at this stage the aircraft that best suits airline requirements within the realistic and reasonable capabilities of industry and developmental cost factors.

Twice the manufacturers' proposed SST designs have been evaluated in great detail, and further evaluation is scheduled later this year and next year as the work goes forward. Continual monitoring of contract work is, of course, also a part of the program.

The current state of manufacturers' designs as evaluated demonstrates, specifically, the feasibility of building a United States SST that can carry in excess of 40,000 pounds for 4,000 statute miles, at close to three times the speed of current subsonic jetliners, and do so at seat mile costs comparable to the best of today's jets.

Principal characteristics representative of the potential U.S. SST design, as evidenced by evaluation, are as follows - and I will come back to some of these points.

1. Payload/range

42,000 pounds at 4,000 statute miles

2. Speed

Mach 2.7

3. Primary Structural Material Titanium 4. Sonic Boom

2.0 pounds per square foot acceleration and 1.5 psf cruise for domestic operation, with 2.5 psf in acceleration and 1.7 psf in cruise allowed for long range international flights over water. Normal atmospheric pressure at sea level is of course 2,117 psf.

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by Raymond B. Maloy Assistant Administrator, Europe, Africa, and the Middle East Federal Aviation Agency

5. Noise

1,500 feet from centerline of runway 116 PNdB; 3 statute miles from start of takeoff roll, 105 PNdB; 1 statute mile from runway on approach, 109 PNdB. These, as you see, represent reduced community noise levels compared with current fully-loaded long range subsonic jets, with an increased noise level 1,500 feet from the airport runway from these large, highthrust SST engines.

6. Passengers

230 in mixed configuration (10% first class, 90% coach) with standard seat spacing.

7. Takeoff Speed

160 knots

8. Approach Speed

135 knots

9. Airports

Capability of using ports.

10. Operating Costs

existing

air-

Seat mile costs at transcontinental and greater ranges less than current seat mile costs of the best of today's long range subsonic jetliners.

11. Profitability

Return on average investment, before interest and after taxes, of approximately 30%.

An important example of design progress in the program has been gro~th in percentage of payload. A few ~hort years ago, ma1or aviation manufacturers were talking abou~ paylo.ads on the order of 6 percent of aircraft gross weight, with their aim of course somewhat higher.

But these were the figu th 路 . . . . res ey were then seeing as real 1st1c within. the state of SST res earc h, st u d y, an d d es1'gn to t h at point.

When th~ design phases of the U.S. SST program got under way in 19~3, ~he ,;ederal Aviation Agency considered 8 percent typical in planning for SST operation, and 10 percent as a most desirable goal.

The best of the design proposals evaluated in our first design evaluation in early 1964 indicated a payload of 7 percent, but at an unsatisfactory range of 3,300 miles. The validated figures showed that this design would take a payload of 30,000 pounds to this maximum distance.

The second evaluation at the end of last year showed the figure at 9 p~rcent-more than 40,000 pounds for a rangke of 4,000 miles - on the basis of current design wor.

Th~re has been improvement over the past several years in a number of key areas - in materials lift-overdrag ratio, sp;cific fuel consumption, range figures. In the early 1960 s, for example, it seemed reasonable to think in terms of ranges that ran up to 2 500 miles for gross weights of 350,000 pounds or so '

Both figures have now gone up appreciably. Maximum gross weights are in the neighborhood of 500,000 pounds, alongside the increased range. But improved aircraft efficiency, very largely in the area of aerodynamics, has kept the increase in payload percentage comparatively "ahead" of the increase in gross weight.

In terms of passengers capacity, the primary component of payload, both manufacturers' designs currently provide for 200-plus passengers - once again an evolutionary increase from the concepts two and three years ago that provided in most cases for 100 to 125 passengers.

The FAA request for proposals establishing performance objectives for the transport raised these sights somewhat, to the area of 125 to 160, in the summer of 1963, and the increase accelerated as design moved forward.

Weight, naturally, is a pivotal factor in achieving a satisfactory transport vehicle - with regard to both aircraft operating efficiency and airport compatibility and the effort to hold down the weight of the aircraft is an important factor in development.

The subject of airport compatibility has received major attention from the start in the SST program. This was reflected in the request for proposals establishing aircraft performance objectives in 1963, and again in the design contracts with the two airframe and two engine companies that have continued since June 1964.

Under these contracts, the companies were directed to consult airport executives of fifteen large airports in the United States in connection with compatibility of designs.

The airport operators stated their design views in writing to the Federal Aviation Agency as part of the secondround evaluation. The fifteen airports in every port of the country were not being "selected" for actual SST operations, but were appropriate to provide the airport input for this evaluation purpose. Such airport participation will remain an essential part of development of the SST. We surveyed airports throughout the United States a few years ago and found that more than 50 airports would be capable of handling SST operations, either at maximum gross weight conditions for takeoff on intercontinental operations or at lesser loads such as those associated with transcontinental or shorter route lengths. It is absolutely essential to the commercial success of the supersonic transport that it be capable of operation at these shorter route lengths, perhaps down as low as 500 to 600 .miles. I do not say that service requirements would necessitate the use of 50 or more fields in the United States for SST operations, but the capability would be there.

Let us turn to the matter of engine noise. This is pereven n:o~e important to the airport's neighbors than it is to. the airline and airport operators, if this is possible.

Noise suppression hos been a factor in the U.S. SST program from the start of research in 1961. The work stateme~t fo~ each of the initial engine research contracts a~ t~at ~ime included the requirement for working toward d1minut1on and suppression of noise. So far as I know, this is the frrst engine program ever undertaken that inclu?ed noises .as a primary factor from its inception. ~01se has continued to play an important role in objectives both for the engine and airframe companies as the program has gone through design phases.

~O_PS

Noise cha.ra.cteristics have been evaluated by noise experts of the 101nt government team using the established and accepted standards of the Society of Automotive En-

gineers A-21 committee. Representatives of the airlines, airframe companies, and engine companies, along with the government, agreed to utilization of these procedures.

The SST engines could well achieve a real advance in this area.

As you know, the most usual way to describe aircraft engine noise today is in "perceived noise decibels", or PNdB. The largest current jets at maximum landing weights generate approximately 122 PNdB one mile from runway threshold on opproach. On the runway, at the start of takeoff roll, today's turbofan powered airliners create about 108 PNdB 1500 feet from the centerline of the runway. This figure represents a decrease of about 5 PNdB compared to the same airplane using turbojet engines. The community noise three miles from brake release on takeoff is about 120 PNdB without power reduction. These figures are for maximum operational gross weights and therefore represent maximum noise values.

On an average, of course, noise levels will be considerably less because aircraft are so often operated at lower weights than maximum gross weight allowable.

Now how would SST noise levels compare? In June 1964 objectives for the SST stipulated 118 PNdB one mile from the threshold; 118 PNdB 1,500 feet from the runway centerline; and 108 PNdB three miles from initiation of takeoff roll with a cutback in power to maintain 500-feeta-minute climb. For the design contracts since, on the basis of evaluated progress, these levels have been further reduced to 109, 116, and 105 PNdB. One of the primary community-noise-suppression. factors for the SST will be the capability of the larger, higher thrust engines to take the aircraft to a higher altitude at any given point during the initial climbout. This increased altitude will result in reduced noise for the community.

A corollary capability for this high-thrust engine would be varying power settings in each specific airport-community situation to reach the optimum setting so far ~s noise is concerned in any given case. This capability will be an outgrowth of the fact that the SST will not normally be thrust-limited during takeoff. In addition, as we have seen, a substantial number of SST operations would be expected at shorter ranges and reduced gross wei~ht conditions, once again a highly significant factor in noise reduction.

Industry has been working in this area since the start of the program. Major effort has been devoted to inlet noise reduction. Under one approach, variable geometry in the inlet design would have the capability of sig~ifl足 cantly reducing the annoying compressor whine duri~g approach and landing, and during power cutback in mrcraft climbout. The inlet automatic control system would adjust the variable inlet area during these periods. In the choked configuration, the centerbody holds a Mach number grater than .85 in the inlet throat, suppressing compressor noise from the inlet. The low power setting combined with the high Mach number at the throat provides the noise suppression.

Another promising approach could be used, either independently or in conjunction with variable geometry, to suppress inlet noise. This approach wo_uld provide ~~r acoustically treating the long supersonic inlet ducts to e 11 minate discrete frequencies. Acoustical treorment would be applied to the inlet walls in much the same way as

7

acoustical ceiling tile is applied in an auditorium to help eliminate noise.

In itself, the lenghts of the inlet is expected to mitigate noise to some extent.

The solution to engine exhaust noise does not appear as straightforward as the approaches I have discussed for inlet noise reduction. There are, however, a number of basic design approaches being pursued by the engine contractors to suppress these low frequency exhaust noises. Basically, the designers are hoping for important reduction through design on devices that lower the average velocity and smooth the velocity pattern of the jet.

Engine nozzle designs that increase the shear area of the exhaust plume and promote mixing with secondary and tertiary airflows would promise a reduction of PNdB level for the engine exhaust. The design approaches being explored include nozzle modifications and retractable exhaust noise suppressors.

In connection with this noise design work and other areas, it is important to remember that what we are talking here today is theory extremely solid theory, but still theory. Nobody should leave here with the thought that the noise problems of the supersonic transport have been solved, or that I have suggested they have been, but we do believe that important work is under way.

Let us look at some other SST characteristics around the airport.

This transport should have the capability of coming over the threshold in the range of 135 to 145 knots. Liftoff speed, at maximum takeoff weight, will be in the range of 160 to 175 knots. The thrust of the engines will be in the order of 50,000 pounds per engine for a four engine transport. The aircraft will not take off with full power, because the thrust is not required for takeoff,. but for transonic acceleration. Therefore, from some viewpoints, this aircraft can be mu~h .more effective around 1·he airport than current subsonic 1ets.

For example, slush on the runway is a problem today from the standpoint of takeoff speed - where you rotate and how much of the runway you use up. If there is slush on the runway with the supersonic transport and there is a problem on takeoff, the reserve power is there to c~m­ pensate for it immediately. If there is a loss of an engine on takeoff, there is no problem with respect to the total power required to insure a safe takeoff. From these standpoints 1he transport should be better than what we have today.

With respect to fuel reserve, this transport will have to meet all of the reserve requirements of the current subsonic jets, but how those requirements will be spelled out will have to be delayed until we know more about the requirements of the aircraft. Specifically, it will have to be able, as today's planes, to come down and take a look and then go to the alternate perhaps 300 miles away.

The reserve fuel required to perform this function is_ a factor of the configuration of the transport, the engine design, and the fuel flow at low subsonic speeds. .

There has been some question about the manouverability of this aircraft around the airport. It should be ~s . capable of maneuverings as th e curren t large subsonic jets. ·11 The SST will climb faster after takeoff because it WI · t in order have to gain altitude at the t h ree m1·1 e poin . to reduce the noise level on the community, but the_ aircraft will not be significantly different in its attitude

8

during climb. In the transonic speed range, passengers could note the increasing thrust of the engines but there should be little other sensation attached to going through the "sonic barrier".

In cruise, the aircraft will be much like any aircraft we know today. It will have adequate visibility to meet the stringent requirements of operational safety. The pilot will have weather radar better than we have today. There is relatively little weather, as you know, at the altitudes at which this aircraft will fly, in the order of 60-70,000 feet.

There are thunderheads and clouds at those altitudes, although they are not as frequently encountered as at

35-40,000.

In descent, this aircraft will be quite normal. It will handle about the same as today's aircraft. The SST will require good low speed handling characteristics. Major attention is going to this in the design and development program.

How about sonic boom? This is another important area toward which major effort has been directed. The most notable recent programs were the study of public reaction in the Oklahoma City area and the study of structural and material response at the White Sands Missile Range in New Mexiko. Extensive data on the Oklahoma c;ty program, and preliminary data in the White Sands program, has been available for some time now, and I am certain that many of you are familiar with it.

You may not be quite so familiar with some of the earlier programs. There have, actually, been eleven separate research programs in the United States in the past seven years.

