IFATCA - The Controller - February 1977

D 21003 F

JOURNAL

OF THE INTERNATIONAL

0,F Al R TRAFFIC

C:ONliROl!LERS

FEDERATION ASSOCIAtlONS

In this Issue: Air Traffic Control In Japan One Language, or more, In ATC? Modernization of FAA's Flight Service Stations

FRANKFURT

AM

MAIN

FEBRUARY

1977

VOLUME

16

NO. 1

STANSAAB - the Swedish data systems company, specializing in modern Air Traffic Control, where high demands are placed not only on systems but equally on controller performance. A modern ATC simulator for controller training is therefore an important part of any advanced ATC programme and consequently a logical product for Stansaab.

- .

• 'C.·

. ·~~~....

The advanced System Simulator for ATS - SATS - installed in Sweden's Air Traffic Services Academy at Sturup, Malmo.

Stansaab's simulator projects: SWEDEN - the Board of Civil Aviation System simulator for Air Traffic Services (SA TS). Most on-the-job training is replaced by realistically simulating the controller environment. Modular system design also permits rapid reconfiguration for investigating future operational system requirements.

- simulator for Swedish Air Force (TAST) provides training facilities for radar trackers, observers, height operators and intercept controllers.

EUROCONTROL - display system for the Experimental Data Processor (EDP) at the Eurocontrol Experimental Centre, Bretigny, France.

FEDERAL REPUBLIC OF GERMANY - simulator for training Approach Controllers and Precision Approach Controllers for the German Air Force.

SOVIET UNION - air traffic control system simulator for Aeroflot, similar to SATS, but with additional facilities.

Stansaab Elektronik AB • Veddestavagen 13 • S-175 62 Jarfiilla • Sweden

IFATCA

JOURNAL

OF

AIR

TRAFFIC

CONTROL

THECONTROllER Frankfurt am Main, February 1977

Volume 16 • No. 1

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

OHlcers ol IFATCA: J-D. Monin, President, 0. H. J6nsson, Vice-President (Technical), H. H. Henschler, Vice-President (Professional), E. Bradshaw, VicePresident (Administration), T. H. Harrison, Executive Secretary, H. Wenger, Treasurer.

Editor: G. J. de Boer, P. 0. B. 8071, Edleen, Kempton Park, Tvl., 1625 South Africa, Telephone: 975-3521 Contributing Editor: V. D. Hopkin (Human Factors) Managing Editor: Horst Guddat, Otto-Bussmann-StraBe 7, D-6368 Bad Vilbel 2, (Federal Republic of Germany).

Telephone: (06193)85299 Publlahlng Company, Production, Subscription Service and Advertising Sales Otllce: Verlag W. Kramer & Co., Bornheimer Landwehr 57 a, 6 Frankfurt am Main 60, Phone 43 4325 and 49 2169, Frankfurter Bank, No. 3-03333-9. Rate Card Nr. 6.

Printed by: W. Kramer & Co., Bornheimer Landwehr 57 a, 6 Frankfurt am Main 60 (Federal Republic of Germany).

Subscription Rate: DM 6.- per annum for members ol IFATCA; OM 10,- per annum for non-members (Postage wil I be charged extra).

Contributors are expressing their personal points ol 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 and opinions expressed, It does only accept responsibility lor publishing these contributions.

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

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

CONTENTS

Air Traffic Control in Japan

6

More about the Use of the Computer as a Teaching Tool for the Training of Student Air Traffic Controllers .

11

SINTEO: A Selective Interrogation

16

System for SSR

The Narrow Margin

19

One Language, or more, in Air Traffic Control?

21

AN/TPN-25 Precision Approach Radar

27

The Last Approach

32

Canada's ATC Simulation

Centre

FAA's Flight Service Stations In Modernization

34 Process .

37

News from IFATCA's Corporate Members

43

Cartoons: Helmut Elsner.

Aircraft

on Stamps

46

Fotos: Archiv, Federal Aviation Administration, Marconi Radar, National Tourist Office Cyprus, Raytheon.

Comments on ATC Topics

47

ACNA - Air Traffic Controllers Association of Morocco .

52

Publications-

53

Advertisers In this Issue: Stansaab (inside cover), International Aeradio Ltd. (page 3), Hollandse Signaalapparaten (page 5), Plessey Radar (page 14/15), Ferranti Digital Systems (page 28/29), CYATCA/IFATCA '77 (page 49), Cyprus Airways (page 51), Racal Thermionic (back cover).

and Record Review

Letter to the Editor

55

IFATCA's Corporate Members

57

__,, __

From The Tower ...

Air Traffic Controllers And General Aviation Traffic One of the main articles in this issue is devoted to the modernization program of flight briefing facilities available to general aviation pilots in the United States, and controllers the world over would do well to ponder the tremendous economic impact which this side of flying produces throughout countries around the globe. Especially since in so many areas, Civil Aviation authorities, incredibly, seem to have little understanding for and spare equally little thought about the importance to their economies which general aviation generates. It is therefore not really surprising that this disregard on the part of their employers influences too many air traffic controllers into thinking that the only traffic of importance they handle is airline traffic, and that general aviation aircraft should take second, third or last place in the airways system or airport traffic zones where they are responsible for the control of air traffic.

Controllers should start getting away from the old worn-out idea that general aviation traffic counts for little, and instead adopt a far more positive attitude towards the problems which this dynamic side of aviation now increasingly faces. National controllers' organizations, and IFATCA as well, should start giving support to those general aviation bodies which are demanding a bigger slice of the airspace cake. We as controllers have no reason to favour airline operators at the expense of other airspace users. At present, we are getting the worst of both worlds, what with a body like IATA, for example, which time and time again shows its disregard and ignorance for the air traffic controllers' legitimate aspirations, and, on the other side of the scale, we have general aviation pilots who - often with justification - believe that controllers do not grasp the economic importance of some of their operations, and consequently incorrectly relegate to second plan their interests.

Let us therefore seek greater contact with business aircraft organizations, and listen far more attentively to their arguments than we have done until now. And, once we appreciate some of their points of view, let us then turn around and start influencing our employers accordingly.

The Value of Regional Co-operation within IFATCA The Federation's five Nordic Member Associations have during the past four years managed to co-operate very closely in matters relating to IFATCA. This co-operation dates back to November 1972 when representatives from Norway, Sweden, Finland and Denmark met in Oslo, and decided to meet regularly twice a year thereafter. In November 1973 Iceland was accepted into the group, and all five countries have since participated in the meetings.

A programme for Nordic co-operation was drawn up in 1973 which outlined the purpose of the programme, namely: to improve aviation safety by exchanging viewpoints from those involved in operational ATS-work; to make the Associations' weight felt with their national authorities, for example through representation on committees, etc.; to strengthen IFATCA policy in the Nordic countries; to strengthen the position of the Nordic Associations within IFATCA, and to make known their common interests to the Federation.

The five Associations try to reach a common standpoint in matters relating to IFATCA. Where such a common standpoint has been achieved, the Associations undertake to sup2

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Fromtake-offto landinghe hasto rely on beacons, communicationscontrol systemsand other navigationalaidsto

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port the line at IFATCA Conferences. Furthermore, they endeavour to establish sub-groups within IFATCA to deal with specific matters, such as was done in the subject of civil/military integration.

There are several reasons why such co-operation proved successful within the Nordic region. Firstly, it has always been a Nordic tradition to cooperate closely in a number of subjects, most of them unrelated to ATC. Secondly, nationals of the five countries involved speak more or less the same language, and thirdly, they have much in common in social standards, education, outlook, etc.

All five IFATCA's Nordic Member Associations firmly believe in the value of their cooperation, and they can thoroughly recommend the idea to other groups within the Federation who may be tempted to follow their example. Hungary and Austria have also established a close relationship within IFATCA.

Farewell Message From The Editor This is my last issue as Editor of "The Controller" as the Executive Board of the Federation late in 1976 decided to accept my resignation. I shall not bore you with farewell phrases, but there is one thing I would like to say before I depart from the IFATCA scene.

During my four years as Editor I have been astonished to notice the still widespread indifference displayed by so many air traffic controllers regarding the obvious and absolute necessity to have a strong voice representing controllers' vital interests at an international level at forums which matter so much to us, i. e. ICAO, ILO, etc. We see the sad spectacle of national organizations of controllers whose activities stop at their national boundaries and who ignore the world beyond. Amazingly, these organizations think that they can achieve meaningful professional recognition for their members without international involvement.

Until they change their attitudes, and until air traffic controllers in general are prepared to make far greater financial and other sacrifices, we shall just not get what we are after.

Finally, to IFATCA members, these parting words: You have a priceless asset in "The Controller", an instrument without parallel in placing the controllers' aspirations in front of those who matter. Make sure you keep it.

,,International Law As It Concerns The Air Traffic Controller" Mr. McCluskey's series on International 1977).

Law will be continued in our next issue (May GdB

IFATCA - Now A Legally Registered Organization The 23rd September 1976 is a significant date in the history of IFATCA as it marks the end of a measure of uncertainty regarding the legal position of the Federation. Following studies and other forms of inquiry since 1967, which resulted in a number of resolutions being accepted (1), the decision was subsequently taken to move the "siege sociale" to Switzerland (Annual Conference 1968, Munich) and to have IFATCA inscribed in the Swiss Commercial Register (Annual Conference 1975, Melbourne), giving the Federation legal Swiss nationality in this way.

After the various problems which come up in such a procedure as a matter of course, had been solved, IFATCA's Standing Committee Ill (Finance) and Standing Committee VII (Legal Matters) have now made it known that the registration of the Federation as an Organization on the basis of its Constitution and in accordance with Swiss Law (2) has been effected. The registration has primarily achieved that IFATCA now has its own moral personality and it clarifies the question of indemnity of the Members, the Executive Board and Officials of the Federation, as well as the liability of the Organization. It can therefore be said that today the Federation stands on a firm legal footing.

(1) "International Law", by E. McCluskey, "The Controller", Nov. 1974; "Study on Indemnity of the Exe• cutive Board of IFATCA", by A. Avgoustis, LLB. and E. McCluskey, IFATCA Working Paper 74. C. 16; "Achievement of the Indemnity of the Executive Board of IFATCA by the Constitution and the Establishment of the Federation on a firm Legal Footing", by E. McCluskey, IFATCA Working Paper 55/'75.

(2) "Swiss Civil Code", Articles 60 et seq.

H.U. Heim, Member SC. Ill and SC. VII.

4

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5

Air Traffic Control in Japan

by Norimoto Nakada

The Organisation The Civil Aviation Bureau of the Japanese Ministry of Transport has the responsibility for two Flight Information Regions, Tokyo- and Naha FIR's. The FIR's are adjacent to six surrounding Regions, namely the Honolulu- und Anchorage FIR's to the east, the Taipei- und Taegu FIR's to the west, the FIR of the USSR to the north and northwest, and the Manila FIR to the south.

Japan has eight international airports, of which Tokyo International and Osaka International are the major centres. In addition, there are 41 other civil and 30 military aerodromes handling IFR traffic. The Civil Aviation Bureau runs four Area Control Centres, eight Terminal Control Areas and 21 Towers for civil traffic. The number of air traffic controllers working at major ATC units is as follows: Tokyo ACC (12 sectors) 309, Fukuoka ACC (3 sectors) 115, Naha ACC (3 sectors) 67 and Sapporo ACC (2 sectors) 47.

At Tokyo Terminal Approach and Tower, there are 100 controllers; at Osaka Terminal Approach and Tower 76; Nagoya Terminal Approach and Tower 57; and at Fukuoka Terminal Approach and Tower 46 controllers are employed.

Air Traffic Control in Japan began when three ex-pilots attended the ATC course at the FAA Academy at Oklahoma City in 1950 and on their return became instructors at the ATC Training College run by the Civil Aviation Bureau.

Since 1954, approximately • 50 university graduates have been recruited every year with the object of staffing the ATC services in Japan which had until then been managed by the United States Air Force. Consequently the transfer of jurisdiction of ATC services within the Tokyo FIR was completed in June 1959. In 1969, the Aeronautical Safety College was established and about 100 junior college graduates for a short term (6 months) course and 40 high school graduates for a two-year course are being trained there every year. In Japan, only male applicants are accepted to the controllers' ranks and they must be of Japanese nationality. (Details of the training at the Aeronautical Safety College were given in the November 1975 issue of "The Controller" - Ed.) The basic hours of duty for shift working controllers are 36½ hours per week; in addition, all controllers are required to put in eight hours of administrative work every week. Each year, 20 days of paid leave are granted. Controllers are paid an extra 8 0/o of their basic salary, and a further supplemental allowance for each working day depending upon the traffic volume or type of facility, is granted (Table 1). Time and a quarter of basic salary for working night shifts, and double time and a quarter for working on national holidays are paid additionally (there are 12 national holidays during the year). A controller employed at an ACC with 15 years of experience and aged 37, for example, receives approximately 3 million yen (US $ 10,000) annually, whereas the general government officer's level is approximately 2.5 million yen annually.

6

Facilities

Licensed Controller

Assistant Controller

ACC Terminal Approach (Tokyo,Osaka,Fukuoka Naha, Nagoya) Terminal Approach (Others) Tower (Major airports) Tower (Others)

510 yens 470 yens

350 yens 350 yens

350 yens

220 yens

350 yens 220 yens

220 yens 200 yens

Table 1: Allowance for ATC Duties. Controllers are paid 8 'lo more

in addition to basic salary, and a further supplementalallowance for each working day depending upon traffic volume or type of facility (US S 1 - 300 yens).

Table 2 gives an idea of the traffic volume at a number of airports, and the traffic handled by the four Area Control Centres during a given year. For Tokyo and Osaka International Airports, the Japanese Government has put the ceiling at 460 operations a day since 1970. Airlines serving these airports, of course, are pressing for the cancellation of the ceiling. But considered from an air safety point of view, taking airspace structures, runway/taxiway layout and conditions, radars and other equipment and restrictions imposed due to noise problems into consideration, controllers would like to see this level maintained at least for the time being.

Airport

Tokyo lnt'I Osaka lnt'I Nagoya Sendai Yao Miyazaki Kumamoto Hiroshima Takamatsu Kagoshima Obihiro Fukuoka Naha Nagasaki Chofu

Name of Facility

IFR

VFR

Total

164,189 "141,029 32,329 11,418 2,645 30,753 17,936 12,351 11,917 34,088 2,358 59,356 46,761 10,029

6,502 3,501 60,213 42,760 65,547 41,927 44,568 15,921 7,598 8,811 32,869 7,179 42,378 17,566 34,831

170,691 144,530 92,542 54,178 68,192 72,680 62,504 28,272 19,515 42,899 35,227 66,535 89,139 27,595 34,831

Traffic Amount

Tokyo ACC Fukuoka ACC Sapporo ACC Naha ACC Table 2: Airport- and EnrouteTraffic Movements(1974).

406,015 231,774 84,056 71,224

The Association Since its foundation in 1962, the Japanese Air Traffic Controllers' Association has steadily increased its membership. From a total approximately 1,200 civil controllers, 88 0/o are members of the Association. Although its activities are more technical rather than professional, the Association's aims and objectives are mostly similar to those of IFATCA. The aims and objectives are: 1) To promote and uphold a high standard of knowledge and professional efficiency among controllers.

2) To assist and advise the flying public in the development of a safe and efficient system for civil aviation.

3) To promote mutual benefit and friendship with each member of the Association and also related agencies.

In order to promote and maintain close contact between all members, the Association publishes an official journal "Koku-Kansei" ("Journal of ATC") bimonthly, which is highly regarded by people inside and outside the Association. Continuous and close contact with ALPA-Japan has been established and a joint meeting is under conside• ration to be held annually to discuss and solve problems which exist in Japanese aviation in the professional and technical environments.

The President of the Association is Mr. Tan Hayashi, and the management is the responsibility of a number of directors. Mr. K. Tasaka is Secretary-General. Japanese controllers are active sportsmen, and the most popular sports are tennis, skiing and mahjong.

Noise Abatement Noise abatement is taken very seriously in Japan, and controllers are constantly called upon to incorporate noise abatement procedures in their operational clearances.

Osaka International gives the most serious problems regarding aircraft noise, as the airport is surrounded by dense housing areas. The following anti-noise measures have been taken: 1) Noise Protection Shelters: Since some dwellers live close to the taxiway for runway 32L, shelter banks or walls are provided to protect them from aircraft noise. Also for other housing areas, noise protection fences or shelter belts have been completed.

2) Replacement of High-Noise Aircraft by Low-Noise Jets: Noisy CV880's have been replaced by other types of aircraft. Although B747, L 101 and DC10 jets are equipped with lower noise engines, city authorities do not favour the operation of Jumbo type jets into airports serving their communities.

3) Curfews: In 1965, it was found necessary to introduce curfews at Osaka lnt'I, and in 1970 the following classification was laid down as determined by the noise intensity: Intensities of Noise

Hours

6:30 7:00 20:00 20 :00 22:30 -

7:00 20:00 22:30 22 :30 6:30

100 phon 107 (depart) 100 (landing) 107 75

Table 3: Intensities of Noise. Intensities of noise are observed at a point 1.5 miles from the end of the runway. The restrictions mean that jet operations at night are prohibited between 22:30 and 07:00.

Mr. Tan Hayashi, President of the Japanese Air Traffic Controllers' Association

4) "Rolling Take-Off": For the purpose of reducing the effect of aircraft noise to dwellers nearby, "rolling take-offs" are demanded of pilots.

5) Steepest Climb: Steepest climb is executed voluntarily by airline pilots.

Automation The ATC automation programme in Japan is progressing steadily in three defined steps, in the following manner: Step

Type of ATC

Development

First step

Procedural

Second step

Radar

Third step

Combination of Procedu· ral/Radar

Manual to Flight Data Processing (Phase I) (FOP) Radar to Radar Data Processing (Phase II) (RDP) Combination of FDP/RDP (Data (Future) Links)

Feature

Strategic Control Tactical Control Combination of Strategic and Tactical Control

Table 4: Planned ATC System Development.

It all started as the result of an analysis into the desirability to relieve controllers from routine and time consuming clerical duties. A specification was developed for a Flight Data Processing System (Phase I), and in 1965 Nippon Electric Company Limited (NEC) was awarded a $ 3.3 million contract to manufacture the system. The first FOP system was installed in Tokyo ACC and went into operation in 1970. It has been running 24 hours a day, 7 days a week. For the next step (Phase II), the Civil Aviation Bureau contracted the Nippon Telephone and Telegraph Corporation in 1973 for the installation at all four ACC's of the Radar Data Processing System, to be completed in 1977.

7

The new Tokyo ACC Building, to be opened in February 1977

As part of Phase II also, the installation of a new updated Flight Data Processing System by Nippon Electric Co. was taken in hand with the expected completion date any day from now. These two systems will be functionally combined and they will strengthen the inter and intra-facilities co-ordination between the Area Control Centres of Sapporo, Tokyo, Fukuoka and Naha and the major Terminal Control systems (the ARTS-J at Tokyo and Osaka International).

The first FOP system has been applied to enroute Air Traffic Control for real-time preparation of flight progress strips and the display of related updated flight information.

It automatically accepts online input of flight plan information over teletype lines. The central processing units (CPU's) and all other equipment are fully duplicated, and synchronised processing ensures fail-safe operation. For real-time processing of numerous entries of flight plan data at peak hours, the system is designed to respond in less than 3 seconds on 95 per cent of all input.

The system stores data such as control maps, airports, departure routes, airways, jet routes, fixes, wind information or control release points to Terminal Area Control, etc., for flight plan processing. A flight.plan is analysed and stored in a drum storage as the data base with an estimated time of passing over each reporting point; this time is determined by taking into consideration such factors as climb rate, climb speed, wind effect, and so on.

A departure flight progress strip is provided to the departure control sector, and when its departure time is entered, appropriate flight progress strips are printed out at the control sectors which have jurisdiction over the flight route concerned. The system can accept various input information from a control position by using a keypack/CRT entry device or a printer/keyboard to update the stored flight data. About 20 updated messages are prepared for altitude, route, revision of estimated time of arrival, and some query formats are also in use.

Most of the updated messages are displayed on a CRT at the control sector concerned. The process of analysis and updated data for each flight are stored in disc storage as the system recovery data in case of a system failure and are also recorded on a magnetic tape for a statistical analysis. If he wants to, the controller can get any flight data, upper wind data or a detailed description of the departure route of a flight, by using a keyboard or keypack entry devices. The system covers the whole area controlled

by Tokyo ACC, but when the new FOP system has been 8

taken into use, coverage will have been extended to cover the Control Areas of all four ACC's.

Terminal Area Automation Japan's Civil Aviation Bureau has adopted U.S. made automated radar systems at Tokyo International Airport and Osaka International Airport. The system called ARTS-J is basically the same as the ARTS Ill used at the major terminals in the United States, but the radar sources (primary and secondary) and digitizers are manufactured in Japan.

At Tokyo International, the system has been operational since March 15, 1976. Both the hardware and the improved ATC procedures based on the automated system have established a fairly good reputation among controllers and pilots.

Outline of the New Updated FDP System The new updated FOP triplex CPU system is being installed in the new Tokyo ACC building located 20 miles north-west of Tokyo. This system adopted a concept of centralised data base host processing; the hardware complex is composed of three central processing units with each having 1 mega bites core storage and the related communication control equipments. Any two units of CPU's can be selected for dual online operation and the other is a standby in case of unit failure, program tests, training or system evaluation with new terminal devices. In the other ACC's, satellite communication progressing computers, connected by a 2400 bps data transmission circuit to CPU, handle ATS messages between FOP and input/output devices in these ACC's. FOP input/output devices at each control position are flight progress strip printers and CRTs with entry keyboards.

The main functions of the new FOP system in the dissemination of flight plan data to the RDP system in the four ACC's, the ARTS-J systems at the Tokyo and Osaka TMA's, the Aeronautical Data Processing System for the Flight Information Service, and the Air Defence Facilities, are: 1) IFR flight plans related to the four ACC's will be sent to CPU by flight strip printer keyboards.

2) Updating of related flight data by entry of departure time, altitude change, route change or other messages.

These messages are displayed on CRTs at each control position concerned.

200-miles bright display analogue raw video radar used at Japanese ACC's

3) Flight departure strips are printed at each control position of the ACC's concerned by flight strip printers.

4) Supplying flight data with assigned discrete beacon codes for RDP's in the four ACC's.

5) Supplying flight data with assigned beacon codes for ARTS-J in the major terminals.

6) Print out of the enroute flight progress strips at each control position in the ACC's concerned.

7) Recording of all flight data for statistical purposes.

The flight progress strips and transfer messages are automatically received over a 2400 bps data line in the adjacent ACC well before the flight reaches the control boundary. The flight progress reports or updated messages are also displayed on the CRT for controllers in the adjacent ACC which reduces telephone co-ordination between controllers. An assigned discrete beacon code for an individual flight and necessary data are provided by FOP to the Enroute and Terminal Radar Data Processing System for radar and flight data correlation.

Outline of the Radar Data Processing System The whole airspace over Japan above 15,000 feet MSL is being covered by eight long-range Air Route Surveillance Radars. Two ARSR's are located in the Tokyo ACC area, one in the Fukuoka and one in the Naha ACC area. Before the end of 1976, four more ARSR's were added to the operation of radar data processing. Normal primary and secondary radar video signals are extracted and provided to the digitiser at the radar broadband microwave receiver site. Noises are automatically eliminated and detected targets are classified as primary, secondary, or both correlated. Mode C height information, identity code or emergency transponder replies are also detected. Those digital secondary target data are transmitted to the ACC's by the 4800 bps dual data communication circuits.

Radar data processing is performed at each ACC by the RDP system, each system comprising the radar data extractor at the receiver site, tracking control unit, central processing unit, and Plan View Display with a display control unit. The system is duplicated for fail-safe operation except the display subsystem with one hot spare unit to five for a fail-soft mode. A pair of tracking control units are used for each radar site. This unit converts aircraft position from polar to Cartesian coordinates. Secondary radar data are

automatically tracked and smoothed by tracking logics and passed into CPU. Primary radar data without correlation of secondary data are not tracked but fed into CPU to be displayed as untracked targets.

The pair of CPU's in each ACC receives flight plan data from FOP, correlates it with radar data and passes display information onto the display control unit. Hand-off data between sectors or to other facilities are also exchanged through CPU's, as well as the supply of system status messages to the system monitor and the recording of data for statistical purposes. The display control unit will keep display images of the plan view display, control entry devices, and select display data such as target labels of flight lists.

The Raytheon 22 inch Plan View Display, installed at each control sector, enables the controllers to select either one of three categories of display mode, that is TV mode for raw target video display, full digital mode for all alpha-numeric display and mix mode for raw radar and digital data display. Alpha-numeric data are fed to the Plan View Display through the digitiser, tracking control unit, CPU and display control unit. On the other side raw target videos are sent into displays through a 48 KHZ narrow band bypass channel independently of the digital channel.

The Plan View Display presents an aircraft target or symbol with an alpha-numeric label for each tracked aircraft, including aircraft identification, altitude derived from Mode C response, assigned altitude or velocity vector. Also a departure list, arrival list, altimeter and the list of coasting or suspended tracks are presented.

The future will see the separately developed FOP and RDP systems more closely connected within a one-machine concept in the A TC loop of man-machine-aircraft.

