IFATCA - The Controller - FEBRUARY 1976

JOURNAL OF THE INTERNATIONA OF Al R TRAFFIC CONTROLLERS.

......

IFATCA'76 · 26-30APRIL· IFATCA'76

THE CITY OF IFATCA'S XVth ANNIVERSARY CELEBRATION

IFATCA

JOURNAL

OF

AIR

TRAFFIC CONTROL

THE CONTROLLER Frankfurt am Main, February 1976

Volume 15 • No.1

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

Officers of IFATCA: J-D. Monin, President, 0. H. J6nsson, Vice-President (Technical), R. E. Meyer, VicePresident (Professional), E. Bradshaw, Vice-President (Administration), T. H. Harrison, Executive Secretary, J. Gubelmann, Treasurer.

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

Telephone: (06193) 85299 Publishing Company, Production, Subscription Service and Advertising Sales Office: Verlag W. Kramer & Co., Bornheimer Landwehr 57 a, 6 Frankfurt am Main 60, Phone 43 43 25 and 49 21 69, 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: OM 6.- per annum for members of IFATCA OM 10.- per annum for non-members (Postage will be charged extra) Contributors are expressing their personal points of view and opinions, which must not necessarily coincide with those of the International Federation of Air Traffic Controllers' Associations (IFATCA).

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

Contributions are welcome as are comments and crlticl~m. No payment can be made for manuscripts submitted for publication in "The Controller". The Editor reserves the right to make any editorial changes In ~ai"u~c;lpts, Which he believes will Improve the mater a wit out altering the Intended meaning.

W~itt~n permission by the Editor is necessary for reprinting any part of this Journal.

F~tos: Archiv, L. Allwin, Bonny, Eurocontrol, J. Four-

CONTENTS

Air Traffic Control in the Soviet Union

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4

The AGARD 20th Guidance and Control Panel Meeting; Symposium, Part II

11

Aircraft Noise and the Air Traffic Controller

15

The Integration of Supersonic Transport into the ATC System

18

International Law, Part VIII

23

Surveillance Radar designed for improved Target Visibility

27

More about Radar Data Processing Problems in the U.S. ·

30

ATC at Copenhagen (Kastrup) Airport .

The General Aviation Pilot and Air Traffic Controllers · Secondary Radar for the smaller Airport News from Member Associations News from Corporation Members Airports and their Control Towers (3) .

Welcome to New IFATCA Corporation Members

32 34

36 39 40

43 45

46

nier, J. Lawrence, Marconi, Plessey, Gustav A. Ring, Stansaab

The Pilot's Point of View

Cover: Horst Guddat

News from the Federation .

Cartoons: Helmut Elsner

Publications Review .

Advertisers In this Issue: APCA/IFATCA 76 (inside cover), Rohde & Schwarz (page 3), Selenia Radar (~a~e 4), Cossor Electronics Ltd. (page 7), Ferranti D1g1tal Systems (page 24/25), International Aeradio Ltd. (page 47).

This issue contains the French Bulletin "La Gazette" ..useful information about the 15th Annual Conference. Lyon. France. 26-30 April 1976.

48

49

Editorial Stress On The Air Traffic Controller Much has been said over the years on the subject. Many papers have been written and presented at international gatherings, such as medical symposiums, and many more will undoubtedly see the light of day in times to come. Recently, a new Interesting study was accepted by IFATCA as its official presentation to the medical symposium which will be held in the United Kingdom shortly under the auspices of the British Guild. This frank study by a practising air traffic controller comes straight to the heart 9f the various stress factors under scrutiny.

Under the heading "Administrative Stress administered to the Controller", we read the following: "Senior Departmental Officers at Head Office and Regi~nal Office level are responsible for running the Air Traffic Control system, and many have been engaged in this field for upwards of 20 years or more. By accident of chance, as traffic increased they have been forced into senior positions with less and less contact with the active control of aircraft; consequently the majority have had no controlling experience for upwards of 20 years or more. This lack of up-to-date experience has had a detrimental effect on aviation with the constant, some unnecessary and finicky, others almost dangerous and many confusing changes to the Rules of the Air und ATC procedures. This has an overall stress effect on the controller as he is forced to bend, to interpret widely, or even break, these changes in order to expedite his air traffic with safety, realising that in recent years the only consistent factor in the ATC system has been change.

"Their remoteness from the operational aspect of aviation has conditioned these administrative officers to accept 'a reasonable margin of safety' as their philosophy of the airport, airways and ATC system. Their increased involvement in the administration of the system has meant that they remain trapped in the belief that fear of downgrading or dismissal of the controller motivates change, possibly because that type of discipline was instilled in earlier years and any temporary compliance makes them believe that controllers are only motivated by this fear and that individual controllers or even the controllers' Association would be changed by promoting and encouraging this concept."

People outside operational ATC, who have read this new study with interest, have asked if this type of stress really is administered to the controller. Judging from the letters and documents that come before me, I have no hesitation in replying in the affirmative, adding that in my belief this is a general world-wide trend, possibly with some exceptions here and there, and that in many places this type of stress has to be experienced to be believed and understood. There is no argument that in the running of a modern ATC service in our supersonic age, there is no room for a DC-3 mentality, but if this is pointed out within the environments of some Civil Services or other Aviation Organisations, they either don't want to see it, or cannot grasp it.

Yet, the answer is so simple. Involve the practising, operational controller directly in every facet of ATC operation, from national law-making to the drafting of regional and local procedures right down to the ordinary routine tasks at station level, and listen to him. There are some enlightened administrations who do just that. But many more do not, and more often than not the operational controller's viewpoint is ignored. Until they follow suit, aviation safety in their regions will not be what it should be. Every organisation of air traffic controllers should constantly ask to be represented at national, regional and local meetings where ATC comes up for discussion.

GdB

The Controller's Legal Liability (Part II)

by A. Avgoustls, LL. B.

oue to considerations of space, the second article in this series will now be published in our May 1976 edition.

2

ATC ground-to-air equipment

I

for frequency ranges 100 to 162 and 225 to 400 MHz Safety in aviation is only possible with precise electronic instruments and communications systems, such as those Rohde&Schwarz has been developing , producing and bettering for the past forty years. Rohde & Schwarz also offers you perfect service, from planning right down to maintenance and training.

Receiver - transmitter - transceiver for radiotelephony, solid-state and of flexi ble modular design : VHF/ UHF simultaneous receiving equipments EU 25 .. ./ED 21 ... with several channel receivers operating on one antenna. Along with this go preamplifiers and multicouplers.

VHF-AM 50-W transmitter SU 151 (1 channel) or SU 156 (6 channels), broadband design , no time-consuming tuning when changing crystal. VHF transmit-

ting system NU 156 (next to operator) , with six primary transmitters SU 151 , two standby transmitters SU 156 and automatic switchover unit. UHF-AM 30-W transmitter SO 131 (1 channel) of broadband design.

VHF-AM 10-W transmitter/receiver NU 001/2502 with transmitter SU 116 (6 channels). VHF-UHF 10-W transceiver XT 3039 - multichannel equipment particularly suitable for emergency status.

VHF/UHF antenna systems The multiple-utility omnidirectional antennas of the series HA 53 (above left) are particularly suitable for t'.an~mis­ sion and reception in ATC appl1cat1.ons.

Splitters and filters available for ~witch­ ing several transmitters or receivers to one antenna.

~DE &

Rohde & Schwarz Postfach 80 14 69 D-8000 Milnchen 80 Bundesrepubllk Deutschland (Fed. Rep . o f Germ any) Telex 5 23 703 (rus d) Electroni c Measurement s and Tel ecommuni cati ons: Development, manufac ture, safes and service, known t or " el ectronic precision" Independent concern (est ablished 1933), represented in 80 coun tries

SCHWARZ

selenia airport and • air traffic control systellls

Selenia offers advanced equipment for Air T raffic Control in c luding: • RADAR S • BROAD BAND AND NARROW BAND LINKS • DIGITAL DISPLAY SUBSYSTEMS • COM PUTERS • PRIM ARY AND SECONDARY RADAR EXTRACTORS • SIM ULATORS A ND DIG ITA L INTERFACE EQU IPMENT • AUTOMATED A IRPORT SUBSYSTEMS as we ll as • COMPLETE AIRPORT TURN-KEY PROJ ECTS

together with wide experi ence in: • SYSTEM DESIGN • SYSTEM IMPLEMENTATION AND INTEGRATION • LOGI STIC SUPPORT

- - - - -k

~-

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INDUSTAIE ELETTRONICHE ASSOCIATE SpA. CIVIL RADAR AND SYSTEMS DIVISION Via Tlburtina Km 12.400 - 001 31 Rome, Italy Cables: Sel enla Roma Telex: 61106 Selenlat Phone: 43601

Air Traffic Control in the Soviet Union New Developments on the Way Air traffic in the Soviet Union, as In all places where there has been an increase in air activity, has been accompanied by great changes in recent years. The performance of different types of aircraft has become more and more advanced and, with a general Increase in traffic, the demands on the technical traffic services and equipment have been intensified.

This rapid development creates many problems for the Air Traffic Control organisation, which is responsible for the technical traffic service and has the task of conducting air traffic in a well-ordered manner within the framework of international and national safety requirements.

A continual increase in procedures, which are to a great extent manual, is not, in the long term, adequate. Adding additional personnel does not produce the desired effect, since co-ordination occupies so much time that a corresponding increase in effectiveness fails to materialise. It is also desirable to decrease the human factors involved in the resolution of complex traffic situations.

An obvious way to ease the problem is to utilise Air Traffic Control aids, such as computers and electronic displays.

This automation permits better deployment of personnel and aims to increase traffic capacity without change of the traffic service structure, while - at the same time - functional safety is held at the highest possible level. It is, therefore, natural that the Soviet Union, as in other highly developed countries, has now decided on such an automation of Air Traffic Control. An order for ATC equipment, with a contract value worth 318.5 million Swedish Crowns (approx. $ 72 million), has been placed with one of IFATCA's Corporation Members: Stansaab Elektronik AB., Jarfalla, Sweden. ~he Soviet state purchasing authority V/O Elektronorgtechnika, acting on behalf of the Ministry of Civil Aviation and the national airline Aeroflot, is responsible for the purchase. Deliveries are to begin in 1976.

The project is of the 'turn-key' type, and as prime contract~r, Stan.saab will be responsible for the design, supply an.d. mstallat1on of the complete ATC systems package comprising fully op.era~ional units with computers, displays, radars, com.municat1ons, buildings, standby power supplies ~nd all ancillary services including documentation education and training of op erat•iona1 and technical personnel ' A . complete spare pa rt s h 0 Id"mg for two years' operation· will. be supplied, and Stansaab will furthermore provide assistance to the cust • · . t . omer s maintenance service during the f irs operational year c t · onsequently, Stansaab has total ~·ys e~ r:sponsibility towards the customer that the opera1ona units are delivered within the stated time-scale Stansaab Elekt · A . . · ronic B., Jointly owned by the Swedish Government and Sa b s . are contracted f A~ - cania A~., have already installed or West German or C systems m Austria, Belgium, France, land Yugosl Y•. the Netherlands, United Kingdom, Switzer' av1a and Swed Th reputation in th d en. ey have a long-standing systems wh"1ch e evelopment of computer-based ATC present comput er-processed radar pictures . .

Of airspace traffic in • 1 . rea -time. The value of the Russian contract is more than th . for 1974. Stansaab will b ree times the Company's turnover because its prod t• e able to handle the extra workload uc ion methods are h" hi d ·t b 1g Y automate . For example all c· The Co~panyir~~~ a~ard assembly is computer-controlled. average of one computer for every • t en emp 1oyees involved in manufacture.

The . . Soviet order was s ecured ·m the face of fierce compet1t1on, not least from the USA.

Contact with Stansaab In the Soviet Union, highly advanced manual methods have been refined for as long as has been possible, but in the long term these methods cannot go on handling the increased traffic volume, nor can they cope adequately with its growing complexity. The country's Air Traffic Services are run by Aeroflot, the national airline. Aeroflot is the world's largest airline and the Soviet Union's internal air traffic is greater than that of any other country, covering one-sixth of the world's land area. Aeroflot's administration made an early approach to Stansaab and, during discussions, Stansaab took the opportunity to document its specialised knowledge so that out of the operational and te~­ nical system discussions, a proposal for a complete Air Traffic Control system was formulated.

In the middle of 1973, Aeroflot presented a basic specification for the required ATC system. In October 1973, Stansaab made a budgetary offer and corresponding proposals were made by several American companies and by the French company Thomson-CSF. A little tater, an offer wa~ also made by Selenia from Italy. A suggestion for a co-ordinated American offer under the auspices of the Federal Aviation Administratio~ did not materialise. The FAA's view was that the same solution should be adopted as had been developed in the United States, where the different companies acted as subcontractors to the FAA, who had total responsibility.

The American company, IBM, took total responsibility · was for the American (FAA) proposal. However, the price very high, while the technical level of the proposal was. not considered to be in proportion to the price. The Amer~can FAA consortium therefore split up, and separate American offers were made by Raytheon, IBM, Univac and Lockheed.

Ultimately, only Univac remained as a likely candidate, seen from the American viewpoint. Univac's proposal was based on the ARTS-Ill system, designed for Terminal Area co;~ trot and was thus not suitable for En-route Control req~ired by the Russian tender specification.

After the offers had been made, Stansaab had a continual dialogue with different expert groups within Aeroflot.

Presentations and demonstrations of all kinds were made.

In the spring of 1974, a broadly-based sym~osium was held in Moscow for the Russian Academy for Science and Te~h­ nology. The competitors also carried out an acti~e mark~tmg campaign. Time after time items appeared in American journals that Univac was in the final stage of contract negotiations. It can now be stated that the main competition was between Thomson-CSF, also a Corporation Member of IFATCA, and Stansaab. Yet another IFATCA Member, Selenia SpA, became a sub-contractor for the radar stations which are included in the system.

5

TERCAS Since the first request for tenders was sent out in 1973, the project has progressively increased in size. In short, the project, which is called TERCAS {Terminal and En-Route Control Automated System), will consist of four operational ATC systems: three Terminal Control Centres {TCC) at Moscow, Kiev in the Ukraine and Mineral'nyje Vody {midway between the Black Sea and the Caspian Sea), and an Area Control Centre (ACC) adjacent to the Moscow TCC. The four centres will vary somewhat in size and composition according to local requirements and traffic density, but will otherwise incorporate the same hardware. For safety reasons, all computers and other key units will be delivered in duplicate so that if one component or system malfunctions its twin will instantly take over.

The nucleus of each operational centre in the TERCAS system will be a Stansaab multi-computer flight-plan and radar data processing and display system, based on the use of Stansaab-developed 'Censor' computer systems of modular construction. In the event of a fault, their fast operating speed enables re-configuration of the systems to be carried out without interrupting air traffic operations.

Each of the TERCAS centres will incorporate four computers {two of them duplicates), displays, radars, co~mu­ nications, buildings, standby power supply and all ancillary services. TERCAS will utilise data from existing primary and secondary surveillance radars and from radar systems to be supplied under sub-contract by Selenia SpA. All will be fitted with Stansaab radar data extractors for narrow-band data transmission. Computerised· fJight plans will be correlated with processed radar data which give automatic tracking of aircraft movements. The delivery of TERCAS will therefore give Soviet air traffic controllers a computer processed picture of the airspace situation in real-time. The controllers will sit at ergonomically designed consoles, each position equipped with a keyboard for communication with the data system. All relevant data will be presented on displays.

Assistance in building activities and the supply of building materials will be provided by BPA Byggproduktion AB, a Swedish construction company. As sub-contractors, Swedish architects A4 Arkitektkontor AB will act as building consultants. Voice communications sub-systems for the operational centres and the training simulator will be manufactured by TELi, the industrial division of the Swedish Telecommunications Administration. No-break standby power supplies will be supplied by ASEA.

Information Processing for Russian Controllers The traffic flow is determined by the air traffic controller in the centre (ACC or TCC), with the assistance of two principal functions. One function - flight plan processing - is based on information contained in the pilot's flight plan h "ch is stored in the system before the commencement WI f the flight and refers to the estimated flight pat h . S"mce a ~ontrol area is usually geographically extensive, the area is divided into sectors and, in each sect?r, a grou~ of controllers is responsible for control. The_ fh~ht plan 1s broken · accordance with the sectorrsat1on and for each down '"a flight strip is written out wh"1ch ·me Iud es th e a1r· sector eraft 's t'1m e of arrival and departure from the sector. The • and the flight strips together the control1 fhght pans . . enable . . traffic flow rn conformity with safety requ1rethe I ler to pan . . . ·nformation on the flight strrp 1s kept up-to-date ments. Th e 1 6

by using radio reports from the pilot of transit times over the sector boundaries. Amendments, for example due to a delayed start, require a new calculation of transit times and can thus require a re-planning of traffic flow.

Automation of flight plan processing implies that flight plans are fed into a computer and, thereafter, the different controllers' flight strips are distributed, via printers, to the various sectors. When re-planning, the controller may request a new flight strip with revised data.

The second principal function is closely allied with the classification positive control, i. e. all aircraft movements in the control area above a certain minimum height are detected and registered with the assistance of radar stations (primary and secondary). Radar data, in conjunction with the computer, provides automatic track following and, on the air traffic controller's display screen, an air situation picture can be presented comprising the positions of all the aircraft he has under his control, together with suitable identity markings.

The two principal functions coming together at the controller - flight plan data in the form of flight strips - give a picture of the traffic flow as it will develop in the future, while radar data processing gives a picture of the situation as it is at present. The controller utilises both these data sources, control and monitoring. The two principal functions appear in the Russian requirement specification, with the important addition that the computer complex shall be duplicated, with automatic control and monitoring of the computers and automatic connection of the appropriate computer complex.

MoscowACC In the Moscow control area - Moscow FIR (Flight Information Region) - positive (radar) control is exercised over aircraft movements. At Moscow ACC. all radar information, both primary and secondary, is collected, processed and presented on display screens. Moscow ACC differs from the other three centres only in that it controls and monitors air traffic over a much wider area. In this respect it acts as a complement to Moscow TCC, which serves the capital's four airports.

The building will be common to Moscow ACC, Moscow TCC, the Programming Centre and the Simulator Unit, and be completely equipped with electrical power, lighting, heating, ventilation and computer floor, necessary to provide full operational service of the ATC system. The building will have a no-break power supply, suitable space for customer supplied equipment, administrative offices and personnel rooms. BPA Byggproduktion AB will supply building mate· rial, erect part of the buildings and, furthermore, be respon· sible for their fitting out.

Moscow ACC will function round a computer complex consisting of four computers with four central processors.

Two parallel chains will be utilised, each therefore having two computers. Each chain is sufficient for the maximum capacity of the centre. An automatic monitoring system will provide instantaneous switch-over to the second chain if the first develops a fault. In each chain, one computer is responsible for flight plan processing, while the other pro· vides radar data processing. The monitoring function checks the processes within each chain - flight plan processing has priority over radar data processing. Depending on the extent of a fault and its location, a number of different redundant modes may be automatically switched in. The computers are provided with peripheral equipment, such as

In 1984 Cossor SSR will still be watching out for you . It. has been estimated by the Civil Av1at1on Authority that air traffic will increase threefold by 1984.

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

Why? Because airport authorities ~re i~creasingly adopting th e almostinfallible type of air traffic control system pioneered by Cossor, based on Secondary Surveillance Radar.