One of these study efforts answered the question, "Will booms affect light airplanes?". Aircraft on the ground and airborne at Edwards Air Force Base in California were exposed to a series of booms at high overpressures. Neither pilots nor aircraft were adversely affected.

In another study, at Nellis Air Force Base in Nevada, a large group of personnel were exposed to sonic boom pressures up to 120 pounds per square foot _ compared to the 1.5 and 2.0 psf we speak of in connection with SST operations. Glass breakage did not occur in 214 window panes exposed to sonic boom until the overpressure reached 20.0 pounds, something like fifteen times maximum stipulated for supersonic transport cruise. In another study a few years ago aimed at building response data, overpressure levels were held to much lower levels between 2.0 and 3.0 pounds, a~d no damage was experi:nced with gla::;s or ~ther materials. These experiences agreed with later findings at v:'hite Sands, where 5.0 psf was the lowest level at which even poor quality glass was damaged, and damage levels for other materials substantially higher.

Sonic boom study is continuing in the United States.

The National Aeronautics and Space Administration 1 in its ongoing ~a~ic ~esearch program, is studying an approach to diminution of sonic boom through aircraft design t~at _appears promising, although it is not proven out at this lime. The U.S. National Academy of Sciences, at the request of_ the President, is providing guidance to the government in regard to sonic boom. Further flight research, and perhaps simulation as well, are also being planned.

All of this said, let me say that I do not feel the sonic boom should be seen out of perspective. It establishes

important design parameters, as do safety, economics, and other requirements, and in the case of sonic boom, the aim is to see that the supersonic transport will create no more than minimal and acceptable level. The design challenge of the SST is obviously to develop an airplane that satisfies requirements in all of these aspects, and there is good reason to believe that all objectives including sonic boom objectives will be met.

In the field of aircraft control and display, the Federal Aviation Agency set up a major program in conjunction with the Air Force in 1961. This program has explored and continues to explore such matters as handling qualities, cockpit workload distribution, performance, and operational problems - an area that might today be termed "machine-man optimization". The objective here is to give the pilot the best possible flight control tools, including automatic tools, to assure safety and efficiency of operation. The pilot remains the key element in the control loop. We must be certain that the displays available to him in some cases improve on what we have today, in some cases take the place of what we have today, and perhaps in some cases provide information that is not available today. For these purposes, we have used both simulators and test flight programs.

Pilots from FAA, the Air Force, industry, and the airlines have been test-flying twin-jet USAF T-39 aircraft equipped with experimental control and display equipment in the flight phase of this study at the Instrument Pilot Instructor's School, Randolph Air Force Base, Texas.

Major attention to date in this program has gone to the approach and landing phases. At the present time, of course, considerable attention is being devoted to all~e~ther operations independent of the SST program. Ob1ect1ves for the supersonic transport provide that it be compatible with sophisticated all-weather equipments and

techniques that are themselves in the process of development and refinement in this time period.

In the air traffic control area as well, study programs have been under way for some years. These have been quite preliminary to date, but they have brought together an SST flight simulator at the NASA Langley Research Center and the FAA flight simulation laboratory at the National Aviation Facilities Experimental Center in New Jersey in a program that promises to be highly productive as SST development goes forward. The two centers are joined for this purpose by land line in the manner that air-ground radio communications normally link pilot and traffic controller.

What I have been describing in general - and I am sure there is not time to get a great deal more specific is the rather wide-ranging research conducted prior to and alongside of design effort in the United States SST program. These programs have covered a broad range of fields - aerodynamics, materials, structures, propulsion, fabrication techniques, control systems, sonic booms, operational environment, human factors, economics.

We must conclude, I believe, by answering a broad, very non-technical question. What will the supersonic transport really mean to air travel? In answering, I think it is far too easy to use the word "revolutionize". But I don't believe this word presents an accurate picture. SST's will, really, continue the evolution of air transportation that we have seen and experienced. The SST will, in fact, cut travel time in just about the same manner that the subsonic jetliner did when it entered service.

Civil aviation, through the years, has helped change our world - shrinking it in a sense for business and government and the military, enlarging it immensely for the individual human being, and enriching the quality of human life. Supersonic transports will continue this process-safely, economically, and in the best interest of all.

General William F. McKee, FAA Administrator General William F. McKee, USAF (Ret.), was nominated Administrator of the Federal Aviation Agency by :resident Lyndon B. Johnson on June 23, 1965, confirmed Y the Senate on June 30 and sworn in on July 1.

According to President Johnson, General McKee was rec~mmended by Defense Secretary Robert McNamara as.. one of the most knowledgeable and competent adm1n1strators 1 · n th e D e f ense D epartment /1 .

On retirement from the Air Force in August 1964 Gewas Vice Chief of Staff. In September 1964 the N a t.ronal Aeronautics and Space A d mrn1· · he 1omed . strat1on (NASA) as A ss1stant .

Administrator for Management . · FAA ap. Developme n t , a post he held prior to hrs pointment.

ner~I .McKee

M Born at Chilhowie, Va., on October 171 1906, General _cK_ee was graduated from West Point in 1929 and comm1ss1oned a second 1·1eu t enant .in the Coast Artillery Corps of the Regular Army.

General McKee se rve d ·in A rmy assignments · ·rn FIori· da, the Canal Zone c l"f · . . . . ' a r ornra, the Philippines, Puerto Rico and at the Norfolk Naval St t" V b f h transferred to H d a '.on, a., . e ore e . ea. quarters, Army Arr Force 1 n January 1942. · t ed . He received hrs first star in 1945 an d was apporn Chref of Staff of the Air Trans port Command in 1946. In August 1946 he went to Europe as Com man d.rng G enera I

of the European Division, ATC, with headquarters at Paris. In December 1946 he transferred to USAF Europe (USAFE) headquarters at Wiesbaden and became its commanding general in January 1947.

When the Air Force became a separate service in 1947, General McKee returned from Europe to work under General H. H. "Hap" Arnold in setting up the new service. He was appointed Assistant Vice Chief of Staff of the USAF in September 1947 and was promoted to Major General in 1948. He remained in this post for nearly six years.

In 1953 General McKee became Vice Commander, Air Materiel Command, USAF, and continued in that post when AMC's name was changed to Logistics Command.

He gained his third star as Lieutenant General in 1957, and, in August 1961, was named Commander, Air Force Logistics Command, receiving his fourth star at that time.

The following July he became Vice Chief of Staff, USAF, under General Curtis LeMay. General McKee was awarded three Distinguished Service Medals during more than 35 years of military service.

He was also the recipient of the first annual Distinguished Management Award for outstanding contributions in ,A.1r Force logistics assignments.

9

by J. S. Smit

lessons learnt in nine Years SATCO

N. V. Hollandse Signaalapparalen

Paper presented at the Fourth Annual IFATCA Conference, Vienna

One of the lessons learnt in the many years we have been active in the automation of air traffic control is about the controller and his attitude of mind towards automation. In an effort to make a contribution to the discussions at the Vienna Conference, I have chosen to make some remarks on this particular aspect of automation as I believe they fit in your program more than anything else.

Why does the controller have to be bothered with automation now? Why does he have to get part of his work programmed by a machine? Why is his freedom going to be affected, even when it does not seem to go better or easier, or even it may be more difficult to begin with? Why does he have to argue with computer-mad people who ask him silly questions and eventually only produce a printed strip ... ?

In the years I have been concerned with the automation of ATC I have talked, worked, discussed and argued with many controllers from all over the world. And I regret to say that I have experienced more false notion than comprehension of the subject automation. Indeed, the controller who is afraid that automation will take away, maybe not his job, but anyway his status, does exist. Also the controller who thinks that automation will bring him heaven on earth, is not a fiction. Automation is unjustifiably condemned; there are also unjustified expectations. As a result, automation is met by many disappointed controllers: some just because it is coming, others because it does not do what was expected.

The answer to all these questions is not obvious to everyone, although it is not difficult. Automation, automatic dot~ pr~cessing, automatic data handling, or whatever name is given to it, is the only way which will enable ATC to make good the arrears and catch up with aviation.

What is so special about automation? Why is there more discussion about this type of equipment than there ever was about any other ATC equipment. The answer is obvious: automation penetrates into the controller's method of working more than any other equipment ever did.

I am not trying to disparage the present role of equipment like radio, telephone, direction finders, radar, etc. when I col I these "tools of the controller". What I am trying to say is that h e is ~laying the_ orchestra of instruments; he is playing it with a considerable amount of freedom. And the orchestra arrangements vary per controller.

Automation will inevitably affect freedom. To a very small extent in the beginning, but slowly it will go further.

To make this clear, let us consider a strip-printing system, 0 simple form of automation. In such a system strips are printed in 0 standard way: the format is fixed, the typesize is fixed, the moment of printing is programmed in a computer. All this is identical lo every controller: a step to a more defined working method of the controller. The introduction of a keyboard for clearance and progress entries is 0 further step: the keyboard has certain input rules to be adhered to. Etcetera, etcetera.

Coming back to my figurative language: the controller will become a conductor leading a trained orchestra and he himself as an individual is no longer making the arrangements.

How far and how fast will it go? I do not feel competent to answer that question. Eventually, I believe, it .WI·11 go f al.. We>~ may expect it will also go fast. But I am · convinced that the control responsibility - i. e. the decision of how the traffic should be cleared - will, in what ioday we col I the foreseeable future, remain on the shoulders of the human controller.

10

. The main reason why automation, and only automation, can do this is that a central data processor will become the coordination-medium. The bottleneck of controller-to-controller coordination will be replaced by controllers working with a computer as 0 common source of information. They have to feed data into that computer, but also can extract data from it. And there we come to the crucial point: the data is available and can be distributed_ to and_ used by many who to-day are devoid of that information for the simple reason that the human coordination-capacity is saturated. There lies the enormous ?dvantage of automation: the ATC system can grow, 1t can do more things than it ever did before. This is the important issue at stake.

Automation will not necessarily make life easier for controllers .. In the beginning, maybe, even the contrary is true .. Espec1_ally_ of those controllers working in an admini~tration ":h1ch 1s actively involved in the development and intro~uct1on of automation in ATC, much will be demanded in terms of skill and perseverance. Automation will ?ffect their wor~ing_ ~ethod and quite likely not always ~n a wa~ every ind1v1dual likes to see it affected. But in introducing. automation in ATC - m ay b e th.1s ·1s h ar d to . say for this audience - the individual controller is not the most important issue ' nor 1 ·s an ·in d.1v1·d ua I con t ro I po . . ~1ti_on. The ATC system, and consequently a v i at ion 1s involved ~nd au~omation of ATC can only be judged from that wide point of view. This, I am afraid, is not alv;ays. e?sy,. in particular not for those faced with the daily d1ff1cu_lties of a particular control position. _Automation will rationalize the ATC system. It may be painful that part of the controllers' freedom will disappear. InII particular that part of "freed om w h.1ch , ·1n fact , • 11

11

means no rules . But this does not mean that the controller in an _automated system may be less skilled than to-day. I believe that automation will require different, but definitely not less and may be even more skill of the human controller .

T~e contr?ller of to-day plays an extremely important role in the history of ATC. It is up to him to take courage and face .automation with an open, positive mind. Then, I am convinced, the result will be positive for aviation, for air traffic control and for the controller.

by G. N. 5. Taylor The Marconi Company

Paper presented at the Fourth Annual IFATCA Conference, Vienna

In Air Traffic Control a radar display is used mainly for monitoring purposes and the ATCO does not normally expect to spend all his time looking at it. He has other things such as the flight progress board to look at as well.

Unfortunately the low brilliance of the conventional radar display means that ATC rooms have to have a low ambient light level if the radar displays are to be used effectively.

Where air traffic density is low a compromise must be struck between the need for a controller to see his radar display in almost darkness and his flight progress board, brightly lit, at the same time. In areas of higher density it is often necessary to have two controllers for each sector, one at the radar display in a dim ambient light and the other at the flight progress board in normal lighting conditions. This immediately introduces liaison difficulties. Apart from the operational problems there is also the depressing psychological effect of working in the sort of jaded night club atmosphere that most radar-equipped centres seem to produce.