Flight planning or strategic data and situational or tactical data will be combined and shown to the controller on a pictorial display in order to provide a more safe and more efficient Air Traffic Control system.

Zen-Unyu and JATCC It may be of interest to IFATCA members to hear a brief outline of the relationship between the controllers' Association and their Union.

Zen-Unyu stands for "The Ministry of Transport Workers' Union". This organisation was formed in 1962 with the aim of improving working conditions, the economic,

9

-----------

-

Partial view of the present FDP system.

In front, the Operation Console; to the left, the System Status Display

political, social and cultural status of its members, and promoting democracy in the government service. Zen-Unyu has been certified as the exclusive bargaining agent since its foundation. At present, it has 10,000 members, including practically all air traffic controllers, with the exception of a very few who are not qualified to join as yet.

The aims and objectives of Zen-Unyu are: to plan the Union's activities and their enforcement; to collect information for investigation and to publicize the Union's activities in general: to promote the educational as well as the cultural status of its members: to enlarge and facilitate mutual aid programmes and the well-fare of the members; to investigate, study and publicize matters concerning the democratisation of the administration: to strengthen cooperation with other friendly organisations.

Zen-Unyu has achieved great achievements in its various fields of operation. For air traffic controllers, the following benefits were obtained: an 8 per cent Air Traffic Control special allowance to the basic salary has been granted; the Union has achieved a 36 hour working-week for controllers; Zen-Unyu has done its best to support those controllers who have been involved in aircraft accidents (one oc-

curred in 1960 on the runway at Nagoya Airport, and another in 1970, on the runway at Tokyo International Airport).

Zen-Unyu consists of several specialized divisions. They are Land Division, Maritime Division, Aeronautical Division, and Research and Institute Division. Each has its own committees. The Aeronautical Division has also a number of committees, such as the Committee for Pilots, the Committee for Radar and Radio Maintenance Personnel, the Committee for Air Traffic Controllers, etc.

JATCC stands for "The Committee for ATC", representing the 1200 members of the Japanese Controllers' Association. JATCC works out draft proposals on future operational activities and submits them to the Central Committee of Zen-Unyu for follow-up action. The Committee aims: to improve the working conditions of air traffic controllers: to promote the social as well as the economic status of air traffic controllers; to assist and advise in the development of safe and orderly systems of Air Traffic Control; to make suggestions for better government understanding for the needs of air traffic controllers; and to cooperate with international organisations whose aims and objectives are similar to those of JATCC.

The Operation Console in the FOP Room, with an operator making a command entry into the system

10

More About The Use Of The Computer As A Teaching Tool For The Training Of Student Air Traffic Controllers*

by G. E. Krug, Director, Eurocontrol Institute of Air Navigation Services, Luxembourg

For a multiplicity of reasons, nowadays there is no obvious solution in every case to the problem of adapting teaching methods to the requirements of modern life, and this is especially true of professional training, which must keep pace with technical developments if it is to be of real use to trainees. The training of air traffic controllers is no exception to the general rule, particularly since the introduction of automation at control centres is bringing about far-reaching changes in the tools and working methods used, changes which themselves are far from completely stabilised.

The various A.T.C. schools and training centres have had to find the ways and means best suited to the purpose of such training. In this context, it was felt that the simulation method, already used to achieve the greatest possible realism in teaching Air Traffic Control methods and procedures, could be rendered more efficient by the use of computer units specially adapted to air traffic simulation. The Eurocontrol Institute of Air Navigation Services has therefore been equipped with a digital simulator known as "INSTILUX", which Is its principal working tool for instructing trainees in A.T.C. methods and procedures.

The "INSTILUX" Simulator and its Use as a Teaching Tool Since the simulation facilities were installed, the lnstitute·s major concern has been to seek to make optimum use of the tool thus provided, firstly to satisfy the trainee's actual needs through the instruction provided, and secondly to discover a truly educational use for the tool's available potential. In pursuing these two objectives, the Institute has had occasion to consider in depth the scope of the conversational facilities which air traffic simulators generally possess.

The last phase of the trainee-controller's course is devoted to practical training in control methods and procedures so that the in-service training can be carried out under optimum conditions in the shortest possible time.

For this phase of the training, working conditions must be provided resembling as closely as possible those which the trainee will find in his future control centre. Such an approach implies simulation exercises with a very high degree of realism - which is possible only with the help of computer facilities having display and input/output devices and a major programming effort.

The Institute has therefore endeavoured to equip control positions with facilities for valid simulation of the conversational mode used at automated centres. For this reason simulation programs have been developed to reproduce the major functions of the automated systems now in use, and to provide displays on panoramic and tabular screens combined with the use of computer input keyboards, in particular touch-wire keyboards.

Although simulation exercises which reproduce nearreal situations are certainly essential during the final phase of the trainee-controller's course, this type of simulation is generally acknowledged to have the drawbacks inherent in its merits, in other words, realism and freedom of manoeuvre, although desirable, have certain disadvantages such as:

• This article, first published in the Eurocontrol Review and translated from the French, goes more deeply into the use of the computer as a teaching tool than the brief mention given in the article describing the Eurocontrol Institute of Air Navigation Services, which was published in our August 1975 issue.

the need, during the simulation exercises, which are all equally complex, for a large number of staff, many of whom will be responsible solely for simulating the pilots of the aircraft reproduced in the system; the difficulty of constantly monitoring and analysing trainees' individual reactions in the different control situations simulated.

It was therefore found necessary, from the teaching point of view, to examine the possibility of using the conversational facilities of the simulator more effectively in order to achieve simulations having the following main features: scope for each trainee to work as far as possible at his own pace and according to his own requirements; means of compelling the trainee to make a systematic study of the problems set; ability to react immediately to each trainee's response so that the teaching could keep in step with the individual's progress; facilities for playing back- each trainee's exercises, and also for the individual and overall analysis of results to detect errors and consequently make the necessary corrections to the teaching method.

Such simulations, which may be called analytical, in conjunction with the composite simulations, can provide practical training for trainee-controllers well adapted to actual requirements and more consistent from the teaching point of view. Such arrangements should normally achieve better use of the potentialities of the digital-type simulation units by making all the working positions, including the pilot positions, available to the trainees during the analytical simulations.

The Approach Adopted by the Institute With a View to Optimising the Use of the "INSTILUX" 's Conversational Facilities Given the general principles, the next step is to consider the practical approach adopted by the Institute in dealing with the problem as a whole. The first point to be noted is that the conversational tool described below is a byproduct of the programming work carried out to integrate the tabular screens (EDD) and the touch-wire keyboards (TID) in simulation work.

11

"E X E R C I SE 1Alf).<;J?)s1JAI

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The conversational facilities currently available are elementary, and consist mainly of a date display in tabular form associated with an EDD/TIO touch input device. A master program (known as TOUCHY) has been developed on the basis of this tool. In very broad outline, the external process is as follows. In the case of each constituent TIO display key, the entire EDD/TIO display presented after selection of that key can be defined by program. In this way all possible sequences can be determined from an initial display, each step leading to a new overall display comprising tabular data (EDD part) and possibilities of switching over to the subsequent displays (TIO part). In addition to this main program there are supplementary programs consisting essentially of a "display assembler" whereby the entire structure and contents of each constituent (EDD/TIO) display can be defined externally in plain language, and in a simple manner.

points and determining, for each of these output points, the following constituent EDD/TIO display; this definition will be made by using the "TIO" part (Table I).

Although the preparation program is one of the major elements in the range of possibilities that a system of this type must offer, provision must also be made for recording of exercises in order to be able to develop the analysis programs which may be considered necessary. Moreover, the ability to show each trainee a faithful image of his work in printed form is an attr,active feature which should help to achieve the teaching aim of each exercise in a manner adapted to each trainee.

Extracts from one of the first exercises used to supplement conventional teaching methods are given below. This is basically a multiple-choice test (Table II).

It is of paramount importance to enable the instructor to define his exercises in plain language with no other constraint than that inherent in the example to be worked. The type of preparation form used for the definition of an exercise is shown by way of example. Each form relates to a constituent (EDD/TIO) display and, without any further analysis of the form, it can readily be seen that the instructor is able to define, for each sequence of his program: the information he wishes to present and the form in which this information will appear. This definition will be given in plain language in the "MESSAGE" field, which corresponds to the grid used on the screen to display the data;

The Institute has available, thanks to its digital simulator, conversational facilities comprising 12 working positions in all, each equipped with an EDD/TIO unit (which can be used for dialogues between the trainee and the computer). A problem still to be considered from the technical and teaching point of view is the integration of the panoramic screens (known as SOD) available at each working position in the conversational unit for the purpose of combining the dynamic component, which is provided essentially by the movement of traffic on the panoramic screens, with the analytical component, which can be obtained, as previously stated, by the combined use of tabular screens (EDD) and keyboards (TIO).

At all events, this article has endeavoured to show that the problem of using conversational facilities and their

the output possibilities sequence, by labelling 12

to choose from in the current each of the possible 20 output

Prospects

6, )

WHATIS THE MINIMUMHEIGHT A PILOT MAYFLY OVER THE SEA-,-, -A-

150 METRES

-E:-

150 FEET

-C-

500 METRES

-D- THERE IS NO MINIMUMHEIGHT LAID DOWN 'TW-SET 4 'U-PROGf,AMRECORD 'BRANCH 10 "IF 9 'SCORE 2 'FRAME 10 'MESSAGE 10 7, ) WHEN2 AIRCRAFT Af,E APPROACHINGHEAD-ONAND THERE IS A DANGEROF COLLISION WHATACTION SHOULDBf. TAKEN??

-A- THE FASTER AIRCRAFT SHOULDGIVE WAY. -E:- E:OTHAIRCRAFT SHOULDALTER HEADINGTO THE LEFT, -C- THE AIRCRAFT ON A WESTERLYHEADINGSHOULDLOSE HEIGHT ANO FLY UNDERTHE OTHER. -0- BOTH AIRCRAFT SHALL ALTERHEADINGTO THE RIGHT, 'TW-SET 3 "01 -A- A '02 -E:- A '03 -C- A "04

-D-

A

'U-PROGRAMRECORD "BRANCH11 'IF 4 "SCORE 2 "FRAME11 'MESSAGE 11 Table II

integration in the practical training course for trainee controllers should be examined more thoroughly, since it is highly likely that in this way the training could be made more effective.

The Institute has had the opportunity of discussing this matter with the French authorities, and in particular with experts from the Ecole Nationale de !'Aviation Civile, and has noted their special interest in developing teaching facilities and methods for the practical training of controllers. Accordingly, though the lnstitute's experience is still limited, it might serve as a basis for joint study of the problem and lead to the generalised use of simulators not only to simulate air traffic but also as effective training aids.

Postscript by the Author Since the publication of this article in the Eurocontrol Review, two important steps forward have been made by the Institute in the use of conversational facilities offered by computerised ATC systems: The first concerns the integration of the panoramic screens, known as "SOD" (Synthetic dynamic displays) into the conversational system of the INSTILUX Simulator. This step has been achieved with the support of the French authorities who have entrusted the Institute with a study carried out by a group of Institute and French staff members in the framework of a longer-term post-graduate training for two engineers on detachment from the Ecole Nationale de !'Aviation Civile at Toulouse (the French Civil Aviation Academy) to the Institute. Although the first results of the integration of the SOD with the data appearing on the EDD are promising, it is obvious that there is still a long way to go before a full use may be made of the SOD in this conversational capacity.

The second equally important step concerns the awareness by all concerned of the "documentary support function" which a conversational system could provide to the operational controller in a real-time ATC system configuration. It is obvious that much background data relating to airspace organisation, geographical and meteorological

conditions, local procedures, typical flight pattern of the traffic operating in the area of a given centre or in a sector of that centre, etc., and which are stored and updated in the centre's computerised data bank could be made accessible to the controller via conversational facilities for his recollection, memory up-dating, familiarisation and training.

Let us for example take the case of a controller newly assigned to a given sector or a student controller assigned to a given position for OJT. With the help of an off-line conversational link they could familiarise or train themselves on their area or sector by assimilating individually all related data and procedures without absorbing time of their supervisors, colleagues or training officers, in direct connection with their control duties or even during the execution of such duties in times of reduced traffic density.

In the same order of ideas but facing much higher degrees of complexity, a real-time on-line use of such conversational facilities could be envisaged. Let us think of the controller's call for met data, danger areas or special other restrictions related to a specific trajectory which could be added or suppressed from the Display through conversational facilities.

In both cases the conversational system would act as an external memory of the controller and in later stages of development, it could even be extended to include automatic reminder and tell-back functions. All these ideas need however to be studied in much greater depth, particularly in order to define the transition line between on-line and off-line functions and the conditions under which online functions could best be integrated into the existing system configuration.

The technical evolution in computerisation, particularly the development of mini-computers and of the display techniques, makes the use of conversational systems in Automatic Data Processing technically more and more feasible.

The real difficulty which has still to be overcome in this context is the proper definition of the tool called "conversational system". As the problems inherent in the use of computerised systems for such purposes are the same irrespective of the individual system configuration, it seems only natural that efforts should be pooled to find practicable solutions. Their application must be made contingent upon careful studies undertaken by the interested parties on the basis of commonly agreed principles.

The Institute is aware that its own efforts in the use of conversational facilities in computerised ATC systems constitute only an initial endeavour towards a realistic solution.

These efforts are not more than an opening in this vast field of pedagogical and operational applications of computerisation in ATC, but the Institute believes that the experience gained so far, although still very limited, may nevertheless pave the way for more widely accepted solutions. Its special recognition is expressed to the French authorities for their active support in this joint first step.

Sitting one day at a quiet Sector, I inadvertently put my foot on the floor mike switch, and sat happily singing to myself. As I removed my foot to move to a more comfortable position, a TWA Captain asked over the frequency, "Say can you whistle because you sure as Hell can't sing." But then came a second voice, saying: "Disregard, Moncion, that was only the Captain and he's been bitchy all the way over on this crossing." {CATCA Newsletter)

13

Your ups anddowns areour business Plesseyintegrateddisplaysystems,data processingtechniques, primary and secondary surveillanceradars, instrument landingsystemsand navigationalaidsall contribute to smoothingoutthe upsanddownsof the ATC business.

New facilities,such as automatedtarget labelling,are giving the controller the information he needsin clear uncluttered form so that his decisionmakingis madethat little bit easier.

That's what we call progress.

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Airtrafficcontrollers aroundthe worldrelyonPlesseyRadar for the mostinformativedisplays ~603P229

SINTEQ: A Selective Interrogation System For SSR

by H. W. Cole, Marconi Radar Systems Limited

Introduction

The Evolution of SINTEQ

The !CAO specified SSR system uses a common frequency for the ground-to-air path (1030 MHz) and a separate common frequency for the air-to-ground path (1090 MHz).

The purpose of this arrangement is to enable the system to be used anywhere in the world with the minimum of frequency adjustment. Aircraft transponders have an omnidirectional antenna and ground interrogator antennas carry interrogations not only in their main beam but in their sidelobes also. Broadcast replies from aircraft replying to one interrogator can be received by other responsers via the ground station antennas sidelobes. These two systematic drawbacks have been overcome by use of Interrogation Sidelobe Suppression and Defruiting techniques.

The existing SSR system is capable of conferring unique identity upon 4093 individual aircraft in a service area (4096 less 3 codes reserved for Emergency/Comms Failure/Hijack). The data selection capability of the SSR decoding system is such as will isolate all, some, or any one of these unique individuals if within the interrogator's range. One sweep of the interrogator's antenna through 360° is enough to establish range, bearing and identity of all aircraft within the system's radar cover. All that is required is to remember these data and subsequently interrogate only when the antenna beam is pointing at the required aircraft.

A system operating in this way produces all that ADSEL and DABS attempts to do by way of great reduction in interrogations, suppressions and fruit. Early last year a patent was granted covering the invention of a new system named SINTEQ (Selective INTerrogation EQuipment), using the above principle, which trials have shown to be effective.

When a transponder receives signals resulting in "Suppression of Reply", the transponder is inhibited for a specific period. When transponders are replying to one interrogation they are also inhibited from receiving other requests to reply - thus there are two sources of generation of system dead-time. In order to prevent transponder output stages from overload, de-sensitization of transponder receivers takes place at a specified interrogation rate. Although this latter characteristic does not create deadtime, it effectively denies service to interrogators at the longer ranges.

In areas of high interrogation density the combined effect of these factors can create situations where SSR tracking is made difficult and sometimes impossible so it was for this reason that means of reducing the system load were sought some years ago. The ICAO specification has already paid subscription to ttle need to reduce interrogation density by recommending reduction of interrogation power wherever possible and setting a limit to interrogation rate. In the United Kingdom a special IFF/SSR Joint Users Committee was set up in an attempt to prevent unnecessary proliferation of interrogators as a means of stemming the growth of the problem.

Recent developments and proposals (ADSEL in the U. K. and DABS in the U.S.A.) attempt to get at the root of the problem by fairly radical changes to the existing SSR system. The principle of both ADSEL and DABS is that aircraft transponders are modified to include circuits which would recognize a coded address sent from ground-to-air.

Arrangements are also made to interrogate only in the direction of selected aircraft. Only those aircraft carrying the correct address would reply so causing a great reduction in interrogations and replies to be achieved provided: a) aircraft transponders are fitted with ancillary circuits to recognize codified addresses in the interrogation pattern; b) the general position known;

of aircraft

required

to reply is

c) either ADSEL or DABS systems can be made compatible with existing SSR ground and air equipments and their signal characteristics.

16

The SINTEQ System General • SINTEQ breaks the service area into contiguous cells the trials equipment used approximately 6000 cells, each of 5.6° by 2 nautical miles dimension. These values were used only for convenience and, as will be appreciated later, are not optimum. Range and azimuth counters, running in real time, allow each of 6000 store locations to be set with a 'O' or a '1 '. A cell would be set if it corresponded to the time at which an aircraft signal is present. The pattern of set cells are fixed for one antenna revolution. It is thus possible to use the store contents as a source of gating signals for the interrogator trigger. Thus the interrogator is silent except over those azimuths representing the beginning and end of 5.6° sectors. Not only is the interrogator silent but also the responser output is inhibited due to the absence of receiver gating. This has two effects: a) to remove all fruit except during interrogator 'on' time; b) to allow this 'on' time to be further reduced by excluding outputs outside the range increments containing wanted replies.

Start-up In order to locate aircraft and decide in which cells they are located, it is necessary (as with ADSEL and DABS) to execute continuous interrogations for effectively one revolution and to repeat this broadcast at regular but infrequent intervals to gather new targets. This broadcast is effected by inhibiting the SINTEQ for one octant at each revolution of the antenna, so reverting to normal continuous operation and allowing this octant to precess. Thus a complete 360° update covering all aircraft occurs every eight antenna revolutions. Alternative arrangements are easily possible, for example, SINTEQ could be inhibited over specified arcs to allow special corridors of interest to be

served normally at every antenna revolution. Alternatively, an arc could be totally unserved by interrogation, if desired.

An 'operator over-ride' facility is provided so that in times of emergency normal transmissions can be made.

Azimuth

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--

oO,60, oO, oO,

' O Stop

6rn+ 1,rn+ 1111111!1

Keeping Track of Targets

\

Arrangements must be made to counter the possibility of targets not being in the same cell for successive revolutions of the antenna and these arrangements are best understood by way of example: Consider the system from start-up and that 'all aircraft' are required as targets.

Initially, SINTEQ will inhibit trigger to the interrogator until the antenna reaches North. It then will start its first broadcast octant and those aircraft replying will cause bracket pulse decoded video to be passed both to the PPI and to the SINTEQ. The normal run length of replies is in the range 10 to 20 per system beamwidth. For a cell to be declared occupied, a certain minimum number of replies must be found within the cell's boundaries, typical values being in the range 5 to B. Replies received in the first octant will cause cells to be set wherever the minimum criterion has been met. Arrangements are made for immediate neighbouring cells to be set as well, so that on the subsequent antenna revolution interrogation will be made over an arc wide enough to ensure that target movement is catered for. At the next antenna revolution, the second octant will allow broadcast interrogation only over the area dictated by the stored cells and their immediate neighbours. This process continues until the eighth antenna revolution by which time interrogations will be made in the full 360° only when necessary, i. e. when the antenne is in the azimuth region of aircraft.

The system is now reacting to 'all aircraft'; of these consider only a few are of interest. These aircraft can be selected in a manual system by passive decoding filters and thus produce output pulses only from the selected aircraft. If only these pulses are fed to the SINTEQ, only these aircraft locations will be stored and other aircraft previously replying will drop out of the system within one revolution because no video pulses from them will go into store for retention.

1 0 Start

"• om+ orn

Range

'I

2nml

s.s· Approximately 7 s1rikes for 'cell occupied'

Occupation stored for 1 antenna rev.

OFF----~---· Cells examined in real time In range and azimuth order.

'Sc-t' cells generate azimuth gate of SSA i/p triggers.

Note: Aesponser gating inhibits output of replies in absence of i/p triggers.

Fig. 2 Cell structure in SINTEO trials

very simply as a series element into an existing ICAO standard interrogator-responser system using manual decoding equipment. The trials equipment had only a limited number of store locations, each cell fixed at 5.6° by two nautical miles. These proportions are wrong for optimum use and it is likely that the best values are half this azimuth and twice the range dimensions, i. e. 2.8° by four nautical miles.

The trials equipment was arranged so that only the neighbour cell in the direction of rotation of the antenna was set. This demonstrated that: a) The 'neighbour set' logic is necessary; b) When the logic is implemented it works.

The cell structure and other relevant data on the SINTEQ trial equipment is shown in figure 2 and the general level of traffic in the 160 nautical miles displayed area of the test site is shown in figure 3. The photograph was taken by exposing the film for about 10 successive revolutions.

Three different types of signal can be seen and are identified as: a) Fine dots from zero to maximum range over discrete arcs. These are bracket pulse decoded fruit outputs from the system, from which the defruiter had been removed. b) Bracket pulse decoded aircraft replies of beamwidth approximately 2.25°. These are registered as 'high white' on the film.

SINTEQ Trials An experimental SINTEQ has been built and successfully evaluated and figure 1 shows how it was introduced r-

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Fig. 1 Showing SINTEO Trials Arrangement

'Set' Threshold

Figure 3

17

Figure 4

Figures

c) Underlying the aircraft signals are arcs indicating the cells which have been set. They were produced by modulating a video oscillator by the gating waveform called out from the SINTEQ store and thus describe the arcs over which the interrogator was triggered.

Figure 4 illustrates the need to set neighbour cells. A trials aircraft fitted with a standard ICAO transponder was allocated a unique code by arrangement with the British Civil Aviation Authority (A5567) and directed to fly radially to the south east. The range rings are at five nautical mile intervals with ten nautical mile rings emphasized. The film was exposed continuously for about 40 or 50 revolutions.

The radial track was established and maintained without loss. At about twelve nautical miles the aircraft was instructed to fly in a westerly direction, i. e. against the rotation of the antenna. As only the neighbour cell in the direction of rotation was set, together with that containing the aircraft it was possible for the aircraft to escape cover. This loss of target continued until the updating octant covered the aircraft. This loss and recapture can be seen repeated a number of times. The photograph also examples very well the cell structure.

A common effect in SSR is the receipt of replies via reflecting surfaces near the interrogator. At the MRSL trials site at Rivenhall in Essex, there was a large hangar presenting just such a surface, producing replies by reflection from the trials aircraft. The reflected reply's track can be seen to the south running south east from about 13 nautical miles. Since the system was set up to react to code A5567 and the reflected reply had this code, naturally the SINTEQ treated the reflection as a wanted target. Due to the geometry of the target/antenna/reflecting surface the 'ghost' target apparently moved in the direction of rotation of the antenna. Therefore it was covered by the neighbour cell indicated in figure 2 and could not escape coverage as could the real aircraft.

It should be noted that a modified SINTEQ properly used in conjunction with a rudimentary tracking system, could be used to inhibit reflections if unique codes were ascribed to aircraft.

Figure 5 shows three selected targets, one of which was the trials aircraft. The film was exposed for approximately

16 revolutions. The target to the north east carried code A5513 and was initiated at 30 nautical miles and was travelling south. The target to the east, initiated at 32 nautical miles carried code A1143. This was airways traffic following Red One to the east. The target to the south was the trials aircraft initiated on its final approach to the airfield at Southend in Essex (the centre of the video map circle due south at 18 nautical miles). The track length differences express the different airspeeds of the targets.

18

Figure 6 shows the same display (40 nautical miles range) a few antenna revolutions later than shown in figure 5 but using 'all aircraft' bracket pulse decoded input to SINTEQ. This shows the first two targets mentioned above (A5513 and A1143) further into their tracks with A1143 just visible at the tube edge due east but the trials aircraft had just landed and so disappeared from radar cover. From this example can be judged the reduction achieved in interrogation density relative to a normal 'broadcast' interrogation system.

Other Useful Features The trials equipment was constructed to demonstrate that the basic idea behind the system is practicable and this it obviously has done. Other features in the developed design can enhance the value of SINTEQ in alleviating the SSR's problems. Among these are the ability to use simple logic which derives a signal the d. c. of which is proportional to range. This d. c. signal could be used to set the value of an r. f. attenuator between the interrogator-responser and the antenna (i. e. between X and Yin figure 1). This enables just enough power to be radiated to serve the target at the greatest range on any arc requiring interrogation.