Recent SSR developments by Cossor mean that more aircraft informa-

cossor.,

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

Cossor's first experimental SSR was produced in 1950. Conti~uing development has led to the introduction of the SSR 990, a complete air traffic control system incorporatin g advanced data processing and display techniques.

It leads the world in radar technology.

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

--

~· ··'°· ""~ . ~, ...H!,- .

The first operational SSA 990 system is now being installed for the C iv il Aviation Department of the Hong Kong Government

Cassar SSA is servi ng Austr alia. Austria, Burma, Denmark.

France Hong Kong, Indi a, Lebanon. Netherl ands. Norway.

Philipp'ines, Sweden, Thailand , Turkey, Un i ted Kingdom. Zai re .

7

The advanced Simulator System for Sweden's ATC School at Sturup, Malmo 's new airport. The system is used for joint civil /military controller training and became operational in October 1974. The Soviet Union will be supplied by Stansaab w ith a simi lar unit but with some additional facilities.

disc stores, magnetic tape stations, line printers and tape recorders.

A large number of console groups will be provided for the controllers. Each console is divided into a number of positions and air traffic controllers will work at these posit ions where display screens are grouped together with control panels for feeding data into and out of the computers, controlling th e display presentation, processing flight strips, communication with adjacent control centres via telephone and to pilots via radio etc. The control positions have been designed in order to give the best possible working environment - in periods with high traffic density, controllers can be exposed to severe stresses. One console with three positions will be manned by technicians for system control.

A communi catio n system will bet built for communication both within the centre and with the different external installations. The system is in several parts, including an inte rcom installation with fixed wiring, a telephone installation with exchange for connection to the external telephone network and equipment for recording of operational speech communication. TELi , Nynashamn, will supply the complete speech communication system and will adapt its own eq uipment for mounting in consoles and to match the Russian teleph one network, including control and r:non.itorin~ fun.ctions for ground radio (VHF) for communication with aircraft. The company has had considerable experience of supp lying similar equipment to civil and military airports, both inside and outside Sweden. TELi will use L. M. Ericsson as s uppl ier of the telephone exchange. In addition to speech communication , a network will also be provided for data communication.

Moscow TCC While Moscow ACC is therefore responsible for a large area com mon to a number of airports and, in principle, monitors aircraft on airways, Moscow TCC has the responsibility for the overseeing and contr? I of aircraft which f~y oscow's airports. As 1n the ACC. control 1s to an d f ro m M . . ·t· · e is always based on radar information and the pos1 1ve, 1. · . pmen t is . to a large extent, the same as for Moscow equ1

8

ACC. The air traffic controllers' procedures will here also be based on data processed flight plans. The computer system will have two parallel chains, each with one computer with corresponding memory and peripheral equipment.

One chain is responsible both for flight plan and radar data processing and has sufficient size for the entire centre capacity. Control and monitoring functions give automatic changeover if a fault is · detected. The number of console groups amounts to twenty, and each consists of a number of positions with equipment similar to that for the Moscow ACC. Moscow TCC will also have direct data communication, both with the ACC and with the airport control towers where processed radar information will also be presented on displays.

Software is structured in the same way as for the Moscow ACC. There are differences in a number of special modules - Moscow TCC is responsible for approaches to and departures from the area's four airports and this requires special procedures. Voice communication also is designed in accordance with the same principles as for Moscow ACC. but is naturally adapted in size and operation to Moscow TCC. And here also TELi is responsible for s upplying the equipment. The data communication network is completed with Alfaskop terminals located in the control towers of the four airports. Flight plan data and meteorological information may be exchanged over the term inal syste m.

Programming Centre A programming centre is provided for. The operational centres' work procedures are determined to a great extent by the software which has been fed into the computers.

Software comprises an important part of the project and it has been specified in detail by Stansaab, in close collaboration with Aeroflot's operational specialists. The software system has software both for the functioning of the computer system itself and for technical traffic procedures.

The centre is to be constructed round a computer complex, with all the peripheral equipment which appears in the operational centres. For presentation, four Alfaskop terminals are used. Appropriate software will facilitate production of different types of program intended for the

Simulator Input Position of Stansaab's SATS System with the computer control desk in the foreground .

operational centres. Programming may take place in either a time sharing or batch processing mode. A compil er for high level language will be provided, as well as aids such as editing programs, diagnostic routines, etc.

Controller Training and Simulation of Traffic Situations In order to educate and train their air traffic controllers, Aeroflot's contract specifies the delivery of a simulator.

Instructors will supervise the trainees and, using different forms of recording, the instruction can be replayed for analysis. The simulator not only provides for education and training, but will also be used for testing and improving technical traffic procedures. The training centre will be constructed on the same principles as the operational centres, with the exception that the computer complex is not duplicated. There are fourteen consoles. In addition, there are fifteen positions for pilot functions. All aircraft echoes are generated by the computer.

Instructions from the trainee controllers are sent via the communication system to the pilot positions, where they result in inputs to the computer for changing/ correcting the movements of aircraft echoes. The situation of the pupils at their consoles is, therefore, as in real life. A ll their decisions and instructions are co ntinually recorded and may be replayed for ana lys is. Since two of the centres, in addition to narrowband transferred radar pictures, also have raw radar presentation , the simulator is provided with equipment which can reproduce the types of signal which are obtained from radar stations. The principles of operation of the simu lator naturally are the same as those which apply for the operational centres. ~he communication system, together with the recording equi~ment, has a more flexible design than that which is required fo r the operational centres. Widely differing traffic proc:du.res may be si mul ated, which require different communication routes. TELi is also the s upplier of this equipment.

Kiev and Mineral'nyje Vody TCC's The centres Kiev Tee and Mineral'nyje Vody TeC, serv-

ing the terminal areas Kiev and Mineral'nyje Vody, are constructed to the same pattern as Moscow TCC, but their traffic density is lower. The computer system is duplicated and has a large capacity for flight plan processing . The number of conso les amount to nine.

Kiev TCC differs in two respects from Moscow Tee. Radar data is transmitted in a narrowband form over telephone lines, but in addition there will be a broadband link for transmission and p resentation of raw radar. This results in the provision of sweep generation units and, in add ition, the display tube type must be selected for darkroom presentation. In centres w it h only narrowband radar transmission, daylight presentation can be used. Furthermore, the centre will be provided with a special fu nctio n for t raining controllers.

Mineral' nyje Vody TCC resembles the centre in Kiev.

The capacity figures are somewhat sma ller. Here also there is broadband transmission from the radar stat ion, as well as a special fun ction in the centre for training controllers.

Complete Radar System to be Delivered to Complement Existing Radars Proj ect TEReAS includes t he delivery of a n_u mber of complete radar stations, fully prepared for operational serv ice. Moscow ACC will be connected both to radar stati~ns delivered under the Stansaab contract and to already ex1~t­ ing soviet stations; th e latter will now be provided with duplicated extractors for narrowband t ransmission of rada r data over telephone lin es.

Signal outputs from the Russian rad ars fo llow a~ce~ted standards and provide no special problems. Taking into account the operational req uirements for the different radar stations, a basic specification for the radars was drawn up.

This has been used for evaluating the availabl e radar stations on the world market. After the evalu ation was completed, Selenia SpA was selected as supplier for the rada r stations. Each radar station will be duplicated. In general, a very high requirement has been placed on complete radar coverage with good operation, even in precipitation and seve re g round echo conditions. Starting from the spec if ied data for eq uivalent echoing area and detection probability,

9

Stansaab Elektronik AB's Invol vement in the installation of digital display systems in Sweden and other countries will be of much importance when the Russian system Is installed. This photograph shows the new centre at Gothenburg which became operational recently. An identical system is in the process of being installed at Sundsvall, North-Sweden.

the horizontal and vertical range was calculated. The necessary specification for the radar co rresponds very c losely w ith the requirements that the Swedish Civi l Aviation Authority pl aced on the new radar stations which w ill be req uired for the ATCAS project in Sweden.

Aeroflot is responsible for all work in co nnect ion with secondary radar. Data from these stations, together with data from primary radar, wi ll be fed to a duplicated extractor. By evaluating and processing the received strike pat-

ICAO Language Laboratory Proves Successful

A n English Language ICAO training proj ect was begun in January 1974 in Central and Eastern Europe. Funds for this venture were made available by IATA to improve the quality of Engl ish spoken by air traffic controllers in Poland, Hungary, Czechoslovakia and Bulgaria. In monetary terms, this is a small-scale project, but with regard to the number of participants and the total number of man-hours of instruction, it takes on a more impressive aspect. By the scheduled end of the project, 300 ATC personnel will have received 35,000 student-hours of instruction.

There are three main areas of concern in the t raining c ou rse : modern spoken English, the general and technical vocabulary of the field of aviation , and the specific ph raseology used in radio communicat ion. Th~ st ructu~es · · 9 95 per cent of standard conversational c omprisin . . Engl..1sh · rated · nto dialogues progressively increasing 1 are incorpo • in length and complexity. The dialogues are presented _as ·in d1v1 · "d ua 1 Iesson s and memorized by ,,the students with . . the aid of " ideograms" or "pictographs . At this learning students are stage, no wri"tten words are seen • and the . not permitted to write. After the introduction and explana.on o f a 1esson are comp leted • the new sentence patterns t1 are drilled in the language laboratory.

10

tern, the extractor will produce a data message containing only useful information. This wi ll comprise data concerning all detected aircraft in the radar's coverage area, together with information indicating the areas where heavy precipitation is being encountered. By setting appropriate criter ia in the different logic units of the extractor, extraneous information (ground echoes etc.) will be reduced to a m in imum. The extractors are provided with control and monitori ng faci lities fo r switch-over in the event of a fault. Russian direction finding stations (VHF) are also incorporated into the system.

Stansaab will take data from these for inc lusion in the extractor message to the centre.

Radar towers will also be provided for the radar stations included in the contract. These are built of st eel and w ill provide the necessary height fo r t he antenna and be constructed to withstand exte rnal environmental cond itions. The radar antennas will be protected wit h a radome against wind and weather. At each radar site, there are included standby power supply, spare parts storage and vent ilation equipment. It is intended to purchase the radomes in Norway, where they will be manufactured under American licence by Selca (Norcem). The Norwegian company has had a number of contracts for the same type of radome in Sweden.

At Kiev TCC, transmission of radar information is made via a cable. At Mineral'nyje Vody TCC, terrain conditions require transmission to be made via two mic rowave links, even though the distance is not great. Each link is provided with an intermediate station (reflector). T he transmission principles are very si milar to those w hich are used for television, with the addition of equipment for the modulation and demodulation of radar signals, together w ith telephone channels for com munication and monitorin g of the radar station.

A language laboratory is not a teaching machine and it is not designed to repl ace a teacher. Rather, it is a tool, albeit a very effective one, which reinforces proper speech habits previously introduced and explained. It is of little value in teaching vocabulary; this is not its purpose.

The advantages of a language laboratory are obvious · In a normal classroom situat ion, a teacher can ask possibly six questions per minute, producing six responses. In one minute of laboratory drill, a group of 25 stu dents can produce 300 responses, and also hear the teacher's response to verify and to repeat their own.

Th is project has served as a model classroom fo r many interested observers from the Host States, as well as from the USSR and the German Democratic Republic. And it already has produced a marked improvemen t in the quality of communication. One of the problems encountered has been the difficulty of making 25 ATC person nel available fo r classes at the same t ime. This is especially difficult at smaller airports, where the work schedule is not as flexible. In Czechoslovakia, the Administration managed to make 25 students from airports all over t he country available for an intensive six-hour-a-day course of twomonth duration to be repeated four or five times, depending on time available. It is in this type of course that t he best results can be achieved.

(Laird D. Taylor, Instructor, English Language Laboratory. !CAO Technical Assistance Bureau, in the !CAO Bulletin)

The AGARD 20th Guidance And Control Panel Meeting/Symposium, Part II

by V. D. Hopkin From 20 to 23 May 1975 In Cambridge, Massachusetts, the 20th Guidance and Control Panel Meeting of AGARD was held on the topic of "Plans and Developments for Air Traffic Systems" . The present status and future plans for much of Air Traffic Control were covered in the proceedings. The Symposium consisted of seven sessions covering respectively navigation, surveillance, automation, airports, approach and landing, advanced concepts, and system performance measures. Navigation, surveillance, and automation were covered In the November 1975 issue of 'The Controller'.

Airports The papers in the fourth session on airports were classified in relation to capacity, surface surveillance, wake vo rtices and fog dispersal.

Dr. R. M. Harris of the Mitre Corporation examined the impact of future air traffic control technology improvements on aircraft capacity. The capacity improvement developments considered included metering and spacing of final approach traffic, wake vortex avoidance systems and reduced longitudinal approach spacing, reductions in lateral spacing fo r simultaneous parallel instrument approaches, improvements in runway design, and microwave landi ng systems. The impact of these various capabilities and benefits on majo r United States airport terminals was discussed and certain changes were predicted within the next three years. These included a reduction in longitudinal spacing from three miles to two miles , much improved accuracy of timing in approaching aircraft, progressive red uctio ns in lateral spaci ngs down eventually to 3,000 feet spacings, frequent use of dual lane runways, the adoptio n of curved app roaches and departures to meet noise abatement requirements, the occurrence of semiautomated surface traffic control, and a substantial increase in the overall IFR operations rate.

The first of three papers on s urface surveillance was given by Mr. H. N. Griffiths of the Royal Radar Establishment who considered secondary radar for ground movement control. Existing secondary radar systems provide inflight monitoring of aircraft but do not identify and label aircraft movements on the airfield surface. A method of using secondary rad ar for ground movement identification was outlined which could have sufficient positional accuracy to label a high definition primary radar display of airfield ground movements. He described an experimental ground movement secondary radar installation at an airfi eld and the results of trials with it, which were encouraging.

Methods of improving the performance of the basic system were indicated and future developments suggested.

The second paper on surface surveill ance was by Mr. J . W. O'Grady and his colleagues of the Air Transportation Systems Centre. They predicted that the need for improved airport surface traffic control would reach c ritical stage in the United States by about 1980 when s ~ face traffic levels during poor visibility cond itions would~ co nsiderably higher than today, due to the forth . e deployment of additional categories 2 and cl omd'.ng 3 an ing . syst~ms. The requirements of an advanced airport surface traffic contro l system had been developed, and th "d ent"f" e techno Iogy 1 11e d f or t h e sensor part of th E I . th . t ff e system .mp oying e air ra 1c control radar beacon repli es fro~ aircraft transpo nders and tril ateration rece·i ve f .. . rs o r accurate pos1t1on location and. vehicle identification enables the senso r system to satisfy the performance d d" an rea in ess

V. David Hopkin

requirements of 1980's goals. A system is currently being made to enable an empirical validation of these proposals in order to confirm that they are viable.

The third paper on surface survei ll ance was by Mr. G. G. Plottin of the Central Telecommunications Laboratory in France w ho described the CORAIL automatic runway surveillance equipment. This equipment has been shown to provide total and permanent s urveillance of the runway, with the abi lity to detect intruders such as cars, small planes and bird flocks. It has been preferred for the display . . t ed t o lead to about a 20 D/o of final approach and .1s est1ma . .increase in lan ding . . · traffic during Peak hours · Because 1t also gives information on exac t pos1Ton 1 at touch down and · ·t rovides a powerful on actual speed and deceleration 1 P . analysis tool for the statistical treatment of landing data . . . d b Dr J N Hallock and his Two papers were dellvere Y • • • . . co lleagues of t he Transportation Centre, both dealing with ices One of these concerned the aspects of wa k e vo rt · . . t· of predictive techniques for wake vortex avo1d esc n p ion k dance and the other described the resu lts of the w~ e voreathrow Airport. Future work 1s plantex programme at H . dy Airport. Aircraft wake vortices represent a K ne d a t enne . t· · 1mpe · d 1m . ent to inc reased runway capacity. epa ra ion maior . . en·ten·a mu st be conservative most of the time so that traffic

s

11

can be unnecessarily delayed by always adhering to the present inflexible regulations. Systems employing vortex tracking sensors or meterological sensors to determine safe reduced spacings are being designed, and any wake vortex strategy must rely upon the ability to predict vortex transport and decay. Models based on observed vortex behaviour have been built and are being tried. Over 9,100 vortex pairs have been recorded at Heathrow airport and subsequently they have been analysed and their motion correlated with the meteorological conditions. If the cross wind component near the runway threshold exceeds 5 knots vortices linger near the extended runway centre line for a time in excess of one minute for less than 0.5 O/o of the landings.

This small remaining percentage is almost entirely due to vortices from heavy wide-bodied jets.

Dr. H. Wenzel described current research on fog dispersal and showed a film of his findings. Dr. Wenzel is based at Linde AG in Munich, Germany. He described a ground based fog dispersal system which offered improved prospects of economic warm fog dissipation by using a new heat pump system with favourable thermodynamic properties which result in an essentially low power requirement.

The artificial visibility improvement by fog dispersal systems is considered a valuable aid for safe aircraft operation under all weather conditions, and he believed that international co-operation should be encouraged on fog dispersal and in research on resolving the problems associated with it.

Approach and Landing The fifth session on approach and landing comprised five topics: microwave landing systems, instrument landing systems, visibility measurements, independent landing monitors, and metering and spacing. The microwave landing system being proposed by the United States to the International Civil Aviation Organisation was described in a paper by Mr. J. Del Balzo of the Federal Aviation Administration. A further presentation was given by Mr. J. Benjamin setting out the different approach adopted by the United Kingdom to microwave landing system design. The paper

by Mr. Del Balzo reviewed the International Civil Aviation Organisation's work programme for the development of a new non-visual approach and landing guidance system for international aviation, outlined the main design features for the competing techniques being considered currently, and then described the thoughts in the United States which had led to their proposal to adopt a system based on time reference scanning beams. The paper from the United Kingdom gave a parallel presentation indicating why the United Kingdom has based its system on doppler techniques. The French, German, UK, US and Australian proposals mentioned various advantages and disadvantages claimed for both ground derived and air derived systems and these are set out and discussed broadly in the papers. The French and German systems are ground derived, and the Australian, United Kingdom and United States systems air derived. Although the presentations tended to emphasise that the relevant facts were all agreed and that the differences arose over matters of their interpretation and relative importance, it emerged that the claimed agreement on _tac.t~ was incomlete particularly on issues such as the rehabrlrty and deveiopment potential of the various for~s o~ ~icrowav~ landi~~ rtain key issues were 1dent1f1ed as bemg cntrsyst e ms . Ce . . . . nd on these the mam dec1s1on would rest. These m1 ca a . . . b t . k eluded multipath aspects, monitoring, air orne cos s, ns ,

12

and spectral efficiency. Currently there is room for disagreement on whether these are all the key issues, how important they are compared with other issues, and what their relative importance in relation to each other is.

Mr. G. Chin and his colleagues from the Transportation Systems Centre presented a paper on instrument landing system performance prediction. They described in technical detail a physics model which was based on electromagnetic scattering theory and which had been developed for predicting comparative instrument landing system localiser and glideslope antenna array performance and course structure degradation resulting from a change to an airport environment such as the addition of new airport structures or terrain modifications. The theoretical predictions from the model were compared with flight deck data and good agreement was found. So far the model has been used to predict the expected degradation of course structures at several airports. The glideslope model has been used to predict and compare the performance of three image type antennas. Acceptable course results can often be found with only one type of glideslope antenna without performing a major terrain regrading. The model can be applied by airport planners to assist the prediction of the effects of proposed airport layout on ILS performance, by airport managers to assist predicting the effects of airport structure on lLS performance, and by central planning staffs to assist in choosing among alternative localiser and glideslope systems.