Such a situation is obviously not tolerable and for the past ten years or so work has been proceeding on ways of producing a PPI display having sufficient brightness to enable it to be seen under normal room lighting and daylight conditions. In the last two or three years there has been an increasing interest in bright displays from ATCO's and at some centres in the world particularly in the United States a considerable number of bright displays are already in operation.

What basically is the problem in producing a bright radar display? Essentially it is the fact that a PPI radar picture has a very slow data renewal rate, the whole screen being scanned once per revolution of the radar aerial. Any attempt to brighten the scanning trace alone adds nothing to the improvement of the display itself.

What is required is some way of brightening the afterglow or stored part of the picture because it is this that the controller actually looks at.

The conventional PPI display using a cathode ray tube having an aluminium-backed sodium fluoride phosphor has now reached a high degree of sophistication. It has by far the best definition and sensitivity to weak signals of ~n~. type of display and is capable of more individual flexibility at lower cost than any bright display system. The ?ctual display unit which is built around this type of tube is compact and simple and is ideally suited to both simple r~w radar and complex computer-controlled systems with high speed alpha-numeric characters . . If one could merely make this type of display 100 times brighter b . .there 路is no d ou b t that 路1t would supersede ot I1er n.ght display systems overnight. Unfortunately it is not quite as easy as this although, as will be explained later, future ?evelopments in the display of radar and other inf?rmat1on .for ATC purposes will probably be along the lines of this type of display. . The first s~ccessful method of producing a brighter PPI display was in the conversion of the radar picture into

the form of a television signal which could be displayed on a normal type of television monitor. Initial experiments of pointing a television camera at a radar display were not very succesful although reasonable results were achieved by using special camera tubes. The system was much more successful when a special scan conversion tube was used and after several years work good systems have been produced in France and the United States. Basically the tube consists of a storage layer in the form of a plate in the middle of the tube, a writing gun faces one side of the plate and a reading gun the other side. The writing gun is operated in a similar way to a normal radar display cathode ray tube and in effect "writes" a radar picture in the form of electrostatic charges on the plate.

These charges are stored on the plate which is meanwhile scanned by the beam from the reading gun in the form of a television raster. The output signal is taken from a collector ring adjacent to the storage plate. As the storage plate is completely scanned 50 or 60 times a second by the reading beam a picture of normal television brightness is displayed on the monitor. The storage time of the converter tube can be adjusted to provide a gradually decaying radar picture of several minutes persistence.

The system is basically fairly simple if only a raw radar display is required. The monitors can be quite simple, provided they have good timebase linearity, and a large number can be used with a single converter tube. Different sizes of monitor display can easily be provided as tubes are available up to approximately 27 inches (67 ems.) in diameter. The resolution is not as good as a normal direct view fluoride tube but is probably adequate for short and medium range applications with conventional ATC surveillance radars. Brightness is good enough for use in moderately lit rooms although it is not really high enough if a display is required in the control tower cab. The brightness level is of the order of 75 ft. lamberts compared with a frgure of 1 to 2 ft. lamberts for the afterglow of a fluoride tube. It is necessary to use about 1,000 lines to make up the raster if lineiness is not to be annoying to the controller although the system itself is not at present capable of this degree of resolution. Flicker can be reduced a great deal by the use of a frame frequency of 60 cycles rather than the conventional European frequency of 50 cycles. The difficulties start to arise as soon as flexibility is demanded. For example all monitors working from one scan converter are obliged to display the same radar range. Similary the same degree of off-centring must be accepted at all monitor positions.

The only satisfactory solution to this is to have one scan converter for each monitor display and although the writing circuits and some on the reading side can be shared between a number of converters the increased cost is considerable.

Further complications arise when data handling has to be added. Track markers must be fed in on the "reading" side of the systems if they are not to appear on all moni

11

tors simultaneously and to maintain accuracy between the reading side and the radar signal on the "writing" side demands a high degree of mechanical and electrical precision in the scan converter. In addition it is not very easy to produce even a simple ring marker on a television system and a considerable degree of complexity is required if markers and alphanumerics have to be displayed. In fact, the further ATC systems progress towards synthetic displays, the more complex and less suitable scan conversion seems to become.

An alternative approach to the production of bright radar displays has been the development of the direct view storage tube (DVST). This also has a writing gun which directs electrons on to a storage plate. The plate is normally charged negatively and the radar picture is written on it in the form of areas of positive charge. A "flood" gun is mounted coaxially around the writing gun and this floods the storage plate with slow speed electrons. The plate acts like a stencil and allows the electrons through on to the phosphor screen only in the positively charged areas. The phosphor is of a high efficiency short persistence type and emits a pale green light under electron bombardment. The plate has an exceptionally long storage capacity and, for use in a practical PPI application, means must be provided to allow it to recharge slowly at a controlled rate. As the whole of the storage plate is being flooded with electrons all the time the light output from the phosphor is continuous. The flood gun current is of the order of milliamperes compared with microamperes of beam current in fluoride and television displays, so the picture can be very bright. Figures of 1,000 to 2,000 ft. lamberts are normally realised and the display is quite bright enough for full daylight use in the control tower cab.

In operation a PPI display built around the DVST is very similar to the conventional direct view fluoride display. Each display has independent control of range changing and off-centring; persistance is adjustable to suit operational and ambient light conditions and a switch allows the radar picture to be instantly erased when required, for example when the off-centring is changed.

The resolution, although not quite up to the fluoride display, is now good and probably better than a scan converted picture. Accuracy is as good as a fluoride and in fact the whole display design is identical in practically all respects to the conventional type. The only differences lie in the provision of an intermediate high tension supply and the erasure circuits.

The development of the DVST hos been rather slow, first of all due to the problems associated with the tube manufacture. Early tubes only hod a 4 inch (10 cm) useoble diameter but an 11 inch (28 cm) tube is now available, having a useful screen diameter of 9 1/i inches (24,5 cm).

Larger tubes have been made in the United States although their resolution is not good enough for normal radar applications. There were a number of problems associated with the peculiar characteristics of the tube, these have now been solved and the daylight viewing PPI display has now reached the production stage. In production forrn it can be identical in size and shape to a normal fluoride display and has the advantage that it can be designed to work from the same back-up equipment.

Its introduction into ATC centres can therefore be made simply and economically.

12

The outstanding problem has been the introduction of markers and alpha-numerics to these displays. If applied in the normal manner there is a danger of the markers "smearing" and tending to confuse the radar picture. This problem has now been solved in the laboratory and it only remains to apply the solution to a production design.

As far as its economics are concerned, the DVST comes out well. Although the tube itself is expensive, its life is confidently expected to be of the order of 1O1OOO hours or more. The cost per hour therefore compare s very favourably with a fluoride tube. As the actual display circuits are very similar to those of the fluoride type the cost of a complete DVST display is also of the same order.

In ~ractice,. therefore, the DVST display comes close to the ideal bright fluoride display postulated earlier in this paper.

Yet another type of tubes has been produced which may have so~e applications as a bright PPI display. This is the fibre optic tube. It consists of a conventional fluoride cathode ray tube but in front of the phosphor are placed a large number of small transparent fibres each lying with one end against the phosphor and the other towards the front of the tube. light from the phosphor enters each frbre, travels along it and emerges at the other end. In effect each phosphor acts like a small lens the sum effect being to concentrate the light output over ~ comparatively narrow ang~e. of view so that a brighter picture is produced: In add1t10.n each frbre is coated with an opaque material so that light can neither enter nor leave it except ~t the. ends. C~nsequ:ntly extraneous light from the room in which the display is operating is not reflected from the front surface of the tub e an d th e picture · contrast ·1s ·improved.

No figures on the performance of the tube in radar dis.play .are available but the brightness is believed to be quite high. Whether a narrow viewing · · angle wou Id b e acceptable for ATC purpose is open to doubt.

What of the future? It is clear that in the next few years. more . data handling syste ms w1·11 b e use d ·in h"1g h traffic density areas and the 0 ut pu t f rom sue h sys t ems . will probably. be indicated on synthetic PPI displays. In these. there will .be no raw rad ar s1gna · Is an d no sIow IY rotating trace. Aircraft will be ind· t d b d "th .d _ . d h . h h ICC e y ots WI I en tity an e1g t s own by I h · h . . a P a-numeric characters. Ot er information can easily be indi'cat e d as we II . 8 ecause .t 1 .1s not necessary to show raw rad ar ·1n f ormat1on · t he d o ts and characters can be cycled aro d · "di un quite rap1 y an d th e . present fluoride raw radar display . A spec1a . I me d'1um per. sistence phosphor can be used to . . . remove any fl"1ck er. I n add1t1on to being bright the displ ay ·1s very sh arp Iy d ef1ned and of excellent resolution.

This type of. display . is . available t o d ay an d pro d uces a very good _picture. It is In fact virtually identical to the modern fluoride PPI. but with 0 change o f p hosp h or on th e tube face.. The ob1ection to the fluo ri·d e t u b e o f h av1ng . . . a . low brightness 1s immediately remo ve d once syn th e t"1c displays are accepted. Scan conversion then becomes an unnecessary complication ' a corn pi·1ca t.ion w h.1ch gets worse the more data handling methods are .111 t ro d uce d .

Summarising the plan ·t· d" . . . pos1 ion 1splay situation 1t can be seen that a logical developme n1 h as t a k en p ace ' over 1 the years. from the original two ph osp h or t u b e, th roug h the fluoride . . frxed coil . display ' on to th e h"1g h spee d ch ar~cter wri.ting fluoride display and then to the synthetic display with only the latter being bright enough for use

in conventionally lit rooms. Scan conversion appears as a diversion from th is main line of development in order to achieve a bright raw radar p icture. As such it fulfi lls an immediate ATC need but it is not really suited to further development into the field of synthetic displays. Attempts to adapt the technique to these ends can only result in costly complex ity.

The Direct View Storage Tube ha s also been d eveloped to meet an ATC need but a s both technically and

Canadair transportable Control Tower on Display at Paris Air Show One of Canadair's latest developments is a transportable con tro l tower, wh ich in less than one day can be erected by two men and be fully operational.

The tower is designed for a number of applications such as a permanen t air traffic control centre for sma ll airfields or underdeveloped areas, temporary traffic control for emergency use and control for rapid deployment of military forces on forwa rd airstrips. It con be transported by on aircraf t or medium helicopter having a door opening size not less than 45" X 46" (l.143 m X 1.168 m) and a payload capability of at leas t 5,600 lb. (2,538 kg).

Completely self-conta in ed wi th its own power generator and batteries, the tower is equipped with survei llance radar, VHF v isua l direction finder, identification radio beacon, rad io communications foci lities and a communications logging recorder.

Th e structure consis ts of thirty-one assemblies that interlock together to form a hexagon-shaped control raom.

Fully insulated, with six viewing panels of one-quarter inch heat absorbing trapezoid glass, the room is air-conditioned with ventilation and heating to match cl imatic conditions ranging from tropic to arctic.

Provision is mad e for levelling by screw jacks attached to the floor panel structu re.

operationally it is a close cous in of the conventional direct view fluoride display it is not diverging from the main stream of development and it probably has on assured future as a very bright synthetic display for use in h igh ambient l ight cond itions. The storage characteristic may also be useful in reducing the load on the computer equipment by allowing a slower recycl ing time to be a chieved.

SOLARTRON High Resolution Video Map

SY 2046 For the first time shown at the Paris Air So lon 1965, the Single Bay vers ion of SOLARTRON 's H igh Resolution Video Map is identical in performance to the Double Bay version w hich was on display at the IFATCA Confe rence, Vienna. It is intended to meet the case where equipment room is limited. The only disadvantage, from a maintenance viewpoint, compared with the Double Bay version, is tha t it does not provide room for a built-in oscilloscope.

.. . . .. ..

:.