Suppose a group of aircraft were on one bearing to be served by the interrogator and the range of the furthest was 80 nautical miles. Suppose also that there were other aircraft able to be interrogated and even more in the surrounding area to be suppressed. By reducing the r. f. power, both unwanted interrogations and requests to suppress would be reduced with a consequent reduction in deadtime in the service area.

Another feature could be the inhibition of output of the responser in the range domain except during those time intervals in which aircraft replies can exist. This would greatly relieve decoding, defruiting and processing elements of useless load. It could also lead to a design of defruiters less complex than those in current use. Another possibility is to arrange the system give continuous interrogation at very low level to cover airfields, for example, and to use SINTEQ to switch power to higher levels only when and where needed.

Operational Deployment Although currently conceived as having direct application in systems using manual decoding equipment, SINTEQ can also be deployed in systems using automatic decoding.

It is even possible by careful system design to cater for applications where an interrogator station serves a number of remote operations sites.

It is obvious that the benefits of SINTEQ are, like the joint use of smokeless fuel, best felt when a number of users in one area combine in its use.

SINTEQ is covered by a current patent.

The Narrow Margin Today, in the United States, we labour under the yoke of what is called governmental cost effectiveness. What this dictates is that the Federal Aviation Administration can spend only so much to save lives. It is not what is needed for the safest system possible. It is how much safety you can squeeze out of X number of dollars.

One solution several years ago was to make the controller the butt of whatever capacity problems or financial restraints existed. It was taboo for an airport to experience traffic delays. Heaven forbid. Never mind weather, visibility limitations, equipment malfunctions or work overload. The facility and its management had to "look good." The fewer delays annually, the more points scored.

A controller was a civilian non-com working under a military-like system (after all, national defence was involved).

He could not complain and he had instructions on the same level as the "direct order" from an officer. As in an infantry charge, his ability to take on ever more aircraft was a sign of his soldierliness, his manliness, and his guts. It was an insane period of ATC development.

That was the late Sixties. We now face another major assault on the safety of the air traffic system. The old-time fanatics are now gone or are under cover. But new forces, intentionally or unintentionally, for political reasons or for their own high motives, now are pressing down the delicate margin which every controller must preserve to keep air accidents from happening. It is an assault by many people and groups, for many different reasons. They have a common denominator - they are remote from the operating environment. They lack the insights which only the controller on the line can provide.

We have the purely political pressures to reduce the cost of ATC no matter what. Cost of government has risen so high that panic reactions and decisions result. These pressures do not only come from areas of Congress, but from

Figure 6

by Arthur C. Kohler, Director of Communications, Professional Air Traffic Controllers' Organization (U.S.A.) those in aviation who wish to pay less or fear paying more into the system. We have the environmentalists and community groups which have developed knock-out muscle in the past several years. They are the ones who rationalize that an infinite number of different approaches and takeoffs can be made, all equally safe, and so the quietest one is the best. We have ATC airport planners who have come to the ends of their resources. Now, they grasp at straws to increase capacity of the concrete that is there. Two such straws: perilously close parallel runways, and head-on takeoffs and landings in the same airlane.

We have the research by FAA which never addresses itself purely to safety, but which must always "pay its way" through seeking that ever elusive increased productivity.

Wake turbulence is a case in point. We have the need for advanced technology itself. Poor planning and political pressures have made a nightmare out of each new step into the automated world. Lastly, we have the impotency of FAA. It promises Congress annually increased productivity to have its budget and research and development projects approved. It cannot admit to the things ATC needs desperately, such as more controllers, because that is not the way you play the game in Washington if you are a government agency (although, with FAA under new management, the picture here may change). All these groups have a desperate belief that the narrow margin in Air Traffic Control today can somehow be reduced. But they are not using even basic logic.

Look at separation. Reducing the absolute minimum spacing between two planes must of necessity reduce the safety margin. There is no getting around that. Same as there is only one safest way to fly in and out of an airport.

Change it to reduce noise and you have reduced the safety factor - undeniably. Let's take an ATC facility. Last year there were 25 people there. One controller retires and one 19

Is transferred. Magically, management then decides that only 23 controllers are needed. Judge. Is the operation from that facility as safe using 23 men as when it had 25? Of course not.

The theorists say that automation itself is a new safety factor that allows reductions elsewhere. They talk now about future automated features to allow a still further reduction in the margin for error. But they are still up to their ears trying to get the present system to work - not better, but equally as well as the old. I am beginning to suspect that much of the planning for the future of ATC is done in a dream-world. There is a perfection of operations required which is a bone-chilling fantasy.

Today, so gradually that their import may be overlooked, decisions are being made which will affect ATC and every air passenger from next year to the year 2000. If mistakes are made, they may be years in the discovering. At the moment, the performance of automation is so far removed from its promises that we will all have to sit back on our haunches for a while to re-assess this supposed saviour of aviation's growth pains.

For the reasons above, our Association is going to take an ever stronger look at the decision-making process and the technology which is committed. We have strengthened our National Safety Committee as the first basic step in this direction. PATCO's involvement in preserving and lengthening the narrow margin stretches back to its beginnings. Six years ago we pointed out that the safety system had to be improved because of the increase in jet capacity. One midair collision would wipe out some 600 people, we said, not counting the destruction below from the debris. Certain types of accidents, therefore, should be made virtually impossible. But how pretty are we sitting? In 1974, the National Transportation Safety Board (NTSB) tabulated 467 air fatalities, double that of the previous year, and the second highest since it started counting. Upon reading this report, we were interested in how the public relations pundits would find a silver lining there. Being men of great ingenuity, they did. You see, in 1974, there were fewer accidents. It was really a safe year. The fatalities were only because there were more people aboard each plane. This is precisely what we had warned about six years ago.

The very complexity of Air Traffic Control is what allows it to be misunderstood, or misrepresented. Not so long ago, there were two tragic air accidents just outside our nation's capital. Let's put aside the many issues of what went wrong.

On the one hand, we found the public was naive about the possibility of such occurrences. Second, both accidents clearly proved the all-important human element in the airplane-ATC interface. Yes, the human element. Heed it well.

It is the key to air safety, and it always will be. Its importance has been slandered by mumbojumbo talk of automation and the superiority of the computer over man. But it remains number one.

Since legislators might have been aboard one of the aircraft tragically involved, the FAA moved lightning fast.

It took two steps which, although they have some merits, are hastily-thought-out panic reactions. One was to demand proximity warning indicators within a year on all scheduled airlines. The other was to prepare for installation of equipment at ATC facilities to alert controllers to altitude deviations. Both these actions were taken to placate the public and restore the Agency's shattered image. Both can also bring about a new host of problems, however, without 20

completely solving the old ones. The basic problem of alerting systems is the same as that of the burglar alarm system. It must always give the right signal at the right time, and it must never give a false warning. Too many false alarms, and human nature is to ignore all alarms.

Just where does the NTSB fit in? Alas, it is a group of dedicated and highly qualified men, but it is a toothless tiger. First of all, it can only act after an accident. Secondly, FAA can thumb its nose at any proposal the Board makes and it frequently does. A recent report by the General Accounting Office made this all too obvious. From 1970 to 1974, FAA has not acted upon 222 out of 655 aviation safety recommendations made by NTSB. The Agency also delayed action on many things, and had even lost needed files.

There are few signs that NTSB can force its recommendations into reality. Its only power is to throw the hearings of an accident open to the public. The big drawback here is that there is a mad scramble by the news media for sensational publicity, and few clear facts emerge from the charges and countercharges that different elements of the industry throw about.

As to crashing into terrain and obstacles, NTSB proved prophetically impotent in its Report on Landing and Approach Accident Prevention Forum, way back in October 1972. Once again, only serious accidents effected changes.

Here NTSB was acting with foresight, not hindsight. Unfortunately, it has taken serious accidents three years later to open the public's eyes. The Board said at the time, " ... More than 4500 U.S. civil aviation approach and landing accidents can be expected to occur in 1981. This projection for 1981 is double the number of such accidents which occurred in 1971". Obviously, things are drastically wrong in the Air Traffic Control system. Patchwork measures such as proximity warning indicators, decisions made in the aftermath of an accident, or the heat of public indignation, can remain only that - patchwork.

PATCO has been in the forefront of safety suggestions, too. We share with NTSB a common depression because so few are carried out. One notable exception is the immunity reporting program. We have been fighting for that since 1968. It allows the operators of the system, the pilots and the controllers, to put their expertise and experience into play to prevent accidents before they happen. They can report errors without chancing personal punishment. For each accident, there are a number of things that have been going wrong for a long period of time previously. Reduce them and you reduce the odds. So, score up a big one for us.

Our next step has already been taken. We have been going over the system with a fine tooth comb to find out what has been going wrong. We want a safety analysis superior and in greater depth than has ever been done before - than could be done, because controllers themselves were excluded; controllers, who are the operators of the system. What we are aiming at is an unbiased view of the margin for error in the system today. Based on this, we will recommend standards for controllers to follow. Much of our effort has already been smeared as "slowdown" tactics. Let us assure you that nothing could be further from the truth.

Here we have harnessed the power of the atom, sent men to the moon, and reached man's camera eye as far out as the atmosphere of Jupiter. Let's stop kidding ourselves and learn more about the very real needs of those who fly in our own skies.

One Language, or More, in Air Traffic Control?

World Consensus not Easy to Obtain

by G. J. de Boer Clarity of communication, and complete and positive understanding between pilot and controller, is of vital importance to the safety of aviation. Both the International Civil Aviation Organization (ICAO) and the International Federation of Air Line Pilots Associations (IFALPA) in their policies have endorsed the introduction of a single language for air/ground communications and have suggested that, because English is commonly accepted as the international language of aviation, it should, as an interim step, until such time as a universal language lexicon is developed and perfected, be accepted as that single language. IFATCA has so far not defined a precise viewpoint, although in its unqualified support of the Canadian Air Traffic Control Association (CATCA) in that Association's dispute with the Canadian Government, it is on record as stating that to Implement bilingualism in an already existing single language environment would greatly jeopardize safety in air traffic control. The Federation is expected to declare its standpoint at IFATCA's 1977 Annual Conference.

The Canadian Government's decision in 1976 to expand the joint use of French and English, already practised on a limited experimental basis in the Province of Quebec for ATC purposes, caused a controversy which was felt far and wide, and which culminated in flight cancellations, work-to-rule, walkouts and stoppages. Under the auspices of IFALPA, a well attended Special International Air Safety Symposium was held in Ottawa, Canada, after the Canadian Government's decision became known, and both supporters and opponents of bilingual ATC were able to air their respective viewpoints. In this article both sides of the argument advanced by the parties to the Canadian situation are presented to enable readers to judge for themselves on an issue for which a world consensus will not easily be found.

The Case for the Use of More Than One Language Since this article will primarily reflect the attitudes and opinions in the Canadian environment, the case of those advocating a dual language system is presented first as they are attempting to establish justification for altering the status quo.

Those who advocate the use of more than one language believe that bilingualism in air traffic control enhances the safety of flight and they hold some strong convictions:

ICAO Recommends Choice of Language ICAO has recommended a choice of language in that: The language used will generally be the language used by the authority on the ground.

For international flights, the common denominator will be English.

The proponents of a bilingual air traffic control system rationalize this to argue that it follows that bilingual communications have the sanction of the World Organization until such time as a standard aviation language can be universally introduced. It is readily agreed that the use of only one language in air/ground communications is more desirable than a bilingual system, but this is a theoretical statement because one single language known and mastered by all does not exist. Millions of people speak only French or Spanish or some other language; Esperanto is an ideal that we haven't as yet reached. It is unrealistic to demand that all pilots the world over learn to speak good English before they take to the air; a limited command of English is not enough to ensure safe comprehension of instructions made in unusual or emergency situations.

Therefore it is necessary to give pilots the choice of using whichever language they think is most conductive to their safety and that of their passengers - which the ICAO Recommendation allows - to obtain the maximum of understanding of the controllers' instructions.

Air safety is based on perfect mutual understanding and on the observance of the Rules of the Air. Comprehension is an essential ingredient, and the service is most efficient when the pilot has a thorough knowledge of the language of communication. Thus, if safety is really at heart, bilingualism must be favoured because it increases air safety by promoting better understanding between a unilingual anglophone pilot, a unilingual francophone pilot, and a bilingual air traffic controller. Bilingualism tends to eliminate the risks of confusion and reduces delays, and consequently the danger of accidents inherent in these situations also disappears. Those who say that bilingualism will create confusion and delays and say that this may be dangerous, have never substantiated their assertions.

How can we expect to have precise instruction which must be received, understood and executed rapidly, when the communication vehicle is badly controlled by persons who are marginally fluent in the language of operation?

The vehicle for these extremely important instructions is that of verbal communication and, in the matter of expression, the language which ensures maximum understanding, rapid comprehension, efficient interpretation, is the mother tongue of the user.

There can only be communication if information is transmitted, received and understood. If you do not have any one of these three factors you do not have communication.

You have not transmitted or received vital information.

Bilingual ATC provides greater opportunities to achieve that communication. The importance of the use of the mother tongue in matters of comprehension and efficiency during abnormal periods of stress or tension cannot be denied.

Frequency Monitoring by Pilots no Longer a Safeguard Controllers and pilots who advocate bilingual ATC communications refute the long held principle that pilots should be able to monitor the communications on the radio frequencies they use for the purposes of traffic assessment 21

to the number of aircraft flying in the area. The more dense the air traffic, the more operational sectors, i. e., the more frequencies that are used, the more controllers there are on duty. This makes pilot monitoring of the actual situation an impossibility.

Any monitoring of frequencies serving congested areas by pilots who no longer get enough information for a clear picture of the situation, means more frequency saturation and so adds difficulties rather than eliminates them. Independent interpretations by pilots can only distract controllers from concentrating on providing the necessary separations. The pilot who does as he is told is less of a safety hazard than the one who challenges all instructions because, having listened to conversations that do not involve him, he feels that he is more in the picture than the controller.

The old pilot concept of always listening out is slowly phasing out. Younger pilots of the more recent generation do not, in fact, listen out with the same degree of attention or interest as older pilots. They accept the modern controller for what he is: a highly trained specialist. Pilots are not trained in ATC work and are not ATC specialists.

The United States has been the scene of a well publicized near-miss in recent time. As in that country only one language is used, all persons involved hear and understand everything that is said on a frequency. These exchanges did not, however, permit the pilots to discover the error of the controller. Hence neither of the pilots knew the position of the other aircraft in relation to his own.

Bilingual Operations Reduce Controller and Jerome K. Lederer, President Emeritus, Flight Inc., USA, Moderator of the Ottawa Symposium.

Safety Foundation

They say that for all pilots to know all that is going on around them in today's ATC ·environment is unreal. Much is made of the assertion that constant frequency monitoring permits pilots to recognize errors made by controllers.

But does it? In the present day system they say it is impossible for pilots to comprehend the traffic picture. They feel that pilots cannot possibly appreciate the real significance of the information they might hear, and so there is no longer any need for pilots to listen to all ATC transmissions. About 20 years ago the situation was perhaps different, but today only the controller possesses the ability - in line with the steady trend in shift of responsibility from the cockpit to the control room - of separating the aircraft. The pro-bilingual forces claim that the pilot is no longer able to picture the traffic because of: The use of radar. In the modern radar environment where 5 or 3 miles separation is being applied and where 15 or more aircraft are handled by the same sector simultaneously, it is not possible for pilots to be aware of the traffic situation, since most of the communications are one-way (from controllers to pilots).

The omission of position reports. Aircraft are no longer required to make them in today's automated radar environment. Only controllers now know the traffic picture; pilots do not.

The very complex horizontal and vertical structure of the ATC system with the consequent use of different frequencies within the same sector. ATC is now a complex system in which the airspace is sectorized. The number of sectors or parts of airspace is proportional

2!

Pilot Stress Rapid comprehension by the controller, ensured to its maximum by the use of the language chosen by the pilot, reduces controller stress. In fact, the controller is submitted to additional tension in the opposite situation where he never has the assurance that a foreign pilot really understands fully the instructions given in English. Those who have an insufficient knowledge of English find it difficult to make controllers aware of their intentions, position, etc.

And by the same token these pilots have difficulty in understanding the controllers~ instructions. Thus, the controller's work increases considerably as he has to repeat his instructions and in doing so loses precious time. Even though the pilot may acknowledge the transmission by saying "Roger", the controller can never be sure that the pilot has understood and the controller has to pay special attention.

The exclusive use of English in air traffic control in Quebec in the past constituted a safety hazard. There are over six million French-speaking Canadians in that province, and the great majority of pilots who use Quebec airports are primarily French speaking. This fact of life warranted the introduction of bilingual communications, not at the expense of the established standard of safety but rather because this standard needed improvement by increasing pilot comprehension. And this greater pilot comprehension now makes the controller's task less stressful. According to Canada's Transport Ministry, no incident has occurred in 20 months of bilingual handling of VFR operations at Quebec City Airport, and controllers are now able to manage more rapidly the volume of traffic at peak periods.

As for pilots: greater and more rapid comprehension of the controller's instructions given in the language chosen by the pilot eases any strain on that pilot and gives him

more time to concentrate on his flying. Here also greater comprehension makes for increased safety.

Bilingual Operations are Safe A number of countries around the world have used two languages or more in air/ground communications since the infancy of civil aviation. Countries like France, Switzerland, Italy, Spain, Portugal, Eastern European countries, Mexico, Brazil, and others, use their native language for ATC communications while English is available to meet the needs of international operations.

At Geneva, for example, 30 to 40 D/oof the total traffic is handled in French. The controllers must all be able to speak English and French, although about half of them are German-speaking from origin. Not one airmiss has ever been attributed to bilingual communications. On the other hand, incidents have occurred where pilots, speaking English without being familiar enough with the language, misunderstood clearances, and therefore forced controllers to intervene.

Bilingual and multilingual ATC has been practised in many parts for many years and has met all international safety standards.

The Case for the Use of One Language Only Controllers and pilots who advocate the use of one language in ATC communications see hazards in the introduction of a second language into an existing unilingual system. The people who hold this position are not only those who might be described as "unilinguals" but also include many professionals who could be described as "bilinguals" or "multi-linguals" and who have controlled or flown in ATC systems that were similar. Their case for maintaining unilingualism in ATC systems that are now structured that way, and working toward achieving it in bi/multi-lingual systems, are as follows:

ICAO Recommends Use of Common Aviation Language Aviation by its very nature knows no boundaries. It is an international activity which circles the globe and is practised by every nation on earth. It is precisely because of this that one language should be used in aviation communications, in the same way as Greenwich Mean Time was established world-wide as the standard time for aviation, for an individual pilot may easily land in three, four, five or six countries, or overfly them - each with a different language - in the course of a single day's work.

A single universal means of communication has, of course, long been a utopian dream, and not only in aviation, giving rise to attempts to create a world language such as Esperanto. But especially in aviation, the need to use a single language has long been recognized and the aviation community is further along the road towards a single worldwide vehicle for communication than any other field. That this vehicle is based on the English language is more through an accident of history than any pre-planning, and as such needs no justification. It is a fact of life. !CAO, in recognition of the trend - for safety reasons towards a singular universal language, recommends the use of a common language and the Organization has established that English shall be the basis for the development

Captain Roger Demers, President of the Association l'Air du Quebec, who supports bilingual ATC.

des Gens de

of a standardized aviation language, while - until such time as an agreed universal language lexicon is developed and perfected - English will be the designated common medium. Those advocating a unilingual system, therefore, contend that the ICAO policy is not intended to foster the development of new bi/multi-lingual systems or the continuance of existing ones, bat rather to work toward a unilingual world-wide system.

Air traffic control necessitates a uniformity in communications, one standard set of terms that can be rapidly utilized and understood by pilots and controllers all over the world. Over the years a form of aviation English has been introduced; it is more a code than a language - any layman listening in to aircraft and ATC transmissions will recognize words but will not know what is being said. Today, that aviation/English - for historical, economic and linguistic reasons - is the standard medium of communication; there are a number of other reasons for this care/ully standardized language, such as the difficulty of understanding verbal transmissions over aircraft radios of varying quality. As the only world-accepted standard that surpasses the metric system in use, English is now accepted by more than 170 nations as the Language of Aviation to promote safety and to avoid misunderstandings, and its use is steadily expanding as advocated by ICAO. Historically the progression of language use in Air Traffic Services in many parts of the world has been from the local language to English, and some countries use it domestically in order to avoid moments of misinterpretation which could cause disaster. For example, English is the only language spoken in Germany for IFR, in the Scandi23

navian countries, and in the Netherlands. Eurocontrol is also another example of a unilingual English system in an environment where it is not the native language of the nationals providing the service. What is particularly interesting of Eurocontrol is that after a start using multilingual communications, a switch to unilingual communication was effected after it was discovered that a sufficient comprehension of operations was not afforded in a multilingual environment.

In many countries the flight crews who are nationals of the nation in question, when communicating with ground stations in their own country, utilize the English language and not their own. In such cases the local language is subordinated to English for one reason only: safety. To derogate the use of aviation English as the primary language of aviation by playing down its importance has no logic. It does not make any sense to go counter to the world trend for the sake of any sort of political expediency, and any deviation or exception from the standard is inimical to the interests of aviation safety_ To inject a second language into the delicately balanced world of mixed jet and conventional air traffic in order to accomodate a small number of mainly non-professional aviators who for some reason do not wish to learn aviation English is ill-founded and unwarranted. Representatives of pilots who attended the Ottawa Symposium said that they would take exception if it was implied that pilots, though able to handle an aircraft, would not be able to master aviation English, but that air traffic controllers can. If a Spanish, Dutch or Italian pilot can learn English for ATC, why cannot the francophone pilot? A communications problem could well exist in southern USA with pilots whose mother tongue is Spanish, but there has been no talk of a compromise there to satisfy Spanish-speaking pilots.

Ignorance or error on the part of unilingual pilots not knowing aviation English, or other factors such as weather conditions, may force such pilots to enter airspace where only aviation English is spoken. This leaves such a pilot unable to communicate with ATC and dangerous incidents may occur. One such incident did occur in 1975 and caused a danger to a number of airliners as well as seriously disrupting traffic at Toronto International Airport for a lengthy period.

The Elimination of Some of the Safety Redundancy Built into the System The ATC-system is co-operative and can only function effectively and safely when both the pilot and the controller aid, assist, and back-stop each other. Controllers and pilots are constantly monitoring each other's radio transmissions and checking for errors. It happens occasionally that controllers catch errors in the read-back of assigned altitudes, headings or routings; in the same fashion, pilots, hearing clearances and instructions being given to aircraft other than their own, are able to maintain a mental picture of the sky around them, and as a result of this picture they are able to catch occasional errors in such clearances and instructions. These constant checks avoid incidents which at best may be near-misses and at worst could cause a mid-air collision.

From experience pilots know that the majority of information they get that is of value to the safety of their flights comes from listening to the transmissions on the frequency that is being used by everyone else. There are no other checks and balances on effectiveness of the system for 24

there is no shared surveillance data. The only clue to operational normality and the only cross-check on controller performance and pilot compliance is the shared communication link. When the flight control is mixed as to the language being spoken, this cross-check is lost_ The nature of the air traffic system also changes from co-operative to unilateral with the resulting and unacceptable loss of redundancy.

If communications are allowed in two languages or more, those pilots who are only proficient in one language will be disadvantaged in that they may understand only part of the conversations they hear, or at times not at all, and they will be unable to mentally visualize the positions of other aircraft relative to theirs. Hearing a transmission but being unable to fully understand its meaning, pilots will not know whether another aircraft's flight-path or position will affect their aircraft's path or position. Knowing that another aircraft may be near but not knowing its relative position, altitude, direction or speed can be disconcerting to pilots who rely on a firm grasp of all the relevant data available to them for the safe progress of their flight.

One question being asked is: Will pilots listening on a frequency under IFR conditions, with anywhere from one to fifty pilots listening at the same time, and getting information without saying a word, receive the same information under a bilingual situation where they will be unable to understand all transmissions? The simplex aeronautical frequency utilization, which lends itself to such a capability, will not be utilized to its fullest and the present level of safety will be derogated, is the pilot's answer. They contend that they will not be able to unobtrusively gather essential data such as clearances, weather information, and possible hazards to navigation, and that this will result in increased frequency usage and congestion.

It has been said that the ATC system currently operates with various aircraft on different radio frequencies so that communications monitoring does not really exist. This is not true for usually all aircraft sharing the same airspace around airports - which is the area where mid-air collisions are the greatest threat - are on the same frequency and do hear the conversations with the aircraft around them. At a busy airport there may be dozens of aircraft in the circuit and every pilot is monitoring the common frequency. He knows his position relative to the aircraft in front of him and adjusts his mental alertness according to what he hears and understands from the controller. He is preparing his approach and landing because he comprehends the tempo of operations. But could the operation be considered "safe" or "expeditious" if all pilots concerned couldn't understand what was being transmitted to all other pilots? The pilots say not.

There is almost complete ease of operation with a common language. Standardization of terminology helped make this come about, eliminated areas of uncertainty, and made vastly simpler a very complex business. Moving away from a common language in the air, with resultant loss of system security, is therefore a retrograde step.