Mr. I. A. G. Stage of Marconi Radar Systems presented a review paper on the measurement of runway visual ranges.

He started from the basic recommendations of the International Civil Aviation Organisation and made a fundamental appraisal of the instrumentation and system requirements.

He showed that the definition of the operational requirement contains an assessment of the instrumentation task and stressed the need for representativeness in the measurements taken. The processes of selecting and developing the instrumentation techniques using supporting data processing were shown to provide superior system performance. Results from evaluation trials confirmed that an automated runway range system was better than an observer in providing operationally useful data. During the past few years runway visual range measurement has developed from an era of laboratory experimentation into the age of automated photometric measurement, with a highly adaptive data processing and control system. An effective instrumentation solution for glidepath and taxiway visibility assessment can therefore be envisaged tor the tutu re.

A survey report on independent landing monitors was given by Col. G. Tinsley of the Federal Aviation Administration and his colleagues. Because of the continued interest in independent landing monitoring systems, proposals have been made for a wide variety of techniques and devices to enable the pilot to check on the primary landing instrument system and to ensure that the approach and landing are proceeding safely. Some independent assessment that an approach is progressing safely may be essential for operator acceptance of approach guidance based on a single electronic signal. Several related projects and developments were described in a series of short papers, each of which summarised the basic concepts, technical characteristics and current stage of development. Wherever possible a summary of tests results was included. Some of the proposed developments have not fulfilled their initial promise when subjected to field evaluation and other evaluations are still at initial stages. Systems also vary in the amount of

new equipment they employ and in the extent to which they can rely on equipment evolved for another purpose.

A paper by Mr. J. M. Bonny of the Royal Radar Establishment described a programme of research on computer assisted approach sequencing. He emphasised that the study was on an experimental prototype system to investigate the feasibility of providing computer assistance in the aircraft sequencing task, the prime evaluation being related to the traffic at London Heathrow Airport. Computer assisted approach sequencing is an advance towards computer assistance not only with data handling but also with actual control functions. As a result it is believed that the advance must be undertaken cautiously. The system of computer assisted approach sequencing as described aims to provide a small but significant increase in capacity in an environment where the controllers themselves are highly experienced and skilled. As a result its main achievement may be to raise the efficiency of the weaker controllers and hence lead to a rise in general efficiency rather than to improve still further the high standards already achieved manually by those with most experience. Further development of the computer assisted approach sequencing programme was envisaged to attain the level of experienced controllers. Meanwhile the system is being considered in relation to other modes of operation whereby the reduction in liaison which is achieved when computer assisted approach sequencing is available may be harnessed towards achieving higher aircraft movement rates even with an increased proportion of wide bodied aircraft.

Advanced Concepts The sixth session, on advanced concepts, comprised six papers, the first two of which dealt with future system studies, the second two with dispersed systems and the last two with satellites.

Dr. R.H. Reck of the Transportation Systems Centre presented a paper which summarised an advanced air traffic management system study. This considered United States plans for air traffic management systems in the late 1980's and beyond. The existing or third generation air traffic control system is currently being extensively modified to keep pace with expanding requirements and will eventually result in the so-called upgraded third generation system. Nine major improvements to the present system are envisaged, namely intermittent positive control, discrete address beacon system, flight service station automation, upgraded en route and terminal automation, airport surface traffic control, wake vortex avoidance systems, area navigation, microwave landing systems, and aeronautical oceanic satellites. Beyond this system the alternatives of the satellite based system or an extended upgraded third generation system are being -considered and deductions made on their implications for design studies and necessary research.

High levels of automation particularly of routine functions are currently envisaged. The benefits which various categories of users would derive from alternative proposals are being considered, and also their relative costs.

Mr. H. Dibley of the Air Traffic Control Systems Committee of the United Kingdom spoke on behalf of this committee and described how it had functioned and the contents of its recommendations. The terms of reference of the committee were to consider and propose long term planning concepts for a new air traffic control system on 8 national basis, taking account of the international implications. Several professional bodies were represented by pi-

lots and controllers, and other experts also served on the committee. The paper emphasised the need for user participation in forward planning and the value of the detailed participation of users in long term system design studies.

The committee adopted a strategic rather than a tactical approach to planning, and emphasised the need to plan the total system rather than to perpetuate the type of current system in which ad hoe on the spot tactical decisions have frequently to be made. The committee advocated a preplanned system operating in limited air space. In relation to long term planning the committee strongly advocated strategic thinking and active collaboration with all the users of the system.

Mr. M. Connelly of the Massachusetts Institute of Technology considered applications of the airborne traffic situation display in Air Traffic Control. The results of several real time simulation tests were reviewed in the paper. These tests sought to determine the value of displaying traffic and map information in the cockpit, and to discover the effects of such information on ATC procedures and capacities. They found that such a display is a valuable aid to the pilot in executing certain functions, specifically resolving conflict detection and resolution, conforming to airspace structures, keeping precise spacing in trail, merging, sequencing, monitoring runway occupancy, using backup procedures after an air traffic control failure, approaching one of two closely spaced parallel runways operating independently, and taxying on the airport surface. In a study of metering and spacing in a terminal area such an aid eliminated all violations of spacing minima, and halved the dispersion of arrival times at the runway threshold. If the metering and spacing schedule was made available to the pilots, and if their flight instruments were modified to assist them to execute an approach exactly according to that schedule, the dispersion of arrival times at the runway threshold was found to be less than three seconds.

Mr. P. Hamburger of the Raytheon Company described a new system architecture for air traffic control automation.

Current automation of en route and terminal centres in the United States is based on interfacing radar outputs to resoluti.on displays through one or more large scale computers which provide a variety of automation functions, including tracking controlled aircraft and compiling alphanumeric blocks of information about each aircraft. For areas with less concentrated traffic a system architecture with numerous small computers sharing the processing has significant advantages. Such a modular and more flexible approach enables the computer requirements to be fitted to the size of the air traffic control centre and the programming to be related more precisely to the traffic requirements. Two approaches are possible in the assignment of minl-comp~t~rs to air traffic control functions One of these is to sub-divide f~n.ctions and assign a mini-~omputer to each of ~h~-cs:~~ d1v1ded functions. The other is to use several mmr. puters to Perform the function once or several times 1 ~ t~e f · . ' rmes wrthm unction is performed in a similar way many 1 • th flight data 1 e system. For example systems compr sing • • d' lay processes processes, radar processes and various isp . t devices at a can each utilise display outputs and en ry single console position. ts were Two papers in this session on advanced concep h rtz 0 f the Massac uONUS aeroconcerned with satellites. Dr. I. G. ~tlg 1 setts Institute of Technology described the C ·t He gave sevenautical radio navigation system by sate ll 1e. . t satellite systems rat arguments in favour of this concep · have high avionics costs but they are flexible and a much

13

smaller number can replace the large number of ground based equipments and sites which are currently needed.

Three kinds of satellite systems were described. The first of these was a random access air to satellite technique whereby a unique signal was transmitted by each aircraft and thence to a ground processing centre. The second was a co-ordinated air to satellite technique where each aircraft is interrogated discretely by the satellite and the aircraft responds with a transmission signal which is sent to the ground via the satellite. The third alternative is a satellite to air technique which consists of a navigation system in which the satellite transmits to the aircraft only and the aircraft position is determined by multi lateration, this information then being data linked to the ground. The advantages and limitations of these three alternatives were discussed in the paper.

Mr. D. R. Israel of the Federal Aviation Administration described a proposed aeronautical satellite system. The reason for considering it was that North Atlantic control is mainly based on voice now but there were limited frequencies available which were subject to various degradations.

He described a system which was not operational and which was being considered for system demonstration tests and evaluation only, in order to gather data as a basis for proceeding towards an internationally agreed operational satellite system. Within this programme three segments were distinguished. One would be a space segment which required full international co-operation and co-ordination. The other two segments described were a ground segment and an avionics segment which called for co-ordinated national programmes rather than international ones.

System Performance Measures In the final session on system performance measures two papers were presented. Mr. K. J. Brauser of Messerschmitt-Bolkow-Blohm described measures taken of control capacity of air traffic control systems. The work was based on the assumption that executive control capacity is the most critical part of the air traffic system since it is the one most sensitive to overload, and therefore it was contended that executive control capacity represents the capacity of the whole air traffic control system in most cases.

Three distinct methods of measuring executive control load and control capacity have been developed. In the first of these the total time consumption of all executive control tasks generated by all aircraft movements occurring in the area of jurisdiction is measured. On this measurement control capacity is reached when a clearly defined non working time decreases to zero according to the time consumption measures. An alternative is to adopt a partial workload measure, namely R/T channel load, which has been shown to be a constant 'proportion of the total workload. Some variation according to this measure related to different air traffic control procedures has been found. The third method is to use questionnaires to obtain estimates by controllers of their control capacity. These questionnaires were given to controllers at the end of their control load measurement watch and also to others who had not taken part in measurement activities. The results from the three methods fitted well together when they had been weighted. A f rther method of estimation is by means of a statistical u aluation of flight progress strips which since they conall the control data related to air~raft movements are correlated with the control effort required.

::in 14

A paper by Mr. H. Gent of the Royal Radar Establishment described the index of orderliness which is a measuring rod for air traffic control systems. It provides a numerical estimate of system performance at any moment of time and its calculation requires a basis of conflict prediction and a threat weighting formula. The index is then essentially a weighted count of potential future conflicts. If a conflict avoidance system is simulated then the index of orderliness measures obtained from it contain valuable information on the response times of the system. The index is closely related to a complete air traffic control system viewed as a hierarchy of control loops. The index of orderliness can be used to give a quantitative measure of the style of an air traffic control system as well as of its performance. If the index of orderliness is used as a measure it distinguishes successfully between a system relying heavily on collision avoidance procedures which gives large values on the index and a system where preplanning predominates and tactical intervention is rare which gives a low value on the index.

The Co-Chairman of the Programme Committee of the conference, Mr. D. R. Israel, summarised the proceedings of the conference and drew some conclusions from them.

Some comparisons were drawn between this conference and the previous AGARD Conference on Air Traffic Control in Edinburgh three years ago. The emphasis on topics had changed and so had the people working on the subject since there was little overlap among authors of papers at the two conferences. A much greater preoccupation with costs was associated with more critical appraisal of new technological developments. The evidence for these now had to be stronger than hitherto before the necessary expenditure to introduce them or even to evaluate them could be incurred. The lull in the expansion of air traffic provided an opportunity for air traffic control planning which must be used. Certain aspects of the subject, including human factors, probably warranted more emphasis than they had received.

Dr. A. Benoit, the Chairman of the Programme Committee and of the AGARD Guidance and Control Panel, in his concluding remarks, asked for comments and constructive proposals on the programme which has been given and on future meetings which would be held. The topic had again attracted a very large attendance of delegates and their views on how the topic of Air Traffic Control should be treated in future within AGARD and particularly by the Guidance and Control Panel were sought and would be welcomed.

Conclusions It is anticipated that the proceedings of the conference will be issued in due course. They provide a good up-todate summary of current plans and developments in air traffic control systems, a comprehensive survey of current and !uture technical developments of relevance, and a glimpse mto the long term plans for air traffic control systems. Inevitably in such a broad subject as Air Traffic Control there can be disagreements on whether certain topics were correctly emphasised. But on the whole this conference provided a thorough and detailed appraisal while contriving to be surprisingly broad In attempting to cover the whole subject, as the previous conference in Edinburgh had also done. A recurring theme was the need to be cost conscious, to be cautious and critical in accepting new developments, and to be sure of their value both operationally

and financially before they are introduced. Automation clearly will increase and some of the results which can be obtained already are technically highly impressive.

In some future systems the quality of the data on which Air Traffic Control is based will be very greatly superior to the quality of data in current systems. From the point of view of human factors specialists the conference gave an insight into the technical developments and also revealed that the incidence of future human factors problems does not seem likely to decrease. Many of the technical aids have only been evaluated to show their feasibility, and the work of optimising the man machine interface so that their potential can be fully realised has to be completed and in

some cases has not even been begun. Nor have the broader implications for Air Traffic Control as a profession had much influence on the choice and progress of technical development, but there is a growing recognition that the mere provision of an aid is not enough to ensure that it works effectively. While there were fewer papers at this conference than at the previous one specifically concerned with human factors, there seemed a greater awareness of human factors problems than before and a willingness to accord them greater relative importance. How much of the current goodwill towards human factors will be translated into practical steps remains to be seen, but the acknowledgement of its important role is e,ncouraging.

Aircraft Noise And The Air Traffic Controller*

by R. M. Green, Australian Department of Transport

Introduction Some years ago, a previous Director-General of the Australian Department of Civil Aviation, as we were known in those days, described aircraft noise as "perhaps the most important problem facing the aviation industry." I would go further and say that not only is it still one of the most important problems facing us but, until comparatively recently, it has also been one of the most neglected problems. There is nothing to ga,in by examining why this was so but, with the benefit of hindsight, it is evident that had a real attempt been made in the late 1950s and early 1960s to come to grips with the problem we would be in much better shape today. 1 doubt that anyone would accuse me of overstating the case; we have all experienced the problem in varying degrees, at first hand. The Notices of Proposed Rule Making emanating from the U.S.A. indicate the degree of priority afforded to noise abatement in that country while the image of a multi-million dollar facility lying idle in Japan bears testimony to the efficacy of organised community response should the aviation industry fail to take action - and take it quickly.

Historical Historically, it was not until well after the Second World War that aircraft noise became a significant problem to the community, at least insofar as Australia was concerned.

In 1954, when earlier aircraft were replaced by Super Constellations and the turbo-propeller Viscount was introduced on the domestic scene, the rumblings of public reaction were overlooked or were largely ignored. 1959 saw Qantas operating the Boeing 707 and in 1964 pure jet aircraft were introduced on the domestic air routes of Australia. The noise of the jet engine plus more frequent schedules to cater for public demand brought things to a head in our country and protests against aircraft noise began to take the form of strong letters to Members of Parliament from irate constituents. This pattern had already emerged in other areas of the world, notably the U.S.A. and parts of Europe, so it was no real surprise that we were following

suit. I should mention here that the general impression of Australia as a vast country of wide open spaces, sparsely populated with cattle drovers, is not true of the eastern coastline along which most of our population is congregated. In fact, at Sydney we are in the big league as far as noise problems are concerned.

In November 1968, the Australian Government formed the House of Representatives' Select Committee on Aircraft Noise to investigate the problem and make recommendations on ways and means of overcoming it. In 1970 the Final Report was published and it listed 29 recommendations ranging from the adoption of a system of land zoning around airports to installation of noise monitoring equipment at selected sites. It might give you some idea of the intensity of feeling that prevailed when I say that during the course of the Select Committee's investigations Federal Elections were held and four seats changed hands because of dissatisfaction in noise sensitive electorates with the attitude displayed towards aircraft noise. I do not want to lay too much stress on the matter of protests by the public because, as a barometer of public opinion, protest letters must be ~reated with great caution. There are those who are motivated to Protest on the slightest pretext while there are many others who will suffer in silence, so to speak. :rotests do indicate, however, that something is wrong and it was apparent that throughout the world people were no longer prepared to accept aircraft noise. It is true that other sources of noise such as road transportation and lawnmowers etc. were also receiving a degree of attention but people are motivated towards cars and lawnmowers and the protests were nowhere near as intense as were those ~g~inst aircraft noise. It may seem to be a little unfair but it is a fact of life and it is no longer good enough for us merely to point to the benefits of aviation and claim that some inconvenience must be tolerated. People now express dissatisfaction more readily and, as the general standard of education rises, they become more critical. We have to raise our standards of performance to satisfy the comm~­ nity because those organisations which cannot raise their standards will ultimately be passed over.

Remedies • This paper was presented at IFATCA's 14th Annual Conference held at Melbourne, Australia, 14-18 April, 1975.

When one thinks of ways in which the problem can be tackled, the first thing that comes to mind is to quieten the 15

noise at its source - the aircraft engine. In recent years major advances have been made in this regard by the engine manufacturers and the fanjets of the Lockheed Tristar, the Airbus, the DC-10 and the newer Boeing 747s are significantly less noisy than the engines which powered preceding generations of jet aircraft. It is true to say that we now have aircraft engines which, for the first time, have noise reduction incorporated as a design principle. This has not been achieved without considerable cost and it appears that the cost will escalate sharply for any further reduction in noise which might be achieved. In other words, we are approaching the stage where the price to be paid for each decibel of noise reduction may be prohibitive.

Furthermore, as engine noise is reduced airframe noise becomes more apparent.

By this I mean the noise caused by an aircraft in landing configuration passing through the air and discounting entirely the noise of the power plant. Tests conducted with a C-5A Galaxy have revealed a surprisingly high noise level from the airframe alone and Lockheed have also discovered that airframe noise is already a detectable component in the overall noise levels of the Tristar. In any event, there are many aircraft throughout the world, and there will be for years to come, that are not equipped with the quieter engines. Retrofit or refanning of these engines will have some effect but I do not think I am being unduly pessimistic when I say that I cannot see technology ever providing the total solution to the problem of aircraft noise.

Many of the letters that we receive point out that some airlines appear to be more consider.ate to the general public than do others in the manner of operating their aircraft and there could be some validity in the comments although we know that the message has reached most international operators and that aircraft are, in the main, operated in a very different way to that which was the norm two or three years ago. We all know that aeroplanes can be operated with an eye to noise abatement - the difficulty is, and always has been, one of deciding how far we can go in this respect without degrading safety standards. There is also, of course, a conflict of opinion on what operating techniques are best suited to certain types of aircraft and what techniques give the best results. For example, we believe that, overall, a standard take-off technique aimed at getting the aircraft as high as possible as quickly as possible is probably the best technique for Australia. This, of course, does not equate with the standard take-off of some airlines involving the technique of power reduction or "cut-back" to give it its more familiar name. In Australia we do not prescribe "cutback" as an acceptable technique both from the viewpoint of safety and because we believe that in most cases the unavoidable reduction in climb performance is merely moving the noise problem to areas lying further away from the departure airport.

Nevertheless, if an operator employs "cut-back" as a standard departure technique we will make no objection.

Indeed, in the case of the Concorde there seems to be no other procedure which is anywhere near as effective as a noise abatement procedure. Some aircraft are limited in respect to body angle and cannot, therefore, comply with the terms of our approved rapid climb technique. As air traffic controllers, you will all see immediately the ramifications of an aircraft climbing at V2+10 knots being followed by an aircraft which is limited by body angle to climbing at a minimum speed of V2+30 knots.

To effect maximum reduction of noise during the appro-

16

ach phase of flight, aircraft should remain as high as possible until close in to the airport and should follow the glidepath with minimum practicable throttle setting. Much investigation has been conducted into the so-called "decelerating approach" during which the aircraft approaches with reduced power setting allowing a high initial approach speed to wash off down the glidepath, with flap and undercarriage selection left until the last possible moment. Again, as air traffic contr:ollers, you will appreciate the problem of effectively spacing a gaggle of arriving aircraft when airspace is laterally limited, longitudinal separation is tight and vertical separation is hampered by the first aircraft remaining high for as long as possible.