0 0

••

13

Implementation of Secondary Radar Amendment to EUROCONTROL Information Circular N째 2/1965*

1. Since the publication of Eurocontrol Information Circular N째 2 dated 27th February 1965, it has become apparent that some of the earlier dates for requiring the carriage of secondary radar transponders, already published by certain States and incorporated in the Eurocontrol Circular, cannot be adhered to for two main reasons: a) A large number of aircraft likely to fly in the upper airspace ore not yet equipped with the requisite transponders; b) The installation of ground equipment at ATS radar units has not progressed at the rate anticipated.

2. In these circumstances, and in order to achieve the best possible coordination in the use of SSR in the Eurocontrol Area, 0 revised date has been agreed for requiring the carriage of secondary radar transponders in the United Kingdom and the Netherlands UIRs. This new date, 1st July 1966, coincides with that already published for part of the UIR France.

3. The table below, which supersedes the Annex to Eurocontrol Information Circular N째 2/1965, gives the amended timetable now envisaged, with additional information concerning the Shannon UIR. Published in THE CONTROLLER, Vol. 4, No. 2 -

Dates for Requiring Carriage

Region

1. 7.1966

France UIR Paris Sectors

Flight Levels FL 250 & above

FL 200

Amsterdam UIR

April 1965.

Transponders Remarks

Modes

Codes

A-B

64

Notes 1, 2 & 3

A-B

64

Notes l, 2 & 3

A-B

64

Notes 1, 2 & 3

& above

1. 4. 1967

I

I

Scottish UIR London UIR Preston UIR

& above

FL 250

France UIR Paris Sectors

FL 250 & above

A-B

FL 200

A-8

64

Notes 1, 2 & 3

FL 250

A-B

64

Notes 1, 2 & 3

FL 250

A-8

64

Notes 1, 2 & 3

FL 200

A-B

4096 4096

Note 2

FL 200 & above

A-B

4096 4096

Note 2

FL 200

A-8

c

4096 4096

Note 3 Note 2

FL 200

A-B

c

4096 4096

Note 3 Note 2

FL 250

A-B

4096

c

4096

United Kingdom Civil Aviation Information Circular N째 63/1965 dated 28 June 65 refers.

Note 2

A-B

c

4096 4096

Note 3 Note 2

D

4096

Note 4

I

I

1. 7. 1967

Brussels UIR

1. 6. 1968

France UI R Bordeaux Sector

& above

France UIR Marseille Sectors

& above

Amsterdam UIR Brussels UIR Hannover UIR Frankfurt UIR Scottish UIR Preston UIR London UIR Shannon UIR

I

& above

& above & above & above

FL 250 & above

Entire Eurocontrol Area

- - - - - _ _1_ _ _ _ _ _ _ _ __

14

& above

c

c c

I

4096 4096

I

Note 2

TYPE 1500 MILITARY/CIVIL TRANSPONDER The simultaneous use of common airspace by c i vil and military aircraft intensifies the critical !1ecessity for more efficient A .T.C. systems. Secondary Surveillance Radar provides this '":'P.rovement.

Civil Aircraft fitted with transponders already.benefit from the advantages of such a system , as : 0 t~e ground control stations. Military aircraft can now fit transistorised transponders ~m racmg the entire range of performance features for operation in any A.T.C. Secondary T adar area in the world. . .h~I Cossor SSR.1500 transponder is designed to meet the divers requirements inherent '" CIVI and T _m1"l't • ary operations. het. equipment reliability is extraordinarily high; yet the transponder is designed for ~tn muous operation at temperatures up to +140°C and altitudes up to 100,000 ft.

(1 1 ~ e;,~emely compact, weighing on ly 27 lbs, yet inco~porates all militar_y and c_ivil modes T' ' ' B! C .and 0), and functions in 2 and 3 pulse side-lobe suppression environme.nts. f1 he.~~:11size1s achieved by unusually high component density; whilst retaining sufficient exi 1 1 Y and accessibility fo r rapid maintenance. 'f~eAS~Ri 5 00 complies with the requirements of Annex CCB. to 29/69 CANU KUS (military), · · · · nnex 10, and relevant sections of Arinc characteristic 5320.

f~ OSSOR

COSSOR ELECTRONICS LIMITED (RADAR DIVISION), (Subsidiory o f A.

c. Cessor Limited and ol Roythcon Company U.S.A .)

THE PINNACLES, ELIZABETH WAY, HARLOW, ESSEX. Telephone: HARLOW 26862

1

Flugsicherungs- Beratungsdienst . '

...-

, ..

路.; ~""': ~

"' ':

~

路~

~-2:路-'-

ATS

Air traffic con stituted an essentia l part of the First International Traffic Exhi bition , (IVA) which was held in Muni ch, G erma ny, from June till September 1965.

It was an impressive show and there wou ld be many interesting things to re port about, for instance the excellen t displays of Deutsche Lufthansa AG, or the ve ry in structive airport models exhi bi ted by th e Arbeitsgemei nschaft Deutsche r Ve rke hrsflughofen .

But printi ng space is limited, so we can o nly deal wi th a sma ll cros s-section of the subject which is our main editorial topic: Air Traffic Services.

The Air Traffi c Services w ere wel I de monstrate d at the Muni ch Exh ibi tion by the Bu ndesanstalt fur Flugsicherung (Federal Agency for Air Navigation Services) and by EUROCONTROL. Simulating live conditions, the Bundesa nstalt fu r Flugsiche rung hod prepared severa l stands, mann e d by ATS staff, each representing a branch of

l A IS Office wilh airways chart ZelfoX facs imily transmiller, and visual ~ids for night plan n ing.

2 Tclocammunicalians slalian. The stand a n 1he righl i ll uslral~s lhc objectives of ATS by moons o f va rious mock-ups and displays.

3 En(Jineering and technical maintenance stand wilh several lechn ical equipmenl, monilorand conlrol desk, and mullichanne l recor路 dc rs.

Flugsicherungs- Kontrolldienst Ffughafenkontrolle

'

at the

IVA

the services. The visitors, passing from th e AIS stand via Telecommunications, Tower, and Approach to o mock-up of o n Area Control Centre, cou ld thus fo llow on IFR flight in a ll its phases and gained a lively impression of the tremendous ground organisation which is necessary for the safe and efficient co nduct of flight.

The information a t the stands was supp lemented by a film on radar control, edi ted and produced by o Germon controller.

On the very instructive EUROCONTROL stand, th e European upper air route sys tem was illustrated, and various mock-ups and displays highlighted the particularities and problems of traffic control in the upper a ir space, which hod led to the creation of the European Organisation for the Safety of A ir Navigation.

(Pictures courtesy Bundcsonstolt !Ur Flugsicherung ond EUROCONTROL Age ncy)

4 Control tower cob .

5 Approoch control mock-up.

6 Arca control centre with Oight progress boards, vertical ond Oot tube rodor displays, oreo charts, ond Zetlox locsimily equipment.

.

-

. .

•

~

ATS at the

IVA

--

路------~ Symb olized upper o i r route syste m in the EUROCONTROL member coun tries. In fron t - three-di mensi ona l displ ay of o i rcroft in the upper a i r space.

~ Mock-up of the EUROCONTROL ATC Simu lator, Experimenta l Centre Bretigny.

18

by Tirey K. Vickers and Edward M. Hunter

ATC Transponder Performance Pre-FlightTest Set Purpose The Air Traffic Control Radar Beacon System (ATCRBS) is intended to provide the oir traffic controller with continuous, accurate, and reliable information concerning the rho-theta pion position, identity, and altitude of the transponder equipped a ircraft under his control.

More and more, aircraft sepa ra tion is being based on transponder-derived data. Since 1962 in the United Stoles, a functioning transponder hos been o prerequisite for flight within designated Positive Control Airspace areas.

Because ATCRBS is o co-operative system, i ts successfu l operation depends on the proper functioning of the airborne as well as the ground equipment. In the post, o malfunctioning airborne transponder could either foil to produce a secondary radar target on the controller's display, or in some cases could degrade the display with unnecessary clutter.

Now that more sophisticated beacon equipmen t and a lphanumeric ATC displays are coming into use, certain malfunctions of on ai rborne transponder can produce on erroneous readout of aircraft altitude or identity data on the con troller 's display. These possibilities generate an increasing need for a fast and positive means of checking th e performance of aircraft transponder equipment, at suitable intervals.

To meet this need, th e Hazeltine Corporation has recently completed the design and construction of a new ground-based equipment which is known as theATCTrans· ponder Performance Pre-Flight Test Set. The prototype equipment w as developed under o Federal Aviation Ag~n­ cy contract, and was delivered to th e FAA Nationa l Aviation Facilities Experimenta l Center (NAFEC) in October,

Hazeltine Corporation

The main billboard display is located within 200 feet of the test area, and is p laced for convenient viewing from the cockpit of an aircraft parked in the test pattern.

The remote monitor display is designed for installation in the airport control towe r. However, it may be located as much as five mil es from the electronic equ ipment group, if necessary.

1964.

The Test Set is designed for installation near o ta xi strip, or other conven ient test area, at an airport. Its purpose is to verify the proper operation of aircraft transponders, prior to take-off . . The test set directs coded interrogations to a sing.le aircraft within the test area. If operating correctly, the aircraft tran spo nder sends bock replies which are evaluated ?utom~tica lly by the test set. The test results ore presented immed.iately to th e pilot, by means of o large bil lboard type di sp lay unit. Th ey ore prese nted simultaneously to the to"."er controller, by means of a remote monitor disp lay unit.

Hardware The test set ·s . · t . 1 comprised of the electron ic equ1pmen group shown 1n F 1 h h ig. ' t e main billboard display s own · F. in 1gure 2, and th h · F 3 It . e remote monitor display s own in 1 igure . · F.a so includes a 5-foot L-Band horn antenna. As sh own 1n 1gure 4 the h d · I 150 f ' orn antenna is in sto l le approximate Y eet from the center of the destignated test area.

The electr?nic equipment group is housed in a shelter hut, on the. airport, within 100 feet of the main billboard display. Thi s eq uipmen t group contains on interrogator/ receiver, a video processor, a se lf-test unit and the related power suppl ies. '

Fig. 1

Equipmenl Group

19

Test Functions

......• :·-• • .• • • ,... ..

• •• :·.. r• • ... .r-•a.

• .' ·"''' ... .

-· -.

I • .-... ..

--·• re .... :

The test set is d esigned for continuous outomotic operation, in checking the following transponder paramete rs : Receiver Sensitivity Transmitter Frequency Pulse Spacing Mode C Altitude Report

•• ~·· • • •• ·~t ... ~

Tronsmitter Power Pulse Width Mode 3/ A Identity Code Number Identification of Position (l/ P) Feature

Th e var ious functions of the Test Set may be exp la ined by referring to th e simpl ified block diagram shown in Figure 5. Blocks ore numbered fo r easy reference.

Th e Coder (1) generates the tim ing and gate pulses for the Electronic Equipment Group. Essent ially, it divides the test cycle into Mode 3/A and Mode C intervals.

The Transmilter (2) genera tes low-level RF inte rrogations.

The Attenuotor (3) limits the output of the transmitter to o leve l w hich, when detected by the tro nspo nder at the 150 foot opera ting range, will el icit a reply only if th e tronsponder's receiver sensitivi ty is above the minimum specified level.

The Self-Test Unit (4) detects the RF transmissions and evaluates th e m for proper pulse spacing; during the dead portio n of each du ty cycle, it gene rates o syn thetic rep ly (Code 0000) which is checked by the vi deo processor in the some manner o s the a ircraft replies.

The Duplexer (5) prevents transmission s from le ak ing into the receiver, and also routes the re p lies from the ante nna direct ly to the receiver.

The A ntenna (6} local izes the transmitter a nd receive r pattern to the test area shown in Figure 4. At the nom inal operating range of 150 feet, the ante nna patte rn covers o 50-foo t wide area, between 5 and 15 feet above the ground.

The Preselector (7), w hich is essentia lly o 1 090 megacycle bond pass filter, prevents undesire d frequencies fro m interfering with the ope ration of the receiver.