Bilingual Communications Increase Controller Workload and Stress Controllers in busy Towers and IFR Units maintain a mental picture of the identification, altitude, routing, and position of twenty or more aircraft at any time. The introduction of a second language will mean that they must also now remember which of them they have to speak to in the

one language and which in the other. Imagine the consequences if a controller has to first decide which language to issue emergency instructions in if he is operating a multilingual sector. Given the pressures exerted on him by a dangerous situation, he might well choose the wrong language and a mid-air collision could result. Any confusion engendered by the use of more than one language is totally unacceptable where the protection of human life is involved.

Air traffic control necessitates clear and concise communication, split-second reflex in thought and action, instant decisions and instructions. The use of more than one language in an interchangeable manner would severely strain, if not altogether destroy, the capability of controllers and pilots to effect the quick reactions of thought and speech. If a controller who spots a problem needing immediate action first has to mentally translate his commands, what would the outcome be? Even the use of one language sometimes poses difficulties and dangers due to the inherent ambiguities in language.

The stress factor on controllers is one that cannot be ignored. There is ample evidence to show that there is appreciable stress involved in the controlling function. To require controllers to practise in more than one language imposes additional stresses in an already bad situation. We will end up with controllers who cannot maintain a language proficiency which is in keeping with the high level required in ATC use.

Bilingual ATC, by inducing greater psychological stress among controllers, would have an adverse effect on the efficient flow of traffic during peak operations. In the United States, with unilingual English ATC, nearly 300 air traffic system errors were attributed to communication problems in the last four years. A bilingual system would create greater potential for communication errors.

Bilingual Operations Increase Pilot Stress The desire to bilingualize is not practical in some areas, and primarily not in areas involving both high technology and a critical safety factor. The air traffic control field is one of those areas.

One of the worst aspects of bilingual control is that it affects a pilot most during the phase of flight where most accidents occur. Statistics have shown that over 70 0/o of accidents occur during take-off or landing. Consider the situation on the flight deck of an airliner during take-off and climb. The take-off is done using somewhat less than full power to conserve engine life. The climb-out is segmented by power reduction for noise abatement, minimum speed noise abatement climb, normal climb thrust application, climb at zone limiting speed, and finally acceleration to enroute climb speed. During this time the crew change the configuration of the aircraft up to four times, use three different navaids to negotiate the standard instrument departure, switch radio frequencies, carry on a running conversation with ATC, and are expected to stay alert and watch for other airplanes. Then if you put the pilots under the additional strain of doing all this in a two-language environment, you have significantly increased the chances for an accident.

Consider the consequences of even momentary indecision at a crucial time by a pilot made unsure of his situation due to language confusion. Pilots operating in busy airspace are all too familiar with the long wait for a break in other conversations before they can call an air traffic

Jim Livingston,

President of CATCA, who supports unilingual

ATC.

controller. Those pilots wishing translations of communications they do not understand might request them, and controllers who feel that translations are necessary in the interests of safety might be required to provide them. Even if it were possible to do so it will further overcrowd these busy frequencies, but all too often it will be impossible, leaving dangerous gaps and uncertainties in the minds of unilingual pilots. In Canada, Ministry of Transport officials have stated that it may be necessary to reduce the rate of traffic flow by around 30% to ensure that safety is not compromised in bilingual operations, surely a clear indication that the Ministry which is proposing the policy is admittedly unable to guarantee that a bilingual system would be as safe as the present unilingual system.

Bilingual Operations are Unsafe On February 25, 1960, a DC-6 collided with a DC-3 over Rio de Janeiro. The controller used Portuguese for communication with the DC-3 and English for the DC-6. The two aircraft, using the same frequency, both under IFR, collided at about 5,000 ft. The DC-3 went into a flat spin and crashed into Guanabara Bay. The DC-6 also crashed into the Bay, killing all occupants except four. All evidence developed by the Court of Inquiry proved conclusively that the use of two languages was a major cause - if not the primary cause - of the accident. If all communications by Rio Approach had been conducted in the same language there would have been an excellent chance that one or both pilots would have recognized the hazard and called for corrective clearances or taken evasive action.

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At the Ottawa Symposium, a Toronto businessman-pilot stated that while flying into Quebec City recently he had been involved in two near misses. One was on an IFRapproach where, if the controller's avoidance instructions had been in French he would not now be alive, and the other was on an IFR departure during which he had to take evasive action; just prior to this he had heard the controller speaking in French to another aircraft but had no idea what was going on. He said that he would avoid the province in future.

Other reports of losses of separation due to language difficulties are currently under investigation both in Canada and in other countries. This includes one in Europe where two jet transports were involved and one of the aircraft captains has stated that had both aircraft been control led in the same language he would have been aware something was wrong prior to having to take evasive action.

Bilingualism in ATC: Safe or Unsafe?

In winding up, the perplexing fact is that the experts do not appear to agree among themselves. Many hold that bilingualism compromises safety; others with equal sincerity and authority, maintain that bilingualism enhances safety. Critics of the use of two languages often contend that, although it might work in areas with little traffic, it could never be successfully done around busy world airports such as Montreal, New York, etc., at least not at their present levels of traffic - witness the Canadian Ministry of Transport's anticipation that Montreal area traffic would have to be reduced by 30 % to accommodate bilingualism.

Some point to the Paris area, surely not a backwater, as a successful operation in two languages. However, it must also be pointed out that the French Air Line Pilots Association has recently requested that the Government of France introduce a unilingual English• system at the major Paris airports.

President J.-0. Monin of IFATCA said at the Ottawa Symposium that although multi-lingual air traffic control was practised in areas of his country (Switzerland), and to the best of his knowledge without any difficulties, he was not in a position to comment on the Canadian system or what effects a move toward bilingualism in it would have.

Despite the assurances of the Prime Minister of Canada and the Minister of Transport that bilingualism would not be expanded in the Canadian ATC system unless it was consistent with the requirements of safety, all national Canadian aviation organizations indicated skepticism that politics would not be placed before safety. As a result of their insistence a three-man judicial inquiry has been appointed to investigate all implications of Canada adopting a two-language ATC system. This Commission of Inquiry will work parallel to, and evaluate, the results of the simulation studies being conducted by the Government on the ramifications of a bilingual ATC system. At the completion of the studies, and as a result of evidence adduced before it by interested parties during its hearings, the Commission of Inquiry will table its report and recommendations before the Parliament of Canada. The Government is presently committed to introduce only those findings of the Commission which are unanimous and not to introduce those which are not of unanimity of the judges. Present timetables indicate that this process will take from fifteen to eighteen months.

26

Conclusion The use of languages should never be a sentimental, emotional or political issue, but only a means of conveying information to other persons. Once this is accepted, it could be said - as someone did at the Ottawa Symposium - that in aviation this item is a problem_which either has no solution or is no problem.

(Acknowledgement: The writer acknowledges the assistance rendered

by Mr. W. J. Robertson, IFATCA's Regional Councillor for. North an_d Central America, in improving the contents and presentation of th,s article)

A special report on air safety in the U.S. prepared by six retired airline pilots who had been commissioned by the Federal Aviation Administration, has been attacked by PATCO. The controllers' union feels that the obvious bias towards pilots showed up in many areas of the Special Air Safety Advisory Group's report, although it also included many observations which recognized and commended the professionalism of the air traffic controller.

PATCO Executive Vice President Robert E. Poli has written to FAA Administrator John L. Mclucas that a more valid and useful study could have resulted had six ex-air traffic controllers also formed part of the advisory group.

"Since this report has been completed utilizing only pilots, it should be taken for what it is: the viewpoint of half the team only."

"The six ex-airline pilots who constituted the advisory group did offer experienced insight into cockpit problems, but displayed a not unexpected 'pilot bias' when examining the Air Traffic Control system. While it is interesting to note their characterization of the atmosphere of ATC facilities, these impressions also serve to denote their unfamiliarity with the ATC working environment and controller characteristics. Both the cockpit slant and the ATC unfamiliarity contribute to the essential one-sidedness of the report. Because, in our opinion, the study has only been partially successful, we recommend that the Agency implement another advisory group utilizing ex-air traffic controllers to study the system and to make recommendations."

(PATCO Newsletter)

Recently, a civilian air traffic controller received the U.S. Air Force Communications Service "Aircraft Save Award" for the first time. He was Eugene Traynor who simultaneously guided five Air Force jets to safety during emergency landings at Tinker Air Force Base, Oklahoma, in November 1975.

Traynor was working the RAPCON when, in rapid succession, a flight of six F-105 jet fighters bound for the base declared emergencies. Two were experiencing electronic difficulties, while five were critically low on fuel. Adding to the crisis. the Precision Approach Radar had become inoperative because of a thunderstorm, and bad weather and visibility were present. Normally, of course, such aircraft are routed one at a time. Because of the fuel shortage, Traynor handled all five planes using radio instructions and surveillance radar.

The Award cited the controller's "outstanding service to the US Air Force and said that his "professional ability and cool head averted a multiple USAF aircraft disaster." FAA Administrator John Mc Lucas also praised Traynor's performance, "in keeping with the highest traditions of our Agency."

(PATCO Newsletter)

AN/TPN-25 Precision Approach Radar And Associated Units A New Concept in Modern Solid-State PAR Equipment Precision Approach Radar (PAR) is a concept with which the air traffic controllers of the 1970's are no longer familiar.

Those who still are will probably only remember that PAR was a rather elaborate but nevertheless very effective instrument in talking down pilots in bad weather to a safe landing. Controllers who have actually talked down pilots on PAR equipment will swear that this landing aid is the safest of all, and they will back up this contention with a string of personal experiences. The only major argument used against PAR has always been the very high cost of purchase and operational use.

Raytheon Co., USA, a close Associate of IFATCA's Corporate Member Cossor Radar and Electronics Ltd., have designed a new improved Precision Approach Radar System, primarily destined for the U.S. Air Force, but which could be adapted for civilian use at a very much lower cost than the PAR equipment which has been available until now.

An examination of what this particular system has to offer should be of interest to IFATCA members.

The AN/TPN-25 System The U.S. Air Force, in specifying the fully transportable equipment required to land both fixed wing aircraft and helicopters in areas where severe weather occurs, called for weather performance in precipitation of 50 mm/hr at a range of 20 n.m. Other specifications included selectable glide slopes from 2 degrees to 13 degrees in 0.1 degree increments, full coverage volume of 20 degrees in azimuth and 15 degrees in elevation, selectable decision height markers and the capability to track six aircraft simultaneously. Additional specifications called for the capability to cover any of four separate runways on an airfield if a change in wind direction necessitated new coverage.

In meeting design specifications, Raytheon employed a unique phased array antenna, which electronically scans the entire coverage volume twice per second. Simultaneously, aircraft on final approach are tracked with monopulse antenna beams for high accuracy. The only time the antenna moves is when a new runway is taken into use due to changing wind direction; it can be controlled remotely to any of four runways on an airfield. The PAR can be programmed to slew 270 degrees at the touch of a button to achieve the four-runway coverage. Each controller may select the appropriate glideslope angle for the type of aircraft under his control for final talkdown. A small digital computer is used to generate glide slope and azimuth course lines and to track the aircraft with fire control accuracy. The constant 15 degree x 20 degree search scanning provides excellent coverage on small fixed wing and V/STOL aircraft.

Advantages over former PAR systems include: lower cost, less complexity, less weight, full digital beam control, ~imultaneous search and track.

AN/TPN-25 Precision Approach Radar Antenna

Normal PAR and High-Performance PAR The AN/GPN-XX Normal PAR employs solid-state technology for improved reliability and reduced maintenance costs when compared with older, existing PAR systems that now operate in areas with low-density air traffic. It is a dual channel system and is based on existing designs of systems previously employed throughout the world where low density fixed wing traffic in fair-to-light weather is the requirement. Existing similar systems can also be retrofitted to this modern Normal PAR design as has been done for the U.S. Air Force.

The AN/GPN-XX High-Performance PAR is a vital element in the modernization of Air Traffic Control system operations at permanent bases with high density air traffic.

Incorporating the same technical features of the TPN-25, the HI-PAR, a low-cost, phased array system, will equal or better the performance of the TPN-25. The scan volume of 20 degrees in azimuth and 8 degrees in elevation combined with a 20 nautical mile range and the capability to simultaneously track six aircraft provides optimum performance under adverse weather conditions. In addition the HI-PAR can cover any of four separate runways by remote operation of the antenna and has the capability of automatically sending guidance information to the aircraft via data link.

All PAR's are capable of remote operation in an existing permanent control center or transportable operations shel27

Ferranti simulators

put years onyourstudent • controllers

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

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

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

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

handling heavy air traffic with minimum delays.

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

Ferranti Limited, Digital Systems Division, Western Road, Bracknell, Berkshire, RG121RA. Telephone: 0344 3232. Telex: 848117.

FERRANTI The real thing in simulation

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ter. Full performance from - 65 to + 125° F without air conditioning is achieved, but air conditioning may be provided for personnel comfort. The system operates in winds to 65 knots and survives to 130 knots.

Contrasts with older Systems Tests with the TPN-25 have shown 100 0/o success in tracking aircraft approaching a runway in heavy (5 inches/ hour) rain. Under the same conditions, the company's older approach radars were able to track only 6 0/o of the same aircraft. A 20-mile final approach range under two-inch per hour rainfall is now possible. Up to now, two or three miles was the maximum. Up to six aircraft spaced three minutes apart can be controlled on the system's variable glidepath.

Previous systems handled only one aircraft at a time on a fixed glideslope. Digitalized electronic scanning replaces the mechanical scanning of the past.

Specific scope photos and plots show, for example, the TPN-25 maintaining solid track of an aircraft being vectored deliberately through storm cells from about 6 miles out, while the older radars also acquired the target at about 6 miles, but subsequently dropped to an unusable target quality at approx. 3 miles in rain. Another plot shows the TPN-25 solidly acquiring a target at about 8 miles, while the older equipment did not get a usable return until about 4 miles. The contrasting performance was attributed to the pencil beam propagated by the phased array, which is far more efficient than dual fan beams that spread energy over a relatively wide area, along with non-coherent MTI processing and circular polarization.

The TPN-25's ability to function in very bad weather is largely due to a high-power option. The PAR transmitter consists of a solid-state master oscillator with TWT and CFA finals. In good weather, the CFA final is not used and the peak power output is held at about 17 kW. Under foul weather conditions, the CFA final is kicked in giving about 380 kW peak output power to "burn through the rain." In contrast to previous systems, the PAR antenna is constantly circularly polarized.

Other System Performance Features To come back to the PAR antenna: it is a hybrid limited scan design that uses its limited-volume phased array to illuminate a portion of a much larger hyperbolic reflector.

Energy radiated by a 4-layer multimode horn is passed through a honey-comb of only 824 3-bit, reciprocal ferrite phase elements (shifters) in its digitally phase-controlled subarray, which, under computer control, direct the beam to spotlight various portions of the reflector. The antenna achieves a 0.75 x 1.40 degree beamwidth which is comparable to conventional phased arrays having 8,000 elements. This pencil beam is digitally scanned over a 14 x 28 matrix to cover a 15 degree high by 20 degree wide search sector at a rate of about 2 scans/sec. within which the aircraft on final approach may be tracked with monopulse beams at a 20-scan/sec. rate.

Frequency diversity and a variable repetition rate are used to eliminate potential "blind speeds" caused by an aircraft travelling at a constant velocity that puts its position out of synchronization with equally-spaced pulses. Each pulse actually consists of two contiguous 0.5 micro sec. pulses at different frequencies. Each return frequency is processed separately. The average PRF is 3500 and the radar operates in the range of 9.0 to 9.2 GHz. 30

Radar protection is afforded by a digital TR limiter with a range of 0 to 50 dB in 10 dB steps. This self-limiting feature is necessary to protect the receiver against pilots who inadvertently forget to turn off airborne radars when making an approach. The receiver employs a parametric amplifier with a 3.1 dB noise figure.

The PAR digital computer, in addition to affording the capability of tracking multiple aircraft on final approach and to permit operator selection of glideslope angles, also enables the operator to provide dogleg approaches in either azimuth or elevation on two different runways.

Since a fully transportable design imposes strict weight and size constraints on the system, the PAR antenna could not be as rigidly braced as a fixed installation. Therefore, Raytheon engineers compensate for random movements of the antenna electrically. Motion sensors in the antenna support arm generate error signals on the basis of motion in the vertical plane. Horizontal motion is detected by monitoring reference signal reflected by a small, stationary dish planted at the touchdown ends of the runways. Error signals from both vertical and horizontal planes are fed into the tracking and display computer which sends corrected data to the operator's display as well as to the beam steering processor. As a result, accuracies of 1 microradian in elevation and 1.25 microradians in azimuth are maintained in winds up to 65 knots.

Test runs of the system have been made with a variety of aircraft of all sizes, ranging from small, single engine Cessna 150's and 172's through almost every aircraft in the Air Force inventory.

The Precision Approach and Landing Monitor A 'Backup' landing guidance technique that would make data derived from PAR equipment available to activate cockpit instruments or automatic flight controls on board manned aircraft or remotely-piloted vehicles (RPVs) has been explored in preliminary feasibility flights.

When the civil aviation community opted for ILS in preference to GCA-techniques after World War 2, it was motivated by three principal reasons: Pilots wanted control and decision-making data in their own hands during critical approach manoeuvres; GCA radars of that period were far more vulnerable to losing targets in precipitation than a modern pencilbeam, phased-array radar; The high cost of constantly manning many GCA facilities at multitudes of civil airports with skilled radar controllers was prohibitive.

But the new backup technique, it is felt, vests the data evaluation function in the cockpit and can eliminate the need for constant attendance by ground personnel, making feasible the use of GCA data-link information as a sort of precision independent landing monitor.

Raytheon, recognizing the inherent capabilities of the TPN-25 were well beyond the contractual specifications, conducted a special demonstration to display the feasibility of guiding an aircraft to touchdown without voice contact between the pilot and controller.

Since the computer generates the glideslope and azimuth course lines and also tracks the aircraft with respect to the course lines, it also derives the difference between those two pieces of information. The information that was originally intended for the controller's use was relayed via data link to the aircraft displayed on the aircraft ILS meter and became the pilot's steering commands.

The initial demonstration conducted in 1973 utilized standard USAF UHF data link equipment located near the runway to transit to the approaching aircraft azimuth/elevation and range data derived from the PAR's digital computer. Data received by the aircraft were used to drive a standard ILS crosspointed display. They could be coupled to an automatic flight control system, providing full automatic landing capability. Approach guidance was accomplished with the pilot simply flying his indicators as he would on a normal ILS approach. The TPN-25 therefore provides an all weather, highly accurate landing system that allows the pilot to fly his own approach. It also provides a complete approach monitoring capability that is not available to any other landing system.

Since cost is an important factor in aviation and can severely limit operations to a large segment of the flying public, the company developed low cost, light-weight avionics to improve the practicability of its new approach to landing systems. To demonstrate the feasibility of the new avionics, an engineering model was installed in a typical light aircraft (Piper Cherokee) and the test conducted under VFR conditions, by a non-instrument rated pilot. The only equipment needed for the demonstration was a standard ILS indicator, the new Raytheon avionics and a standard milliameter calibrated to read range to touchdown directly. The data link relay of the guidance information was a standard VHF transmitter. Digital pulses were transmitted and received by the aircraft's radio receiver which were then fed to the Raytheon avionics which was connected to the radio output or headset jack. The decoded information was then displayed on the ILS indicator and the milliameter which provided the pilot with the necessary azimuth, elevation and range information to complete his approach.

Digital data was used to minimize errors and in addition digital parity checks were transmitted to eliminate any erroneous data from being received by the aircraft. This is a standard computer technique to remove any false information from the display. In order to insure that the aircraft receives only information directed specifically to the aircraft on approach, the avionics are addressed with the aircraft tail number prior to installation. This insures that all information is transmittecl to the aircraft, is solely for that particular aircraft, and is highly reliable and accurate.

The technique is equally applicable to RPV recovery or to providing an approaching aircraft's pilot with a means of determining precisely his deviation from an optimum radar approach path, even in the absence of verbal instructions from a controller. Instrument indications would be more accurate than an existing VHF/UHF instrument landing system. Normal scale factors would be seen on the instrument display, with maximum deflection representing 1.5 deg. in elevation and 2.5 deg. in azimuth, respectively.

Additionally, a distance-to-touchdown meter would be calibrated from 0-20 n.m. All calculations would be done on the ground, with the data-link transmitting an error signal to drive the airborne equipment. Feasibility flights using the data-link concept were conducted with a USAF Douglas B-26 aircraft. The tests required only some computer software changes and addition of the data link.

By utilizing the system as a landing system and a monitor, the name precision approach radar or PAR no longer applies since it implies the old ground controlled approach (GCA) type of system. Raytheon therefore refers to the system as Precision Approach and Landing Monitor (PALM).

The PALM system also incorporates all those features that have been designated as essential to new landing systems that are presently only in the planning stages.

Since the PALM system is computer controlled, it is only necessary for the proper programming to designate the parameters for each aerodrome. If segmented approaches are considered necessary for noise abatement or obstacle clearance either in the vertical or horizontal plane, then it is only necessary to implement the proper program. The ground display generates a 3-minute trail history which allows control personnel to immediately notice any abnormalities develop during the approach and issue advisories to the pilot. This trail history can also be photographed if for any reason a record of the approach is needed. The PALM is the first system that allows flight recording for the final approach segment from the ground station. In addition to the previously mentioned features, the PALM retains the capability to provide a standard talkdown precision approach to those aircraft that experience avionics failures or are not avionic equipped. This feature is inherent in the PALM and is not in any other landing system in existence or in the planning stages.

The PALM system is available in two versions: the TPN-25 which can be used for both tactical and fixed base situations and has a VSTOL aircraft capability, and the GPN PALM system which has all the features of the TPN-25 with the exception of VSTOL due to the reduced elevation coverage (8 degrees versus 15 degrees) and is a fixed base only system. Both PALM systems provide: Approach Guidance and Monitoring; Multiple Runway Coverage; Greater Approach Accuracy; Low Cost Avionics; System Backup (GCA); and Minimal Real Estate. Raytheon is continuing to explore the full capabilities of its PALM systems and is confident that system potentials will be a major contribution to world aviation safety.

AN/TPN-19 The PAR is actually only one of three modules that comprise a total system which goes under the name of AN/ TPN-19. The AN/TPN-19 consists of: PAR (AN/TPN-25), ASR (Airport Surveillance Radar - AN/TPN-24 system). and an operations control center. Designed to be completely mobile either by land, sea or air, each module folds up into its operator shelter which then serves as a shipping crate.

The entire AN/TPN-19 system can be fully deployed and operational in less than two hours.

The system is designed for very flexible siting, but is also designed to operate at fixed sites in permanent buildings. The shelters can be operated at extended ranges, using the microwave links for data and voice communications, and the ASR can be separated from the PAR by as much as 10 miles or 12,000 feet by cable. The specification for trouble-shooting/fixing the equipment calls for a meantime-to-repair (MTTR) of 30 minutes. In practice, the MTTR has averaged about 20 minutes, the company says. Consoles may be used interchangeably as surveillance or precision approach radar positions, with proper displays selected by push-button.

The AN/TPN-19 communications sub-system is totally integrated to satisfy the overall system requirements and the needs of individual shelters when used autonomously.

The 9 UHF and 5 VHF radios may be used by all controllers. 20 Fully compatible landlines and one HF SSB transceiver are located in the shelters. Between the shelters, 31

there are radio or cable links for full radar, control and audio data transfer, and there is private two-way intercom between all operating personnel inside each shelter.

AN/TPN-24 The AN/TPN-24 Airport Surveillance Radar contains some very important performance capabilities which - the company claims - are not offered by any other ASR. The most important is its ability to detect small aircraft close to ground level. This is due to incorporating a sharp lower beam pattern cut-off for low angle target detection. This was accomplished in a very practical manner by employing not one or two antenna feed horns, but twelve. Eleven of these horns act in a manner to shape the antenna beam and to create the sharp cut-off on the lower part of the beam. The twelfth feed horn is controlled during the receive portion of each pulse in range and azimuth to avoid the returns from close-in hills and buildings. The multiple horn antenna feed produces lobe free coverage to 40,000 feet altitude and 60 n.m.

This feature of the TPN-24 ASR exceeds U.S. civil requirements which are generally interested only in targets above 3 degrees in elevation and fully meets ICAO requirements to detect all aircraft above 1/2 degree in elevation.

In addition to the low angle detection capability, the TPN-24 antenna design avoids the common problem of holes in the upper portion of the coverage due to energy reflections from the ground (multipath).

ATC equipment is required most during periods of severe weather when it is difficult to achieve excellent radar performance. The TPN-24 has several features that minimize the effects of weather and allow the system operation to continue even under the most severe conditions. One technique used is the dual channel operation with frequency diversity which provides the TPN-24 with five times the weather performance over a single channel ASR with twice the power. Should one channel fail, the TPN-24 can continue to operate (with reduced performance) on one channel while the other is being repaired.

In addition to the improved performance that is gained employing the frequency diversity, the TPN-24 is equipped with a special electronic subsystem to greatly reduce or eliminate the effects of heavy rain. It is non-coherent MTI that is automatically switched on to cover just the rain area.

It will significantly decrease the backscatter returns from the rain to allow a small target to be detected within the storm. It also paints a contour of the storm area on the display so that the controller can direct aircraft around, rather than through, this area of turbulence. This circuitry is only used to eliminate rain returns as standard coherent digital MTI is used to reduce ground echoes. No other ASR contains this non-coherent MTI rain rejection feature.