The problems are compounded, of course, if the pilotin-command, who has the final responsibility for the operation of the aircraft, decides at the last moment to vary his expected approach profile. I believe the time is coming, however, when all operating procedures to reduce aircraft noise will be made compulsory if we do not ourselves adopt a responsible attitude to the matter - and by that I mean made compulso_ry by some agency which in all probability will not be orientated towards aviation. The imposition of noise limits at certain airports is an indication of a move in this direction. Fortunately, it seems that operating techniques for noise abatement purposes are being accepted more readily by the airlines now than in the past.

The procedures adopted by pilots can have a quite noticeable effect in areas lying some distance from the airport but they make little or no difference to the degree of noise nuisance suffered by the resident in close proximity to the airport. To be realistic about it, there is virtually nothing that can be done for the person in this category and it is for this reason that land use control is recommended.

Providing that an accurate method of calculating the annoyance factor is employed, it is possible, in theory at least, to define those areas around an airport which are unsuitable for residential purposes.

Where ATC Comes in But at the moment, the art is not as precise as we would wish and in any case it is more of a tool for planning authorities than for operational staff. Nevertheless, Air Traffic Control does make an input to the Noise Exposure Forecasting system and I mention it because many of you will be called upon to make this input at some time, if you have not already done so. The accuracy of any Noise Exposure Forecast, and therefore the validity of the land use zoning, depends to a large extent on the accuracy with which future flight paths and traffic patterns are predicted.

Experience has taught us that our air traffic controllers make a very useful contribution in this regard and I suggest that it is a function that controllers will be called on to perform more and more in the future.

Of more immediate concern to air traffic controllers are the problems associated with incorporating into the overall ATC concept noise abatement procedures such as preferential runway selection, noise preferred flight paths, noise abatement approach profiles and departure techniques. Traffic growth has been enormous during the past 10 or 15 years and I know that ATC facilities have not always kept pace with the increase in air traffic. Safety has always been paramount in Air Traffic Control and always will be. Second in importance to safety has traditionally been the orderly expedition of air traffic and it is understandably hard for any controller who takes pride in his

•.. nevertheless, tell her, that again she was deviating from the noise abatement route!

Conclusion competence to enthuse about ''procedures which, by their very nature, curtail the expedition of traffic. Flow control and the sequencing of traffic by means of speed control are disrupted by the application of noise abatement procedures and the controller's already arduous task is made much harder in almost every way. 1 believe that air traffic controllers should bring to the notice of their supervisors any noise abatement procedure which taxes a controller's capacity to the extent that safety might be degraded a~d the air traffic controllers' associations also have a duty in this regard.

I also believe however that each case must be viewed objectively and dispassion°ately. ATC must retain t.h.e fle~i­ bility to apply procedures applicable to the preva1hn.g circumstances but increased workload, in the present climate, cannot be the sole criterion for discarding noise abatement procedures. It may be that in the future we shall have to choose between expedition of air traffic and application of noise abatement procedures. There are already indications that this may occur sooner than some might think. Social and political interests are evincing more and more concern about aircraft noise and 1 have doubts that a convincing case could be made, even now, for expediting aircraft movements at the cost of reducing the effects of aircraft noise.

Throughout the world, various measures are being taken to improve the image of the airport as a good neighbour and I think the public relations effort deserves our full support. If the public can be convinced that everything possible is being done to combat aircraft noise, a real contribution will have been made to solving the problem.

Unfortunately, misfeasance or the belief that bureaucracy never does all that it is possible to do, is prevalent throughout the community and I would hope that every controller js aware of this in his dealings with the public.

Now that aircraft noise has been recognised as a serious problem there is no doubt that future airports will be constructed with adequate buffer zones around them to protect the general public. It is just not good sense to invest vast ·amounts of money in an aviation facility and then permit residential development around the boundaries, knowing that in the course of time the people living there will press for closure of the facility or a curfew on night operations. Most of the world's airports were in position long before the jet age, however, and land zoning now can have only a small effect as a remedy.

A greater number of quieter aircraft will appear in the future, of course, and it seems certain that a retrofit programme Will be introduced for those noisier types of aircraft that have a useful service life remaining. Nevertheless, aircraft engines will always make some noise. The public's attent!on has been focussed on the aeroplane as a sour~e of noise Pollution and I cannot see the trend reversing '" the 0 reseeabte future. It is possible that it might even intensify as the public becomes aware that even the socalle~ quiet aircraft are still capable of generatin~. a. tot of noise. As the public becomes more vocal in its criticism, 1 't · l'k is 1 ely that there will be a call for more curfews - and · no once a curfew has been imposed on an airport there is chance it will ever be permanently lifted.

It is improbable, therefore that the fight against aircraft noise Will be won as a result ~f some breakthrough in t~ch­ nology or as the outcome of some political stroke of genius.

In my opinion it will be a continuing battle to achieve an acceptable compromise between the demands of the tr~­ velling public for aviation facilities and the need~ of res~ dents near airports for peace and quiet. To achieve su~ll a compromise 1 the full cooperation of various grou~s wif be required - aircraft manufacturers, airline pilots, air tr~, fic controllers, town planning authorities, local counci s and, of course, the general public.

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17

The Integration of Supersonic Transport into the ATC System

EUROCONTROL Experimental Centre, Bretlgny, France. (By courtesy of EUROCONTROL)

The Story of the SST Simulation Work Carried Out in Western Europe* Each new generation of ai rliners - from piston-engined transports to prop-jets and pure jets, through to today's wide-bod ied jumbo jets - has brought new improvements in performance, often far-reaching in their effect on many aspects of airline operation. Each advance in performance has presented the Air Traffic Control system with new problems; each time, ATC has been able to integrate the new w ith the old . Now Concorde presents the greatest s ing le leap fo rward yet achieved in aircraft performance.

Using the most sophisticated aids to simulation and assessme nt avai lable, ATC planners have been able to cover most of the pl anning permutations necessary to ensure smooth integrati o n o f supe rsoni c airliners into the ATC system. Of g reat importanc e has been the preparatory work carried o ut by Eurocontrol, the European Organisation for the Safety of Air Nav igation , at its Experimental Centre at Bretigny s/ Orge, near Paris.

• ) Adapted for "The Controller" from a paper written by Mr. L. G. Clarke (Euroc ontrol) , which appeared in a recent Issue of " Supersonic Age ". and from a paper presented by Mr. F. P. Carson (al so of Eurocontro l) to Convex 7 4, the Sympos ium and Exhibition of the British Guild of Air Traffic Co ntrol Officers held In Bournemo uth.

Oc tober 1974.

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It will soon be ten years or so since the Eurocontrol Committee of Management set up an Operational and Technical Working Group to study the special requirements for introducing SST operations in North West Europe, and to co-ordinate t he efforts of all those involved so that there should be no wastage of resources. During this time, there has been a series of real-t ime simulation exercises car ried out at the British ATC Evaluation Unit at Hurn and the Eurocontrol Experimental Centre at Bretigny; fast-time simulati on has been used by Eurocontrol to study particular aspects; members of the Group have been involved in the work of the ICAO SST Panel and the NAT SPG ¡ t here has been close liaison with the manufacturers of 'concorde ; and inputs of information have come from expert organisations such as RAE Farnborough. As a result of all this activity, we now await the arrival of the SST to check out the validity of the proposals which are, after all, still based largely on simulation. So let us look at what has been done to prepare for the integration of SST's into Europe's ATC system.

The Centre at Bretigny has as its principal tasks the testing and evaluation of different ATC o rganisations and systems under present and future traffic conditions. For this it is equipped with a dynamic ATC simulator which was the first of its type in the world to be brought into se rvice. It enables airc raft flight paths, radar data information displays, ground/ ground and air/ground com~unications to be sufficiently realistically simulated fo r the app ro priate air

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and ground environments to be represented in the Centre's operations room. As the start of com merci al operations with Concorde w ill introduce a new dimension into Air Traffic Control, it was logical, therefore, that the Centre wou ld be charged with undertaking a study of the problems involved in handling civil transport ai rcraft effecting acceleration cli mb and deceleration descent to and f rom supersonic speeds over large areas w hich s pan national frontiers and embrace air routes and flight levels already heavily loaded with subsonic traffic. For the first time ever, ATC syste ms will have to handle such traffic, and one does not need to be an ATC specialist to imagine the control and co-ordin ation problems that this cou ld produce in the busy traffic areas of Western Europe.

To p repare the way for the establishment of a su itable route stru cture for SST tracks across the North Atlantic, and to establish procedures for supe rsonic transport aircraft a series of sim ulation studies were perfo rmed at the Exp~rimental Centre between 1968 and 1973. The first realtime si mul ation study was carri ed out in mid-1968 on the assumption that the initial focussed boo m, during acceleration, would have to be placed over the sea, but that supersonic c limb and c ru ise, as well as deceleration descent, could be performed over land. Seven relatively large upper airspace secto rs at some of Western Europe's main ATC Centres we re sim ulated extending over about 950 NM from 10° E to 15° W and about 450 NM in the N/S direction, and covering possible SST arrival and departure routes for such potential terminals as London, Paris, Frankfurt, Amsterdam and Brussels. The t raffic sa mples included up to 120 s ubsonic aircraft and between 10 and 30 SST's in each exercise. The distributi on of arriving and departing SST's and the number of available ocean ic SST tracks were varied .

On the control side, it was assumed in thi s - and in subsequent simulations - that a processed labelled radar picture

. · e was largely exwas availabl e in all Centres. This exercis f detailed plorato ry, to help in identifyin g probl~m areas or investig ation in future simu lati on st udies. . "th a fi rst expeThis si mul at ion provided Eurocontro 1 wi . ff hts rience of the t actical (radar) handling of supe rsonic ig · I trght cha1 in a civi l ATC environment. Although the specia racteristics of Concorde (in particular the speed ~hange~ in accelerat ion/ deceleration and the high rates of climb an descent) posed problems for the radar controllers, it was also d iscovered that some of these characteristics could be · t'ions. Two used to advantage in certain tact ical s1tua . as pects w hi ch have since figured in nearly all the studi~s are: firstly, special sectorisation requirements where SST s · · g and may appear in some numbers· and secondly, organism ' · Is spac ing the outbound flow of SST's from various termina. ' when there would be competition for the available oceanic track.

Between April 1969 and July 1970, a series of three f~r· of partial th er si. mulations - based on the same premise . ·c operat ion over land - examine · d sectorisat1on su person1 a rrangements an d SST routings in an area si'milar to tha 1 tested in the 1968 simulation. A detailed study was als~ mad e o f different · depart oceanic clearance proce d u res for . h ing SST flights During the last of these s imulations,_ t e . . fl. ht-deck s1muB retigny ATC simulator and the Concorde ig . _ lat . . 1 d voice connec or at Toulo use were linked by d1g1ta an .

Th. · 1 exercise is t .ions for the first time in a i·oint operationa ·. d" trollers 1senabled " live" data to be displayed on the con . h d be estabhs e play at Bretigny and " live" R/T contact to . . . t . · . f e airline pilo s. w ith Concorde flight crews - including ac iv . . t the Not only did this inject a new element of realism kin of the • . . .d d a useful chec o s1 mu 1at1on exe rcises but 1t prov1 e · the ' · airc · raft agains1 perfo rmance to be expected from a live . . t r It was also posth prof1l es ge nerated by the ATC s1mu1a 0 · . . ·t· ted manoeuvres on e s1ble to study the effect of ATC in1 1a 19

SST Project, Simulation of London Sectors. (By courtesy of EUROCONTROL)

aircraft flight path. Finally, visits to the Experimental Centre during the exercises by pilots who had flown the simulator, added a valuable contribution to the results.

Towards the end of 1970 it became clear that - for at least the initial period of SST operations - transonic and supersonic flight would be restricted to sea areas. This raised a new set of conditions to be met when looking for a possible route structure in the transition area: in one way, this had an advantage, from the ATC operational planning point of view, because if solutions for this case could be found, any alternative policy should ease the situation rather than aggravating it. So the~.aim became to route SST's to the sea, as quickly as possible, and to find a route where no sonic boom would reach land. This resulted in a revised route structure, comprising a bi-directional eastwest SST route down the centre of the English Channel, together with a requirement, on economic grounds, for the use of the eastern part of the Channel for the acceleration and deceleration phases of Concorde departures from and arrivals at Paris and other airfields on the European continent.

In view of the heavy subsonic traffic between London and Paris, there was doubt about the feasibility of performing acceleration and deceleration in this area, so a further simulation was conducted at Bretigny in September 1971 with the specific objective of determining "the best methods of tactical control to enable SST flights to perform transonic acceleration, deceleration or subsonic c ruise in the Channel area." The simulation was preceded in JuneJuly by preliminary joint exercises with the Toulouse Concorde simu lator, flown by pilots from Air France, the ARB and CEV (British and French official services) and the airc raft manufacturers, in order to determine and refine the procedures to be examined and to test the "flyability" of the proposed routings.

With sonic boom restrictions and Concorde's particular flight characteristics, the application of tactical radar control methods to handle SST flights in the Channel will be somewhat limited. Nevertheless, it was found that tactical interventions cou ld be kept to a minimum by making full use of Conc orde's special characteristics to provide profile separation between arriving and departing SST flights and, in some situations, between supersonic and subsonic aircraft. The main conclusion was that "the use of the Channel area for accelerating and decelerating SST's is a viable proposition. provided that safeguards are incorporated into the acceleration and deceleration c learances to

20

provide profile separation between simultaneous oppositedirection SST traffic". Other results from the simulation related to sectorisation, co-ordination procedures, communications requirements, and SSR code allocation procedures.

This simulation was complementary to one conducted in the UK early in 1971, concentrating on problems in the south-western approaches to the London Control Area. The combined results of these two simulations therefore provided SST planning authorities with an ensemble of operational information covering the whole transition area of initial European SST operations.

The 1971 simulations were complemented by a series of exercises in December 1972 and January 1973 which were designed to examine possible routings through the western part of the Channel for SST traffic between London and West Africa, and to investigate the possibility of applying to SST arrivals into Paris the technique of linear holdings.

These exercises were again jointly performed with the Concorde flight-deck simulator at Toulouse. On this occasion, the simulator was operated by flight crews provided by Air France, British Airways, Iran A ir, Japan Air Lines, and Pan American. Pilots representing the FAA and IFALPA also participated in the trials. As in the previous Channel area simulation, the simulated ATC sectors at Bretigny were manned by controllers in current operational practice from the London and Paris Centres. For the control of the simulator flights, a small ATC cell at Toulouse, representing aerodrome and approach control services of London Heathrow and Paris Charles de Gaulle, was also manned by controllers from France, the UK and Eurocontrol. Subsonic traffic loadings were based on 1978 forecasts but the number of SST flights in each traffic sample was in excess of that forecast, in order to produce a reasonably high number of SST/ SST and SST/ subsonic aircraft interactions for analysis purposes. Depending on the traffic situation simulated (morning and evening), the total number of aircraft in each two-hour exercise period varied between 162 and 205.

As in the previous studies, results of the simulation were obtained from analysis of recordings of Concorde profiles and controller workload (R/T and telephone) , supplemented by comments and suggestions made by pilots and controllers at post-exercise de-briefings and in specially prepared questionnaires. Among other results, this simulation showed that for flights from London to West Africa routing via Looe, in Cornwall, will be the most satisfactory.

SST Project, Simulation of French Sectors. (By courtesy of EUROCONTROL)

It was here - during the last simulation exercise - when the technique of "linear holding" was tried out. In fact, this is an early deceleration and descent which causes a planned delay in arrival at desti nation. By this means, the aircraft absorbs a fo recast TMA delay - or part of it - in a more economical way than would be possible by following a normal optimum profile and then entering a holding stack for a prolonged period. The technique was si mulated for Paris arrivals , and the early deceleration produced no problems provided it was sufficiently early and the aircraft rerouted onto the subsonic routes ·after deceleration. Inwardbound Concordes were descended to be in subsonic flight before entry into the Channel area and were then routed along the normal subsonic route structu re via Dinard and Chartres. This meant that only delays of 15 minutes o r more could be absorbed by linear holding, forecast delays of less than 15 minutes being absorbed in the normal manner by o rbital holding in the Terminal Area. Clearly, the successful application of a linear holding procedure will depend upon the route, the availability and accuracy of forecast ATC estimates of termin al delays, and the existence of suitable lo ng-range communications links for the transmission of these delays to the aircraft. It will also require the establishment of suitable procedures within the Terminal Area to enable linear-holding aircraft to be slotted into their rightful positions in the landing sequence.

Another conclusion of this simulation was that a departure routing via Jersey might be required for Paris SST departures, in addition to the principal departure routing via Le Havre. Other results related to routings within the Paris Terminal Area and refinements to acceleration/climb c learances for SST departures along the mid-Channel route. Suggestions were also mad e for some standard R/T proced ures for the control of SST flights.

A fin al point worthy of mention is that the joint exercises with the Tou louse Concorde flight-deck simu lator, both in this and in previous simulations, produced two distinct sets of results. Not only did the Toulouse simulator contribute realism to the ATC simulation at Bretigny, but the Bretigny simulation contributed similar realism to a study of cockpit procedures and workload being conducted in parallel at Toulouse by the manufacturers' Operations Group.

Another element, w hich has had to be covered during the studies, is the co-ordi nation of acceleration clearances for departing SST flights from different te rm in als compel-

ing for a limited number of slots on the oceanic tracks. It will be appreciated that little possibility will exist for ATC to adjust the progress of an SST departure once acceleration has started, so the time and place of starting acceleration wi ll, in effect, determine the time of entry into the foreseen oceanic track structure. Since the entry time at the oceanic boundary is determined within fairly narrow limits once acceleration has commenced, t his entry must be adjusted by changing the time of acceleration. This can be achieved by a pre-departure clearance, given a time to reach the acceleration datum in order to accelerate at that point without any delay; or by a random clearance, given en-route, which may involve additonal subsonic flight beyond the acceleration datum in order to delay arrival at the ocean entry point. (It works out, roughly, that each two minutes of subsonc f light beyond the datum causes one minute of delay at the ocean boundary). The spacing required between successive SST's using the same ocean track (a value of 10 minutes was used in the simulation exercises) will therefo re have to be established befo re the acceleration clearance is issued.

So, the time for starting acceleration must form part of

~he clearance to enter a particular ocean track, while ad-

j ustment of spacing between successive flights can be achieved by applying delays to the start of acceleration, thereby P~olong ing the length of fl ight at subsonic speed and delaying the time of arrival at the ocean boundary. The c~lcu lation of a number of interacting clearances can obviousl.y become quite complex when the con troller has to take into account each aircraft's preferred oceanic ~rack, how much delay can be accepted on that track before it beco mes more economical to take the next preferred trac~ - may be with a different delay· then calculate how tong it · ass umw ·11 i ta k e the aircraft to reach the' ocean entry point, . ing a certain amount of flight at subsonic speed, a period of acceleration followed by supersonic cruise-climb; and, finally, apply this calculation in reverse to arrive at the acceleration clearance time.

It has been recognised for some years that thes~ clearlerat1on da. ances for a series of tracks with different acce t ' I eventual inu m points and points of departu re and, a so, It flight re-c learances could not be calculated manuall'.. · ' · ted centralised is therefore foreseen that a computer-assis · SST strategic c learance unit, equipped with rapid commu·11 be necesnications links with the appropriate sectors, wi 21

NAT ORGANISED TRACK SYSTEM FOR SST AIRCRAFT 1976+

sary as soon as this is justified by the number of SST operations. The existence of this unit - commonly referred to as the SST Clearance Cell, and to be set up at London ATCC to handle all the oceanic clearances for SST traffic - has been an assumption in all SST simulation exercises conducted at Bretigny. In addition, an arithmetical model has been developed by Eurocontrol to carry out fast-time evaluations of different methods of clearing aircraft according to point of departure, route, etc. and so assessing the most likely way of achieving optimum loading of the oceanic tracks, the total delays that might occur in different traffic conditions, and so on. Some interesting initial results were obtained; but as the simulations were based on traffic predictions which are now unlikely to be realised for quite some time, work in this field has been suspended. However, the tool is developed and waiting to be used at the appropriate time.