The Attenua tor (8) ad justs the receive r threshold, a nd checks transpond er powe r by re jecting any reply sig nal s which ore wea ke r than th e establi she d norma l, based on the nomina l operati ng ra nge of 150 feet.

The Receiver (9) conve rts RF replies to video fo r subsequent processing. It conta ins o frequ e ncy discriminator which generates a n accepted signal on ly for replies which ore within the assigned transponder frequency range of I 090 ± 3 megacycles.

•

20

Equipment Ins tallation Pion

• I

......... :

'•

CODE • • -1Tf!ME AL! I I - u

t ...

'.~I I

\

I

~

. .. .... ...

t

·~,

f

I

~!1

=199M :'" :•i ..-: ..

• ·: ·+-::!~~Ills • ... .... ;:.I .. ..

ICENT Fig. 2

Main (Billboard) Displa y for Transponder Pre.flight Test Set

Fig . 3

Monitor Displa y for Tra nsponder Pre-Fl ight Test Set

BILL80ARO DtSPLAY OESIA(D

C(NT£R lltl!

FOA AIACAAH BEACON ANTEN.l4A

I

I

TAX I STRIP

fig. 4

• t

I TRANSMITTER

CODER

ATTENUATOR

DUPLEXER

SELF - TEST

1

PULSE ~10TH I POSITION EVALUATOR

MOD~!

3/A DECODER

J-=Ec..;_NA~B=LE:...........it-t---~

RECEIVER

ATTENUATOR

12 MODE C DECODER

14 MAIN DISPLAY

1.3 EVALUATOR

ANgO~~:~LAY t---------~ 15 MONITOR DISPLAY

fig. S

System Block Diogram

The Pulse Width/Position Evaluator (10) rejects reply pulses which are either too narrow, too wide, or outside the time tolerance of the assigned reply positions.

The Mode 3/A Decoder (11), detects Mode 3/ A bracket pulses, at which time it reads out the Mode 3/A reply and converts it into a binary coded decimal (BCD) format. The decoder also detects an 1/P indication if one is present.

The M~de ~ D~coder (12) detects Mode C bracket pul~es, at which time 1~ reads out the Mode C reply, which is rn the SSR Automatic Pressure-Altitude Transmission Code (MOA Gilham Code). It translates this code first into binary form, and thence into BCD format.

The E~aluator and Display Control (13) evaluates the criteria and controls the d"ispl ays accor d"rng Iy. Th e selftest . unit . also · Broutes the decoded Mode 3/A an d Mo d e C re p I1es, rn CD format, to the display.

The M~in D!splay (14) and the Remote Monitor Display (15) have 1dent1cal functions. They translate the Mode 3/A and Mode C BCD information into numerical displays.

They also decode and display the readout data associated with the self-test ' the no go rn d.1cat1on · Mode 3/ A an d Mode C brackets, and the l/P function. ' 11

11

plus or minus ( ±) sign (indicating altitude above or below sea level) and the decoded altitude value, in frve figures.

As the displayed value corresponds to pressure altitude, to the nearest 100 foot increment (or 500 foot increment, depending on the reply code used), rather than to the actual altitude of the transponder above sea level, this readout can be expected to vary within a few hundred feet of the actual airport elevation (depending on the local barometric pressure); but should correspond closely with the pressure altitude setting obtained from an altimeter in the aircraft.

The pertinent test data remains on the display only as long as the aircraft transponder antenna remains within the antenna pattern of the test area. As soon as the aircraft leaves the pattern, the display reverts to the NO GO indication.

A complete check of transponder performance on Mode 3/A and Mode C, together with l/P, requires less than two seconds. If the pilot is watching the billboard, he can complete the check, while taxying across the beam of the test pattern, at a speed of ten knots or less.

Summary of Test Set Characteristics Antenna:

Frequency Gain Beamwidth VSWR Transmitter:

Frequency Power

Modulation Pulse Spacing

•

Pulse Width Interrogation Rate

Display Format and Test Criteria ~he main (billboard) display is designed for viewing by a_ pilot up to 200 feet away. The display surface is six feet high by eleven feet long. The display surface of the remote monitor unit is approximately one foot square.

If the results of the self test in the Electronic Equipment Group are acceptable, the words TRANSPONDER TEST are lighted and the displays are permitted to operate. If a malfunction of the self test is detected, the entire display is automatically shut off.

If a satisfactory Mode 3/A bracket is detected, having correct frequency and power level, the normally illuminated NO GO display is extinguished and the word CODE appears, followed by the numerical readout of the Mode 3/A (identification) code being received. The pilot checks this four-figure numerical readout to see that it corresponds to the code number set into his transponder control panel.

If an l/P function is present with a proper Mode 3/ A reply, the word !DENT is displayed.

Mode C data is not read out unless Mode 3/ A data is also being displayed. Processing of a Mode C bracket pulse causes the word ALTITUDE to appear, followed by a

Horn type, vertical polarization 1 020 to 1100 me.

20 ± 2 db. l 9J in H plane l 6c in E plane ;; 1 db.

Receiver:

Frequency Sensitivity

Pulse Width

Pulse Spacing

1 030 ± 0.2 me.

Established by variable attenuator (approximately 5 milliwatts) Pulse - 8 ± 0.1 /tsec.

Mode 3/A -21 ± 0.1 .usec.

Mode C 0.8 ± 0.1 .usec.

200 pulse pairs per second, with Mode 31 A and Mode C interlaced 1 : 1 1 090 ± 3 me. greater than 1 090 ± 3.2 me.

Established by attenuator Accept: 18.5 dbw (at 150 feet) Reject: 17.0 dbw (at 150 feet) Accept: 0.45 ± 0.1 ."sec.

Reject: less than 0.25 usec. or greater than 0.7 usec.

Accept: ~t_- 0.5 .11sec. from nominal pulse position Reject: less than 1.15 11sec. or greater than 1.7 11sec. from nominal pulse position Accept: Reject:

21

The S. R. T. Philosophy on ATC Automation

by J.

Edwards

Standard Radio & Telefon AB, Sweden

Paper presented at the Fourth Annual IFATCA Conference, Vienna

Present situation There are considerable extremes in the extent to which ATC is required or provided in the world. Therefore, there is little prospect of building a complete system which would satisfy the existing or forseeable requirements at all locations. It will not be disputed that there is a considerable requirement for modernising existing methods at the majority of ATC centres. The problem is in designing a system which is capable of partial integration, so that really constructive steps can be taken to build up a system which will suit the varying local circumstances.

In view of the development and operating costs of present and future aircraft, it is important that such aircraft should have an Air Traffic Service available which enables them to operate with maximum efficiency wherever they may be. All too often an aircraft leaving the upper airspace, entering a busy terminal area and eventually landing at a comparitively little used airport is exposed to largely differing degrees of control capability which are caused by incompatible standards of equipment. Should an aircraft which is equipped for automatic landing not be offered a smooth transition to the commencement of the approach, then these incompatibilities will become increasingly embarrassing to aircraft operators, air traffic controllers, and the governmental authorities responsible.

We emphasize this point, because from the outset, it has been the aim of our company to avoid the situation where automated processes could only be offered as very complicated and costly installations which could only be fully justified in areas with a heavy traffic density.

Obiectives Based on the above philosophy, Standard Radio & Telefon AB has designed a system which will: a) enable air traffic controllers to be presented with processed data in such a way which will allow them to perform their planning and executive tasks with the least possible administrative hindrance. b) allow a smooth introduction without having to use all the equipment immediately, therefore easing the training burden and allowing time for gaining controller familiarization without undue pressure. c) provide controllers with radar data and data from other sources at a reasonable cost. d) provide means of realistic co-ordination between civil and military authorities, thus easing the existing limitations of airspace organisation. e) fully utilize the existing separation standards and provide a means of gradually reducing them as more experience is gained. f) enable governments to procure au:omated equipment as required, with the assurance that each step taken is towards a more complete system and in the process no equipment is rendered obsolete.

neral, however, an examination of any particular situation would sho~ that '.he framework is correct and adaptable '.o automat10~ with no revolutionary change necessary m the allocat1on of functions to the sub-divisions of existing ATC centres.

In the. S~T approach, the major difference to existing methods 1s m the question of displaying flight information to the co~trollers. Al.though radar has for a long time been cautiously described as only being a lubricant to a basic syste'?1, there can be no doubt that it has now become a ma1or control equipment.

By the introduction of a high-speed computer for cooperation with the radar, the data obtained by the radar can nowadays be utilized by the controller for a t t. . fl" h u oma 1c trac k mg, 19 t progress prediction, conflict warning etc.

~ith these fu~ctions presented on the PPI and on electronic tabular displays the controller can b "cl cl ·h · · e prov1 e • wit a p1ctoria 1 view of the area for which h · "bi Th" · h. e 1s respons1 e.

1s gives 1m a continuously updated presen t a t•ion . of the For this reason we pi ace th e em _ . traffic. progress. . p h as1s on. pictorial displays. The major function of the c~mputer m our system is to produce data for a real-time picture for the controller.

Having provided th·IS, ·t · th en • • I IS possible to ~xamme the auxiliary functions necessary for the completion of the control requirement Info t· . h . h. . rma ion on all fl1g ts wit m an area which is stored and ' processed by the c~mputer can be shown both on the PPI and on tabular displays. ~he same information may also be presented ~y automat1ca~ly printed flight strips. When the constant display all information in strip form is not necessary, the strips can be provided immediately upon request from the controller.

?f

Basic Principle of the System In order to achieve a fast accurate and 1 · ne · . ' xpens1ve data processing . . and presentation system , SRT h as ch osen to use the d1g1tal data handling method through-out the ATC system presented here.

I . h This digital principle, which is used not . on y m t e computer, b ut a Iso m the PPl's and tabular d' I · the following advantages: isp ays, gives Full correlation between flight plan 0 d d d . . n ra or ata.

Visual presentation of flight progress d t

a a.

Visual intercommunication between co t II . . n ro ers and ad1acent centres and positive transfer of t con ro.1 Automatic tracking and symbol identification.

Video-correlated or raw radar as well h . PPI picture available. as synt et1c Narrow band radar picture transm·1 . h lines. ss1on on te 1ep one Composite display on the PPI of p' t f I remote radars. ic ures rom 1oca or

General Approach

lnterscan presentation of vector d DF . 'd . an - 11nes, v1 eo mapping and runway extension lines.

It is usually considered that not all the functions of existing systems currently have the right emphasis. In ge-

Bright daylight PPI presentation achieved by inexpensive additional equipment.

22

Automatic flight strip printing and updating.

Conflict seorch by computer with a larm s ignalling on PPI. Magnetic lope recording of radar and flight progress data etc.

Prepared for integ ratio n of SSR.

Building-block Units of the System A brief ind ividual description of e a ch of the major equipments wi ll be given be low. The rea son for this is that our system is o typica l building block system. Th e req uireme nts of various custo mers co n easily be met a nd eco nomica lly integrated by this method. Furthermore, any system con be extended, as required, by the simple addition of fu rthe r 'blocks '.

In the descriptions that follow, the main components, i. e. th e p ictorial displays and the compute r, ore dea lt with first.

The PPI

Daylight picture of PPI display, photographed under normal ambient light conditions. The Daylight Presentation System is based on d igitalizing the rodor information, storing it, ond presenting it 16times per second on the PPI screen.

The Tabular Display

The control desks used in the SRT system ore provided The tabular display is used for th e presentation of adwith one or two PPls dependi ng upon the requi re me nt for ditional in format ion about the targets which appear on different positions. Th e input information consists of radar the PPI, or information processed by the computer. The sweeps and symbols fed in digital form which means that presentation is mode on a rectangular cathode ray tube, no e rror be tween symbols and sweep wil l occur. The video w hi ch con show fl ight progress data for six aircraft simulsignals ore fed in the tradi tional form. It is possible to taneous ly. choose between row or correlated video, or composite Doto prese nte d on th e tabular display con be : tra ck video of the corre lated signal s from two o r more rada r number, co ll sign, type of a ircraft, speed in knots and in stations. All symbo l markers and vectors lines ore displaykm/ h, route, leve l in feet and in meters and ETA at fixes. ed as interscons. Instead of presenting both radar sweeps By using his keyboard, the controller con transfer data and interscons, the PP I con be used for d isplaying synto other controllers either in the some centre or to on th etic informa tion. It is possible to move the picture in the adjacen t one. x and y direction, by means o f off-centering controls up to o distance corresponding to four radi i of the screen.