Another feature of the TPN-24 is its siting flexibility. In addition to the capability of being sited 10 n.m. from the operations center, it also can be tower mounted or installed in permanent buildings. This siting ability allows the TPN-24 to be installed at the most efficient locations for complete and effective radar operations.

GdB

The Last Approach

By Ed Gillet

The rain had fallen most of the night and into the day.

Now the air had chilled and was drifting in from the sea with a taste of salt and the fog was thickening so that its presence could be seen and felt. As he turned onto the airport road he glanced at his watch: one-thirty in the morning.

The fog was so dense now his headlights bounced back as if in protest of penetrating an unknown wall. He reduced speed as he went south of the hangar line and through gaps in the fog he could see the hangars were cut in half by gray-black clouds. It felt like a giant hand had descended and compressed the buildings and trees to a new flatness.

The rain and fog had taken their painter's brush and created a soggy French impressionist painting of the airport.

He drove over the access road to the base of the control tower. He knew the beacon was flashing its white and green signal but except for a greenish cast to the wetness above him, it was not visible. He sat in the car for a moment with the lights out to regain his night visibility and his head was pounding again as his thoughts turned to a stiff drink to ease the pain. Not now, he thought, may be later.

He put his head on the steering wheel trying to remember. Remember what? How do you remember something if you can't recall what it is you're trying to dredge up? What came first, the headaches or the drinking? Or is it the egg or the chicken? He could think more clearly now as to why he was there. He was going up to the tower office and clean out his desk. The controllers would be gone since midnight 32

and he would be alone. His tower was one of the first to feel the economy moves with a reduction of hours of operation. There would be no one here until six o'clock in the morning. His mind wandered back to when he headed the busiest tower in the country. No closing at midnight or any other time. Now his thought process was clearing like fog in late morning. He could remember the staff meetings and the headaches and the drinking. Warnings from friends in the Regional Office. More warnings and letters and then a transfer to succeeding smaller operations until his last assignment here.

He held no ill will towards any of them. Why, hadn't they worked for him when they were boot controllers? Always a phone call to warn him when Regional people were on their way. They would look out for the old man. He smiled for the first time in days as he recalled the fine young people he had trained and promoted to positions of responsibility throughout the organisation. Now the temptation was too great and he reached for an ever-present bottle under the seat. Just a small drink to get warm. He continued to sit there mustering up the courage to go to the office. For the second time a smile crossed his face as he recalled his retirement party. Had to hold it in the hotel; his boys had flown in from every corner of the country to say goodbye to him. Bet they had a Xerox copy of the announcement in every Regional Office, Centre and Tower, and may be in other places too. His thoughts went back to the headaches and then to the attack. He never called it a heart attack,

just an attack, as if he didn't want to wake up his assigned Angel and remind him how close it was.

He had been in the office for about thirty minutes and had filled two shopping bags with trophies, plaques and certificates. He tried not to let his thoughts wander again, but several of the plaques made him think of the fine Association conventions he had participated in both as a socalled ATC expert and hell raiser extraordinary. He finished packing and left a note for Mary, the office major-domo, so she wouldn't think the office had been ransacked.

Ransacked, who in his right mind would steal this stuff?

It was then he decided to climb the two flights of stairs to the tower cab for one last look. One last look at what ... fog? His mind made up, he climbed the stairs slowly, ever so slowly.

As he reached the top of the stairs he could hear a faint call on the radio. One of the guys must have left the tunable receiver on. Surely no one was flying in this weather?

He walked to the local control position and stared out in the darkness at an ever-changing white to green mist as the beacon revolved. Again he heard a faint call. "Mayday, Mayday, November Six Eight Papa, Mayday, does anyone hear me?"

He could feel a sharp pain in his chest as he picked up the mike. "Nan Six Eight Papa, this is Rockdale Tower, over." He half hoped there would be no answer and that some other facility would hear the aircraft. "Rockdale Tower, this is November Six Eight Papa, I can hear you very weak.

I have had a complete electrical failure and am using my son's battery radio. My last known position put me somewhere near Rockdale. Can you find me and get me down?"

For the first time he looked up to the daylight radar scope above his head and through the rain clutter he thought he could make a primary target five miles west.

"Nan Six Eight Papa, this is Rockdale Tower. We are closed and there are no qualified people on duty here. The visibility is zero. Stand-by and I will call the Centre and get you a clearance for a radar approach to the Air Force Base.

This is the closest radar facility to us, over."

"Rockdale Tower, that won't help me now. I'm down to about five minutes of fuel. I was holding, waiting for the weather to clear. Is there anything you can do? Over."

He didn't answer right away. His thoughts went back 30 years to other approach control and radar rooms by the dozen until they merged into one darkened pit with red and green lights. It was at least 20 years since he had done a radar approach.

"Rockdale Tower, do you hear me? This is Six Eight Papa, Over."

"Six Eight Papa, this is Rockdale Tower, Roger, I hear you. Say your heading. Turn right heading zero nine zero ...

Roger, radar contact six miles west of Rockdale Airport.

This will be a radar approach to runway zero nine, wind zero nine five degrees at eight, altimeter two nine nine zero.

Say your altitude and type of aircraft ... Turn left, heading two seven zero degrees ... Report level one thousand five hundred ... Turn left heading one eight zero degrees ...

Turn left one two zero degrees ... Five miles from the runway, perform cockpit check for landing; start a normal rate of descent ... Turn left zero nine zero degrees ... Three miles from the runway, report approach lights in sight."

He knew the aircraft was answering but who was he talking to? Was it his voice giving these instructions? Why on earth did he have to take a plane with people and drive them through the fog, for an approach to what? His chest

filled with pain as he watched the target closer. He could hear a voice giving instructions to descend in the fog. It sounded like a tape out of the past. When the aircraft started its approach, he had called the town's fire department and told them to come out to the airport and stand by next to the tower but not to go on the runway until he gave the word. He turned the runway and approach lights to full intensity.

"One mile from the runway, report runway lights in sight, cleared to land." The pain was severe now and he knew what it was this time. He stared at the radar scope as the target disappeared over the last slash mark. Silence. Then a loud burst of power from an aeroplane engine close by.

"Rockdale Tower, I'm sorry but I didn't see the lights until I started a go around. I don't have enough fuel for another let-down."

"Nan Six Eight Papa, turn left two seven zero, level off at six hundred feet, this will be a two mile turn on ... Left one eight zero ... One three zero ... Zero nine zero, start descent ... When I say over the lights, cut the power and pull back on the stick gently and stall out ... Over the lights, cut power, now!"

Again silence. He gave himself 30 seconds and then started calling, Six Eight Papa, Rockdale Tower, over. Over.

Over. Over. His voice seemed to echo from the fog. Nothing could be heard but the squeaking of the beacon. "Engine One, proceed onto the runway and advise if you find the aircraft." A voice from the fire truck answered from somewhere in the fog below saying they would search the runway.

Some time went by and a constant chatter over the air indicated no trace of the aircraft on the airport. Police units searched the roads west of the airport for signs of fire. The fog continued to swallow up everything except their voices.

He got up now and paced the cab floor and stared at the radar indicator he had trusted. "Damm you! You told me the plane was right over the runway. You lied to me."

He talked to the radar scope and demanded answers. But no answers came. Finally, in a fit of rage, he hurled a coffee mug at the green image above him. The pain was now intense and it brought him to his knees. He looked up beyond the scope and out into the fog. With his knees on the floor and his head in his arms, a position he had not assumed since childhood, he begged God to forgive him.

For some unknown reason he clutched the mike in his hand as he died, as if God could hear him better on a clear frequency.

After several unanswered calls, the fire lieutenant dispatched one of his men to the tower. He found him in the cab and administered oxygen in a futile attempt to restore his life. While he did so the phone rang and the fireman answered it.

"Hello tower. This is the pilot of November Six Eight Papa. I'm calling from a gas station on the airport road.

I wanted you to know after we landed our batteries went dead and I turned off the runway onto what I thought was a taxiway and taxied about half a mile or so before the engine quit somewhere near the highway. Then we walked to this highway. Are you the man who brought us in? My wife and children want to thank you too."

"No sir. I'm a fireman who was out looking for you. The man who guided you down is not here now but I know he would want to know you are safe. Yes Sir, I think he would want to know that very much." (reprinted from the Journal of ATC)

33

Canada's ATC Simulation Centre* Canada is in the process of upgrading its ATC training facilities, and an ATC Simulation Centre has been constructed which is as real to controllers as 747 simulators are to pilots in training. Not only this, but the centre goes one step further: it simulates both present and future control situations. Training, however, is only secondary as the centre's main use is for research and development. This means that, if a control problem has to be worked out, or there is a need to experiment with new ways of controlling air traffic, this can now be done at the ATC Simulation Centre.

Located in a corner of a large government building in Hull, Quebec, the centre makes present simulators look as modern as a Super Connie. Specifically, the present ATC training simulator at the national training school in Ottawa has only one small computer (a PDP-11 target generator), surrounded by a mass of students and instructors. The new simulator in Hull has an entire room filled by a single computer. The equipment includes a maze of radar consoles and data boards, supported by an equally large maze of pilot position terminals in an adjoining room. The exercises simulate actual control conditions necessitating a- great deal of computer power.

The aircraft simulated on the radar screens actually respond in a manner identical to their real life counter-parts.

They take off, travel to their destination and land, all under the direction of a controller.

The display consoles differ from existing radar screens by presenting digitised radar information. This means that aircraft are represented by a triangle and a dash to the aircraft's flight identification and altitude. The image also includes four trailing dots to indicate the speed and direction of the aircraft. The flight identification and altitude can be moved to various positions about the triangle to avoid conflict with other data on the screen. The radar displays are digitised and simulate the radar screens to be used in the Canadian Air Traffic Automation Programme (the Joint Enroute Terminal System, or JETS, manufactured by IFATCA's Corporation Member CAE Electronics Ltd., Montreal). The JETS digitised radar display will be created by co-ordinating aircraft transponders with more sophisticated ground radar and a computer.

Of the seventeen control positions, ten are for training and seven for research and development. For the ten training control positions, there are ten radar controller trainees, ten data board trainees, ten support controller trainees, and ten pilot operators. Depending upon the complexity of the exercise, each pilot position operator is capable of flying up to 15 aircraft. In research and development, three radar displays are used by three controllers backed up by data board controllers, three support controllers also with radar displays, and six pilot positions. The other one radar display is for use by the supervisor.

The system can provide a variety of exercises in various configurations. It is capable of simultaneous and separate • Adapted for THE CONTROLLER from an article by Steve Jeffery, Evert Communications Ltd., Ottawa, and from an article by Ben Mooy, Digital Methods Ltd., Ottawa, first published in the CATCA Journal.

34

use for research and training purposes and for all exercises the controllers hand-off aircraft to each other just like the real thing. Digital Equipment of Canada computers were chosen for the simulation centre because they could provide the necessary interfacing capacity. For example, Digital's DEC System 10 computer has a multi-processing facility and can be interfaced with up to 32 mini-computer systems.

Almost as important, the mini-computers are small enough to be located in the housing of the radar displays. The functional specification for the system and the software for the DEC 10 were developed by Digital Methods Ltd. The software system consists of a tracking module, a pilot control module, and a radar generation module. The different modules interface through a large Data Base. All this operates under a DEC monitor.

How the System Works A program is selected for training or research and put on the central computer. The central computer feeds the information to the mini-computers which in turn drive the radar displays.

The radar screen may display an area with the radius of conventional radar ranges. When the controller observing the displays detects conflicting flight paths, he radios the pilot in the same way as he would in a real situation. In this case the pilot is a clerk sitting in the pilot position. When this pilot receives the information, he types in the required flight alterations to the central computer. The data goes to the DEC System 10, which contains all the flight specifications of the aircraft, and the screen image is altered in accordance with the aircraft's capabilities.

Each of the aircraft is provided with five flight profiles: departure, enroute, holding, approach and emergency. In turn, each of the profiles contains: a minimum, normal and maximum speed; normal and expedited bank angle; deceleration rate; acceleration rate; normal and expedited climb rate; and normal and expedited descent rate. On early simulators, if the controller was buddy-buddy with the pilot position operator, he could have the aircraft execute instant 90 degree turns. With the Hull centre, there is no cheating.

The pilot position only tells the plane what to do and the central computer does the actual manoeuvres according to the aircraft's specifications. For example, if the pilot types in a request for the aircraft to reduce its speed to 100 mph when the plane's minimum speed is 200 mph, a message appears on this screen advising that the procedure is outside the aircraft's capabilities. The pilot position would then advise the controller verbally that 200 mph is the plane's minimum speed.

An exercise area of 600 by 600 nautical miles is used as no allowance for earth curvature is needed for such a small area. A total of 160 aircraft can be tracked at one time (80 research - 80 training), with speeds from 0 - 3,000 knots, altitudes from 0- 99,000 feet, and a rate of climb from 0- 30,000 feet/minute. All this certainly enables the centre to load simulated airports and air routes to their limits.

During an exercise, the supervisor has complete control over it. He can freeze or continue the exercise, he can delete irrelevant targets and start up new targets. The supervisor can "quick-look" any controller's screen, which means

.. -,

that he gets identical data on his screen in the same brightness, the same character size and any other special condition existing on the selected display. During the exercise statistical data is collected on magnetic tape. This data contains all pilot commands entered, all controller commands entered, and target data.

l

;,'j/_fi!:f;~~--11

Systems Within The simulation centre has four major sub-systems: the central computer complex, 30 situation displays (radar consoles), 18 pilot position consoles and the communications sub-system.

Central Processor - The computer hardware for the central computer complex was supplied by Digital Equipment of Canada. The main computer room is lined with a DEC System 10 computer, linked to the PDP-11 mini-computers housed inside the radar displays. The DEC System 10 has a core memory of 128,000 words and makes use of a range of peripherals including a moving head disc memory, two magnetic tape transports, a line printer, a teletype and two Cathode-Ray Tube (CRT) terminals.

Situation Displays - The situation display sub-system consists of 30 radar consoles, 17 of which are supervised by nine PDP-11/05 mini-computers; the mini-computers are connected to the main computer through high speed transmission lines. Each mini-computer with 8,000 words of memory drives two displays, with the exception of the supervisor's display which has one to itself. The other 13 units are in the JETS configuration and will be installed in 1977.

Pilot Positions - The pilot position consoles, in addition to their primary function of serving to simulate "pilots", can also be used for program development of the ATC simulator.

All of the pilot position terminals and most of the DEC System 10 were used to develop software (computer programs) for the centre. Each pilot position terminal has a video screen which displays information as it is called up.

Integrated with the screen is an expanded keyboard for calling up information and providing directions for the main computer. One advantage of these units is that they are self training. When a clerk is being trained for the job, a program will be put into the computer and, by following the directions on the screen, the clerk will learn how to use the keyboard and "fly" the simulated aircraft. Training time is estimated to be between three and five days, not including basic ATC familiarisation.

Communications - The communication sub-system pro• vides all radar and pilot positions with the required simulated radio circuits, hot lines, inter-phones and dial-up telephones. The system uses Frequency Division Multiplexing, with a PDP-11/35 mini-computer providing control for channel switching.

tl)

I·. _:: ,. '

-

Controller Display with Communications Panel

a point to intercept while flying the new heading, the alti· tude to fly at, the airway to intercept while flying the new heading.

As one can see, a "sequence" is more flexible, but also more complex to use. "Sequences" are designed for aircraft manoeuvres such as heading, speed, altitude, departure, hold, approach and route. Furthermore there are "sequences" which allow transponder settings to be altered, request estimated time of arrival at a point and report at a specific point.

Some of the more interesting sequences are: The Speed Sequence - The speed at which an aircraft can fly is determined basically by the manufacturer of the aircraft. Performance profiles for the various stages of the flight, such as departure, enroute, approach, hold and emergency are supplied by the maker of the aircraft. These profiles show the ideal speed to fly at various altitude levels.

They also indicate minimum speeds.

Pilot Terminals Hereunder follows a more detailed view of the pilot terminals which are used to "fly" the aircraft.

"Functions" and "Sequences" - The commands to control the aircraft are basically of two types: "functions" and "sequences". The difference between these is the degree of complexity of the manoeuvre required. For instance a function is provided for heading corrections, requiring only the new heading of the aircraft to be entered. The sequence for the heading on the other hand gives various options, which are: a new clearance limit, the direction of the turn, the new heading, instead of a new heading the number of degrees to turn, the rate of the turn (normal bank-angle or expedite),

Typical Equipment Layout in R & D Area

35

When the flight plan indicates a speed higher than the ideal speed then the computer programs will generate an altitude/speed profile which is parallel to the ideal profile but not exceeding the maximum profile. As the ideal profile is not always parallel to the maximum, it could be that at the current altitude the requested speed is within the maximum limits. At higher or lower altitude levels however it is possible that the newly generated profile does exceed the maximum, in which case the maximum profile is followed from that altitude onwards. These profiles also cause aircraft which require no controller intervention to change speed automatically when the altitude changes. If however the controller instructs a new speed, then the pilot operator could use the speed sequence to change the aircraft's speed and to ignore the profiles (provided aircraft characteristics are not exceeded). The use of profiles of this type makes it possible to fly the aircraft very much as in real life.

The Squawk Sequence - This allows an aircraft to "squawk", causing its present position symbol to flash on and off on the radar screen for sixty seconds. This is to be used to identify an aircraft on radar in a busy traffic area.

Furthermore, the code transmitted by the transponder can be changed. The "mode-C" altitude can be switched on or off, if of course the aircraft is equipped to do so.

More dramatic options are to transpond various emergency codes, such as radio-failure and emergency. In all cases a specific code will start flashing on the radar indicating the emergency for that specific aircraft. The controller could in case of emergency use simulated radio channels to tell the pilot to execute an emergency descent.

The pilot position operator would receive the command through his head-set, and use the Emergency "function" key. All he is required to enter is the altitude the aircraft is to descend to. When the emergency is terminated, the transmission of the emergency code can be stopped by again using the squawk sequence to switch the transponder to normal.

The Route Sequence - If it is required to change the route of an aircraft, the pilot position operator can do this using the "route" sequence. It allows him to specify a completely new route, to become effective either immediately or at a specified point on his current route. The new route can be specified in various forms, from simply direct to a radio beacon to the more complex following an airway till intersection takes place with a radial of a radio beacon.

The Hold Sequence - When the aircraft gets into a busy traffic area, the controller can request the pilot to enter a holding pattern. The pilot operator, using the "hold" sequence, can then direct the aircraft to the holding point and specify the holding pattern. The pattern is laid down by specifying the hold direction, the outbound heading and the holding point. The outbound track can be flown for a certain time or distance. The aircraft would automatically leave its holding pattern whenever the clearance limit is moved up.

The Approach Sequence - The aircraft might then go into a terminal area and be given an approach clearance.

The pilot would enter the specified approach manoeuvre by using the "approach" sequence. The manoeuvre specified should bring the aircraft into position, altitude and heading, to enter the final approach-path. While making these manoeuvres the pilot could be requested to make progress reports. As far as simulation is concerned the air-

36

craft is considered non-active as soon as the centre of the runway is reached at runway altitude.

If however the approach is to be broken off during these manoeuvres, a missed approach can be instructed, and the aircraft would terminate the approach. The missed approach instruction could indicate to climb and go to a specific point and wait for further instructions. If new instructions are not given before this point is reached, a holding pattern is automatically generated and entered.

Altimeter Correction, Weather Conditions and Instrument Errors - A final function key of interest is the altimeter correction key. Aircraft do not usually fly at constant altitudes but at constant barometric pressure levels. When entering a different weather zone the pressure could change the aircraft's altitude quite drastically. The controller would however keep an eye on the pressure in its area and relay its readings to the pilot. The correction of the altimeter setting would cause a different reading on the altitude readouts. An automatic climb or descent will immediately start in order to stay at the instructed altitude.

During the total flight, weather conditions are simulated.

Wind strength and direction affect the track and speed of the aircraft, as does the barometric pressure affect the altitude. All of these weather parameters can be changed continuously.

To get even closer to real life, the system has allowed for the simulation of instrument errors. These errors affect the heading readouts (compass). altitude (altimeter readout) and the speed (speed readout).

Anyone Having Problems?

The centre is necessary for several reasons. Perhaps the most significant is complete testing of proposed solutions to control problems without having any disruptive effects on the real system. For example: if terminal controllers in Winnipeg have a problem, they can now use the simulation centre to find a solution. Controllers from Winnipeg and from the centre would work together to test solutions. Thus the centre would simulate airspace and aircraft that would never be available for experimentation in real life. In the same way, control standards and criteria for traffic, airway structure, aircraft types, volume and spacing can all be subjected to testing without disrupting any airports or endangering any aircraft. Further, controllers can be trained more thoroughly before being put into the real life situation.

The system was in the making for quite some time.

A description of the system and an estimate of the cost was completed in December, 1969. The program was approved in April, 1970 and by July, 1972 the Ministry had started to procure equipment. The central computer was delivered in February, 1973 and 18 pilot displays arrived in April, 1974. By October, 1974 the radar displays were being delivered and delivery of the communications sub-system took place in January, 1975. The centre commenced operation in April, 1975 although the delivery of the JETS displays did not take place until recently.

The staff is there to provide the environment and help in testing any problem. Training staff also directs some initial training and updating of IFR controllers. Some controllers will also come to the centre for instructor training.

The centre cannot operate without input from the outside - without problems to work on - problems normally provided by the average controller. With problems a plenty in the controller's daily routine, the centre should never be short of work.

FAA's Flight Service Stations In Modernization Process*

by G. J. de Boer

Home of the first AWANS, Charlie Brown (Fulton County) Airport

An Answer To The Challenge Of The Decade A major FAA objective in its Upgraded Third Generation air traffic system plans is improvement of the old manual FSS system. Airport-based Flight Service Stations provide vital information to general aviation pilots, significantly contributing to flight safety. The FAA currently operates more than 300 of these stations in support of general aviation activities, and their importance to flying is clear when over 98 % of the total active civil aircraft fleet in the United States are considered general aviation aircraft, and that there are over 750,000 general aviation pilots.

General Aviation is the fastest growing category of aviation, and its growth rate constitutes the challenge of the decade, which cannot possibly be ignored. In the U.S., it has doubled in volume during the last 10 years, and it will account for the greatest increase in the number of aircraft, pilots and hours flown over the next decade. By the early 1980's, the fleet is expected to grow from 153,000 to 230,000, to reach 262,000 by 1985. About 70 % of the over 30 million general aviation flying hours today, and which the FAA forecasts will reach about 55 million hours in 1985, are revenue producing. They include executive, business, air taxi, charter, rental, training and commuter • Adapted for "THE CONTROLLER" from details supplied by Mr. Bruce C. Abernethy, Director of Data Systems, Garland Division of E-Systems, Inc. (U.S.A), to whom any queries regarding this modernization process should be addressed.

flying, and add significantly to the nation's economy, totally dispelling the "flighty" image that General Aviation consists mostly of personal, local pleasure flying.

The number of services logged by Flight Service Stations are expected to almost triple by 1985, from 56 million in 1974 to 151 million in 1985, and this does not take into account general aviation activities at non-FSS and non-FAA airport control towers. It has been estimated that by 1990, such growth would compel the FAA to almost triple its manual FSS work force from today's 4,700 to well over 11,000.

Unless drastically overhauled, the existing FSS system, now costing annually around $ 80 to $ 85 million, would cost an estimated $ 300 million per year to operate by 1990.

Most of the present stations are antique, some are very busy, and some have relatively little load. The current system has difficulty in meeting the demand; it is configured along geographic lines that no longer coincide with the patterns of greatest general aviation activity resulting in great disparities in personnel productivity and utilization.

Second, and perhaps most important, it is "technologically obsolete" in equipment and procedures that require vast amounts of paperwork. The system is labour-intensive and response to the increased work load by making the system larger is not cost effective. The solution seems to lie in the installation of new automated, modern solid state equipment and facilities, with automated storage, processing and display features that will accomodate this expected general aviation growth without proportionate increases in FAA manpower and other costs. Highest priority has been given to those functions where automation is expected to yield the 37

Before AWANS: In-flight position at the preAWANS Atlanta FSS

greatest increase in productivity, efficiency and economy providing flight information and aviation weather to pilots and accepting, preparing and transmitting flight plan information by FSS specialists. The many services and functions performed by these specialists, with little or no control of aircraft involved, are more readily automated, in comparison to their counterparts in the Centers and Towers who operate in a real-time control environment.

Examination of the current FSS operations indicated that in order to provide improved services and flight safety to general aviation, the primary automation goals must be to improve the timeliness and usability of the information available to the FSS specialist and to the ultimate user (the pilot), to improve the productivity of the specialist by making all information necessary for pilot briefings readily available to him at his position, and - as much as possible, eliminate the generation and handling of paper. Once developed, the Agency estimates that the planned automated system could operate at one-third the cos( ·,of the present manual system.

surface aviation weather observations. Emergency services concern flight assists, such as to VFR aircraft that are lost, and the search-and-rescue alerting function and participation with search-and-rescue units.