As a result of all the activities which have been co-ordinated through the Eurocontrol Working Group, all the necessary preparations for the start of SST operations have been made. It is appropriate to pay tribute to the excellent irit of international co-operation between all those who sp h participated in the spec1"f"1cat"ion, preparat·ion an d cond av~ 0 f these studies. Just as Concorde itself is a splendid uc e of what can be achieved by close international coexamp.1 n so ·n a different way, ·1s th e war k ach"1eved t opera 10 • 1 . . h h Eurocontrol and its member-states to provide an ~;~u;ystem in western Europe geared to handling this fine • aircraft.

The occupational hazard of the ~TC p 1anner 1s the conovide improved equipment and procedures stant nee d to Pr . the ever increasing performance and moveto mateh up to ·r traffic The SST presents more new probment ra t e o f a 1 · . . ly however, the SST gestation period has ate rt lems. Fo un • . .

1 nners time to permutate most of the possible given t he pa

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planning variations. Procedures, resulting from simulation are now being tested in a live aviation environment. The proving flights are allowing the controller time to learn and evaluate the SST, and prove that our planning has not been in vain. Because, in the final analysis, it is the controller in the operations room who either makes or breaks the system.

Language Problems The following is an actual transcript - only the idents deleted - of a recent exchange between an aircraft and an Aeradio facility: Aircraft: We have a sick patient on board wearing a Medic Alert bracelet with the code EFTHIMIADIS STOP Would you check with a doctor and ask for meaning.

Aeradio: We checked with hospital here and they have no knowledge of meaning STOP Do you have any knowledge of the language?

Aircraft: We have doctor on board and he advises that the word is the Christian name of the patient. Sorry for misunderstanding.

(CATCA Information Bulletin)

Some Plain Speaking The Guild's image and representation of ATC and Air Traffic Controllers must reflect what ATC and what Controllers really are, not what the traditionalists would like them to be and not what they are not.

(John Toseland in 'Transmit', official journal of the British Gulld of Air Traffic Control Officers)

International Law Part VIII

by E. McCluskey, Chairman U. K. Subcommittee, IFATCA Standing Committee VII (Legal Matters)

International Institutions (1): United Nations Organisation In this series of articles we have had a chance to take a first look at the principles of International Law and it is logical to look now at some of the International Organisations which are involved in the application of International Law. These Institutions can be divided into five groups: judicial, parliamentary, governmental, specialist and secretariat. The United Nations Organisation is by far the most important International Institution and falls into the category of parliamentary (the General Assembly) and governmental (the Security Council). In most countries in the world the UNO is a highly political subject so it is not proposed to deal in depth with the UNO but to highlight the effect on International Law of the Organisation and to make allusion to the air traffic controllers' involvement with the UNO. If the last sentence had been written when IFATCA was founded no one would have believed that the controller could be affected by the UNO except indirectly through one of the UNO's specialist organisations such as ICAO or the World Meteorological Organisation. It is not only a measure of historical events but also of the growing strength of IFATCA that we can now find our Federation dealing directly with the world's most important International Institution. We shall look at other Institutions in future articles.

From the point of view of International Law the United Nations Organisation is the only Organisation uniting most of the States of the world in such a way as to influence the Law of Nations. Therefore it is the only hope for improvement and codification which this series of articles has constantly claimed is necessary for the eventual rule of law in the World Community.

The League of Nations was set up to promote international co-operation and to achieve international peace and security. These are basically the principles of UNO. It is inevitable that there are similarities between the League of Nations and the UNO. UNO had of course to try to correct serious defects. The League Covenant did not contain even the beginnings of World Government. The League had the rule of unanimity which in any organisation is bound to paralyse it. The UNO has six principal organs: the General Assembly, the Economic and Social Council, the Security Council, the Trusteeship council, the Secretariat and the International Court of Justice. The last will be the subject of a separate article. For our purposes we must look at the General Assembly and the Security Council.

The Charter distinguishes the functions of thes~ two organs by making the Security Council have the primary responsibility for the maintenance of peace and by precluding the General Assembly from dealing with peace in a way which could embarrass the Security Council. This has been one of the shortcomings of UNO since social and economic matters which are laid to the General Assembly can be causes of international friction and with the Security Council limited to Security it can do little that is constructive and tends to cut off the permanent members from the feeling of corporate responsibility which was of great value to the Council of the League of Nations. The General

Assembly consists of all members. Decisions are taken on a simple majority vote except on important questions where a two-thirds majority is required. These are: recommendations on maintenance of peace, election of non-permanent members of the three Councils, admission, suspension and expulsion of members, budget and any question which a simple majority decides should be considered important.

Apart from controlling the budget, all the General Assembly can do is discuss and recommend, initiate studies and consider reports. It cannot act on behalf of all the members and its decisions are not directions to States.

The Security Council consists of five permanent members: China, France, USSR, UK and USA plus other members elected by the General Assembly for two years. Most of the Council's decisions concern pacific settlement of disputes and threats to peace. Decisions of the Council are binding on members, and it should be mentioned on specialist organisations of the UNO such as ICAO. We have seen throughout this series that the Great Powers are only willing to accept International Law if they agree with it and decisions of the Security Council are no exceptions so each of the Great Powers has a veto. On matters of procedure decisions can be made by any seven members and a member of the Council which is a party to a dispute must abstain from voting. However, the Great Powers can use the veto on the question of whether there is a dispute or not. The veto was required in order to set up an organisation with real power but it has been an expensive price to pay since it has set back International Law to a great extent. UNO will never be effective until States, governed by politicians who blow with the wind, have the same confidence in another State's intentions and policies and the same absence of diversity of interest which the States of a Federation such as the USA, Canada, Australia, Switzerland, UK or the USSR must have if their State is to endure. The Great Powers at present just flatly refuse to have a "burden'' imposed upon them by a majority of small "uninterested" States. The situation might not have been so bad if the USSR had not used the veto to stifle investigation or to make its own view prevail. Reaction from the other permanent Members reduced their actions to the same level of selfish politics and it soon became clear that the Security Council could not carry out its responsibilities.

The prospects for peace and supranational International Law looked black.

The invasion of South Korea by North Korea underlined the world's frustration. However this became the event which put the UNO back on to the rails. With the deliberate absence of the Soviet delegate to the Security Council, three major resolutions were passed. The existence of armed attack was established; North Korea was called upon to withdraw her forces; and member States were recommended to put their forces under UNO command. Realising her mistake, the USSR again blocked action by the Security Council and the situation was remedied by placing Korea on the agenda of the General Assembly. The Unit-

23

Ferranti simulators put years on your student 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 i~entical with those used operationally, and simulated RT and intercom are provided. With this equipment the trainee learns how to cope with aircraft identification, separation, sequencing, the allocation of levels, routing, stacking, and other problems.

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

handling heavy air traffic with minimum delays.

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

Ferranti Limited, Digital Systems Division, Western Road, Bracknell, Berkshire, RG 12 IRA. Telephone: 0344 3232. Telex: 848117.

FERRANTI The real thing in simulation

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. I

ing for Peace Resolutions established procedures whereby the General Assembly filled the gap itself and re-established the system of collective security required in the UN Charter and at the same time the credibility of the UNO itself.

The validity of such Resolutions was strongly challenged by the communist States but it was argued successfully that conferring special powers on the Security Council did not take away the inherent right of individual or collective self-defence, thus falling back not only on Article 51 of the Charter but also on the well established principles of International Law. Uniting for Peace Resolutions have now become an integral part of the Constitution of the UNO. They have been used to deal with the invasion of Egypt by Israel, France and the U.K., the invasion of Hungary by the USSR, the crisis in Lebanon and Jordan in 1956 and the Congo crisis in 1960, not to mention the Cyprus crisis and the ArabIsraeli wars in more recent years. The first military action of UNO was in Korea where the command was direct to the UN military commander and through him to the Security council. On subsequent occasions inclusive of disputes between Greece and Albania and Greece and Bulgaria subcommissions were set up but finally the Assembly required certain States to put some members of their armed forces permanently in readiness for United Nations service with the chain of command through the United Nations Commander direct to the Secretary-General. The first steps had therefore been taken towards a recognised World Police Force.

What therefore is the position of the UNO in International Law? This was considered in the International Court of Justice in an Advisory Opinion on Reparation for Injuries suffered in the service of the United Nations. After Count Bernardotte, the Swedish member serving on a UN Commission, had been murdered by Israeli terrorists, the General Assembly wished the Court to establish whether the UNO could bring a claim against the responsible State with a view to obtaining reparation. The Court decided that the majority of the World's States could bring into being an entity having objective international personality and not only recognised by the States which set up the Organisation. This does not mean that the United Nations Organisation is either a State or a super-State or that it has the same rights and duties. It means however that it is a subject of International Law capable of possessing international rights and duties and of maintaining its rights by bringing international claims. Its actual rights and duties depend on purposes and functions specified or implied in its own constitution and developed by international practice and where it is clear that these could not be carried out if they required concurrent action by foreign ministries of its members. This Advisory Opinion can equally apply to specialist agencies of UNO such as ICAO and to other International Organisations set up by States either worldwide or in specific areas of the world, such as NATO, the Warsaw Pact Organisation, the European Economic Community, etc.

Where then does the air traffic controller fit into this ummary of the United Nations Organisation? Firstly those :ho are employed by International Organisations set up b States gain the protection of the Organisation itself but t:ey also equally take on a. respons!bility to act as interf onal employees and act illegally 1f they use their inter~:t:onal position to benefit th~ir home State. Those who work for ICAO will have experience of the very extensive

26

insurance cover given which is a result of the Bernardotte case.

Probably the first occasion when air traffic controllers were directly affected by a UNO decision was when Katanga tried to secede from the newly independent Congo (now Zaire), and alongside the action of the United Nations Forces, ICAO had to find urgently not only instructors but also practising controllers. This was a case of supporting the efforts of the UNO. However, United Nations action in more recent years has led IFATCA to question just whether some "legal" decisions have not tended to be "political" in nature and doubtful to us when we consider their effect on air safety, and on the running of our Federation.

Prior to the recent coup d'etat in Portugal, ICAO following a UNO decision on sanctions on Portugal, acted in the writer's opinion against the basic principles of the Chicago Convention. Portugal had refused to accept resolutions of the General Assembly on the subject of Declaration on Granting Independence to Colonial Territories. At the 19th Session of the ICAO Assembly, ICAO members passed a resolution to the effect that Portugal should not be invited to any meeting convened by ICAO except as provided for in Articles 48b, 53 and 57b of the Chicago Convention. Further, Portugal would not be provided with documents nor communications except where the Convention specifically provides that documents and communications should be provided or when documents are required for a meeting to which Portugal was invited. This may have been a correct "legal" decision but it is difficult to see how such action could have anything but an adverse effect on the safety of air navigation and it should be remembered that the same members had taken the decision despite the fact that portuguese airspace would still be used by their aircraft and by their own citizens as crew and passengers. It is all the more surprising that such a decision should be taken when no th'mg of this nature has even been proposed agai·nst States which undermine air safety by receiving hijackers as heroes.

Action by the United Nations brought protest ~r~~· IFATCA's Standing Committee VII and the Federat10 Ex~cutive ~oard following the Turkish action in Cyprus. T~: United Nations Forces not only closed Nicosia Airport th not only denying a major airport to Cyprus but also den~-, ing a dive . .

I sut I rsron airport to aircraft to and from lsrae · d bY that w~re n~t enough, the maintenance of facilities use with overflying aircraft was prohibited IFATCA has a1on9 U ·IFALPA and ICAO . the ni made strong representations to f the ted Nations with so far no effect. Resolution A 36. ~ofve­ Melbourne Conference shows not only IFATCA'S in from ment but the good sense shown by the delegate~urkeY ?yprus (holding also proxy votes for Greece) an~ therein what for them was a highly political matter. It. ·~ s are fore to be regretted that some United Nations dec1s1~;h the taken a~parently Without sufficient consultation WI experts in the fields concerned . . · 0 s1t. In the first article in this series we explained the pf om •on of Rhodesia in our Federation. Our colleagues :nc~hodesia because of United Nations resolutions on s nfetions were unable to participate in the Melbourne co ·te ranee because the Australian Government insisted des~. representations of the Australian Association and IFATC s Executive Board on application of the UN Resolutions to the letter. This was all the more amazing since the delegates from Rhodesia could have travelled on British passports. Such only proves that the sanctions which have gene-

rally failed against Rhodesia can nevertheless be applied against one or two private individuals. The Australian Government was legally c orrect. But it is surprising that the U. K. Gove rnment tolerates non-acceptance of its passports. It s hould be noted that some Governments which app ly these sanctions against private individuals, are quite prepared to let their airlines be controlled by these same individuals. Again the law is app lied when it suits and when it is easy and the protests w ill be least. So in our fight for higher standards of safety throughout the wo rld in res ponse to action of the United Nations Organisation, the IFATCA manual now contains the most unfortunate resolution ever passed at Confe rence, Melbourne Resolution A 50. This resolution can have the effect of debarring Member Associations from ever being host to Conference because there w ill always be some nationality unacceptable

to some Governments. Surely th is is a situation which all the members of the United Nations Organisat ion should be attempt ing to end under the Declaration of Human Rights instead of adding more and more d ifficulties to be overcome by Organ isations such as our own which are voluntari ly working for greater safety and at the same time greater understanding between nations an d therefore world peace.

Having looked at t he United Nations, the scene is now set to look at some of its specialist agencies. The next article will deal w it h the International Court of Justice.

For furth er study : United Nations Charter; Harvard Law Review 1953 page 251, Leo Gross; The law of Nations Brierly O.U.P. , Chapters I ll and VIII; International Law Vol. 1, Schwarzenberger, Stevens, Part 7; Oppenhe1m¡s International Law Vol. 1, Lauterpraellt, Longmans, Chap. IV, Part 1; Review of t he United Nations, US Senate, Government Printing Office.

Surveillance Radar Designed For Improved Target Visibility

by Alan Hartley-Smith, Senior Systems Engineer, Marconi Radar Systems Ltd.

By designing around problems inherent in higher frequency operation, modern surveillance radars can offer better performance for both en-route and terminal area control ...

For many years, we have advocated the use of the longer wavelength s fo r airfield contro l and approach radars where extreme range capability is not as important as the ability to see a target in all weath ers and in spite of severe ground clutter. Th is view has been supported by many c ivil aviation autho rities around the world so that Marconi 50-cm rad ars have been pu rchased by close to twenty of the major airline operating countries outside the U.S. and U.S.S.R., with some 60 separate installations.

However, it became evi dent that operational and radio environmental requirements were making it necessary to produce an alte rn ative radar in a frequency band with mo re space available and which did not conflict with general broadcast requirements. In addition, increases in traffic speed and density and the need to reduce aircraft spacing gave rise to a requirement for a radar with a narrower beamwidth and, if possible, a s lightly greater range so that it had the capability to operate in the du al ro le of terminal area and en-route surveillance.

This latter requirement can be met by increasing the horizontal aperture of the 50-cm antenna and indeed the first equipment of this type, the S.670, has been installed.

However, the other factors, coupled with a requirement for turn ing rates of 15 rev./min. forced the consideration of a higher frequ ency band and the design of the S. 654 radar.

Design Considerations The obvious band to adopt for the alternative radar was the 23-cm band. We knew f rom our experience of designing and operating radars in this band for the last 20 years that it s ho uld be possible to produce a radar which wo~ld compare in performan ce with the 50-cm systems. To achieve this, the aspects needing particular study were: Performance in rain; Elimination of permanent echoes; MTI (moving target indicator) velocity response; and Clutter rejection .

27

The 50-cm system is virtually unaffected by rain. A 23-cm system receives returns from weather some 1~ dB greater than those on the 50-cm system. However, a circular polarizer fitted to the antenna would reduce returns from rain by at least 12 dB so that this requirement could be met with negligible effect on its performance in other respects.

The 50-cm system is fully coherent; that is, a pulsed amplifier chain fed from a crystal oscillator drives a _klystron amplifier output stage. This means that transmitter and receiver instabilities are negligible and clutter cancellations up to 35 dB are possible with careful setting up of the MTI system. The coherent system also means that second-time-round clutter returns can be cancelled by a simple two or three pulse canceller. Altho~gh this ca~ability is not often required in Northern Europe, 1t becomes important in the Mediterranean and the Middle East.

A 23-cm system has to use a magnetron transmitter and experience had shown that although cancellation ratios up to 30dB were possible, the limit was usually set by the magnetron and varied with life, with running conditions a~d from sample to sample. If 23 cm was to compete with 50 cm it was essential to obtain a magnetron which allowed the full system capability to be achieved.

A study of the current tubes revealed the main causes of poor performance and a new design was init~ated in the English Electric Valve Company by the Marc~~· Company.

The new tube had improved frequency stability and was tunable for greater flexibility of use. It also could be tuned to the stable reference oscillator rather than the reverse, thus avoiding loss of cancellation during retuning. Short and long term frequency stability were further improved by the use of vapour-phase cooling. Field tests showed that cancellation of permanent echoes by more than 40 dB could be obtained. Since then over 40 of the new transmitters/ receivers, Type S2011, have been supplied and the tube has been adopted by other manufacturers for their own equipments.

Unfortunately the cancellation of second-time around echoes is not an inherent property of a magnetron cohostalo system, but with the use of the six period stagger and prf discriminator system, provided by one of our digital signal processors, second-time around echoes can be largely eliminated. At 50 cm and using a prf of 400 pps the first blind velocity occurs at about 200 knots and a simple double or triple stagger produces an acceptable response to moving targets. At 23 cm the blind velocities occur twice as often and obtaining an acceptable response was more difficult. However, the advent of digital techniques and stores at reasonable prices meant that multiperiod stagger modes could be employed which gave the wished for response. The system performance was further improved, both at 23 cm and 50 cm by the use of dual channel, phase and quadrature, cancellers.

Three Problems Solved Three particular problems had to be solved in the design of a radar if it was to meet fully the requirements of the current and future user: _ Even with good clutter cancellation, small targets could be lost at critical stages in an approach because the clutter levels were too high for the sub-clutter visibility of the MTI system.

"Angels" could completely obscure the radar picture out to 50 miles. This is particularly true at 23 cm because

28

of the steeper front edge of the MTI velocity response.

Area clutter switching.

Clutter cancellation is limited by scanning effect and, since high data rates are required, there was little improvement possible there. It was therefore necessary to reduce somehow the level of the ground returns arriving at the receiver, yet maintain, as far as possible, the signal level of wanted targets.

When the two signals come from the same part of the beam, little can be done, but normally the ground returns are at 0° elevation angle, and the aircraft making an approach to an airfield is usually at about·3°. An antenna was therefore designed to provide the maximum possible reduction in gain between the +3° elevation and 0°. This could be obtained most easily by working on the edge of the vertical radiation pattern, by tilting the beam up, but the forward gain is thereby reduced and this technique limited to use at fairly short ranges. However, by using a reflector with a large vertical aperture, giving an intrinsically narrow vertical beam, and fitting two independent feeds, one providing normal cover for long range, the other providing the tilted up beam for short range, the desired result can be achieved.