The Computer Video mo ps and calibrati on markers, vector and DFlines a s well as runway extension lines con be presented The CE NSOR computer, deve loped by SRT is o multi o n the PPI scree n. The controller con automatically read purpose high speed data processor primarily intended for th e azimut h a nd le ngth of the vector lin e. Runway extenreal-time data handling. It performs the necessary opesion li nes for 5 runways ol diffe rent airports con be chose n ratio ns for th e automatic tracking process, administration from 16 runway extension lin es stored in the computer. of symbol presentation, intertrock computations and provides information for flight strip printing.

Each controller hos been allocated o specific pointer symbo l which he controls by o ro lling boll. The coordinates The main units in CENSOR ore the arithmetic unit, proof the symbol ore co ntinuously stored in th e compute r. gramme cont rol and the magnetic core me mory. CENSOR When tran sferring the contro l of on aircraft, the symbo l is connected to its own input/output equip me nt and ho s disp layed on the PPI con be transferred to another co n~ertoin specia l fe a tu res to make it extremely fast, which troller's PPI. This transfer con be to on adjacent contro lts necessary for real-time data processing. These include ler, or over telephone lines lo o controller in o distant connection to a common bus line, semi-permanent instruccentre. tion memory, direct memory access, and all programmes executed on a priority bas is.

By means of o specia l process, developed by SRT, it is poss ible to produce a bright radar picture on the PPI. CENSOR is connected to o common bus line which is This enables the controll ers to work in daylight conditions o two way information chan nel connecting all ports of instead o f o ~pec iolly darkened room as is normally nethe processing system, i. e. CENSOR itself and its assocessary. Briefly, the process entails storing the target cociated ex ternal devices such as keyboards, tabular disordinates in o ferrite core memory, where they ore proplays, ch aracter generators radar extractor units, data gressively introduced at the so me rote as they ore receilinks, tape ~ecorders, extra ~emory etc., etc. ved by the radar. Then in on independent reading cycle, The rapid tran sfer of data between external equipment the memory is scanned at o high repetition rote which and CENSOR is very important in this type of real-time determines the target coordinates for presentation on o processing. In most computers one programme hos to be cathode ray tube. As the PPI screen is being scanned more completed before another con be started, but in CENSOR 0 method of direct a ccess to the memory hos been incorrapidly with this method than if row video is presented, th e 'b lip ' which represents the target position will appear porated. This hos t he advantage that on external un it more frequently and not decoy as in the case when the wo nt ing to communicate with CENSOR instead of having PPI sc reen sweep is synchronised with the antenna revoto wait until a programme is comple~ed, will deliver o luti on. signal to the Priority Unit in CENSOR, where the relative

23

priorities of all possible colls ore determined. The coiling units ore then connected to the memory in order of priority. The direct memory access facility also hos the benefit that transfers to and from external equipment con be mode without disturbing the running computations in the arithmetic unit. One programme is usually completed before another is started, but if it is necessary to interrupt a programme on interrupt signal is inserted at a convenient inte rval. Such on order, when delivered to th e programme selector, causes a 'j ump out' of the running programme. When the new prog ramme hos been completed, the interrupted programme is then continued from the interrupt point.

Flight pion doto con be received by teleprinter from adjacent centres and ore fed directly into the computer.

The keyboards at the control positions con also be used for this purpose. The computer stores the flight plans, calculates the ETA at fix points and searches continuously for conflict risks . Flight progress strips may also be printed if required. Each radar controller is presented the so me data on his Tabular Display for those aircraft he is interested in. The computer continuously updates the flight progress situation by printing new strips. By means of the teleprinter network, the computer transmits updated flight plans in real time to adjacent centres.

Tracking con be semi-automatic or automatic; semi-automatic tracking is used in disturbed conditions, but in normal conditions automatic tracking is used.

The tracking is also programmed (boll unit) in the computer and started by means of the keyboard and the rol -

Typical row of controllers desk in on SRT ATC Centre Syste m.

24

ling boll unit. The tracking will automatically correct the flight pion if a deviation is discovered. The computer predicts conflict situations and the controller may accordingly update the flight pion at any time.

Th e design of the computer enables successive extensions of programming faci lities, and also the easy connection of further external devices in the future.

The Video Correlator Th e video correlator, which is connected to the CENSO R computer, analyses on a digital basis the radar vi deo signal and 'reports' a target if the hit pattern complies with pred etermined criteria. This is a most efficient way of detecting disturbed targe ts and makes it easier for the controller to survey the traffic situa tion.

The output from the video correlator is one well defined pulse for each target, which con be used for the extraction of target coordinates (in x and y), which in turn ore fed to th e computer to be used for automatic tracking purposes.

The storage function contained in the video correlator con also be used to enable the information from different radar stations to be presented simultaneous ly on one PPI without any loss of radar informat ion (composite display).

The Input Media Th e input media to the computer, i. e. the ro lling boll and keyboard unit, ore both situated at the controller's desk.

The rolling boll controls either a track symbol or the pointer symbo l. As already mentioned the pointer is used mainly for designation of tracks and for positive tronsfe r to othe r controllers. Th e rolli ng boll is connected to the selected symbol when a wrist-key is pushed. This key hos two d epressed positions, the lower position increases the manoeuvre speed of the ro lling boll four times. By the operation o f a thum b-key, the target position is fed into the computer. The movement of the rol ling ball is followed by two e ncod ers, which ore mounted one in the x and one in the y axis (i. e . 90째). Th ese give the x and y coordinates of the target position to th e computer.

The keyboard is ma inly used for co mmunication wi th the computer. It has s ix rows of spring-loaded buttons and four buttons spring-loaded general keys.

The buttons in the keyboard are connected to input devices in th e keyboard input unit contained in the input rock of the CENSOR com puter. By means of the keyboard, the controller can for example insert data to complete a tra ck or a sk for addi tio na l data to be presented o n his tabu lar display, e. g. to change flight plan information of any or all o f the aircra ft presented.

Narrow Band Transmission of Radar Pictures The NATRAP system, develope d by SRT, is a syste m used to transfer all the useful rodor info rmation on a radar display by means of ordinary telephone lines.

The equipment use d fo r the NATRAP system includes eq uipment for the ext raction of radar data, a buffer memory for the storage of data and da ta li nk termina ls at

both ends. An ordinary PPI w ith fixed deflection coils as described above is used for the display. The PPI can easily b e connected to data handling units for th e presentation of additional data-handled information.

Th e principle of the syste m is to reduce the bandwidth by ig noring irreleva nt information in the received radar signal and by preventing the transmission of fixed echoes, noise etc. Th is is achieved in the NATRAP system by means of a data extractor (Th e Video Correlator). The rece ived radar sig nal is processed, as already described, by digita l techni q ue with the result that only one sig nal is relayed for e a ch target and o nly very few o f the signal s at the receiving e nd ore related to fixed ech eos.

Azimuth information is obta ined from the radar antenna by means of a d igital incremental encoder. Th e information is fed to a digital un it where binary sweep waveforms for x and y coordinates ore generated in rea l tim e. Th e o utput pulses from the v id eo correlator are used to read the x and y coordinates, thus information is given on the positions of all targets a s seen by the radar.

At the receiving end, the information is demodulated and conve rted from serial to parallel form. Th e information is then suitable for processing in a binary computer. A digital to ana logue converter is used to present th e information on a convention al PPI. One or more PPls can be coup led to the system.

Th e NATRAP syste m gives independe ncy of terrain obstacles, increased sca n presentation, improved coverage by easy connection of severa l radar stations to the sam e centre and economic conn ection o f re mote radar stations.

Close -up view o f twi n 16" PPI controllers desk, showing comp~ter input .keyboard with te ll -bo ck un it, rolli ng boll unit and tabular display'.

Picture on the le ft is 0 row radar presenta tion .sent over a microwave link, whilst the picture on the right shows the some doto as tronsm1 ttod by 0 narrow bond link on a normal telephone line.

25

lion and a second port for the procedural control. Both ports should operate togeth er in the integrated system.

The simulator system is very flex ible and is capable of step-by-step expansion. The basic equipment in the system is the digital computer, which con also be used a s a spore for the ATC centre computer. The equipment content and capability is very sim ilar to that of the centre. Extra equipment bui lt into the simulator system is for use by the instructor who simulates the pilot or pilots. The instructor may hove up to two assi stants. The number of pilots being simulated depends upon the number of ai rcraft the centre is capab le of handling.

The simulator system is used to simula te, in real time, all aspects of on aircra ft 'fl ight' and to feed in suggested conflict possibilities so that the controller is trained to handle and respond to all possible variations he is likely to meet in actual situations. The simul ation is usually done in three phases, preparation, the 'flight' and afterwords, the analysis.

The whole exercise, as already mentioned, is recorded on l ope for subsequent analysis, the simu lation itself can be on tape or controlled manually by the instructor, or a combination of both methods.

Thus, by use of the simu lator, it is possible to reproduce all the normal flight characteristics met by a controller, as well as feeding in many variables to simu late al l known situations and to test the controller's capabi lity when meeting new situations.

Picture to ken in Stockholm showing the current traffic situation in the adja cent So uthern Swed is h ond Danish oreos p rovided by the use of NATRAP.

1Oth Annual ATCA Convention to be held at Los Angeles Tape Recording Normol comm ercial tape recorders con easi ly be used in the SRT system. The type suggested is the conventional stereo tape recorder, using normal magnetic tape.

In the ATC centre, tape recorders con be used to make the necessary legal recording of all ATC communications, of flight movements, tra nsfer of control, radar pictures etc.

Th e tape recorder is also used in coses of emergency when con tinuous flight strip p ri nti ng is not req uired.

Shou ld the comp uter break down in such a case the fl ight progress information is sto red on tape and the actual fl ight pion information is automatically printed by the fl ight strip printer.

The simulator suggested for tra ining also relies on the r ecorder for many of its oper ation s. It con have taped i nformation a s 'background tracks ' and much of the simula ted fl ight information is provided from tape record ings. Th e whole simu lation process is recorded on tapes and late r 'play ed bock' for purposes of onolys is by the instructor and controller, enabling useful experience to be gained. In the simulation p ro cess, the tapes with simula ted flight information may be used many t imes or may b e altered sl ig htly so that a different flight p rogram me may be introduced .

Simulator for Training In general, th e ATC simu ltotion equipment consists of two ports, o ne for radar simula tion and data presento26

" A Decode of Progress " is the theme of this year's Annual Convention of the U.S. Air Traffic Control Association, .to be held from October 11 th through 13th at th e lnternottonol Hotel, Los Angeles, California.

The Conference will highlight accomplishments of the past decode and emphasize the goals of the coming ten years. I FATCA Vice President Maurice Cerf and Treasurer Henning Throne will officially represent the International Federation of Air Traffic Controllers' Associations and many representatives of IFATCA Member Associations wi ll also attend the Conven tion.

Meeting of IFATCA Officers at Amsterdam The El ect ive Officers of IFATCA, the Executive Secretary, and the Chairman of Standing Committee I met in Amsterdam from September 20th till 22nd to discuss current matters. Items on the agenda were, inter olia, the R~port the Annual Conference, Vienna, 1965, cooperation w ith IFALPA, the ATCA Conference in Los Angeles, ICAO matters, w_ork programme of Standing Committee I, European Regional Organisation, THE CONTROLLER nam in~tion of Officers, IFATCA budget, appointment of Executive Secretary, Annual Conference 1966 _ Rome and an IFATCA glossary of ATC term s. ' On the second day of th e meeting, the Officers were joined by Mr. Koemos, European representative of the Internationa l Council of Aircraft Owners and Pilots Associatio ns and by members of th e Netherlands Guild of Air Traffic Cortrollers. Details wi ll be p ublished in the next IFATCA Ci rcular.