With regard to NAVAID monitoring and IFR flight plans, serious studies are being undertaken to eliminate these services and their costs as FSS responsibilities, by transferring them directly to airways facilities, Centers and terminals. Dicussions are also under way to eliminate VFR flight plans, except for a special category of VFR flights - and flight following - over lakes, swamps and mountainous regions. The reasoning here is that the requirements for properly working and monitored emergency locator transmitters (ELT's) on most aircraft will make VFR flight plans unnecessary, and this will save in overall manpower and costs. However, at the present time it is uncertain whether VFR flight plans will really be done away with.

What Flight Service Stations Do

As part of a ten-year FAA plan to modernize its FSS facilities, a computerized flight-information processing and display system which was conceived in the Atlanta (Georgia) FSS in 1969, is undergoing a test- and evaluation program at Atlanta. The FAA commissioned the system from the Garland Division of E-Systems, Inc. (USA) in a $ 2.8 million contract. Known as AWANS (Aviation Weather and NOTAM System), the new system is the test-bed for new automated "no-paper work" flight services in the 1980's, and replaces the outdated and outmoded equipment which has been the only method of providing service for over 30 years. The Atlanta FSS is located at the Charlie Brown (Fulton County) Airport, a major general aviation airport.

E-Systems, Inc. started its FSS modernization program in mid-1972. The first part of the AWANS program involved conceptual design which was approved by the FAA. Detailed design started in early 1973 with the system being installed in March/April 1975; it officially became operational in July 1975. AWANS was designed to assist FSS specialists to perform their duties more efficiently,. thus improving flight

Flight Service Stations are essentially a briefing system, both on the ground and over R/T in the air. The purpose of any FSS is to provide to pilots a number of flight information services, grouped into three categories: (1) Air Traffic Control support activities, such as the accepting, processing, disseminating, progress monitoring and closing of flight plans; (2) pre- and in-flight NOTAM and en-route and terminal weather data reception, procession and dissemination; and (3) emergency assistance services. ATC support activities include the handling of IFR and VFR flight plans, relaying ATC messages and monitoring navigation aids. NOTAM and weather information handling involves the collection of several kinds of NOTAM data and aviation weather. It also requires the dissemination of interpreted data to the pilot by means of in-person and telephone briefings, by recorded telephone and radio briefings, by scheduled and unscheduled broadcasts and by en-route air/ ground communications. Many stations also make airport 38

What FSS Automation is Intended to Achieve

i

The AWANS installation

at the Atlanta FSS

safety, by handling a significantly increased work load without fatigue, but does not involve the concept of eliminating FSS positions. It accepts, processes, and provides integrated random access display, of selective NOT AM, weather, radar, direction finding and flight plan data, and urgent messages, advisories, AIRADS, central flow control messages, etc. It speeds up data transmission through highspeed digital links, replacing slow present day teleprinter and facsimile lines. As the FAA's then Acting Administrator, James E. Dow, acknowledged when he launched AWANS in July 1975, the FSS system had failed until then to take advantage of technological developments. "Unlike the Air Traffic Control system", he said, "the FSS system has remained at the technology level of the 1950's. A serious consequence of the system's obsolescence", he added, "was the amount of paper work required to keep it going.

FSS's are inundated with paper from a dozen teletype circuits. Record-keeping ... produces more work, making the flight service specialist a part-time clerk."

The system is intended to achieve, through the application of computer and display technology, more effective communications between the pilot and the specialist, i.e. face-to-face or voice-to-voice. And, it should significantly simplify pre-flight and in-flight briefings. Under the current FSS method, the pilot requests briefing on a route for which he is filing a flight plan; then, the specialist must usually wade through a maze of teleprinted data, facsimile maps and other material to obtain the necessary information.

With the new automated system, introducing the computerized briefing of pilots, the specialist only has to punch keys on a keyboard/cathode ray tube (CRT) terminal, and specific required data - including potential hazards along the route, weather conditions and other pilot-briefing essentials - appear almost instantly on a display screen. The keyboard is designed to enter commands and requests to the computer and is used for editing, storing and purging data.

One of the greatest benefits is speed: the system has available for immediate call-up and review any active flight plan filed through AWANS, and the specialist can recall and display on his video screen information pertaining to a

designated route or area almost instantaneously. Increased speed is one important factor in providing flight safety. In addition, in-depth pilot briefings are provided because of the availability of more detailed data from automated storage.

Of primary importance also is the automated reception of flight plans directly from the pilot.

There are important workload reductions. For example, automation eliminates the time-consuming task of sorting paper. It supplants the specialist's job of formatting flightplan messages and then manually transmitting them over teleprinter networks. Automatic formatting is accomplished and control characters are added prior to the automatic transmission of flight plans; this automatic transmission, also of status messages, significantly increases the number of pilot briefings and flight plans that can be processed in a given time period.

AWANS automatically alerts the specialist whenever information is received that requires immediate attention or action by means of coded flashing signals at the top of the CRT display. This includes both new information such as particulars of inbound flight plans, acknowledgement messages, weather advisories and warnings, and information which has been placed on one of the lists with a suspense time at which further action must be initiated and completed.

This distinct feature, Position to Position Message Communication with a display time factor, allows a message to be displayed at a certain time such as shift coordination.

The system maintains status data on flight plans for flight following, and it will remind the specialist of a problem should a flight plan not have been closed within a reasonable period of the estimated time of arrival. Event reconstruction is provided by the computer to assist in locating any lost aircraft, and if an aircraft is lost, the system enables the specialist to co-ordinate search and rescue operations.

Local weather is monitored by the system utilizing realtime weather sensors. Navigation aid status is monitored and auxiliary equipment controlled in case of primary equipment failure. AWANS can reconstruct, from historically maintained data, the complete events associated with a flight. With this feature all record keeping is automated so that systems operations and weather data are recorded.

39

Data also is available to count the number of flight plans, pilot briefings, the average time per pilot briefing, etc.

The FSS capability can be provided in a modular, modernized building which is movable and expandable.

System Configuration The main AWANS installation at the Atlanta FSS is built around a multiprocessor, mini-computer system, and includes the processors, display controllers, interface equipment and specialist position equipment. There are three processors (communications, display and off-line), each with 64 K words of 16-bit memory, which operate independently on dedicated tasks but communicate through inter-computer interfaces using direct memory access. The system can be reduced to a single processor configuration for low cost installation. The single processor configuration is basically the "fail-soft" configuration of a two processor computer program in existence. The three processor system design includes configuration switching (this allows full operational capability to be maintained in case of processor failure).

Associated with the processors are synchronous modem multiplexers, an asynchronous modem controller, graphics and alphanumeric (A/N) drivers, video generators and refresh memories for local displays, various device controllers and four disk controllers driving eight dual disk drives. There are 16 operating positions with video data terminals (VDT's) consisting of CRT displays and control keyboards. The specialist's VDT's can display A/N data which is recalled from the processor or composed from the keyboard, and can selectively display the NWS weather radar and facsimile data. Three character printers are used to print A/N display data for hard-copy records. A graphics preparation table is used to digitally compose weather maps for data storage and display on the CRT screens. Eleven well-mounted 23-inch TV screens are used to selectively display the NWS weather facsimile maps and weather radar images. Sixteen smaller screens at the operating positions are used in providing pilot briefings.

The AWANS software data base includes a complete U.S. airways system designation with coordinates as well as the weather reporting network including identification and location; it contains the geographic locations and identification of all radio navigation aids, airfields, the airways structure (both high and low altitude) including intersections, and observed and forecast weather data from all locations operating on a scheduled basis.

The installation is modular in design, and can be expanded from a standpoint of work stations, remote terminals and capabilities. Basic modules include a Data Processing Module (DPM). Man/Machine Interface Module (MIM), Data Communications Module (DCM), and Remote Interface Module (RIM). The DPM is a dual computer configuration with automated peripheral switch-over in case of computer failure. This feature assures that critical system functions are available 24 hours per day. The DCM manages all digital communications between the DPM and remote subsystems; it provides a wide variety of communications speeds from 75 baud to 4800 baud (9600 baud is available).

The MIM, within the main frame system, provides interactive capability between man and machine. Interactive graphics and alphanumeric terminals are provided each work station, and unique selection of NOTAM and weather data is accomplished. The DPM processes weather data in a form 40

that is easily usable and comprehensible by pilots. Furthermore, interactive consoles present weather in summary, graphics form as well as currently monitored by real-time weather radars. Flight plan and location of lost aircraft are further presented on the MIM consoles. Computer monitoring of flight progress aids search operations on overdue aircraft.

The Remote Interface Module provides remote terminal operations at field reservations and airport operations offices, but the most important function is pilot self briefing.

Under computer instructions and input interpretation, a pilot files his flight plan, has it automatically checked for completeness and safety and is briefed on all NOTAMS and weather associated with his flight. Another concept, calling for automated pilot self-brief terminals (PSBT) by 1985, involves primary pilot self-briefing with the specialist playing a secondary role, but AWANS today is designed to improve the efficiency of the FSS specialist, with pilot-briefing playing a secondary role. Other RIM work stations provide for "mini-FSS" time shared operations. Utilizing the main frame processor, operators at the "mini-FSS" flight follow, file flight plans and brief pilots via air/ground radio and telephone.

To test the concept of remoting a system, the AWANS installation at the Atlanta FSS is linked to four different remote locations. FAA Headquarters in Washington, D.C. (ATC Systems Command Center, with NWS meteorologists on duty) is connected by a dedicated telephone line and a VDT to request and display any desired A/N data. The FSS at Macon, Georgia, has three operating positions plus one hard-copy printer served by two dedicated telephone lines, through which any desired A/N data may be requested and displayed, flight plans may be transmitted and received, and locally generated weather information may be transmitted. A remote terminal is located at Atlanta airport; it has one operating position plus one hard-copy printer connected by dedicated telephone circuits which can request and receive any A/N data, and can format and transmit flight plans; pilot self-briefing is also provided for. Finally, the Atlanta NWS Weather Service Forecast Office (WSFO) has one operating position and associated hard-copy printer for receipt and transmission of A/N data, plus - additionally - a small mini-computer and six large graphics monitors to display any graphics and/or radar data available at the Atlanta FSS computer. The mini-computer is used to store the graphics data and drive the graphics monitors.

The AWANS Atlanta system is linked via modems over telephone lines to four external data sources. It is linked to the U.S. Weather Message Switching Center (WMSC) in Kansas City, Missouri. Through this high-speed hookup, AWANS completely stores within micro-seconds after receipt all the most current aviation weather observations, areaand terminal forecasts, winds aloft, weather warnings, etc. for the entire United States, Canada and certain selected locations in Mexico and the Caribbean; it can automatically receive and store 13 weather facsimile charts. The specialist can recall and selectively display all available A/N aviation weather information within three seconds or less from the time of request. In turn, AWANS transmits to the WMSC the aviation weather products generated by the Atlanta and Macon FSS's and the Atlanta WSFO. Normally this information is transmitted over the FAA's slower weather teleprinter circuit, known as Service A. It is further linked to FAA's Service B data interchange teleprinter network at Kansas City, which is used to transmit and receive flight

plans, for the reception and selective display of formatted flight-plan messages, and other aeronautical information, and allows AWANS to communicate with other FSS's. It is also linked to the National Meterorological Center weather facsimile circuit at Suitland, Maryland, which supplies graphics data to the system, and, finally, by a dedicated telephone line to the National Weather Service's slow-scan weather radar remoting system at Athens, Georgia, from where radar image information is received which is updated every ninety seconds. A capability also exists to automatically dial up at variable intervals four other NWS radars (the sources generally used are Centreville, Alabama; Waycross, Georgia; Nashville, Tennessee; and Apalachicola, Florida).

The AWANS system has re-dial capability.

AWANS Pilot self-briefing

position

Flight Plan Preparation and Briefing When a pilot calls for a briefing, the specialist uses a flight plan format on the CRT screen to prepare the briefing, and enters the information on the aircraft's identification, route, proposed departure time, time en-route and altitude into the AWANS by using the keyboard, and he will automatically receive complete up-to-date NOTAM and weather information. The computer assists the briefer in retrieving flight plan information. It automatically sorts, formats and transmits the information to associated ATC facilities involved with the flight plan. Safety checks are made by the computer on flight plan data with appropriate briefer alerts. AWANS also provides the briefer with the capability to check all reports, NOTAMS, forecasts, etc. for a particular area, then return to the original route without having to reenter the information provided by the pilot.

Each briefer has the capability to enter flight plans into AWANS for processing. After the information is entered, it becomes the responsibility of the systems data coordinator positions to process, edit and coordinate the information as required. The systems data coordinator must also perform editing functions on NOTAM or weather information to treat improper identifiers or formats which the system cannot store until corrected.

The AWANS has several "lists" or queues into which information is placed until no longer needed, at which time it is placed on a disk for fifteen-day storage. These lists consist of (1) a list of flight plans for proposed departure for which no departure has been received, or in the case of an instrument flight, a flight plan which has been transmitted to the appropriate Center, but for which an acknowledgement has not been received; (2) a list of aircraft which have departed, and messages have been transmitted, but no acknowledgement received; (3) a list of inbound VFR or military stopover flights which have not arrived or on which action has not been completed; (4) a list of aircraft for which search and rescue information has been initiated; and (5) a holding list which holds all information for a period of eight hours after entry, at which time it is placed on the fifteen-day disk.

The supervisor's position controls the entire system. The supervisor can obtain or check any data in the system, or enter any data he deems necessary. He can assign functions to individual positions, control the source of the radar displays, and monitor the overall operation of AWANS. A training cons0le allows a trainee to perform any functions of the other operating positions. This is a necessity because each specialist must become proficient both as a FSS

specialist and as a computer operator on the AWANS. He must have a current area rating and a regular pilot briefer's certificate and be certified to perform computer and radar briefings by the NWS quality control officer and the facility chief prior to operating the system as a qualified specialist at any position.

The in-flight positions have the same capabilities as the briefing positions to obtain briefing information, enter flight plan data and obtain radar data.

The specialist using the AWANS has instantaneous access to much more pertinent data than ever before as the need to use the old request-reply circuit and extensive delays caused by the low speed teletype system is removed, and he finds that one of its greatest advantages is its ability to confine the briefing information to that needed tor the planned flight. AWANS takes all the guesswork out of making decisions and minimizes the need for geographical knowledge from the briefer as to whether a route crosses or passes adjacent to a particular navigational aid or airport for which NOTAM or weather information is available. The system selects only specified routes and only pertinent information, and therefore aids flight planning. A pilot on a long range flight can be briefed as quickly, efficiently and thoroughly as he would on a flight in the local area.

NOTAM information is given in a condensed, standard format containing all that but only that which is applicable to the planned flight. All briefing information is presented in the same sequence as that which is specified in the directives.

The specialist at any position can check any information within the system without needing to coordinate with other positions. Each specialist and the supervisor can coordinate with each other by sending messages within the system.

Filing functions are performed by electronic means. Most paper work functions have been or will be eliminated.

Operational history is maintained for legal and activity analysis. Background software allows historical data to be processed for statistical report generation.

The noise level within the operations room is greatly reduced. There is no bumping, shoving or climbing over each other to obtain required briefing information; it is all available at the specialist's fingertips.

Weather Reception and Briefing An important AWANS function is the interpretation of weather and the analysis of its impact on aviation, and the system will provide much more detailed weather information 41

AWANS equipment at the Macon FSS, Georgia

than the present teleprinter system. Firstly, it will include surface weather observations from 700 nation-wide sites and weather forecasts from 300 of these locations. Secondly, complimenting A/N weather observations and forecasts are graphics weather products. The graphics products are sent to AWANS directly from the National Meteorological Center; they are stored in AWANS for display and are automatically updated on a circuit schedule basis. Lastly, from the 52 NWS radar sites, radar pictures will show areas from a 200 to 320 kilometre radius around them. To reduce transmission time of weather charts (facsimile type) greatly, AWANS utilizes a high-speed 4800-baud digital communications circuit and digital video compaction techniques.

AWANS has one dedicated and four dial-up radar circuits for a total of five simultaneous radar inputs. The dedicated line is generally associated with the local area weather radar (about 200 mile range). Received via a 3-KHz bandwidth circuit, current local and regional weather are displayed to the specialist on a random acces basis. The dial-up is accomplished automatically by the computer by the operator designating the reporting location identifier.

This gives the FSS specialist a real-time look at the terminal area and the originating area before briefing the pilot. The specialist can view the chart presentation on a large video screen in front of ttie· briefing sections, or, for,.more detailed /. ...:; analysis, display it on the individual CRT provided at his briefing position. Like graphics, the radar is digitized and stored for display.

Weather briefings concern the weather at a point, in an area, or along a route. The point or area may be a location with a radius of coverage which can be changed by the specialist to include from zero up to 127 miles either side of the flight path. This feature greatly aids the specialist and the pilot in determining a possible alternate route or airport. On a route, the nominal width of the flight corridor along the airway for which information is displayed is 50 miles (25 miles either side of the route), with the option of changing to either 20 or 100 miles. The same route definition data are automatically retained and used as a partial input to the flight plan filing procedure.

The system maintains three hours of weather reports for trend analysis, while NOTAM and Severe Weather Warnings are maintained until cancelled. The specialist can also request the weather for a specified distance around an individual airport or reporting station, as may be needed for a local training flight. A capability exists to highlight or extract specific weather information from radar or graphics 42

products and generate a simplif·:(ld presentation for briefing. Examples would be to define fronts or severe weather zones.

AWANS maintains an extensive weather data base stored by location, type, area and time. These products can be retrieved either directly or indirectly. Direct retrieval would be by requesting a specific type by location or area. Indirect retrieval is associated by entering departure, destination and route. The flight plan data are compared against the stored weather and the appropriate terminal-en route weather is automatically retrieved for briefer display. Modifications exist for defining area diameter around a terminal or width of the route. The briefing can then be given to the pilot as prepared by the computer. Specific, amplifying data can be obtained by an operator call-up of graphics and/or radar presentation.

Provisions exist for designating weather products for group viewing. Ten wall displays are provid for this purpose.

Several key work stations have a shared, separate display for which critical weather information can be maintained while their dedicated display is being utilized to prepare the briefing.

Latest FSS Development In January 1976, the FAA requested that E-Systems, Inc. start fabrication of a second AWANS system for the Washington, D.C. FSS, which will be co-located with the Washington Air Route Traffic Control Center (ARTCC) at Leesburg, Virginia. The system should be operational in early 1977.

The Leesburg system differs from Atlanta in that it will test the concept of FSS/ARTCC consolidation/co-location and it will evaluate the concept of consolidation of several small FSS's into fewer larger ones. The consolidation concept involves moving local area FSS's into a single facility.

The co-location concept involves utilization of the en-route ATC facilities to house the AWANS system. This concept was advocated by AOPA with the FAA agreeing to test the concept.

There are two points of view on consolidation. One point is that flight safety and pi lot service are best provided by FSS specialists who know the area weather, know the aviation facilities and know the pilot's capability. The other point of view is that the general aviation demand on FSS services are increasing at a rate that dictates consolidation from an economic standpoint. Plans are now being made by the FAA to continue the consolidation/co-location concept if no operational problems are encountered at Leesburg.

Other Applications AWANS has applications in areas other than FSS. Its technology is applicable to many aviation control, safety and weather areas. Airbase operations centers, commercial/ industrial air fleet operations centers and over-the-ocean Air Traffic Control Centers can utilize AWANS. It is a "natural" system for an airport information service supporting airline airport operations offices and pilot briefings. In any situation where pilots require flight information and specific route and terminal weather, or where flight plan filing and closure is required, the E-Systems developed AWANS technology is applicable. It is further applicable to military air force command post operations.

E-Systems, in fact, applied the AWANS experience to the Continental Airlines Flight Operations Center. This system designated SAFE (System for Automated Flight Efficiency) basically is an enhanced FSS with flight planning and release capabilities. The NOTAM/weather data are automatically interpreted by the computer for impact analysis on flight plans. Fuel calculations, alternate airports and alternate equipments are included in data processing functions. Flight following is accomplished by the SAFE computer utilizing airport office "IN/OUT/OFF/ON" reports and ARINC "OVER" reports. Rate Aid tracking is provided for position prediction.

Comparison is automatically made against scheduled operation to determine operation problem areas. While AWANS displays are monochromic, SAFE utilizes full colour displays.

Then there is AV-AWOS (Aviation Automated Weather Observation System). AV-AWOS will be installed at airports

to facilitate automatic collection and reporting of aviation type data. Future FSS's will receive airport weather from AV-AWOS.

Conclusion Some contend that the human element - the personal touch of an FSS specialist - is necessary to ensure flight safety. This is especially true, they say, regarding specialist interpretation of marginal weather conditions based on personal knowledge of the pilot and his aircraft. AWANS emphasizes the human element of flight services. With the developmental concept, as represented by the system installed at the Atlanta FSS, the specialist speaks via telephone with the pilot at home or at the airport, by radio with the pilot in the aircraft, and face-to-face with the pilot in the FSS itself.

News From IFATCA's Corporate Members AEG-Telefunken AEG-Telefunken has been awarded a contract by the Belgian Civil Aviation Authority Regie des Voies Aeriennes for the supply of a Series SRE-M 5 radar for installation at St. Hubert in the Ardennes region. The SRE-M 5 is a development in AEG-Telefunken's SRE-M series, with 2.5 MW Klystron transmitter and digital moving-target indicator system. The new unit will improve surveillance of southern Belgian airspace and provide an additional radar input to Eurocontrol.

Airport Lighting Engineering Consultants ApS This new IFATCA Corporate Member is an Organisation specialising in visual aid engineering, airport navigation, equipment evaluation and selection, installation and service.

Its operational scope ranges from the preparation of studies and the development of plans, to the supervision of projects under construction, as well as their maintenance and management when completed. ALEC will arrange package deals and assemble consortia to work on airport projects anywhere in the world.

The Company was established in 1974 to provide civil and military airport authorities with opportunities to benefit from the wide and successful experience gained by the Organisation's founder in projects undertaken on an international scale. In the following year, a co-operation agreement with Air Traffic Consult led to expanded capability, which today makes ALEC one of Europe's leading specialists in visual aids and Air Traffic Services.

ALEC's major clients include the Copenhagen Airport Authority and the Swedish Airport Authority. At Kastrup Airport, the Organisation is preparing studies for the development of integrated supervision, control and monitoring systems for navaid installations. In Sweden it is evaluating power systems for ATC Area supervision and control for the Swedish Board of Civil Aviation. In addition, ALEC is working on the development of new visual aids for installation in Scandinavia.

ALEC's founder, H. Gynther Hansen, is a graduate of the Copenhagen Teknikum who joined AEG Telefunken's Danish Company from the Danish Army Signal Corps in 1962 as Chief Engineer. Dedicated to power electronics and airport lighting engineering, Mr. Hansen moved to S0ren T. Lyngs0 Ltd. in 1969, and as its Chief Engineer - in collaboration with the Danish Airport Authority - developed the regulator systems and low-power equipment for approach and runway lighting installations now in use at Kastrup Airport. Mr. Hansen was thus responsible for the technology and the development of the power supply and installation methods now employed on more than 40 civil and military airfields throughout Scandinavia. Moreover, he has been closely involved in airport projects in Europe and Africa, including Zurich, Amsterdam and Nairobi, and he has lectured extensively on power electronics and visual aid engineering in many countries, including the Soviet Union.

Air Traffic Consult's Mr. A.G.T. Nielsen was Head of Planning in the Air Traffic Division of the Danish Directorate of Civil Aviation from 1960 to 1974. He has been closely involved in the detailed planning of the Copenhagen Saltholm Airport project, the noise abatement procedures introduced at Copenhagen-Roskile Airport, and the planning of procedures to increase Kastrup Airport's operational capacity by sequential integration of crossing runways into the traffic pattern. He was also engaged by the Saudi Arabian National Transport Survey to provide planning for the national Air Traffic Services.

Heading ALEC's international relations and marketing is Derek D. Dempster, formerly Director of the British Airport Construction and Equipment Association.

Cossor Radar and Electronics Limited Cossor has been selected as prime sub-contractor to install a£ 1¼ million primary radar system at Kuala Lumpur International Airport in Malaysia. The contract was awarded to Raytheon Canada by the Malaysian Ministry of Communication.

43

The radar is to be a Raytheon AGR-803, which has an effective radius of 60 n.m. This will present information on four Cessor CMD2016 radar displays, three of which are in the Control Centre, with one in the Approach Radar room.

Raytheon RDS-500 computers will generate a video map, process arrival and departure flight information and record the latest meteorological data on each radar display. This order is understood to represent the first ATC application of the RDS-500, and its presence in a primary radar system reflects a possible future requirement for radar data processing.

The arrival/departure information takes the form of a mini-table, which can be located anywhere on the display by movement of a rolling ball. With the mini-table comes weather data such as QNH, RVR, wind speed and direction, and air temperature. Data is entered through a Cessor DIDS 430 printer and two Cessor United-four alphanumeric displays. A dual digital moving target indicator is used by the radar, and communication to the control tower is on a broadband microwave link; a video tape recorder will be fitted to record the radar PPI display.

The processing capacity is understood to be more than sufficient for the present application, and addition of labelled displays and code/callsign conversion, if secondary radar is introduced in the future, should be possible within the existing system, the RDS-500 having 32k words of storage.

The primary radar system should be operational by late 1977.