In practice, the system was simplified by transmitting on the normal feed only and receiving on both. In this way only a single transmitter/receiver was required and a 3° signal/0° clutter improvement of nearly 20 dB over a normal system achieved.

Angels present a problem because they can exist at the same elevation angles as wanted targets and since a substantial proportion move at speeds between 20 and 50 knots they are not cancelled by a normal MTI system, particularly at the shorter wavelengths. Doppler compensated MTI can be used to cancel some of them, but if, as is usually the case, fixed ground clutter has to be cancelled in the same area, duplicate systems are required which more than doubles the cost of signal processing equipment. Since the majority of angels occur at low altitudes, about 1500 feet, and short range aircraft are usually at angles of 3° and above, it is possible to emphasize aircraft targets relative to the angels by keeping antenna gain above 3° as high as possible. Also since angels generally have an echoeing area of about 0.01 or 0.02 sq. metres, it is possible by the careful use of swept gain to reduce the angel returns to a very low level of detection probability without losing aircraft targets. Thus our new antenna type s. 1020 makes the best possible use of the large vertical aperture, and separate swept gain waveforms for main beam and composite beam are tailored to match the antenna gain characteristic.

Area clutter switching is of particular importance to make maximum use of the considerable MTI capability, particularly under changing conditions due to anomalous propagation.

One loss present in all MTI systems is the tangential fade when a target's radial velocity is zero. To avoid this as much as possible it is desirable to use the MTI only where it is necessary to remove clutter. The simple method of doing this is to select MTI for a pre-set constant range covering all the local permanent echoes. This has the disadvantage that clutter does not usually extend to the same range in all directions and therefore MTI is used in clear areas where it is not required. An extension of this method allows the MTI region to be divided into sectors, preset to be either an MTI sector or a non-MTI sector. This reduces the clear areas subject to MTI. Neither of these

methods copes easily with changes in the clutter due to changes in propagation. Attempts to improve on this led to the development of automatic clutter switches employing pulse amplitude and duration thresholds to decide if clutter were present at any point in a radar period and select MTI when necessary. These work satisfactorily on solid clutter which extends for a significant range interval, but cannot differentiate between broken clutter and targets within a single radar interpulse period. The consequent residue is unsatisfactory for PPI displays and is likely to overload a plot extractor.

The area clutter switch, which is a recent Marconi development, examines small areas of the plan data and decides by comparison with pre-set references and by comparing each area with the eight surrounding areas, whether or not a significant level of clutter is present. If it is, the information is stored until the next scan of the antenna over that area and used to select MTI for the duration of that area. For a typical system there are 5,000 to 6,000 elemental areas.

Clutter returns can be distributed in various ways and the reference levels stored in the comparator system are pre-set to enable these different conditions to be recognized and the appropriate decision to be taken. The clutter switch output may be used also to ghost in the clutter areas on a plan position indicator.

The ability of the S. 654 to reduce unwanted clutter returns to a level at which they no longer obscure wanted aircraft targets is one of its chief attributes. This capability is amply shown in the accompanying figures. Figure 1 is a plot of signal/noise (in dB) against range for a conven. t{onal cosec2 beam radar. Curve No. 1 is a plot of peak clutter strength derived from an analysis of measurements on an actual radar sited on a high point in mountainous country in Eastern Europe. This is assumed to be a typical situation for comparison purposes. Curve No. 2 is· a plot of signal strength for a 3 square metre target flying towards the radar at a constant elevation angle of 3°, i. e. down the beam. curves 3, 4 and 5 are plots for the same target flying at a constant height of 5,000 ft., 10,000 ft. and 40,000 ft. curve No. 6 shows the clutter level when the MTI system has reduced it by 30 dB. To be visible, target returns have to be greater th~n clutter returns and it is seen that none of the targets 1s visible without the use of MTI once they have entered the clutter region at about 80 miles.

The application of MTI improves the performance a little, all targets being visible in to about 50 miles, but even the aircraft making a 30 approach is then lost until it is clear of clutter at about 5 miles. Figure 2 shows the performance of the s. 1020 main beam, the other radar parameters being kept constant. The five curves represent the same conditions as in Figure 1, and the reduction in clutter level due to the beam shape is noticeable. Figure 3 shows the performance of s. 1020 composite beam on the same basis and it is seen that all the targets are now visible all the way in from 40 to so miles with the exception of the low flying aircraft at s,OOO ft. which is visible from about 25 miles.

In order to illustrate the performance of the S654H radar (Fig. 4), the parameters may be fitted into a range calculation equation. As it is system performance, account is ta~e~ of the duty cycle, range requirements, system transm1ss1on losses, receiver bandwidth, prf stagger, display collapsing and operator losses, antenna beam shape and

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29

atmospheric losses. All of these factors combine to determine the optimum values of the variable parameters. we believe this new radar has been designed to meet present and future requirements, using modern techniques and state of the art components, and costed to match civil aviation budgets. The design has involved a deep knowledge, not only of the equipment parameters, but also of the working environment, under both normal and abnormal conditions.

The High Cost of Failure The average controller washout costs the government $ 55,000. It takes $ 46,000 to train a terminal failure {ave~ rage of two and one-half years). Average Center washout cost is $ 66,000. In initial training at the Oklahoma Academy, only one out of four pass the original test, and only one out of eight make it out of the Academy.

(PATCO Newsletter)¡

More About Radar Data Processing Problems in the U.S. Controllers Comment On The State Of The Art The introduction of Radar Data Processing (RDP) at Air Traffic Control Centres in the U.S. is still giving many problems.

In the past, utilising the broadband system, radar directly saw and presented aircraft on a scope before controllers. In the RDP system, readings from a different beam (narrowband) are fed with other information to a computer which then places a symbol of where the plane is, along with a block of data about it, such as altitude. The controller is no longer seeing a reflection of a plane. He sees a calculation made by a computer.

There were massive malfunctions when the equipment was first installed in 1974. Far too many problems still exist - some may haunt the equipment forever. The posit:on is that the present narrowband RDP system remains a highly unreliable piece of equipment. The controller lives with this unreliability every working moment. He has been exposed to the possible malfunctions and he has worked out emergency methods to deal with them. The danger, however, is a combination of problems hitting a controller all at once - either a number of specific RDP malfunctions, or other problems, as a traffic overload, in connection with RDP. One of the selling points of RDP is that it precisely locates a plane on a scope. This not only enhances safety but might allow closer spacing between planes. But many design flaws have emerged. At present, high speed planes can outrace the computer. When this happens, it literally gives up. Instead, it uses a prediction memory to show where the plane probably is going (known as "coasting"):The procedure for corrective action to rectify a system fault is that suggestions by controllers for changes are sent by the Centres to a focal point in Washington, the National Proposal Change System (NPCS). Later, if changes are made, they come back to the Centres in the form of tapes from NAFEC. In the first instance, NPCS is swamped with thousands of suggestions, many of them pertinent only to one facility - local problems that should be solved locally. The NPCS method drags on at a snail's pace, taking over a year to act on many serious hazards. On the other hand, when tapes do come out correcting the system, they show signs of being hastily and incorrectly prepared. In this instance, the controller loses confidence in the system, and he is constantly forced to adapt to the new procedures, only to know they will be changed again very shortly. More leeway to correct local problems locally should be allowed. Today, no Centre can apply more than five of its own "patches" -

not enough for the number of problems that should b& solved locally.

Eye strain is one of the newest problems to emanate¡ from RDP. Controllers report that there is a harsh glare from the glass of the new display that seriously affects their vision. The glare not only reduces the ability to concentrate, but can have a lasting effect on the eyes. There are several instances where controllers have applied for medical discharges for eye problems associated with the equipment.

Here is the present state of the art regarding RDP problems.

RINGAROUND: Perhaps some more ominous word should have been chosen to describe this serious and perhaps permanent hazard of RDP. When a plane comes to within 15 miles of the antenna, its reception becomes greatly distorted. As a result, it appears on the scope as a number of targets in a straight line, each with a partial data block. The controller then has the unhappy guessing game of determining which is the real contestant, assigning it the full data block and following it along. FAA has reduced some of the ringaround effects by placing absorbent material around the antenna. Ringaround occurs less frequently, but still far too often.

TARGET SWAPPING: The computer can sometimes get confused as to which plane is which. But it does not hesitate. It has data blocks to assign - and it assigns them, even if it might not be to the right target. Much of the original target-swapping has been reduced. But there still remains a dangerous problem with non-discrete transponders. A discrete transponder has an actual code at the end of its "message" (as 01) by which it, of course, can be identified by the computer. The less sophisticated versions have only "00" as the last two digits of their ident.

The solution here might require only discrete transponders in the system.

But radar tuning can also create target-swapping problems. As one controller puts it: "We are dealing with a Model-T radar and a Cadillac computer. No matter what the capabilities of that computer, it can never overcome the limitations of the system it works in."

JITTER: This is one of the things that a non-controller would have to be in a facility to see - to understand it and to believe it. Targets weirdly appear to be walking sideways, crablike, on the scope, wavering back and forth as much as four to five miles on each side. This can well be a permanent problem, since it deals with what are called slipbox seams of the scope itself. That scope is actually divided into a number of "boxes", each 16 miles square.

A different component of the radar reads planes in each

30

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:box of space. But as a plane passes from one box to another, it passes through a seam, the boundary between 1he two areas of radar coverage.

As a result, two different radars start reading the plane inaccurately as to its length and width, actually fighting ¡One another to place the plane in their box. What happens is that the radar and the computer depend on a number of readings along the body of the pla,ne, from nose to tail, called "hits". If it gets, for example, 13 hits of a plane body length, it assumes the plane to be in the centre of that series - at hit seven. A a plane is partially passed 1hrough a seam, therefore, the radar may get hits only from the front position of the plane, but it reads the total plane as being in the sector regardless.

If a series of planes are involved, the garbled readings can get impossibly complex to follow.

PRIMARY CELL ERROR: When those two different radars are reading different portions of the same plane, a sort of multiplication can also result. Each can register its piece of plane as the whole plane, resulting in two separate targets, each in a different box.

RANGE LIMITATIONS: The present RDP allows only several predetermined range selections which are not variable by location. Therefore, if a controller owns 75 miles, he is forced to turn on a range of 100 miles - the closest setting available to him. This creates distractions and greater workload. The limits of the range setting presently are also the height of folly - 6 miles up to 400 miles. No controller on this earth will ever need either.

Here a solution should have been arranged months ago.

PRIMARY CLUTTER: It appears that controllers wm always have to live with the fact that obstacles like mountain range tops register on RDP as a series of dots and pluses. The computer is just doing its job. Something is registering there, and it's reporting that something. Whether it is an airplane or not doesn't matter to its immobile range of "thinking".

DATA BLOCK SWAPPING: This is closely related to target swapping, and the garbling of the code by the computer, especially when the transponder is on Mode C. It has become less frequent a problem, however.

PRIMARY TARGETS: The awful and unavoidable truth is that the narrowband radar does not and probably never will display non-transponder aircraft as well as the old broadband system. Controllers now constantly use the old vertical displays (broadband) to find out where these planes are. If broadband is phased out, there are bound to be serious incidents because the controllers simply will not know where all the planes are.

POOR WEATHER DISPLAY: Some controllers point this out as the worst possible long-range problem of RDP. At Centres now, controllers use the vertical display to monitor weather as well as a check on the horizontal RDP display. The RDP system does not show weather properly, and all indications are that it will never do so.

This lack is tied in with an overload factor. RDP does not have the storage capacity to show weather fully as well as the other information. on the West Coast, for example, controllers must turn the weather display on, then quickly off. If overloaded, the computer simply refuses to take added information. This means there are long delays before new needed information is accepted by it, and displayed.

INCREASED WORKLOAD: Many of the malfunctions listed above, of course, add greatly to the workload of the

controller. There is one individual problem of interim altitude hold which is in a class by itself. In this function, the controller is about to pass an airplane over to another sector and another permanent altitude. But there is an interim period when he assigns the plane for a brief period of time an interim altitude. Under RDP, there is no interim altitude. For that setting, an entire new operation must occur with the printing of strips. This means the controller has to make two steps and a phone call, when previously only one step was involved.

That is more than three times the work. The solution has been worked out in the New York ATCC, but NPCS has not acted nationally. Presently, New York is working on a patch wherein no strips will be printed during that interim setting. It hopes to do this by assigning this interim function to one of the three special quick-action keys the controller has at his disposal. One of the problems with local patches is the tremendous technical manpower needed. Many Centres would not be able to work a needed patch out.

When RDP first started, FAA claimed that the problems were the normal "bugs" of any system that would easily be worked out in a few months by minor changes in equipment placement and software. It simply hasn't turned out that way.

(PATCO Journal)

Achtung Heard over the R/T at RNAS Culdrose, Britain's biggest helicopter base, as a German Navy helicopter flew in to take part in International Air Day. .

Controller to pilot: Be advised of Spitfire and Hurricane to your south-east.

Pilot: Don't they know that the war is over?

(Air way)

Suspension was Excessive In binding arbitration at Miami Center, a 15-day suspension of a controller for alledgedly leaving his post improperly without briefing his relief was reduced to fiv~ days.

It was the first such offense for the controller in question and the arbitrator made his ruling based on Section 70, Chapter 3, "Maintaining Discipline." In this instance, for failure to carry out orders or assignments given by a superior official, First Offense, the punitive actions are "written reprimand up to five-day suspension." Any loss of pay or benefits have been ordered restored to the controller.

(PATCO Newsletter)

Automated Weather Display A number of units of an automated weather display have been delivered to the Washington ARTCC. The system called MAPS, for Meteorological and Aeronautical Presentation Subsystem - displays forecasts, winds, temperature, humidity, dew point, NOTAMS, severe weather. etc., in alphanumeric form on a small TV screen installed at a sector control position. In addition to the basic weather page, tailored to each sector's needs which is automatically updated as new or special reports are received, the controller can select other pages of data which he uses less frequently. The system has provision for alerting the controller to select other pages for important data such as SIGMETS, flow control messages, etc.

31

ATC at Copenhagen {Kastrup) Airport

by Fernand Grange, Engineer, T-VT Division, Thomson-CSF (France)•

aircraft, and therefore they are combined lower and upper

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Air Traffic Control section; the building to the right houses Approach Control and Centre.

sectors. .

The route structure is based largely on one way Airways and this geographical separation of traffic makes it possible to divide both Sectors 1 and 2 into inbound ~nd outbound radar functions, assisted by a common planning controller working with a flight progress board (FPB). to maintain a total picture of the traffic situation within the sector. The planning controller updates his FPB based on air-ground communications and on information received from the radar controller; he is also responsible for feeding estimates to adjacent centres and for ensu ring that proced ural separation minima are maintained between traffic outside radar coverage. Further, as far as possible, he must receive and pass on rad ar handoffs on behalf of his radar controller. Control of traffic in the western part of the FIR is shared between Sector 4 (lower airspace) and Sector 5 (upper ai rspace).

The radar controllers are the executive controllers, and all traffic within radar cove rage comes under radar control. The control room is configured so that the departure controllers are in close contact with the outbound controller. Likewise, the handoff positions are located to facilitate co-ordination between the arrival and departure functions.

A new Air Traffic Control Centre at Kastrup went into operational service in March 1973. This Centre, which p~o­ vides Flight Information Service and Area Control Service within the Copenhagen Flight Information Region (FIR) as well as Approach Control Service for a number of civil airports, is equipped with a highly sophisticated radar data processing and display system. The contract for this system was placed with our fi rm in April 1971 following an international tender, and the system was accepted on site only 22 months later.

A major part of the existing civil air traffic is concentrated in the south-eastern part of the Copenhagen FIR. In this area, the traffic into and out of Kastrup Airport dominates but also traff ic to and from Malmo Airport in Sweden ~nd overflying traffic play an important role. Military ai r traffic movements are mainly concentrated in the middle and western parts of the FIR, where civil traffic activity is lim ited. However, domestic traffic between Copenhag en and a number of airports in Jutland is increasing rapidly, and this factor was taken into consideration in the new control syste m.

How Traffic is Controlled The East Sectors (1, 2 and 3 and the arrival/departure sec) be considered as a large terminal area (TMA) tor . ma~he airports around Copenhagen and Malmo. With serv1ndgt the traffi c to/ from these airports, Sectors 1, 2 and regar o . f ly t ied to the arrival and departure unc3 are very c Io Se . they are located ad1acent to one ant"1ons · consequen tly . . ' . mon control room. Apart from overflying other in the corn . . ctors also contro l climbing and descending traffic, these se • Thomson IFATCA.

32

CSF. Paris, France , is a Corporation Member of

The Automated ATC System The ATC system presents controllers with a clear and unambiguous picture of the air traffic situation on synthetic labelled plan radar displays by means of computeraided processing of radar and procedural data. It is capable of handling up to 2,000 flights per day and an instantaneous traffic load of up to 100 flights.

All flight data inputs needed by the computer to process the picture required by a given sector, and for correlation with radar information, are either prepared in advance and disc stored or they are entered in real time into the computer from flight data positions.

The handoff position takes care of the majority of other inputs (few, it is hoped), giving the radar cont roller as much time as possible to perform his control functions, thereby increasing his traffic handling capacity.

The radars acting as the sensors for the Copenhagen ATC system are a long range primary radar (LRR), a secondary survei ll ance radar (SSR) associated with the LRR, and an airport surveillance radar (ASA). all located on the airport. In addition there is one of two joint-user primary radars (ASRs) whose data are received via broad band video link from a location in the western part of the Copenhag en area, plus two other remote joi nt-user radars in the western part of Denmark whose data are received over 1,200 Baud links.

For Approach Control, the centre of the coordinate system is based on the actual position of the ASR radar at Kastrup Airport. The synthetic coordinates are taken to be over a 128 nautical mile square. For en-route control, all the other radars have a coordinate centre which corresponds roughly to the centre of the FIR. The synthetic coordinates are taken to be over a 512 nautical mile square.

Part of the Area Control Centre; from the left Departure position, then Handover, who i s in charge of inbound flow and crossings ; the third position is Arrival East, the fourth Arrival West.

Basic System Capabilities The processing equipment performs eigth main functions: SSR and primary radar tracking with synthetic labelled plan display ¡ of plots and tracks; automatic SSR and primary radar track correlation ; automatic radar mosaic proc<;ssing; flight data acquisition ; automatic co rrelation of SSR tracks with flig ht data; presentation of flight data messages on tabular d'.spla~s; flight plan up-dating, through keyboard and 1oyst1ck inputs to th'3 computer; and active decoding of SSA data.

In addition, the controllers may view as .bac~ground data o n their radar displays SSR passive decoding slashes, the raw primary radar pi ctures, analogue or dig ital video map and VHF direction-finding (VDF) lines.

Th ere are 16 princi pal radar control consoles. - ea.eh eq ui pped with a main 16-inch radar displ ay, a 9-in~h diagonal tabular display, a functional and alphanum~n c ~ey­ board, a selection panel and a joystick for track des1gnat1on.

The choice of pictures available at ea?h c~ntrol console depends on its control functio n. (Certain criti cal consoles have an aux iliary radar indicator, thus the total nu.mb~r of radar displays is 23, in cluding the technical superviso r s console.) d.