?f

General Purpose Computers and CRT Displays in ATC

by R. Arnolds Telefunken A. G .

Paper presented at the Fourth Annual IFATCA Conference, Vienna

General Purpose Computers As is we ll known, the Federol Germon ATC authority, th e Bundesanstalt fUr Flugsicherung (BFS), decided at quite an early date to use generol purpose computers for the outomation of air traffic control technical aids. As early as at the beginning of 1959 the BFS issued a co ll for tenders for th e supp ly of a general purpose computer for the first step towords automotion of air traffic control. This decision was not so much at hands as it may seem today.

Even the American Federal Aviation Agency (FAA) did experim ental work at that time by meons of specia l purpose computers and specia lly developed input/output devices. However, after the "Beacon Report" was published in November 1961, the use of general purpose computers was adopted also in the United States.

In November 1963, t he Telefunken genera l purpose computer TR 4 was set running in the tower of Frankfurt Airport. It is one of the large-scale digital data processing systems. The number of about 100.000 operations per second may serve as an example of its gr eat capacity.

Figure 1 shows a partia l view of the TR 4 Computing Centre at Rhine-Main Airport.

The first seven electronic cabinets on the left side be-

~81::1

long to the central computer. Apart from the power supi:-¡ ly system they hold the arithmetic, the instruction and t he contro l units as well as the ferrite core memory and the in put/output units. The adjacent four cabinets contain a teleprinter distribution unit by means of which 24 teleprinting channels can be linked directly to the computer.

The number of channe ls can be increased to 62. Fu rthermore, this unit holds an electron ic clock system by means of which normal or real time respectively is indicated to the computer every 10 seconds.

In front there is the control desk with an electric typew r iter and the indicator and control panel for the real time clock. The monitor typewriter is a means of direct communication between the computer oper ator and the computor. The same applies to the 24 telepr inters, o ne of which can be seen in the background. It is of g reat importance that by these means rea l time operatio ns can be carried out, i. e. via each teleprinting chan nel da ta can be fed into the computer at any time without previ ous announcement or de lay being necessary un less information is put out by the computer on the respective channel.

Figure 2 shows t he a rrangement o f t he equipment as it is provided for the first stages on t he way to automation of air t raffic contro l. During the initial stage a bove

I

CJ CJ ~

•

Fig ure l

'

.~

;

,

•

TR 4 Computing Centre, Rhine- M ain Airport.

27

all automatic computation, assembling and printing of flight progress strips and the pertinent processing of flight pion data, meteorological dote ond correctio ns ore tested.

Thus certain operational odvontoges ore expected, e. g. greeter legibility of the strips, fos_ter ond more reliab le execution of the routine tasks related to their preparation, focilitotion of certain coordination tasks, etc. It is also of great importance that thereby operati ng staff and technicians get on opportunity to fami li arize themselves w ith such equipment and the special rules for its effective application.

The necessity to form a group of qualified programmers and system plan n ing staff is only one examp le for new requirements imposed by the use of a digital computer for ATC purposes. In this respect the BFS is following the practice to train, above all, air traffic controllers for programming and operating the digital computer in a one-year specia l course. Also in the United Stoles this way hos turned out to be advantageous as it usua lly assures good compatibility with the particular operotionol circumstances and requirements when the computer is used for ATC tasks. Moreover, p rogramming is in many aspects simi lar to the activity of on air traffic controll er, so that the controller, as experience hos proved, is in generally well qualified for programming.

As con be seen on Figure 2 the input of data necessary for strip printing, i. e. especially fl igh t p ion and meteorological data, is carried out via normal teleprinters. It is quite on advantage that t h is relatively inexpensive seria l equipment con be used for other purposes at o l ater tim e when the printing of control strips will be reduced or even replaced by more effective procedures as e. g. synthetic air traffic presentation on CRT displays.

The first step towards testing the system co nsisted in a long term comparison of flight progress strips generated

by the computer with those written manually. This was o means for eliminating from the computer programs any inadequacies which become apparent only under operation. Today the controllers in Frankfurt ore provided with printed departure strips. In the near future the area control centre, approach control and tower control o f Frankfurt wil l be suppl ied more and more with printed strips as shown on Figure 3.

For the time being the computer is not provided with sta nd-by equ ipment. Therefore, only such tasks, which i n case of a breakdown of the computer con be continued manually or accord ing to the procedures used up to now, con be consigned to the computer. The generation of flight progress str ips, however, is a task of such ki nd. In this case the transition from automatic to manual operation can be secured with relative eose by an appropriate operational orgonizotion. In other coses where this requirement cannot be met reliably, those tasks ore to be tested in parallel with the genuine A TC service. As soon os the computer shell be really used for such tasks, however, its rel iabi li ty wi ll be of utmost importance. W ithout going into detail, it may be mentioned that the problem of rel iabili ty is under investiga tion and that satisfactory solutions a lso for the most stringent requirements o f air traffic control ore emerging.

Some tasks which will be treated in the course of the first test and evaluation stage shall briefly be mentioned here: Tran smission of flight pion data from the Munich a nd H a nnover centres to the compu ter via telepr inting channels; strip pr inting in Munich and Hannover; conflict search and conflict solution calcu lations. When and to what extent such tasks ore performed con only be decided by virtue of the increasing experiences gathered during the current test period. The some applies to the answer to the question wether the computation results ore

ACC FRANKFURT

RADAR HEAD

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to b e presented to the controll er in writi ng vio the tele· printers or wheth e r they ore to be shown on a CRT dis· ploy as it is use d in the second trial phase.

It need no further discussion to show that a general purpose computer with its g reat versatility with respect to programming, program alterations and exchange as well as to its va ri ous possibilities for data input and out· put is sui ted best fo r th e variety of experiments and in· vestig ot ions necessary before the general introduction of d igita l computers into air traffic control. The advantag es offered by a general purpose computer remai n valid even after the operational introduction of d igital computers into ATC because the requirements lo be fulfilled by th e ai r traffi c co ntrol system wi ll change and increa se due to the dynamic development of air traffic.

A very remarkable ex ample of the advantages offered by o general purpose computer is the fact that tests for automatic processing of pr imary radar data ore present· ly carried out at the Frankfurt TR 4 Computing Centre. It is possible to switch over rather quickly to this completely different testing task by subst itu ting the programs for flight progress strip print ing stored usually in the corn· puter by radar data processing programs.

RADAR/TV SCAN CONVERTER

CRT Displays For the seco nd stage of th e automatio n efforts it is planned first of all to test o CRT display developed for universal application in ATC and procedures for digital process ing of radar data. This phase will run mostly in parallel with the first one. Practically it hos already begun with the tests for automatic radar data processing men· lioned before.

The disp lay equipment is presently being developed

by Telefunken and will be used in Frankfurt from the beginning of 1966 onwa rds. Figure 4 shows the set-up of th is equipment. Th e di splay console will be built with re· ference to the FAA specifications for radar bright display equi pme nt and contains o cathode ray tube of 22 inches diameter with extremely flat screen. On the one hand the di splay unit is linked to the TR 4 computer via the dis· ploy control e qu ipment so that synthetic air traffic pie· lures and other control data generated by the computer con be displayed . In order to obtain o flickerfree picture for daylight presentation, o picture repetit ion store causes the pictorial data lo be presented 50 to 60 times per se· cond. Thus the presentation of moving data will not be spoilt by afterglow effects.

DISPLAY CONTROL EQUIPMENT

DISPLAY UNIT

TEST UNIT CONTROL UNITS

SYNTHETIC OllTA FROM COMPUTER TR4 REQUESTS AND INSTRUCTIONS TO ca-tPUTER TR4

~

TV·RAIYIR VIDEO

SYNTHETIC DATA FROM ATC COMPUTER

Figure 4 Air Troffic Display for Rodar. and Computer lnformolion.

29

63 different characters a s well as vectors con be displayed. The character generator used allows a writing speed of 100.000 characters per seco nd. That means !hot up to 2.000 characters con be re presen ted flickerfree. A rolling boll unit enables the operator to move o morker over the screen and to feed the correspo nd ing co-ordinates into the computer.

On th e other hand the d isp lay un it con be con nected with a scan converter, and thus the row radar picture con be disp layed according to the FAA TV-standard with 945 lines. Simu ltaneo us display of the TV radar picture and compute r data is possible. In this case th e amount of computer data is reduced to o max imum of 150 characte rs or 300 characters at a picture repetition frequency of 60 c/s or 30 c/s respectively.

Th e displ a y unit is equ ipped with o keyboard by means of which the following information con be fed into the computer: 1) Orders demanding to change the picture displayed, to odd supplemen tary information (e . g. tabular data) or to exclude ce rta in data from th e presentation.

2) Confirmation of receipt of certain control data generated by the computer.

3) Input of new control da ta (e. g. he ight information) by means of number keys, various interpretat ion keys end, if needed the roll ing boll.

In order to increase the clearness of prese ntation, the following alte rat ions may in addition be carried out on the picture without affecting the computer : Dece ntering and change of scale, brightness con tro l of different catego ries of data which con portly be selected by means of the computer prog ram (e. g. display of mop informat io n with lower brightness).

For tria l purposes the display unit has been desig ned in such a way that the actual viewing unit con be mounted with either nearly horizontal or nearly vertical screen. As indicated on Figure 4, a combination of two screens con

thus be real ized. In the latter case both d isplay units con be connected with one display control equipment.

This short survey illustra tes the great flexibility of the whole concept of development with respect to display of radar and computer data, various possibi lit ies to ma ke use of the control keys being interpreted by the computer program as well as the d ifferent ways to mount the d isplay system. It is intended to use the equipment for area and approach control as well a s for input of radar data into the computer and semi-automatic processing of these data.

Figure 5 shows a mock-up of the display un it, whereas screen pictures d is played on a first laboratory vers ion con be seen on Figures 6, 7 and 8.

Figure 9 shows a schema tic represen ta tion of the air traffic picture by means of which tests will be carri ed out after the installation of the CRT display equipment. Aircraft data coming from the computer ore presented in the way indicated enlarged on the right side of the pictu re.

The aircraft position is marked by a symbol with a smell vector indicating fl ight direction and approximate a ir speed. Control data belonging to this target as e. g. flight number, coll sig n a nd heigh t ore presented as a labe l which may comprise a maximum of 3 li nes at 7 characters each.

The computer program causes the la bel to be in dicated always in that one of the four quadrants surround ing the target symbol which li es op pos ite to the direction vector.

If the labels of two ad jacent ta rgets overlap, one of th em con be e rased for some time. This is done by means of the rolling boll a nd a ca nce l key unless the two aircraft symbols ore overla pping too.

Furthermore, the position of radar blips in case o f si multaneous presentation of the television pitcu re is hown on Figure 9. As men tioned above, in this case the presentation o f computer data is limited. Therefore it is useful to display the fixed information necessary for the mixed

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In order to d ist ingu ish certain information from the o ther data displayed , such information con be presented controlled by the computer program brighter, Oickering, in itolics or spaced with increased character height.

presentation as e. g. map and repo r ting points as part of the tel evision picture.

Th e operational use of this kind of air traffic presentation presupposes thot at least for all controlled targets the raw radar data ore digitalized and that they are processed by he computer. In general, the controller will then ~e able. to make use of the synthetic air traffic picture and in spec ial cases or in cases o f doubt only he will return to the m ixed display.

Figure 8 This is a simplified a ir traffic picture far the purpose of studying moving data on the screen.

As to the input of radar infor mation into the computer and the processing of these information, a secon d display unit of the described ki nd is planned to be used fi rst ly.

This equipment is controlled by a radar operator who constantly uses the m ixed display of computer and radar information. His main task consists in track initiation and d eviation control for rote aided track in g by t he computer.