Decca Software Sciences Limited A new IFATCA Corporate Member, Decca Software Sciences Limited is a company jointly held by Decca Limited and Software Sciences Limited, with a share ratio of 80/20 respectively. It has been specifically brought into being to enable the separate, well-known and complimentary expertise of the two companies to be brought to bear on the broad Air Traffic Control automation problems which they see as important developments for the future. They are particularly interested in real time data processing and display equipment which will aid air traffic controllers at the airports of slightly less importance than the major terminals such as Heathrow, Kennedy, etc. The new Company is aiming at the more medium sized airports in the developing countries around the world.

Thus, it can be seen that it is relevant that Decca Software Sciences Limited should be members of our Federation and they look forward to a close relationship and will do their best to contribute in any way which will further the aims and objectives of IFATCA.

Gustav A. Ring A/S Gustav A. Ring A/S have recently installed their latest Communications Control System at Amsterdam's Schiphol Airport. This new system named GAREX-14 forms an important part of the large SARP II project, which when completed will be one of the most advanced ATC systems in Europe.

The GAREX-14 Communications Control System is computer controlled mainly due to the complexity of the operational requirements. The system capacity is termination of 60 external telephone lines branched to a maximum of 60 controllers. In addition the system will also perform intercom between these controllers. The contract between Gustav A. Ring A/S and the Netherlands Civil Aviation Department is worth approximately £ 500,000.

44

Gustav A. Ring A/S have also recently delivered a 26 position integrated Communications Control System named GAREX-5 to Yesilkoy Airport in Istanbul as sub-supplier to World Wide Wilcox Inc. In addition to the delivery of the Communications Control System for external radio channels, telephone lines and intercom between the operator positions, G. A. Ring A/S's contract also included delivery of complete consoles for the Control Tower as well as the Radar Rooms.

The contract is worth approximately£ 200,000.

Marconi Radar Systems Limited Marconi Radar have been appointed as prime subcontractors for the supply by Svenska Radio of a number of mobile radar Operations Rooms {STRIL) to the Swedish Air Force, bringing extra mobility and greatly improved operational performance from temporary sites.

There are two types of STRIL units, known as operator and tele-cabins. An operations room can comprise any combination of operator cabins, with or without a tele-cabin. The computer used for data processing in both cabin types is the Marconi Locus 16. It was chosen after an evaluation by the Swedish Defence Research Organisation, which compared the performance of centralised and decentralised data-processing systems at a number of modern air-defence and ATC Centres. Decentralised computing showed in front, offering better failure-survival characteristics, simpler hardware and lower weight. These features, regarded as vital to a transportable system, were found in the Marconi Locus 16.

Furthermore, its modular design permits individual computers to be tailored to a variety of specific tasks.

Each operator cabin includes control consoles and dataprocessing computers. The consoles present radar information on a plan-position indicator and touch-mask tabular display, taking rolling-ball and keyboard inputs. Processors control the inputs selected for the displays, as well as the formats used on the display equipment, based on Marconi's Furnace.

Tele-cabins house several computers which control central data-processing. Similar equipment, the radar processor, controls radar data-processing and data-exchange with surrounding systems; a single computer generates simulation functions. There are two disc memories - one for each main processor - on cassette tape store connected to a main processor, and a specialist console with video displays and a hard-copy unit used for technical supervision.

Plessey Company Limited Plessey Radar has a $ 857,000 extension to a previously awarded $ 3.5 million contract from the British Civil Aviation Authority for a processed radar display system (PROS).

Additional equipment covered by the contract extension will allow computer processing of primary and secondary radar for middle airspace controllers (handling flights off airways).

PROS uses the Digital Equipment Corp PDP 11-34 computer, and will operate in conjunction with the IBM 90200 computer complex at the London Air Traffic Control Centre.

Thomson-CSF Because of the growing volume of air traffic resulting from its economic upsurge and the nature of its geography, the Government of Indonesia has decided to modernize its Air Traffic Control facilities. Two kinds of systems are to be set up for the purpose by T-VT, the Thomson-CSF subsidi-

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ary: an en-route Air Traffic Control system and five Approach Control units. The contract for the whole project, which has been awarded to T-VT by the Indonesian Civil Aviation Authority, is worth 80 million francs($ 17 million).

The en-route network will comprise six radar stations (RS 770 secondary radar interrogators) located along Indonesia's mountain range so as to cover the entire airspace of the islands of Sumatra, Java and Bali. The information picked up by these stations, including aircraft identity and altitude, will be transmitted by telephone to three Area Control Centres at Medan, Jakarta and Bali. Extensively automated, these Centres are to be gradually equipped with the necessary facilities for processing and displaying data from flight plans as well as radars. The system which has been adopted allows for future possible growth requirements. It belongs to T-VT's Aircraft series and will accomodate possible future expanded requirements, whether for extended coverage, enlarged centres, or transition to more extensively automated operation to meet increased traffic.

The planned Approach Control units will equip five of the country's main airports, at Medan, Jakarta, Denpassar, Palembang and Ujung Padang. The first three will receive both the data from the local primary radars and the data from the en-route network. The other two will process only the data from the airport radars.

On completion of this first phase of re-equipment, the Indonesian network will include four terminal-area and airport radars (two TA 23s and two TA 10s), six radar interrogators (RS 770) and about fifteen Air Traffic Control positions supplied and installed by T-VT.

T-VT is also engaged on a project in Sri Lanka, and is responsible for the upgrading of that country's ATC system, including the supply of a primary radar at Colombo with four display consoles, two for the Tower and two for the regional Control Centre. Equipment was chosen from the Aircat range, to permit subsequent extension with secondary radar and radar and flight data processing. The initial contract was concluded in April 1976 and the delivery of primary radar has since been effected.

Finally, T-VT has concluded a contract with Finland's National Board of Aviation for the supply of an automated Air Traffic Control system for the country's southern Air Traffic Control Centre. The system to be supplied will also come from the Aircat family, adapted to Finnish requirements. It will comprise secondary radar, radar data processing and flight plan processing; there will be four control positions with large-screen displays.

Aircat systems have been supplied to countries which include Germany, Colombia, Mexico, China, Switzerland, Brazil, Roumania and Ireland.

It is a never failing source of amazement (tinged with overtones of dismay) to me how speedily the time for getting out the CATCA Journal comes around. Have dread to think of a quarterly publication schedule, seeing so many problems with a half yearly one.

(P.B. Munnelly. Editor of the Journal of the Canadian Air Traffic Control Association)

45

Aircraft On Stamps

by G. M. Sinclair, Channel Islands Air Traffic Controllers' Association

Aircraft of the late 1920's and early 1930's In August 1973, the small Republic of San Marino issued at set of five stamps on the theme "AEROPLANI". The stamps are unusual, not only in that they feature aircraft not normally shown on stamps, but also that they show the aircraft in a form not normally seen on stamps. The designer has shown each aircraft in the three positions usually seen only on the drawing board or in technical papers or magazines. This unique treatment of "Aircraft on Stamps" comes across very well when the actual stamps are viewed.

The Couzinet 70 (25 lire) is probably best known by its association with one man - - and by the names given to two particular aircraft. The man was Jean Mermoz of France, and the aircraft were the "Arc en Giel" and the sister ship, the "Croix de Sud". Jean Mermoz was the Frenchman who pioneered South Atlantic air crossings in the early 1930's. Having succeeded with seaplanes (the Latecoere 28), he became convinced that landplanes were best for the service. He found the aircraft he wanted in the 3-engined machine designed by Couzinet. The three engines gave 2,000 h.p. and a speed of around 140 m.p.h.

In 1933, Mermoz flew from St. Louis, Mauretania, to Natal, Brazil (and onwards to Rio) in the "Arc en Giel" with a crew of four and with the designer Couzinet himself as passenger. On the return journey, with some 400 miles to go, the port engine failed. Ships were alerted and a Destroyer put to sea - but the aircraft continued and landed safely at Dakar. During 1934, the "Arc en Giel" and the "Croix de Sud" made twelve crossings of the South Atlantic. Jean Mermoz subsequently became a Director of Air France, but in 1936, whilst flying the "Croix de Sud", he again suffered a port engine failure over the South Atlantic on a scheduled crossing and this time no more was heard of Mermoz or the aircraft.

Shown on the 55 lire stamp is the Macchi Castoldi 72 an aircraft which held the world airspeed record for nearly thirty years. The aircraft was built specifically .to· compete in the 1931 Schneider Trophy race for Italy, but it was unable to do so due to development problems with its unusual engine installation. This produced tremendous torque which succeeded in driving the aircraft round in circles on the water. The problem was eventually solved by employing contra-rotating propellers to cancel out the torque. The design was then vindicated by its high speed results. The MC-72 was powered by a single 2,800 h.p.

Fiat 24 cylinder V-engine and had a gross weight of 6,409 lbs. with a single man crew. The aircraft made its maiden flight in 1931, but it wasn't until 1934 that Warrant Officer Francesco Agello of Italy flew the MC-72 at a world record speed of 423,85 m.p.h. (681,97 k.p.h.) at Lago di Garda. Six months later, in October 1934, Lieutenant Francesco Agello increased his speed record to 440,69 m.p.h.

(709,69 k.p.h.), also at Lago di Garda.

The Antonov 9 from Russia (60 lire) was designed by the famous Russian Andrei Tupolev, and became the most successful Soviet transport aircraft of the inter-war period.

Two versions of this three-engined aircraft were produced - one powered by Russian M-26 engines, and the other

by American Wright Whirlwind engines. The Russian 46

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engines gave a speed of 115 m.p.h. and a range of 620 miles. The American engines gave a faster cruising speed of 127 m.p.h., but decreased the range to 435 miles.

Both versions had a take-off weight of over 13,000 lbs and carried two crew and nine passengers. The maiden flight took place in 1929 and a total of around 60 were built.

However, with increased power from the Russian engines, the centre engine was dispensed with and the twin-engine Antonov 9 was produced from 1933.

The 90 lire stamp shows the Ryan N.X. 211, and this is an aircraft more readily known by the name given to it, and by the flyer associated with it. it is the "Spirit of St. Louis" with which Charles Lindbergh became the first man to fly solo across the Atlantic in 1927. Claude Ryan built his first aircraft in 1926 and produced something like 200 aircraft in all, mainly for the expanding airmail business in the U.S. Lindbergh managed to persuade Ryan to build him a special aircraft for his solo !rans-Atlantic flight from New York to Paris. The cost was $ 10,000 and this sum was collected from subscribers in his home town of St. Louis.

Lindbergh had amassed some 2,000 hours in all weather in the Air Service of the War Department, and since 1925 as an airmail pilot. He knew he was competing against people like Nungesser and Coli, Byrd, Chamberlain, and others to be first across the Atlantic solo - but he had plans to go across the Pacific, or round the world if someone else succeeded before he was ready. However, in May 1927, the aircraft was ready and Lindbergh set off on his epic flight. The Ryan N.X. 211 performed satisfactorily apart from a temporary drop in oil pressure near the English Channel. At this time he was some 2 1/, hours

ahead of schedule and calculated that he had enough fuel to carry on to Rome if he wished. He eventually landed in Paris after dark to a tumultuous welcome.

The aircraft depicted on the 220 lire stamp is the Handley Page 42 E which was the first 4-engined airliner in the world to go into regular passenger service and one of the small band of aircraft which became a legend. With huge wings and heavy bracing - engines in two-up, twodown arrangement - the HP. 42 was described as having "a gentle, lumbering, grace". The engines were laid out this way in order to reduce the noise level. The 42 E was built for the Eastern routes of Imperial Airways and was named the Hannibal class. Four of the type were built and

named Horsa, Hanno, Hadrian, and Hannibal. The 42W was built for western routes of Imperial Airways and again only four were built - named Heracla, Horatius, Hengist, and Helena.

The prototype (GAAGY-Hannibal) flew in 1930 and cruised at 105 m.p.h. over a range of 250 miles and had a takeoff weight of 29,500 lbs. The 42 E's seated six (later 12) in the forward cabin and 12 in the rear cabin with 500 cu.ft. of mail or baggage space in between. These aircraft were based in Cairo to serve the Eastern routes. Utilisation was very high - no aircraft flew less than 12,000 hours. Ironically, after years of safe, reliable service in peace time flying, five of the eight aircraft were lost during 1940.

Comments On Air Traffic Control Topics From Far And Wide John F. Leyden, President, Professional Air Traffic Controllers Organization (USA): It would seem, from scanning the FAA's plans for the future of aviation, that the major changes to come will be in the field of Air Traffic Control. Moreover, after a closer examination of the proposed hard- and software developments to be included in the Upgraded Third and Fourth generations of the ATC system, one may note that a byproduct of this further automation, as envisioned by the Agency, is the almost complete elimination of the air traffic controller. If the Agency planners are correct in their forecasting, the new technology, like data-link, positive control, and metering and spacing, will result in the controller as a manager/technician, watching the machines, monitoring the systems, supplying that - by then - marginally needed human element in greatly reduced numbers. In fact, FAA Administrator Mclucas has said that future controllers will be "system managers".

While this picture admittedly appears bleak to us, we are neither impressed nor convinced. We are reminded of the Agency's prognostications made through the late '60s and early '70s concerning the present Third Generation automated ATC system. ARTS and NAS Stage A were also sold to the U.S. Congress and the American public on the basis of removing highcost manpower, the controller, from the system, and replacing him/her with a more cost-efficient substitute: the machine. But today, there are more air traffic controllers in the system, more than two years after the implementation of ARTS and Radar Data Processing, than there were before. And while the Agency continues to maintain that the automated equipment effects increased controller productivity, not only has this not been proven, but controllers, while considering the equipment an asset, argue that the new systems actually add to their workload due to the additional time and effort spent typing in data, and the complex operation of these sophisticated systems. If one equates increased safety with productivity, then we would agree that the automated systems have made controllers more productive due to the visual presentation of necessary data. But automation has in no way allowed the controller to work more aeroplanes or allowed the system to operate with less controllers. For these reasons I beiieve that the future ATC system will continue to depend on air traffic controllers, to provide the unique and varied services which machines cannot.

Max Winter, Vice President, Professional Air Traffic Controllers Organization (USA), on the subject of management/ controller relations: Some people still believe that a controllers· union is necessarily evil and bad - that management must fight it forever to keep its own authority virgin. But being anti-union is as obsolete as being anti-automation in the radar environment.

David Trick, Vice President, Professional Air Traffic Controllers Organization (USA), in an address to a Symposium for Lawyers at Southern Methodist University: Perhaps the most graphic explanation on the diverse needs and problems of Air Traffic Control came from a person who was not a controller or a pilot; he was a senior system's analyst for IBM. At the time he was in charge of the computer program which IBM hoped would automate the ATC System in the U.S. This was the same gentleman who had worked on the automation project for NASA which resulted in the successful Apollo moon landings. When asked if his computers could lead a man to the moon, why it was taking so many years to write an ATC program, he stated: "In the Apollo program, we had only one spacecraft, flown by highly trained pilots, departing from one known point following one known route to one known destination.

In Air Traffic Control, you are asking us to provide a program that will track and analyze hundreds of aircraft simultaneously, flown by pilots of varying skills, departing from airports ranging from O'Hare International to Farmer Brown's pasture, flying different routes, at different altitudes at different speeds going to different locations. The human mind can cope with that situation, but I'm having a hell of a time getting my computers to do the same."

Andy Anderson, Head of CP7, Adelphi, British Civil Aviation Authority, on the future use of computers in ATC: The use of computers has now progressed through the natural and logical first levels of application, those of flight data acquisition, dissemination and display, but eventually the widespread employment of computers in Air Traffic Control will make possible the use of techniques that can scarcely be considered today. Already, the next most significant step in computer application has been to warn controllers whenever two aircraft were likely, if nothing was done, to get closer to each other than they should. But progress beyond this stage is not certain, although the next 47

step may well be the application of computer technique to assist controllers in the strategic planning of the air traffic flow. For example, one possibility may be to allow the computer to look ahead and calculate safe paths through the airspace, and offer these as possible solutions to the controller.

It is clear that such developments require careful examination, particularly where we are considering the use of computers to assist the controller in his decision making functions and in this it would be quite out of the question to experiment within the actual ATC system. Instead, we have to rely to a great extent on the technique known as "real-time simulation", in which all the essential ingredients of a system are reproduced synthetically, but which provides controllers with the look and feel of coping with a real situation. The function of the computer in a decision making role and the relationship between the machine and the highly trained and skilled controller is still largely unexplored. We are attempting to find out whether the mere notion of computer assistance in the control decision process is acceptable to controllers. Given that this is so and that such assistance is required operationally, we will then consider the extent and nature of the facilities to be introduced which in the medium term will be achieved through the continuing development of our 9020D Flight Data Processing and Radar Data Processing System.

In current experiments, funded by Eurocontrol under an agreement with the CAA, and linking up several fundamental ideas, the warning role of the computer is used to alert controllers to aircraft which stray from their allotted tracks.

The computer's capability to give assistance is exploited by using it to calculate conflict-free paths, and make the results available to the controller in terms of heights to fly, or times to start climb or descent. The method of predicting that aircraft's future positions in space was developed by the Eurocontrol Agency. The work of turning the basic ideas into a practical system is the result of the combined efforts of CP7, Eurocontrol, the R.A.F. Institute of Aviation Medicine and the Air Traffic Control Evalution Unit at Hurn Airport.

The work we have done so far is only a small step along the road towards what we hope will form part of a future control concept which will maintain, and - hopefully even improve upon present high standards of control as we move into a period of increasing complexity. Automation is the key to this new era in ATC only as long as it is used in the right way, particularly with regard to the relationship between men and machines. In our view the computer should be used to extend the innate capabilities of the men in a way that is itself absorbing and satisfying, and which creates a partnership that is much more powerful than either man or machine working alone. We see the man secure as the dominant partner, and would leave you with the analogy of the Slave of the Lamp. Mighty though he was, he always had to ask, "What is your will, 0 master?"

Cpl. C. C. Jackson, Executive Secretary of IFALPA, at IFATCA's Inaugural Meeting at Amsterdam, October 20th 1961: Air traffic controllers at least have this very great advantage: every one spends most of his working life in improvisation of some sort - improving traffic procedures, communications, rosters, etc.

Indeed the whole job is one complex improvisation.

Voluntary organisations like IFATCA are always short of funds, but if anybody can make out on the basis of an 48

inadequate budget, it will be a group of air traffic controllers. This they have been doing all their lives.

Webster Todd, Chairman, U.S. National Transportation Safety Board (NTSB): I am "scared to death" of certain features of the new automated ATC system. I am afraid of what will happen when we lose the last batch of guys that grew up on the broad-band radar and go completely to guys that have come up through the automated radar terminal system Ill or BRITE display.

The old fellows have 2 '/, to 3 minutes of traffic in their heads. It is there and it is there forever. That is the way they were trained. The new guys, if the computer does break down and the scope goes dead, have a 15-second period where they are really pulling things out of their ears trying to figure out what is going on.

I also believe that every new black box that comes along is not automatically an improvement on the system. We need more emphasis on studies of human factors. I really think we have to be careful that we do not get too automated.

Dr. J. L. Mclucas, Administrator, Federal Aviation Administration, Washington, D.C.: I do not think we have taken adequate account of the human factors problems which are involved in automation, and this is certainly an area where in fact we could use some help. The other day when I was out at Leesburg ARTCC, I asked an ATC instructor after his student had finished a particular problem, "What are you doing about conflict alert?" He sort of smiled, because this was a sensitive subject with him. He doesn't know in his own mind whether it is better to train with or without conflict alert.

He said, "If I have a student who accepts conflict alert as a 'given', then he has very little responsibility to avoid conflict himself. Whereas, conflict alert is supposed to be a back-up system, where the controller does 99.9 per cent of the conflict avoidance. And only in the rare case would the conflict alert ever be needed, but the kid who comes in and the conflict alert exists when he first sees the system, he takes that for granted." So, as I say, in the instructor's mind, then, the question is - should you train with conflict alert or without?

Editorial, entitled "Round pegs, square heads'", in U.S. BUSINESS WEEK, November 22, 1976: Controllers probably should be removed from Civil Service pay scales altogether. Few civil servants have jobs as punishing and tension ridden, and each year the load increases as the nation's airports handle more landings and take-offs.

It is therefore absurd for the Civil Service Commission to treat controllers as ordinary civil servants. The controller's job is vital to safe, efficient air transportation. The Commission is involved in a blind effort to force the air traffic controller into a job structure designed for something totally different.

Fred Farrar, Office of Information Services, Federal Aviation Administration, Washington, D.C., in an article published in "Transportation U.S.A.", Fall 1975: The Kansas City Air Route Traffic Control Center is responsible for 181,000 square miles of airspace covering large parts of Kansas, Missouri and Illinois plus smaller chunks of Iowa, Nebraska, Colorado, Texas and Oklahoma.

The heart of the Center is the control room, a cavernous chamber 186 feet long, with 18-inch-thick concrete walls designed to withstand the blast from a nuclear explosion.

16th Annual Conference International Federation of Air Traffic Controllers Associations NICOSIA-CYPRUS 25th-29th

NICOSIA. CYPRUS

April 1977

General Information Location

The Nicosia International Conference Centre. (near Hilton Hotel).

Official language

English Registration fees (per person).

Participants C £ 15.Accompanying persons C £ 10.These fees cover: Participation in the Professional Sessions Receptions, local Transportation, Lunches, Coffee-Breaks, Social Events, Ladies programme.

Whole-day Tour including lunch, kindly offered by Cyprus Tourist Organization.

Air Transport

Cyprus Airways and Olympic Airways have agreed to grant to Conference participants, and accompanying persons, 50 % rebate on all available fares for flights to Cyprus or Greece (or to any airport called by Olympic and Cyprus Airways for onward connection to Cyprus).

Ladies' Programme

In addition to the general social activities in which the accompanying ladies will participate, a diversified program will be arranged for them during session time.

Secretariat:

16th Annual IFATCA Conference CYATCA, Civil Aviation Nicosia - Cyprus

Statue of Aphrodite in the Cyprus Museum of Nicosia, Cyprus is believed to be the birthplace of the Greek Goddess of Love, and as such is recorded in Homer. A temple of the Goddess exists at Paphos and the beautiful locality Fontana Amorosa, believed to be the Goddess· bathing place.

Conference Programm Monday

25. April

Tuesday

26. April

Wednesday

27. April

Thursday

28. April

Friday

29. April

Registration Opening Ceremony Working Sessions Dinner Working Sessions Lunch Working Sessions Dinner Working Sessions Lunch Working Sessions Evening Free Working Sessions Lunch Final Plenary Session Dinner Party Conducted Tour with Lunch at Seaside resort( optional)

The Ancient Kourion Theatre enchanced by its idyllic situation overlooking the Sea provided, and still continues to provide, accommodation for an audience of about 3.500 people. Kourion I ies on the south-west coast of Cyprus 12 miles west of Limassol.

49

There are four rows of radar stations - one for each of the 37 sectors into which the Center's airspace is divided.

On an average day each of these is manned by two controllers. One follows the aircraft on the screen and the other assists him with paperwork and other tasks.

The Center employs 488 air traffic controllers - about half of them in various stages of training - and 115 electronics technicians and engineers who keep the radar, computer and other electronic equipment functioning properly. The cost of the Center was $ 23 million and the monthly operating cost is $ 1.1 million. On a busy day it handles 4,500 aircraft.

Jack S. Reynolds has been a journeyman controller at the Center for the last five years. He is working a sector that includes parts of eastern Missouri and southern Illinois.

He is responsible for all the aircraft under instrument flight rules from the ground to 23,000 feet. Other controllers are responsible for aircraft flying at higher levels and in other sectors. Thus Reynolds is handling aircraft bound for St. Louis, giving them directions to the point where the approach controllers at the St. Louis Airport take over. At the same time he is gradually bringing them down in altitude.

He is doing the same thing in reverse for departing aircraft after receiving them from St. Louis departure control.

Reynolds confirms the undercurrent of tension which one can feel. "You can stand behind a controller and say 'that looks pretty easy to me. You just turn those airplanes and they miss each other.' But you sit down in that seat and now it is not just data blocks, not just target symbols.

Now they represent people and if you make a mistake at any one moment, you could be responsible for the deaths of three or four hundred people. And that is definitely a factor in your mind. The tension is not something you sit there and worry about, it's just a job. And you have to realize, I think, that it is a job with a zero margin for error, where 99 per cent is not good enough. There are a lot of jobs where the quality control people say 'if we can get 99 out of 100 right, that's beautiful, we'll buy that.' But Air Traffic Control is not that way."

Reynold's fingers are continually working the computer keyboard. "We are about 50 per cent computer operator now. We are talking to this machine a great deal of the time.

But despite all the keyboard work, I like· the new system and consider it a 100 per cent improvement over the old system."

What kind of people make good controllers? "Not the ones that like to take a lot of time making up their minds," Reynolds says. "Some people like to weigh all the facts and take a lot of time making a decision. But the controller has only a short period of time to make up his mind. And he has to make it work. He can't change his mind in the middle of the stream and try something else.

It also requires undivided attention. "Most of the time you're handling five or six planes. But there will be periods when you are working 15 to 18 aircraft and your concentration is so intense that someone could walk up behind you and ask a question and you'd never hear it. Your priorities are always in the front of your mind."

If the demands of the job are great, so are the rewards.