Movement consoles are equipped with tabular isp 1ays and keyboards. Each radar display may present one of two raw radar backg round pictures on which is superi mposed the synthetic labell ed plan picture. Keyboards linked to the computer system enable the operator to initi ate orders and to introdu ce or modify fl ight data. The joystick is used by the radar operator to designate a radar plot on the screen for track initiation or termination, active decoding and handoffs.

Moreover, each radar console is provided with a selection panel which enables selection of : synthetic radar ; up to five synthetic video maps (four approach and one en- route); runway lin es (up to 10) ; VHF di rection finding (up to nine VDF chann els); active decode (an ON/OFF decode function key is provided, used in conjun ction with the j oystick) ;

-

quick look (to permit any operator to view on his screen the label s of any other sector, 15 keys provided); all SSR (enabling all SSR targets with si mplified labels to be seen simultaneously).

Assistant and movement consoles are fitted with a tabular display and a keyboard for flight data processing.

There is one flight progress board and one assistant position for each of the five sectors and two movement positions. In addition , there are four tower positions: tower move ments, ground control , local co ntrollers I and II, the last th ree without keyboard. In all there are 31 tabular displays.

The Computer System Data processing is based on a Cll-10020 central computer, wh ich includes two real-time clocks, eight automatic in put-output channels and a direct input-output facility.

Peripherals inc lude two on-line keyboard pri nters, two disc stores (800,000 bytes each), a card reader, a buffered line printer, a fast paper t ape read-punch unit and a magnetic

This i s Centre Sector IV ; in the middle Planning Controller Civil & Military. to the right i s IV A manned by a Civil Controller, to the left IV B with a Military Controller. The realisation of an integrated system.

33

tape unit. The computer storage capability is 36,000 16-bit words - 18,000 internal and 18,000 external.

Radar and keyboard data are received through a special unidirectional coupling unit which is connected to a standard input-output channel. Through this channel are received plot data from four radars plus keyboard and joystick data.

In addition to handling radar and flight data, the computer system provides the output to the display system through the coupling unit connected to the external memory bank. This permits two synthetic generators to read data inside the external memory at the same time as the central processing unit. These data correspond to radar tracks display and tabular display. Programming is modular, with resident and non-resident modules.

In the radar processing system, an extractor and plot processor handle digitizing, filtering and correlating of raw information from the SSR and LRR; a second plot processor is linked to the Danish radars for processing. Outputs

of both plot processors are routed to the radar display system.

In the radar display system, a data selector receives radar plots from the processing system and tracks from the computer. It stores data entries from the joysticks, keyboards and selection panels and routes these messages to the computer for tracking. It then collects computer track data which are fed to the synthetic generator. The latter acts as a digital-analogue converter by generating from the plot message the suitable waveforms for the head selector units; it also generates the digital video map, runway lines and VDF lines.

The head selector units receive the information to be displayed on each radar screen and route them, after scale and off-centering adjustment, to the corresponding viewer unit.

The tabular display system, essentially a tabular generator, converts the computer messages into suitable waveforms for flight data presentation on the corresponding tabular display unit located on the radar and FPB consoles.

The General Aviation Pilot and Air Traffic Controllers The following comments by Dr. Alan Frosst, Vice-Presl¡ dent of CAOPA (Canada), are a brief resume of his dis¡ cussions with members of the Canadian Association, which we recommend to controllers the world over.

The primary objective of Air Traffic Services is to facilitate the operations of IFR high-performance jet traffic at the major terminals and not VFR general aviation, and I am very concerned that the controllers, the people who operate the system, do not have much of an appreciation of the needs of the VFR pilot and the environment in which that pilot operates. For this reason, I would like to address these few comments to all controllers with the hope that they will become more familiar with general aviation and the VFR pilot and more appreciative of his problems. In this way, controllers will be better able to relate the requirements of the control procedures in the air traffic system with the needs of VFR flying.

General aviation has come of age. There are over 40,000 licensed pilots in Canada, 36,000 of whom fly more than 15,000 general aviation aircraft, and private individuals now own over 11,000 of these aicraft. These range from two and four-place single-engine aircraft, with cruising speeds of 125 to 180 mph, to six and eight-place twin-engine aircraft that can cruise well over 200 mph for distances up to 1200 miles. With the advent of increased technology in the field of avionics, a large portion of these aircraft have sufficient communications and navigation equipment to enable pilots to fly them anywhere in North America, if not the world, and many of the higher performance models have equipment which meets or exceeds the standards required for airline-type operations. By 1980, it is estimated that there will be 20,000 general aviation aircraft in Canada, and as good a guess as any is that these aircraft will be flown by over 60,000 pilots.

In comparison with these figures for general aviation, the Canadian airline fleet numbers approximately 250, with only 185 aircraft of a gross weight of 100,000 lbs and over, and by 1980 it is expected that there will be little growth in these numbers. .34

General aviation aircraft, therefore, constitute better than 96 percent of the aviation fleet in Canada, and considering that the scheduled airlines serve barely 7 percent of the 871 airports in Canada, these aircraft have become an integral and necessary part of the Canadian air transportation system in providing air transportation between the 93 percent of the airports and communities not served by the airlines - and also to the 7 percent which do have airline service. In addition, general aviation serves hundreds of other communities and persons which have small airstrips, many of which have been built by private interests.

A survey carried out in late 1971 showed that 20 percent of the aircraft movements at Toronto International Airport and 25 percent at the Toronto Island Airport are itinerant business aircraft - general aviation aircraft. By conservative estimate resulting from interviews conducted, these businessmen spend over$ 10 million a year in the Metropolitan area, not to mention the very significant trade and commerce which is carried on during their stay. Combined with other available data, it has been estimated that the economic impact of general aviation on the Gross Provincial Product in Toronto is at least$ 80 million per year, and the Ontario Ministry of Transportation foresees that the contribution from general aviation in the Province of Ontario will grow to over $ 800 million per year by 1980. It can be seen readily from these figures that general aviation plays an important part in providing complementary air transportation services to all Canadians and is vital to this country.

General Aviation Piiots General aviation pilots and their aircraft are therefore not people and machines to be flouted or ignored. In many cases, they are flying for a purpose not any less important to themselves or the country than many people who fly on the airlines, and they require full consideration in respect of their needs and should be dealt with in as conscientious and effective a manner as possible.

It is certainly recognized that many pilots who fly light aircraft do so for the pure pleasure of flying - and in many

cases, these pilots may never fly more than 50 miles from their home base. On the other hand, the maturing of general aviation has prompted greater and greater numbers of general aviation pilots to travel long distances to visit relatives, friends and places or to conduct business by a means that compares favourably in price with standard-sized automobiles. Often the cost is lower than airline fares when all of the seats in the light aircraft are filled. But regardless of their mission, VFR general aviation pilots will, at one time or another, require an interaction with the air traffic controllers, and for this reason I feel that it is very important for controllers to have a full appreciation of their needs.

VFR general aviation pilots are not airline transport pilots, although the latter group served the same apprenticeship, and as such, they must not be expected to have acquired the same level of_ experience and proficiency. Air traffic controllers, on the other hand, are all professionally trained to carry out a full-time responsibility to a very high degree of proficiency, as a result of which it is often difficult for them to accept that all pilots are not equally proficient.

Private Pilot Training The training of a private pilot involves a mm1mum of 35 hours of flight time and 20 hours of ground school instruction, but because of increasing requirements for knowledge1 the average student pilot acquires 45 hours of flight time and nearly 40 hours of ground school. Combined, these two aspects of private pilot training provide the stu.dent pilot with the basic skills and knowledge ne~ded to handle an aircraft with reasonable competency. But 1t takes many, many additional hours of experience f~r the priv~te pilot to acquire the kind of k~ow-~ow that will enable him to handle a wide variety of s1tuat1ons,. and he should .not be criticised because he lacks cert~m a~vanced ¡ skills.

Rather, in situations which warrant d1scuss1on, he should be guided and educated in order that he can learn and improve. .

For instance, the student pilot learn~ the bare essent~als about weather during his course, and it takes a lo~g tim~ ¡ ters with a variety of meteorological s1an d many encoun . b f h can do a good job of analysing weather . . t uat ions e ore e conditions as they pertain to each flight. Goodness only knows with all the years of experience, back-up data and comp~ters that qualified meteorologists are not always right - as' every pilot will readily attest - so one cann~t expect a private pilot to be infallible. He. must lear~ h~s limitations but when the information provided for him is not 100 p~rcent accurate, there is no way that he can make . assessments that will always be right.

Navigation training is good in the course of private pilot instruction, but many cross-country flights ar~ needed before the pilot becomes proficient in map readin~, VO.R and ADF. During his course, the student pilot is trained in the essentials of pilotage, crosswinds, fuel managem~nt and a host of related requirements for safe and effective cross-country flying. After he has completed the co~rse, however he must get out and practise these other various types of ~errain before he can be expected to have the kind of ability to navigate with complete proficiency. .

The quality of instruction provided at many flying schools and clubs is very good, but because instructors are naturally looking for better paying positions than they can earn instructing, it is little wonder that we see t.1ps and

downs in private pilot training. Sometimes the expansion in the airlines takes a large percentage of the experienced flying instructors away from training. It takes time to train a good instructor, and the problems of training and keeping good instructors are reflected directly in the quality of the private pilots produced.

For many years ground school courses have been taught by advanced private pilots working their way towards a commercial licence and only during the past few years have we seen a trend towards hiring really competent and experienced pilots to handle this part of the training. Audiovisual and other good instructional aids are more readily available now but these cost money and their purchase is not always financially justified at the smaller training schools.

In general, however, VFR pilots are recognizing more and more the desirability to learn as much as they can and this attitude is resulting in improved flight safety. It must be appreciated, though, that there are a large number of pilots who cannot afford much advanced training or who do not fly very much. These pilots must fall back solely on their private pilot training and although they may be competent to handle local and short flights, they will not have the knowledge or the advanced skills of a commercial general aviation pilot.

All of these factors are important to the air traffic controller in his dealings with general aviation pilots who have a very wide range of experience. We are working to improve the situation by encouraging pilots to upgrade themselves, but for every pilot who does improve his qualifications through experience and additional instruction, another new pilot comes along in this dynamic and vital industry.

Each of us, therefore, who has a role and responsibility in aviation must do his part. In particular, the air traffic controllers must be continually aware of the changing situation and maintain a thorough appreciation of the needs of general aviation.

(Canadian Flight)

General Aviation: ATC Planners Please Note In the United States we have a pretty fair-sized general aviation community. We fly about 50 per cent of the total passenger airlift. Also, general aviation now makes more use of the US IFR system than all of our airlines together.

The day is approaching when general aviation will become the standard method of moving by air between communities throughout the United States and the Western Hemisphere.

(Max Karant, Senior Vice-President, US Aircraft Owners and Pilots Association)

A New Education Programme The U.S. Civil Service Commission has approved an education programme which will allow students to be eligible for training in Air Traffic Control through college, study-related curricula. To be eligible, students must be working towards a four-year degree and must complete two years of study before entering the cooperative education programme, as well as pass the FAA medical and aptitude tests for ATC work. Students successfully completing appropriate work and academic requirements will be eligible for non-competitive appointment to ATC jobs.

35

Secondary Radar for the Smaller Airport*

by D. A. Storrar, Plessey Radar Limited

into a form which clearly presents identity, height and aircraft plan position.

As a result of the considerable experience of large A TC data-handling systems gained by various Ai r Traffic Control authorities and by the electronics industry it has been possible to use recent technological advances to design equipment which overcomes problems that a few years ago were insurmountable. Industry is now offering comparatively inexpensive systems, small in physical size, which will display automatically processed SSR data derived either from an SSR collocated with a primary radar or from one several miles away. Additionally, and of great importance, the remote SSR pictu re can be centred on and combined with the local primary radar picture so that secondary responses overlay the track of the primary radar echoes.

Plessey AR-15/2 T erminal Area Radar with On-Mounted SSA Aerial

The information contained in ai rcraft responses to Secondary Surveillance Radar (SSR) interrogation s is of value on ly if the relevant data can be presented to the appropriate air traffic controller in a suitable and timely manner.

In the past there have been certain difficulties in doing t h is and whi le it is not suggested that all the difficulties have been overcome, there have of late been so me interesting and significant advances. One cause of difficulty has been t he fear of proliferation of SSR interrogators whi ch. if it occurred, would exacerbate the problem of over-interrogation w hich in turn causes garbling and poo r presentation of SSA data. Suggestions for the use of low-power interrogators overcome only part of the pro blem in that a transponder o nce triggered gives a full strength reply received at long ranges. Airport authorities have the refore been d iscouraged from acqu iring their own SSR eq uipment.

Secondly. although it has long been possible to re lay SSR a nd other rad ar data by microwave links from one site to another it is usua lly of little practical use for an approach control ler to be presented with an air situation centred upon a radar many miles away. Thirdly, a further deterrent to the widespread use of SSR has been the bulk and cost of the data-hand ling equipment necessary to convert the SSA s ignals from the ir rather uniform ative analogue garb

• Th . paper was presented at Convex "74. the Convention and E h "blt' os he ld at Bournemouth , U.K., in October 1974, under the 1 the British Guild of Air Traffic Control Officers. The x • oon ausp ices o 1 . . · hes 10 thank the Directo rs of the Plessey Company for their aut hor wos . .

• .. kind pe rm iss ion to publis h th is article on .,The Controller .

36

One such system is the Plessey Series 200 automated ATC system; another is ARTS II which has been specified

by FAA in the United States (this system was qescribed in our November 1974 issue - Ed.). These systems are intended for terminal area Air Traffic Control and typically they provide additional facilities in approach rooms al ready equipped w ith primary radar. The majority of the descriptive material in this paper refers to the Plessey system.

Similar but rather more complicated eq uipm ent is available for en-route Air Traffic Control applications.

The typical primary radar picture will be fam iliar to everyone and needs no further mention. W it h automatic SSR, signals indicating plan position, identity and height are received from each responding aircraft wit hin the coverag e of the SSR. An automated SSR data-handling system is usually designed to accept, process and store the responses · from about 200 aircraft and each air t raffic cont roller can select any or all of this information for his radar display. The information wanted is displayed on a so-called label ; a leader line ties the aircraft response to t he label and labels associated with aircraft are ori entated in such a way as to avoid confusing overlap. Small dots behind each aircraft symbol indicate the ai rcraft's directio n of movement. The label shows the flight level of t he airc raft ; information from the ai rcraft's altimeter is relayed as part of its SSR mode C response and the rel evant barometri c press ure has to be entered into the co mputer which th en automatically applies the ONH cor rection to th e received altimeter reading of those aircraft that are below t he transition level.

Regarding the four-figure code which is allocated by ATC and transmitted by the aircraft, the user of t he automated SSR system has the choice of whether any particular aircraft is d isplayed with its four-fig ure code o r with any other designation such as callsign or airframe number.

The choice is made by using a keyboard to info rm the computer of the desired designation and the associated fourfigure code. The computer will associate a code/ callsign pair fo r a predetermined time, e. g. 30, 60 or 90 minutes depending on the instruction entered on the keyboard .

After that pred etermin ed time the code number may be re-allocated and if received will be di splayed as a fou rfigure number unti l t he keyboard is used to input a new code/ callsign instruct ion.

In the Plessey system each label consists of two lines and each line of eight characters or spaces. The unused spaces in the label may be filled by any alphanumeric characters at the discretion of the ATC authority; for example a two-letter code indicating aircraft destination or route and/ or a code showing which control position is responsible for the airc raft. It is not yet clear what is the optimum amount of data to be displayed alongs ide a radar blip and also there is room for further experiment regarding the format in which the data is presented.

Another aspect that requires continuing thought is the way in which aircraft labels are selected for display. It is vital that each controller should have confidence that an .automatic system is presenting information on all the air.craft for which he is responsible and on any other aircraft in their vicinity. But he will not want irrelevant data which ¡clutters his display unnecessarily. The compromise which we have currently adopted provides facilities for each individual display position to have three airc raft label filters.

These are set up in the operations room . a) There is a height filter which enables a controller to have labels displ ayed only for aircraft between two selected heights. b) There is an azimuth sector filter which selects labels between any two preset bearings. c) There is a set of six code filters wh ich are used to select or deselect the labels of six different categories of SSR code. For example one filter might be set to select for display only those codes beginning with a figure 5 or to deselect, that is eliminate, all such codes and to display all o ther codes.

In all cases, the position symbols (but not the labels) of transponding airc raft are also shown on the d isplays regardless of the filters and, by depressing the quick-look or 'filter override' key, a cont roller may bring up .all the labels for immediate identification of any target. If any aircraft transmits one of the three emergency codes then, regard less of the fil ters, a flashing label will appear showing which eme rgency has occurred and the airc raft's flight level or altitude.

The ability to write figures and letters on the radar display is uti lised to provide a tabulation of important data.

Currently in the Pl essey system the tab area shows: a) A digital c lock read-out. b) The barometric pressure. c ) The 3 filter setting s: Height, Azimuth and Code. d) A 12-digit message from the supervisor to all controllers. e) An indication o f an emergency response received w ithin the system, even if not within the area cove red by that partic ular display.

In principle any information may be written on the radar sc reen and it is our intention to add a tabulation listing the aircraft about to enter each co ntro ller's sector.

It is worth noting here that some of the technical facilities descr ibed imply certain organisational arrangements; for example to permit the automated system to tabulate a list of aircraft it must be someone's job to enter the r~le­ vant flight plan details. As ano.ther. ~xamp le'. .the setting up of the code filters might be s1mpllf1ed by giving thought to the allocation of the four-figure SSR codes.

The SSR hardware which provides the facil itie~ desc ribed can be co-located with the primary radar with the advantage that on ly one tower and turning gear is required ;

Automatic SSA Display Presentation

in this case one building would house all transmittingreceiving equipment and th is would normally be connected to the displays by cab les laid with in the aerodrome boundary. Such an SSR system was ordered from Plessey by Jersey and was integrated with the prim ary r adar already installed at that airport. A very similar system was ordered

by DGCA Mexico for installation at Monterrey Airport but in that case a Plessey AR 15/2 primary radar was ordered with the SSR equipment, also 22-inch diameter displays.

Howeve r, it is important to note that it is not necessary to co-locate secondary and primary radar. The SSR may be several miles away from the primary rad ar and con nected to it by only a single telephone line. Such a system was demonstrated by Pressey at the last Farnborough Air Show when visito rs were able to inspect a live display showing both the video from the local Plessey 10 cm p rimary radar already owned by t he Royal Aircraft Estab lishment and

Luton Airport Radar Roo m

37

the automatically processed picture relayed over a telephone line from the Civil Aviation Authority's SSR installation at Heathrow approximately 20 miles away. I think I am right in saying that this was the first time that a live system was demonstrated anywhere using local real-time primary radar and remote SSR automatically processed so that the SSR data appears on the display as if it is centred on the local primary radar. This type of system was ordered

by Luton Airport who also take their SRR signals from the Civil Aviation Authority's installation at Heathrow while Plessey has supplied the AR 15/2 primary radar and the SSR data-handling equipment.

The plot and code extractor associated with the SSR equipment converts the video responses from the SSR interrogator into digital messages which record, for each aircraft within cover, the plan position, its four-figure SSR code and, if it is responding on mode C, its height. The significance of converting the real-time analogue signals into digits is that digits may be relayed economically over a telephone line and may then be operated on by a general-purpose computer which can be programmed to output the data in whatever form it is wanted and whenever it is wanted.