Th e necessary expedients are rolling ball and interpretation keys. Only at a later stage a fully automate d procedure for track initiation and tracking will be tested operationa ll y and in coordination with t he controller working at the ATC display. In both cases it is provid ed that the identification of the rada r tracks is ca rried out by the air traffic controller.

TABULAR INFORMATION ....,.(REPORTING POINT WITH NUMBER OF

EXPECTED APPROCHES FIR BORDER

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31

Corporation Members of the International Federation of Air Traffic Controllers' Associations The Air Traffic Control Association, Washington D. C., U.S.A. Cessor Radar and Electronics Limited, Harlow, England The Decca Navigator Company Limited, London ELLIOTI Bros. Ltd., London Hazeltine Corporation, Little Neck, N. Y., USA IBM World Trade Europe Corporation, Paris, France ITT Europe Corporation, Brussels, Belgium The Marconi Company Limited Radar Division Chelmsford, Essex, England N.V. Hollandse Signaalapparaten Hengelo, Netherlands Philips Electronics, Netherlands Selenia - lndustrie Elettroniche Associate S. p.A. Rome, Italy The Solartron Electronic Group, Ltd. Farnborough, Honts., 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 concerne~ with the maintenance and promotion of safety in air traffic to join their organization as Corporation Members.

~orpora~ion Members support the aims of the ~e~eration by sup~lyi,ng. the Federation with technical information and by means of an annual subscription. The Federations international journal "Th troller" is offered as a platform for the discussion of technical and procedural developments field of air traffic control.

For further information on Corporati~n Membership please contact Mr. Ernest Mahieu, Honorary Secretary, IFATCA, Cologne-Wahn Airport, Germany.

32

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lf'he ~lnl~eirnational Federation of Air Traffic Controllers Associations Addresses and Officers AUSTRIA Austrian Air Traffic Controllers Association Vienna Airport Austria President First Vice-President Second Vice-President Secretary Deputy Secretary Treasurer

H. Brandstetter H. Kihr H. Bauer R. Obermayr W.Seidl W. Chrystoph

BELGIUM Belgian Guild of Air Traffic Controllers Airport Brussels National Zaventem 1 Brussels Belgium President Vice-President Secretary Treasurer Editor

Chairman Vice-Chairman Secretary Treasurer

Fred. Lehto Jussi Soini Heikki Nevaste Aimo Happonen

FRANCE French Air Traffic Control Association Association Professionnelle de la Circulation Aerienne B. P. 21 Aeroport du Bourget, Seine France President Vice-President General Secretary Secretary Treasurer

Maurice Gregoire Francis Zammit Maurice Cerf Jean Flament Emile Mercier

A. Maziers R. Sadet R. Tamigniaux R. Maitre 0. Haesevoets

CANADA Canadian Air Traffic Control Association P. 0. Box 24 St. James, Man Canada J. D. Lyon President W. B. Clery Vice-President L. R. Mattern Managing Director E. Bryksa Secretary-Treasurer J. R. Campbell IFATCA Liaison Officer

GERMANY German Air Traffic Controllers Association Verband Deutscher Flugleiter e.V. Cologne-Bonn Airport Porz-Wahn Germany Chairman Vice-Chairman Vice-Chairman Vice-Chairman Secretary Treasurer Editor Director Deputy

W. Kassebohm E. Reddmann M. Bahr H. W. Kremer F. Werthmann H. Prell J. Gartz G. Riediger H. Krause

DENMARK Danish Air Traffic Controllers Association Copenhagen Airport - Kastrup Denmark Chairman Vice-Chairman Secretary Treasurer

Henning Throne H. Dall J. Thilo P. Bressam

FINLAND Association of Finnish Air Traffic Control Officers Suomen Lennonjohtajien Yhdistys r.y.

Air Traffic Control Helsinki Lento Finland

GREECE Air Traffic Controllers Association of Greece Air Traffic Control Athens Airport Greece President Vice-President General Secretary Treasurer Councillor Councillor Councillor

Chr. Tzamaloukas G. Elias C. Kioupis P. Vasilakopoulos B. Egglezos P. Math ioudakis H. Kopelias

33

ICELAND Air Traffic Control Association of Iceland Reykjavik Airport Iceland Chairman Vice-Chairman Secretary Treasurer

Valdimar Olafson Jens A. Gudmundsson Einar Einarsson Guolaugur Kristinsson

IRE LAND Irish Air Traffic Control Officers Association Aeronautical Section O'Connel Bridge House Dublin 2 Ireland President Vice-President Secretary Treasurer

D. J. Eglinton P. J. O'Herbihy M. F. McCabe P. P. Linahan

IS RAEL Air Traffic Controllers Association of Israel

President Vice-President Secretary 2nd Secretary Treasurer Member Member

J. van Londen J. L. Evenhuis W. G. van Blokland P. J. Stalpers J.C. Bruggeman G. J. Bakker L. D. Groenewegen van Wijk

NEW ZEALAND Air Traffic Control Association Air Traffic Control Centre Dept. of Civil Aviation, 8th Floor, Dept. Bldgs.

Stout Street Wellington, New Zealand Hon. Secretary

R. G. Roberts

NORWAY Lufttrafikkledelsens Forening Box 135 Lysaker Norway Chairman Secretary Treasurer

F.Oie P. W. Pedersen A. Torres

P. 0. B. 33 Lod Airport Israel Chairman

SWEDEN Jacob Wachtel

ITALY Associazione Nazionale Assistenti e Controllori della Civil Navigazione Aerea Italia Via Cola di Rienzo 28 Rome Italy Chairman Secretary

C. Tuzzi L. Belluci

LUXEMBOURG

Swedish Air Traffic Controllers Association Air Traffic Control Bulltofta Airport Malmo 10 Sweden Chairman Secretary

SWITZERLAND Swiss Air Traffic Controllers Association V. P.R. S. Air Traffic Control Zurich-Kloten Airport Switzerland Chairman

Luxembourg Guild of Air Traffic Controllers Luxembourg Airport Luxembourg President Secretary Treasurer

Alfred Feltes Andre Klein J.P. Kimmes

NETHERLANDS Netherlands Guild of Air Traffic Controllers Willem Molengraafstraat 22 Amsterdam-Slootermeer Netherlands

34

Carl Ahlborn Lennart Jogby

Bernhard Ruthy

UNITED KINGDOM Guild of Air Traffic Control Officers 14, South Street Park Lane London W 1 Master Clerk Executive Secretary Treasurer Director Deputy

L. S. Vass G. Monk E. Bradshaw A. Field R. W. G. Mundy N. Alcock

URUGUAY Asociation de Controladores de Transito Aereo del Uruguay Potosi 1882 Montevideo Uruguay Chairman Secretary Treasurer

President Vice-President Secretaries

Treasurer Vocals

U. Pallares J. Beder M. Puchkoff

Dr. Carlos G. Osorio Manuel A. Rivera Dr. Alfredo Monque D. R. Solazar J. Blanco Villanueva Miss Amelia Lara F. Arturo R. Gil Prof. Vicente Smart D. Alfonso Parra

YUGOSLAVIA

VENEZUELA Asociacion Nacional Tecnicos Transito Aereo Venezuela Avenida Andres Bello, Local 7 8129 Caracas, Venezuela

Yugoslav Air Traffic Controllers Association Jugoslovensko Udruzenje Kontrolora Letenja Direkeija Za Civilnu Vazdusnu Plovidbu Novi Beograd Lenjinov Balevar 2 Yugoslavia President Secretary

I. Sirola A. Stefanovic

Altimetry at High Altitudes with a View to the Vertical Separation of Aircraft EUROCONTROL Report 1/65 by Dr. Ing. Frhr. von Villiez With the introduction of high-flying jets, and even more so, with the advent of SST, the problems of vertical separation at high altitudes have developed into a pressing issue and various national and international bodies are working on their solution.

In view of the fact that pressure altimeters will probably continue to remain the most suitable means of determining altitude, a decisive step forward was achieved when, in 1964, agreement on the extension of the Standard Atmosphere from 20 kms to 32 kms was reached.

In a recent study, the Eurocontrol Agency examined the suitability of pressure altimetry for the vertical separation of aircraft at high altitudes and looked into the possibilities of applying other methods for the determination of altitude.

A review is given of the various physical principles of altimetry, followed by a discussion of the extended Standard Atmosphere and an analysis of the errors in pressure altimetry. Methods for the determination of height are also considered. The conclusions of the study can be summarised as follows: Only pressure altimetry has sufficient potentialities for the application of vertical separation standards presently used above Flight Level 290 for aircraft which, in the foreseeable future, will operate in the altitude bracket from 40.000-80.000 ft.

Present day altimeter instruments have an accuracy in the order of ± 1 mb (3 times standard deviation figure), which amounts to ± 720 ft at 80000 ft according to the standard atmosphere. It has been shown that this figure

can best be used for all practical applications. Any improvement beyond this figure, e. g. down to ± 0.75 mb, can only be achieved by much more sophisticated calibration procedures, which will never be reached in daily operation. It is imperative, however, to agree a common calibration procedure in order to benefit from the instrument accuracy presently available. Recently the FAA adopted a rule on altimeter tests and inspection, which confirms the conclusion drawn in the report.

With regard to the flight technical error, the report accentuates the lack of statistical data for other categories than civil jet aircraft, as well as for flights at higher levels than ~hose usually used, i. e. above 40 OOO ft. A separate study within the Eurocontrol Agency is being devoted to a theoretical determination of the flight technical error with the assumption of several error distributions.

This is going to be a very important contribution for the assessment of vertical separation standards.

Attention has been drawn to the fact that the growing utilisation of secondary radar and there particularly the extension to Mode C operation (automatic altitude reporting) will undoubtedly be helpful to monitor and avoid deviations from assigned flight levels induced by flight technical errors.

Referring to a pr-evious study the author unde1·lines once more the importance of a clear presentation of altitude indication to the pilot. A digital altimeter read-out is being described as a favourable solution to overcome the ambiguous or at least difficult to inte1·pret cockpit instruments still in current use.

35

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36

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Selenia products are V11arking far safety in the air

ATCR systems and ~ETEO~ radars from SELENIA have been chosen and are in operation for the Air Traffle and Weather Bureaus Authorities of 15 Countries.

It is not by chance that thes~ highly specialized products, often connected into large systems, have been designed

by Selenia for so many ex.acting user~ and operate in such different environmental conditions. .

Selenia has a staff of engineers ~ork.mg on t~~ problems connected with safety in the air: all the experience acquired by years of research and production in the military and professional electronic field is put to good use to reach one basic goal: Keep the Ai.r Traffi~ safe. . . .

Selenia is prepared to give a~I .kind of assistance in solving the problems concerning Air Traffic: from the study of the best system to the training of personnel, through research, design, construction and installation of complete networks, including Terminal and Air Route Control radars, Weather radars, data handling and display systems, microwave links, remote control and data transmission equipment, etc.

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Precision or improvisation?

Decca/Harco is the only system that provides all the f acilities for th e ~ uto.matic, .acc urate navigation of sub- and supersonic aircraft. With the Data Link this in -fl ight information is co ntinuou sly relayed to th e ATC centre.

In the air Decca Omnitrac-:-the world's most advanced lig ht-weigh t airborne di~ita l compu ter-provides undistorted charting with automatic cha~t changing and the ghost beacon facilit y which g ives bearing and distance to any point. Its function also includes auto-pilot coupling and automatic altitude control which maintain respectively any desired f light path and the required fl ight profile. The depa rture, if any, from the scheduled time of arriva l at any selected point is indicated on the ETA meter.

On the ground the Data Link permits t he accurate display of th e identity, altitude and position of all co-operating aircraf t. It is economical in the use of the ra dio frequency spectrum, is not ambiguous and has a service range to th e li mit of the communications band being used. Its twoway faci lity reduces use of speech and eases th e work- load by eli minating routine reports and messages. With t he Data Link the Air Traffi c Control ler ca n interrogate aircraft in the order he req uires, and he can be sure also that he and the pilot are using the same navigatio nal data .

decca/harco cuts out the guesswork The Decca i\J avigator Compa ny Limited 路 London