Reynolds says: "To me, the rewarding part of Air Traffic Control is that you get an immediate reinforcement. You can see these airplanes being separated - descending, climbing - you are moving traffic. And there is no carry over. When you make a decision, the outcome of that decision is there for you to see. It's not like decisions which 50

so many make and they have to worry about them for the next few months or so.''

Reynolds adds that he doesn't think he would be happy in any other kind of job. "Once you key yourself to the job - key yourself to the pace that it demands - you'd find any other job very slow and without much challenge.''

David Trick, Vice President, Professional Air Traffic Controllers Organisation (USA): Many people, it appears, want to keep the air traffic controller out of the cockpit, but after a crash and the litigation that flows from it, they are the first ones to try to bring the controller into the cockpit.

Like IFATCA, IFALPA has its problems with IATA. We read in a recent IFALPA News Bulletin regarding the 20th IATA Technical Conference - Safety in Flight Operations (Human Factors): "If the 'last Frontier' in Aviation Safety is 'Human Factors', as Dr. R. R. Shaw, Assistant Director General - Technical - of IATA believes, and if pilots are an important factor in aviation safety, and if pilots are human, and if IFALPA represents 50,000 airline pilots, then you might ask: Where is the report of the IFALPA representatives to that Conference, an.d the response would be: there isn't one because we were not invited. The IATA meeting prejudiced its chance of success by not inviting IFALPA - in the same way that a Medical Congress would not be of much value if only administrators were invited and not doctors who actually tend sick people.

In some areas of interests, IATA and IFALPA very properly go their own ways but deep concern must be expressed that a 'closed' meeting of such importance should have been held without IFALPA representation. There were airline pilots present as delegates of airlines, Flight Operations Directors, Chief Pilots, Chief Instructors etc., and it is not alleged that they are less well motivated toward improved safety than we in IFALPA, but we do claim that IFALPA is a unique source of real life operational experience and information which is unmatched by ICAO, IATA or individual airlines. The most important reason why we should have been there are two human factors: Trust and Mutual Confidence."

PATCO strongly backs recent National Transportation Safety Board recommendations in its report on the fatal crash of an Eastern Airlines airliner at JFK Airport June 22 1975, killing 113 persons.

The Board recommended installation of new equipment to measure and identify wind turbulence at airports, and the increased training of pilots and controllers to recognize and identify dangerous turbulence. The U.S. controllers' union said these measures, along with previous NTSB recommendations to give controllers the authority to deny take-offs and landings in hazardous thunderstorms, would go far to reduce the chance of such accidents.

In a letter to NTSB Chairman Webster B. Todd, PATCO said: "We feel that these recommendations, when taken with those you made in April 1974, that controllers be authorized to deny approaches and landings during thunderstorm conditions, will go a long way toward preventing recurrences of crashes like the Eastern Airlines' accident at J.F.K." (PATCO Newsletter)

;,..

Larnaca

.,;,

Cairo Jeddah

Bahrain

It's been the same old story ....

Since time immemorial Cyprus has been called "the crossroads of the Mediterranean"such were the comings and goings.

So its hardly suprising that an International airline had root here.

And grew.

Today, CYPRUS AIRWAYS is pleased to announce, there are more comings and goings than ever. To more places than ever ...

15 major cities in Europe, Middle East and the Gulf States-and in splendid comfort, with fast comfortable jet liners.

Cyprus Airways THE AIRLINE OF CYPRUS

51

ACNA-Association des Controleurs de la Navigation Aerien ne (Morocco)

The Air Traffic Control

Center at Casablanca·s Nouasseur International Airport.

ACNA and SCNA ACNA, one of the five air traffic controllers' Associations who joined IFATCA at the Federation's 1976 Conference at Lyon, was born in 1972. Before that date, Moroccan controllers were organised in a union together with other civil aviation personnel. They were drawn into a strike which lasted for 11 days, but this dispute did not result in any improvements for controllers and some of them were even imprisoned at the time. After this, the air traffic controllers decided to set up a professional organization without union affiliation with a view to achieving genuine recognition for the controllers' profession in Morocco. At first, only those who worked at the Air Traffic Control Centre at Casablanca's Nouasseur International Airport belonged to the new group, and it took about one year to group together other controllers who worked in control towers spread throughout the country. At present, almost all Moroccan air traffic controllers are members of ACNA. SCNA, the Union as it is constituted today, was established in 1974. Controllers who belong to ACNA are now also grouped in this Union, but the two organisations - of course - have different Boards who function separately. Although both groups have generally the same aims, they employ different methods to achieve them. There are two main Unions in Morocco: the U.M.T., which supports the Government, and the U.G.T.M., which supports the Opposition.

SCNA is affiliated with the U.G.T.M. 52

Our colleagues in Morocco work under trying circumstances. First of all, they claim to receive little understanding from their Ministry. Secondly, there is the competition between the country's main Unions; the tendency of U.M.T. is to generalise all problems and this makes it difficult for controllers to obtain the professional recognition which they have set out to achieve. This is an old story about which IFATCA members are only too familiar. Another standard problem is added through the activities of other groups of employees such as the radio technicians who wish to have the same status as air traffic controllers.

Generally, however, controllers believe that they have the sympathy of the Director of Aviation, but his powers are very limited.

Conditions of Employment Recruitment: University entrance qualification is necessary.

Training: During training at the ATC School, the students receive 480.- OHS a month (approx. 120 U.S. dollars). After one year at the School, they have a further year of on-thejob training to undergo before being allowed to sit for their local ratings_ Weekly hours: Controllers work a 40-hour working week.

Salary: Varies from 1100.- OHS to 1600.- OHS per month, and is comprised of a basic salary plus allowances which come to: basic 700.- OHS plus allowances 400.-

OHS, to basic 1000.- OHS plus allowances 600.- OHS. In addition to this, controllers receive a sum of 32.- OHS monthly for doing shift work.

Pension: Varies between 40 % and 60 % of basic salary to reach a maximum of 600.- OHS monthly. Controllers as other public servants may retire after 21 years of service and must retire at 60 years of age.

Usually controllers have the same conditions of employment as the "adjoints techniques specialises" (specialised technical assistants) with the exception of the controllers' 40-hour week: the specialised technical assistants work longer hours.

An additional problem at Casablanca is that the Centre and the Airport at Nouasseur are 35 km away from the city and there are transportation difficulties. Generally it can be said that the conditions of employment are not good, and for that reason many of the controllers are trying to obtain better jobs. Fifteen controllers (a quarter of the total staff) working at the Centre are attending university and hope to obtain university degrees.

Conclusion ACNA is determined to benefit from its affiliation to IFATCA. Well aware of the advantages of public relations, the Association has mentioned its willingness to organise a meeting of the Executive Board of the Federation, and to organise an IFATCA Annual Conference in Morocco at some stage in the future.

Our fellow controllers belonging to ACNA are faced with the usual problems which are experienced by controllers in all developing countries. In the words of IFATCA President Monin, who visited the country not long ago, the Federation has a great responsibility towards them and we shall have to consider more carefully what the Federation can do to help the Member Associations in those countries to achieve recognition for their profession. ACNA should gain from their contacts with other Member Associations of IFATCA, but the Federation will have to define a general policy with a view to give better assistance.

ATC The Moroccan FIR is huge, extending to the North to 36°N 12°W, to the extreme West to 31°25'N/15°50'W, and to the Azores and Canaries TMAs. The boundary to the South extends to 27°40'N and to the East to the Algerian boundary.

The Centre at Nouasseur operates three sectors: one sector controlling Airway R10 coming down from Spain to Casablanca with an extension leading towards Marrakech; one sector controlling Airway A26 between Casablanca and the Algerian boundary, and the third sector is sometimes split into two and provides advisory services in the rest of the Moroccan FIR. The Centre controls between 500 and 1000 movements per day. Visitors to the Centre are usually impressed by the way the advisory sector(s) provide advisory service to the busy traffic which flows between Europe, the Azores and the Canary Islands, and to South America.

There are eight international airports in Morocco, namely: Nouasseur (Casablanca): 40 to 60 scheduled movements per day Tanger: 30 scheduled movements per day Rabat/Sale: 40 scheduled plus military movements per day Agadir: 25 scheduled plus military movements per day Marrakech: 20 scheduled plus military movements per day Oujda: 10 scheduled plus military movements per day Fez: 10 scheduled plus military movements per day Alhuceima: handles only seasonal traffic.

Technical Equipment The country is covered by 9 VORs and one VOR/OME. The Centre is equipped with primary radar but controllers complain that there are so many "angels" that the equipment is useless. There are advanced plans for the introduction of SSR. Air traffic controllers do not undergo radar training.

Communications Morocco is a country of great contrasts. As a vital staging post between Africa's West Coast and Southern Africa, there is a quite sophisticated automated communication system.

Publications- and Record Review

Claudia Jones

Oshkosh Tower, and Claudia Jones - tape cassette, available from Fun Flite Enterprises, P. 0. Box 144, Fort Atkinson, Wisconsin 53538, U.S.A., price $ 5.95 plus postage and handling costs.

This is a half-hour recording of Oshkosh Tower (Wisconsin) communications on August 2. 1974,when air traffic controllers handled a world record 13.645 aircraft movements in one day at the annual air show. The fastmoving patter lets the listener in on moments of tension, suspense and good humour as the world's tightest traffic pattern is handled with breathtaking efficiency with the sky turned black with inbound aircraft.

The systems message is this: as traffic density increases, the available channel time per airplane decreases. To move traffic, the non-essential call-ups and other formalities have to be eliminated.

In this example, air-to-ground communications are limited to a callin of aircraft colour and type when the inbound aircraft crosses a check point 1 'h miles NW of the airport, starting downwind. No identification numbers are used as they would take too long to say.

Tower communications then revert to a "don't call us, we'll call you" basis; the Tower identifies the aircraft and tells the pilot which air·

53

craft to follow in the pattern. All pilot acknowledgements are accomplished by flashing the landing lights or rocking the wings: these old-fashioned procedures have the priceless advantage of not using any channel time, while assuring the controller that the right pilot got the message.

The tape starts with the Tower landing all taildraggers on runway 18 and all tricycle-geared aircraft on runway 27: later everyone is using 27 with a unique piggyback landing procedure where No. 1 is cleared to land on the runway numbers while the No. 2 aircraft levels off 50 - 100 feet above the runway. As soon as the controller detects a satisfactory slowdown of No. 1, he clears No. 2 to land beyond the runway midpoint. Meanwhile No. 1 is expediting his turn off the runway so that No. 3 can be cleared to land on the numbers and No. 4 cleared to fly down the runway. As No. 2 seats off the runway and No. 3 starts to slow down, No. 4 is cleared to land beyond the midpoint ... And so it goes on, in a continuous sequence.

Any resemblance between the controller's patter and the stuff they print in the ATC Manual is purely coincidental. But the traffic moves, at a rate which would be unattainable if standard 2-way radio procedures had to be employed. The tape should be required listening for R & D planners and others who are trying to figure out how the Upgraded Third Generation goodies are going to solve tomorrow's traffic problems.

The other side of the cassette offers five calchy aviation songs

by Claudia Jones, Las Vegas entertainer and chief flight instructor with Oasis Aviation, the Piper Center franchise in Las Vegas, Nevada (some lady indeed, judging from the accompanying photograph sorry, chaps, no telephone number at hand). Her songs offer an appealing variety of themes varying from the fascination of flight to chuckling aviation humour. When asked about the lovely 3-part harmony in some of her songs, Claudia said: "that"s me singing with me singing with me"', referring to a triple-taping technique whereby the voices are added one by one to the initial recording.

Claudia could be one of the best female vocalists in the country if she wanted to be judging from the way she sings 'The Day I jumped from Uncle Harvey's Plane'. She can sing with sensitivity and feeling, and her love of flying gets through to the listener. Pity though that she never gets round to singing the ever-popular 'I was once Number One in Your Pattern, but now I'm just Number Two in Your Heart".

But you can't have everything.

TKV

Bird Hazards to Aircraft

by H. Blokpoel published by Clarke Irwin, Toronto, Canada, price$ (Bds.) or $ 5.95 (Ppr.)

Letter to the Editor Dear Sir, As a professional ATC Organization, the Air Traffic Control Association, Inc. is interested in professional excellence wherever it occurs. This year our Awards Committee recognizes IFATCA for the professional excellence over the past 14 years of the IFATCA journal THE CONTROLLER. Appropriately, the ATCA Merit Citation Award is to the two Editors who have given so much of their time and effort to achieve this excellence: W. H. Endlich who served as Editor from its first publication in 1961 to 1973 and who was quickly able to establish a fine professional journal in a language other than his own, and G. J. de Boer who in serving as Editor from 1973 to the present has been able to maintain the high standards set by his predecessor.

Please accept this Citation with our congratulations.

With best wishes for your continued success, Sincerely, G. A. Hartl, Executive Director, Air Traffic Control Association, Inc., Washington, D. C.

9.50

Bird Hazards to Aircraft, in outlining problems and prevention of bird/aircraft collisions, is the first comprehensive look at problems birds create for air travellers and some of the solutions which can be applied. Bird Aircraft Strikes have caused a number of fatalities and millions of dollars' damage around the world, and Mr. Blokpoel's book is the first truly comprehensive scientific study of this problem now available. It was written at the request and under the auspices of the Associate Committee on Bird Hazards to Aircraft, National Research Council of Canada, Ottawa, and publication was arranged in association with the Canadian Wildlife Service and Environment Canada.

The volume is well illustrated with photographs and drawings and international in its scope, though the Canadian aspects of the problem are emphasized. A detailed index, 12 appendices and almost 450 references make the information clear and easy to find. The book opens with pertinent information on birds and statistics of bird-aircraft strikes, then covers the methods of reducing the hazard - bird-proofing of aircraft, on-board devices to clear birds from an aircraft's flight path, reduction of bird numbers at airports, and warning techniques during the high-risk seasons of bird migration.

The final chapter describes how bird-strike reduction programs can be organized. As air traffic controllers can expect, special attention is given to the use of radar in trying to determine an "ideal" system to warn of bird movements, the problem of quantifying radar bird data, the calibration of radars for birds, and the research on "bird radars" for use in Air Traffic Control.

Hans Blokpoel, the author, holds a Master of Science degree in Biology from Leiden University, Holland. While in the Royal Netherlands Air Force he worked on the bird strike problem. Since 1967, when he emigrated to Canada, he has carried out radar studies on bird migration, and he has published a series of reports and scientific papers on his work, which has been directed toward a

54

reduction of bird strikes to aircraft en route. Mr. Blokpoel is a wildlife Biologist with the Canadian Wildlife Service in Ottawa, and a member of the Associate Committee on Bird Hazards to Aircraft of the National Research Council.

Although this book will be widely used by those most responsible for flight safety (air traffic controllers, pilots, airport managers, aircraft manufacturers) the wealth of information in it will make it valuable to everyone interested in birds or in aircraft.

GdB

The business community in the U.S. as of late has been showing a greater understanding of the value of the air traffic controller. The September 1 1976 issue of FORBES magazine carried this editorial: "Air traffic controllers are special because while at work their direct responsibility for the lives of air passengers is near total and mostly ceaseless. Air traffic controllers' concerns should concern us all. There are on occasion such things as special people and special cases, and here is a case in point."

(PATCO Newsletter)

Seeb Tower (Oman): Please taxi around the edge of the runway to avoid our newly painted runway numbers.

VC10 Pilot: Seeb Tower: VC10 Pilot:

Roger ... Oops, I've gone off the edge.

Please send a tractor.

Roger.

Sorry to cause you so much trouble, but your tractor has towed us right across your wet paint.

Almost 80 % of the staff of the British Authority are engaged in Air Traffic Control.

Civil Aviation

(Lord Boyd-Carpenter,

Chairman, CAA.)

FAITH And LO, there appear upon the earth in these days Great winged chariots wherein the people do ride; And the chariots are drawn by a thousand horses By ten thousand fiery hourses are they raised up.

Mighty is their sound and swift their travel; More rapid than the flight of an arrow, Even faster than the sound of the ram's horn blown in the hills, And the eagle they leave far behind.

Their flight is marvellous to see; nay, 't is altogether wonderous: For behold! the driver is blind. Yea the clouds encompass him.

The sun hides her face from him, the vapors of the night Draw close about him, and he seeth not.

Then we say unto him, "Go thee now up, for verily the way is clear", And he sees not but he goeth; being blind, yet by faith rises he Even into the heavens.

And later we say unto him, "Turn aside and go thus and so.

For thy chosen path is filled with dangers and with delay."

And straightway, trusting in the word, he turns and takes up The new way that is spoken unto him.

Again we speak to him saying, "Come thee now down and be not afraid.

For the way is clear; and though thou be now blind, In good time will you see a ball of fire running before thee And guide thee safely to the ground."

And it happens even as we have said.

And yet again we hear a voice, crying out in the night, "Help me for I am lost and know not my way nor whither I go."

We look out into the darkness with eyes that pierce the night And see for many leagues; and we find him And turn him from his wandering path; From the rocks and high places we deliver him; Out of the hills we lead him; Into the level land we guide him; And we shepherd him to a safe resting place for the night.

Tommy Eeasterling FAA Control Tower Greensboro, N.C.

Overheard in a Control Tower in Canada: Controller: Pilot: Controller: Pilot: Controller: Pilot: Controller: Pilot: Controller: Pilot: Controller:

For vectors to the PAR approach runway 32 turn left 230.

Turn right 230.

No. Turn left.

Right!

No. Left!

Left 230.

That's correct.

Confirm 230.

Right.

I thought you said "left."

Turn any direction you want.

(CATCA Information

Bulletin)

The letter was signed "Prettiest Swift on the Block," and it ranks as one of the most unusual pieces of correspondence ever received at the Ventura County, Calif., Airport Control Tower. You see, the "Swift" in this case was a 28year old airplane that had experienced a near-accident while making an approach to the Ventura Airport a short time before. But fortunately air traffic controller Lee Westfield noted that the landing gear had not been lowered and alerted the pilot. The accident was prevented, and the Swift (which turned out to be female, incidentally) wrote the Tower crew thanking them for saving her from the carelessness of her pilot/owner. We've seen the letter, and we found it sincere and provocative ("Come fly with me ... I'll really move my tail for you"). but we still have to question the authorship. After all, any airplane that can write its own letters should be sharp enough to check its own landing gear.

By Tractor Or "Railway" To The Holding Point?

Chances are that, before long, Tower controllers will not only control aircraft taxying to the holding point under their own steam, but also tractors specially designed to tow loaded aircraft from the ramp to the runway at speeds of up to 60 km/hr (nearly 40 mph).

It has fallen to the French to produce the first piece of hardware specifically for this purpose, and one massive new high-speed tractor costing in the region of $ 1 million, was demonstrated at the last Paris Air Show. Soaring fuel costs and long taxying distances have made airlines increasingly interested in more economical methods of moving aircraft on the ground. The critical payload/range performance of Concorde, and the long taxying distances experienced at Charles de Gaulle, were the particular factors which prompted Air France to draw up the requirement for a high-speed tractor.

The chief technical problem with towing aircraft to the holding point concerns braking. A reasonably high speed is needed to avoid undue delay and maintain the traffic flow, and the braking forces involved are considerable.

If the tractor is to supply the braking effort, problems oi tyre adhesion and the strength of aircraft nosewheel assemblies arise.

If tests show that the technical difficulties have been overcome, there are one or two other practical problems to be tackled before towing can become a normal practice.

One is the size of the tractor, perhaps making it unsuitable for push-back, and certainly for pulling back a B747 with the tractor positioned under the belly of the aircraft (a standard practice at some airports). There would have to be a change of tractor after the push-back was completed.

Another problem could be the attitude of pilots, who may be extremely reluctant to surrender control of the aircraft during fast taxying to a tractor driver, however well trained.

The use of such equipment for subsonic aircraft is likely to be influenced mainly by economic considerations, although there would also be a valuable contribution to the reduction of noise and air pollution.

In the United States, Lockheed Aircraft Services have also carried out studies (commissioned by the Federal Aviation Administration) with the object of finding ways to reduce noise and pollution on airports. It was intended that ways should be found to reduce the emission of pollutants by 50 per cent and cut taxying noise by 15 PNdB from the levels of 115 PNdB typically experienced on aprons.

It was estimated that the fuel used in a towing operation with a tractor would be 70-80 per cent of that used in conventional self-propelled taxying. Looking at a representative case, Lockheed found that at Los Angeles International, which has 400,000 movements a year, fuel used in ground operations would fall from about 49 million US gallons (185 million litres) a year to about 12 million US gallons (45 million litres). The amount of pollution would fall in direct relation to the amount of fuel burned. In the Los Angeles case, the emission of air pollutants - such as unburnt hydrocarbons, carbon monoxide and nitrogen oxides - would fall by 85 per cent.

An alternative to the use of large tractors is a "railway" system in one form or another, installed in the taxiways. In this cable/guideway idea, a light tractor is used to carry and manoeuvre a towbar connecting the aircraft to a sub55

surface cableway network, which would supply the motive power. An important objective of all the studies was to find a method that would not cause any reduction of airport capacity, but which would even, if possible, allow more efficient utilisation and higher movement rates.

Analyses indicated that capacity would at least be maintained, but the acid test lies in a full-scale field trial. Such a trial could also be used to confirm the cost benefit advantages of the chosen system.

Lockheed recognise the difficulty of not knowing who exactly is the potential customer for the system: the airport or the airline. But they point out that, "given awareness at airport and airline operational level," practical tests could be got under way in a year or 18 months, and claim that a viable system in operation would pay for itself in about three years at a busy airport.

Another company studying the market is Vanley Systems Inc., which proposes an automatic system with a highspeed diesel/electric tractor, able to tow aircraft at speeds up to 35 mph (56 km/hr) depending on all-up weight. At the heart of the Vanley Aircraft Movement System (AMS) is an auto-guidance system which would allow the captain of the aircraft to control the speed of the tractor from the flight-deck. The auto-guidance system would integrate signals from the pilot, from a collision-avoidance unit, and from sensors on the tow-bar and in the aircraft braking system, and would control steering, speed and braking.

It is intended that the tractor braking system would work independently or in conjunction with the aircraft system.

Routeing of the tow vehicles to and from the runway and terminals would be set up by Vanley Systems in consultation with airport and FAA officials. It is intended that the AMS system would be available on lease to airlines and charged according to use.

Airmisses over the United Kingdom, projected a few years ago as likely to be 250 a year by 1976 on trends at that time, are now running at less than hall that rate.

Special VFR Under Fire The U. S. National Transportation Safety Board has urged the Federal Aviation Administration to abolish Special VFR clearances and raise VFR weather minimums outside controlled airspace to that of controlled airspace.

The Board cited 44 fatal accidents in 1964-1972, which killed 105 persons. Special VFR clearances were involved in each case. Weather was the probable cause in one of the accidents and a factor in 38.

In a letter to the FAA Administrator, the Board has pointed out that under current Special VFR, weather conditions could be below the IFR landing minimums prescribed for an airline transport-rated pilot. But a student pilot, or a private pilot with low flight hours and no instrument rating; could be granted permission to land during daylight with a ceiling as low as a 100 ft. if visibility were at least 1 n. m. Search and rescue, police patrol, fire-fighting and other emergency operations could be conducted under waivers of minimum rules, the NTSB said.

(Aviation Week & Space Technology)

Some years ago, two aircraft collided at Nantes; recently, two aircraft collided at Zagreb. But because of that can you condemn the highly professional air traffic controllers who throughout the world arrange for countless aircraft to fly safely anywhere year in and year out, or can you condemn a surgeon who has saved hundreds of lives and who one day makes a genuine mistake? There are risks inherent in all professions, and those who seek most of all to correct, and who deplore the conditions which lead to mistakes, are these professionals themselves.

(FLIGHT International)

Inspector of Police, on French T.V., defending police action where bystanders were killed or injured

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Corporation Members of the InternationalFederation of Air Traffic Controllers'Associations AEG-Telefunken, Frankfurt a. M., Germany Airport Lighting Engineering Consultants, Birkerod, Denmark ASS MANN GMBH, Bad Homburg v. d. H., Germany CAE Electronics Ltd., Montreal, Quebec, Canada Cossor Radar and Electronics Ltd., Harlow, England Compagnie Internationale Pour I 'I nformatique, Le Chesnay, France Dansk lmpulsfysik A. S., Holte, Denmark Decca Software Sciences Limited, London, England Ferranti Limited, Bracknell, Berks., England Glen A. Gilbert & Associates, Washington D. C., U.S.A. Ground Aid Group, Esbjerg, Denmark Gustav A. Ring A/S, Oslo, Norway International Aeradio Ltd., Southall, England International Air Carrier Association, Geneva, Switzerland Jeppesen & Co. GmbH., Frankfurt, Germany Lockheed Electronics Company, Inc., Plainfield, N. J., U.S.A. The Marconi Radar Systems Ltd., Chelmsford, England The Mitre Corporation, McLean, Virginia, USA N. V. Hollandse Signaalapparaten, Hengelo, Netherlands The Plessey Company Limited, Weybridge, Surrey, England Racal-Thermionic Limited, Southampton, England Selenia - lndustrie Elettroniche Associate S. p. A. Rome, Italy Societe Artistique Fran<;;aise,Paris, France Societe d'Applications Generales d'Electricite Paris, France Societe d'Etudes & d'Entreprises Electriques, lssy Les Moulineaux, France

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