The functions of the computer include: a) Converting the range and azimuth measured by the SSR into range and azimuth as seen from the primary radar. b) Code to callsign conversion. c} Commands to each display to generate and position the characters in each label. The character-generator unit need not necessarily be part of each display but it is desirable that it should be so if one is to achieve the quality of characters necessary to avoid mistakes in reading them and to reduce controller fatigue.

The system described has certain features which it is thought will be attractive to ATC authorities: a) There are two data sources, primary radar and SSR, each backing-up the other. Either or both may be duplicated as a further safeguard. b) The system is evolutionary; that is, secondary radar can be added to an existing primary, as in Jersey, or a primary radar can be used with an existing secondary radar as in Luton. In either case, an evolutionary improvement is made by adding additional information to a conventional analogue radar picture. c) By using remotely sited SSR, proliferation of interrogators can be avoided and capital cost reduced. d) The SSR may be optimally sited; for example one may pick a site away from hangars and other large buildings and so reduce phantom echoes caused by reflections from such buildings. e) The SSR need not be synchronised with the primary radar in either rotation rate or in pulse recurrence frequency. This gives the opportunity to optimise the characteristics of the SSR ground station for comparatively long range, thus avoiding the unwanted signals known as second-time-around returns or 'stars'. f) The telephone line and the equipment at each end of it constitute a solid-state transmission system which is more reliable and usually cheaper than a microwave radio link. g) The computer carries out certain routine tasks; for example code/callsign conversion and providing a tabulation of important data. h) Automation reduces the reaction time of the ATC system by improving man-machine communication; for example,

38

if any aircraft within cover transmits one of the three SSR emergency codes, then the corresponding response will immediately commence to flash and the label will indicate the nature of the emergency. This will appear on all displays regardless of the filters set up by the controller. i) Another feature of interest is the rolling ball and electronic range and bearing line; this is a dotted line generated electronically on the radar display and the controller may lay one end of it on any fixed point and the other on an aircraft response, the system can be switched to cause the line to lock on to the aircraft and it will read out continuously the range and bearing of the aircraft from the fixed point.

Other facilities can be added comparatively easily once one has a system in which the data is digitised and is being handled with the aid of a computer; for example, tracking programs can be added so that if an aircraft's response fades temporarily the computer will cause the label to 'coast' for several revolutions of the aerial, while at the same time adding a suffix to tell the controller that this is happening. Tracking can also provide further protection against phantom echoes in that the system will predict the area within which the next response should occur and can reject spurious responses occurring outside the predicted area. Another benefit to be obtained from tracking is that aircraft ground speed can be calculated and displayed as part of the label. These and other facilities now being worked on continue the theme of evolutionary development.

(The Plessey Company Limited 1975)

More Risk at Home than at Work?

Staff of the British Civil Aviation Authority are in more danger of radiation in their homes from the older types of television sets than from any of the Authority's equipment, operated to laid down procedures.

The Authority constantly monitors all its equipment for radiation readings, and there is no environment within CAA where staff themselves need to be monitored.

(Air way)

More Turbulence F. 27 grinds to a halt outside the control tower and an obviously tickled-pink skipper announces that a duck and 8 or 9 ducklings are doing a swift line-astern across the taxiway. Aged but still very-much-with-it senior controller grabs the microphone: "Foxtrot November Delta - Roger - Caution "Drake Turbulence".

"Cocodoodledoo", Australia)

Warnings to Air Crews The U.S. Federal Aviation Administration has revised Air Traffic Control procedures requiring that air crews be warned on a mandatory "first priority basis" immediately after radar-identified aircraft are seen in unsafe proximity to terrain or obstructions.

News from Member Associations France

Make sure that you don't miss the 15th Annual IFATCA Conference, Lyon, France, from 26 tlll 30 April 1976, and the deliclous specialities as were shown at the above stand during the Melbourne Conference. Have a look at the enclosed Information Bulletin " La Gazette" and contact the IFATCA '76 Organising Committee, B. P. 125, Aerogare Passagers, 69125 Lyon-Satolas, France, Immediately.

Nordic Countries Members of the Finnis h, Danish, Norwegian and Swedish Ai r Traffic Controllers' Associations attended an international symposium of civil aviation workers organisations on the subject of labour and health protection of air transport workers which took place in Moscow in mid1975.

Th e Symposium was called on the initiative of t he Central Committee of the Civil Aviation Workers Union of the USSR to promote closer co-operation with aviation workers and their organisations; to poi nt out the most important problems faced by the personnel ; and to strengthen the unity of action in preparation for the forthcoming technical meeting of the ILO on civil aviation (1976-77) .

The meetin g provided a valuable opportunity for the exchange of views and information on issues of labour protection and health of civil aviation workers and emphasised the role played by the organisations in maintaining safe and healthy conditions for the personnel in question.

The participants expressed the need for stronger action in preparation for the forth com ing ILO technical meeting

on c ivi l aviation wh ich can be achieved th rough giving more attention in IFAL PA, IFATCA, the Civil Aviation Section of the ITF, the Aviation Branch Commission of the TUI, of transport workers and other international organisations to the urgent problems faced by civil aviation workers. They strong ly believe that the ILO could and should give more attent ion to the problems of c ivil aviation workers and formulate appropriate conven tions layin g down improved standards for them.

The Nord ic Member Associations of IFATCA, during t hei r presence in Moscow, on this occasion again expressed the Federation 's hope that Soviet controllers wou ld soon be able to participate in t he ever growing involvement of IFATCA in the world of civil aviation.

United States Scheduled Flights of Supersonic Jets New procedures and proper attention to added workload , respons ibilities of controllers and staffing requirements are needed to handle scheduled services by supersonic aircraft into th e United states, PATCO President

39

John Leyden stated in a press release recently. "Under present procedures and staffing, the strong possibility of delays to other flights can be anticipated", he said.

"The Federal Aviation Administration has said not long ago in a statement that no 'unique air traffic procedures' are needed for the SST, but nothing could be farther from the truth. The Concorde SST can only be handled safely in the present air traffic environment if a special study of all the relevant facts followed by specific steps are taken to assimilate this type of aircraft into the existing ATC system." (That the President has a point is clear from the article on "The Integration of Supersonic Transport into the ATC System" published elsewhere in this issue - Ed.) PATCO has also called for the installation of wind shear measurement equipment, to prevent accidents similar to the Eastern Airlines crash at JFK Airport, New York, not long ago. "Evidence is that such equipment has been available for the past three years, but the FAA has not purchased it, underestimating the hazard of wind shear", said President Leyden.

The PATCO Board has called for "the immediate acquisition and installation of any technologically approved equipment which will assist controllers and pilots to determine wind shear conditions." The Board was given a presentation by an established manufacturer of such equipment which reportedly has been available since 1972, and which has many users. The equipment uses sophisticated Doppler sensing, and, the firm says, would have prevented this accident.

A New Deal for Controllers Requested PATCO has asked President Ford's new Panel on Federal Compensation to consider a salary scale for controllers separate from the present Civil Service Commission rating, one that would more justly compensate for the high demands of the work, and which would allow controllers to continue to progress in pay without the need to enter

management. The Panel, headed by Vice President Nelson A. Rockefeller was formed to review federal pay practices.

PATCO Executive Vice President Robert E. Poli, before the group, testified that controllers were unique in the type of work they did, underpaid, and forced to work too many hours during the week. An important issue, he said, is the lack of comparibility, for salary purposes, with any other job or profession. The particular pressures and responsibilities of the job are so unique as to stand almost alone.

The most similar occupation is the airline pilot. But while the average journeyman controller is paid $ 21,000 per annum, his private sector counterpart, the airline captain, is paid on the average $ 53,000. Present determination of the salary is "inadequate, unsatisfactory and inequitable", said Poli. He also cited the need for a dual ladder system, "wherein the controller can continue to progress in salary beyond the present level of his scale as a professional, as he would by entering FAA management."

Shorter workhours were also needed for air safety and for the physical well being of controllers. "Controllers suffer from the 40 hour week more than most - shortened life spans, chronic ulcers and other tension related health problems. Many foreign controllers work less than a forty hour week for precisely these reasons; their governments have recognised the fact that overexposure to this type of tension and anxiety is not only unsafe for the employee, but is also deleterious to aviation safety. For example, Iranian controllers work a 35 hour week, the French a 38 hour week and Canadian controllers work a 34 hour standard week. In other parts of the world it is realised that overextending the physical capacities of controllers can at best only complicate and trouble the already complex field of Air Traffic Control; at worst, it can result in the death of hundreds."

The core of all the problems involving pay, Poli concluded, was the lack of ability for controllers to bargain for salaries and other benefits, as in the private sector.

News from Corporation Members Ferranti Limited The Australian Government has commissioned the Digital Systems Division of Ferranti to supply a second Air Traffic Control simulator for installation in the ATC Centre at Melbourne, scheduled for delivery in 1977. The first simulator is to be situated at Sydney. This extension increases the value of the original contract to ÂŁ 1 1/4 M, and the company claims that this is the largest-ever export order obtained by the U.K. for Air Traffic Control simulators.

Both simulators will be used for training new staff, validating practising ATC officers and for evaluating new aircraft control procedures. This contract emphasises the importance the Australian Department of Transport place on monitoring and improving safety standards in the air.

The two simulators destined for Australia will incorporate displays and computer input devices of the type used in Australian operational ATC systems. They will enable the second stage in ATC automation to be simulated prior to its introduction in the Commonwealth in the 40

late 1970's. Each of the Australian simulators will be ableto provide a complete ATC environment for an air spacesome 1448 miles square and 100,000 feet high. This can be precisely similar to a real volume of air space completewith aircraft, radar, airways, airports, navaids and weather, or it can be varied to meet specific training requirements, and to allow trials of new procedures and routings.

T-VT, a subsidiary of Thomson-CSF (another IFATCA Corporation Member) will supply the displays, scan conversion and digitatrons in the simulator, and this equipment will be similar to that used operationally at the Sydney and Melbourne ATC Centres.

Marconi Radar Systems Limited The British

Civil Aviation Authority has

placed

a

ÂŁ 75,000 order for the supply of a plot extractor evaluation facility which will be used to check the data outputs from ATC radar stations throughout the U.K. The equipment will be based on the company's Locus 16 data processor. As the main control centres in London and Prestwick become wholly reliant on digital data fed to them over conventionar

The Philips involvement in the world of ATC.

telephone lines from primary and secondary radar sites it is essential that the integrity of the data should be of the highest order.

The new evaluation facility will allow the record ing, analysis and cal ibration of the data so that not only the initial performance and accuracy of the remote radar stations may be evaluated but also maintained. A 16in digital plan position display unit and data logging equipment are provided. Th e display unit presents discrete sym. bols for the primary, secondary and combined primary/ secondary aircraft plots; in addition selected targets are provided with plot labels showing decoded secondary radar data compared with the "raw" primary and secondary radar responses. The data logging equipment can be used to provide a sweep-by-sweep record of the positi~n and SSA code data provided by the plot extractor equipment.

With simple adaptation the display cou ld pre!;>eht a radar "picture" of a nearby plot extractor site, superimposed on the local radar picture, simply ~Y . su itable connection by telephone line. Thus a small a1rf1eld with limited radar facilities could be provided with the advantages of a long range primary/ secondary radar system, without the high cost of relevant aerial systems.

Philips Telecommunication Systems Air Traffic Control, radar, ai rport lighting, landing aids, ground guidance and baggage handling are just a few of the electronic requirements in avionics today. The Philips International Group of Companies supplies not only sophisticated electroni c equipment, but also provides entire airports in w hi ch to put them. By arranging finance, construction service and personnel and adding advanced e lectronics designed and produced by the separate skills of its member companies, the Philips Group can offer comp lete packages. .

Philips call this complete package a Tur~~ey Proiect and a Turnkey Project means simply that Phillps turns it a ll on and takes responsibility for everything. It is a concept that can save a Government for example, a lot of headaches, especially in countries which have limited experience of the complex business of modern airport con-

struction, and lack the technical skills to select and put together large quant ities of separate sophisticated equi~­ ments to produce an effective result. It is far more practical for such Governments to negotiate with one authoritative company prepared to take on the entire job and to let that company do all the thinking and accept all the problems. The G roup's companies develop thei r own pr~­ grammes in their own countries, but each one also contributes w hen required to the overall concept. Indeed , any one of them may be elected to lead a project and all ~re linked in a network of research laboratories and service organisations throughout the world .

The companies which exhibited at the last Paris Air Show - by no means all the Group companies in Philips in Aviation - were: Philips Light ing 'Division; Eindhoven, The Netherlands; Phil ips Elektroniki ndustrier A.B., JarHilla 1, Sweden; Hollandse Signaalapparaten B.V.. Hengelo, The Netherlands ; The M.E.L. Equipment Company Ltd. , Crawley, U.K.; and Philips Telecommunicatie lndustrie B.V., Hilversum, The Netherlands. Of these, Hollandse Signaalapparaten gave an overall impression of their radar systems, with the focus on their SARP (Signaal's Automatic R~dar ~rocessing) system for ATC (which was fully d~s­ cribed in our August 1975 issue Ed.). Other exh i~its concerned radar systems for long-range detection, terminal area coverage and airfield surveillance · the wavelengths varying from the 25 cm l-band for long~range working to the B mm K- band fo r precision and high resolution .

The Plessey Company Limited Air traffic controllers will have we lcomed the announcement that an automatic method of cloudbase measurement has be.en introduced by Plessey. The Plessey ceilom~~; transmits a low-powered laser beam and measures c loud base by analysing the reflection. The instru men t. h~s a fieldbased measuring unit with a remote displ ay: it is 6 ft high and weighs 150 lbs.

The laser operates in the near-infrared waveband (9 0o x 10-9 m) so that its radiation is not damaging to the eye. The design of the field unit is such that inadver.tent viewing of the laser is prevented by a protective shield .

41

The Series 9, designed for day light v iewing, will be used by the RRE to evaluate the operational uses of modern , versatile displays, and to investigate control ergonomics. Plessey has developed a new touchwire system to supplement the keyboard which is used to communicate with the computer. The system supplied to RRE will incorporate touchwire inputs as well as the keyboard. This method provid es greater flexibility of communicat ions and higher reliability. The controller has a se ries of short wi res on the console, each of which can have its fun ction individually programmed. To uching the wi re completes an electrical circuit and causes the appropriate fun ction to be performed.

Gustav A. Ring A/S Plessey automatic ceilometer showing (from l eft to right) detachable light shield , the cei lometer and the ceilometer with o uter cover removed. In the background, the Plessey point visib ility meter.

The gallium arsenide laser transmitter is housed in the field unit alongside the receiv ing unit. Laser pulses, at a repetition frequency of 600 Hz and beamed vertically upwards, reflect off water droplets in the cloud and are co llected in the receiver. The field unit is design ed to protect t he optical equipment from the weather and the opti cs ~ re engineered to maxi mise sensitivity to the received laser beam. Received-beam data are mathematically integ rated in t he field unit to give a measurement of local cloudbase. Th e returning beam is very much weaker than t he em itted beam and therefore presents no danger to casual observe rs.

Clo udbase data can be presented in three ranges, the greatest being from 30 m (100 ft) to 1,455 m (4,700 ft) in 15 m (50 ft) increments. These data are stored in the field unit and relayed along a co-ax ial cable, w hich can be up to 4,000 m Jong, to a display unit normally sited in the airport meteorological office. Data are decoded in t he display unit, w hich provi des a graphical display of local c lo udbase against time. In ad d ition , a digital readout driven directly from the field unit can be installed in the control towe r. Info rmation is updated every minute.

The ceilometer only gives the c lo udbase directly above the transmitter. No attempt has been mad e to make the equ ipment capable of acquiring proportional cloud-cover data, a task w hich must still be left to th e experienced eye. It is t herefore necessary to give careful cons ide ration to t he siti ng o f t he unit. Plessey recommends positioning the field unit at t he ILS middle marker (1,000 ft from the threshold), w here the glidepat h w ill be abo ut 200 ft above the threshold elevatio n , the minimum heig ht at w hich a p il ot shou ld first see the ground. Installatio n of the equipment so as to achieve the correct optical alignment is fairly critical, and Pl essey specifies mounting on concrete to w it hin 1 ° of the vertical.

Jn another development, Plessey Radar is to supply five Series 9 radar display units to the Royal Radar Establishment at Malvern , U.K. Each unit consists of a 16 inch display co upled to a mini-computer _with which the tro ll er com muni cates using the associated keyboard . be lieves that the Series 9, for _which this is the . t ord e r . 1 ¡s t he most advanced of its type c urrently f irs . â&#x20AC;˘1a b i e . The d isplay unit can display raw. or syntheti c ava1 . "t her synt hetic data (radar information processed data, so e1 .. . d. t (PPI ) . f in orby the co mp uter) or plan-pos1t1on in 1ca or .on can be d isplayed as required by the controller. mat1

Gustav A. Ring A/S, headquartered in Oslo, Norway, has grown from a small office-machine company into a major manufacturer and exporter of highly sophisticated com munication, alarm and telephone systems. T oday t he company employs approximately 700 people including a large team of highly experienced engineers in the Research and Development Division. Total sales in 1974 amounted to US $ 5,per Norwegian citizen. A similar per capita sales for an American company would gross one billion dollars. Continuous research and development, advanced techno logy and modern manufacturing methods have been combined in the production of: Ring-Master, internal co mmunication systems, fully expandable from 2 - 2000 stations , for commercial , industrial and institutional use.

GAREX, integrated telecommunication systems, controlling rad io channels, telephone and intercommunication lin es in airports, police and fi re departments, port au thorities, military and other communicat ion control cent res.

SCANRING, systems for centralized monitoring of alarms, surveillance of technical equipment, vo ice communi cation and transfer of data, ind ividually o r in co mbination.

ACD 5000, a new advanced and compact tel ephone system for automatic distribution of incoming calls to a group of operato rs. A flexible and modular system w hich achieves an efficiency wh ich earlier has not been possible.

Full computer control of all sub-systems together with an advanced modular software package allows f lex ible grouping of all lines and operators.

85 % of the production is expo rted to more than 45 countries all over the world. Subsidiary offices have been set up in the United States and Western Germany.

~~;ssey

42

The Ring El ec troni cs Centre

In Norway, representing a number of the world's leading manufacturers, Gustav A. Ring A/ S is one of the largest and strongest sales and service organizations in electronics, telecommunications, data processing, office equipment and related systems.

Software Sciences Limited The company has been awarded a contract by the British Civil Aviation Authority to carry out for the Air Traffic Control Evaluation Unit at Hurn Airport a fast-time simulation of arrivals and departures at the major London civil airports. The ATCEU will use the company's TMA (Terminal Control Area) model on a bureau network which will be accessed directly from the Software Sciences offices for consultancy support and operational guidance.

The study, part of an on-going programme of R & D for the CAA. is concerned with the optimum utilisation of runways and airspace in the London terminal area. With a capability of simulating 2000 aircraft movements in two minutes, the TMA model will provide the quantitative data needed for the evaluation of alternative flight departure and route structure strategies.

The TMA model is one of several Software Sciences fast-time simulation packages which have significantly increased both the capacity and performance of models used for large, complex systems in the airspace, industrial, and commercial fields.

In another development, the company is holding a series of courses on Airport and Airspace Planning at various centres throughout the world. The initial course was held at Farnborough, U.K., in October 1975, and f urther courses are planned for Beirut, Nairobi, Singapore and Jamaica (or Trinidad). It is hoped that by holding these courses at regional centres, a wider spectrum of those involved in aviation planning would be able to attend.

The courses have been designed to su pply either a basic or a more advanced level of expertise and can be adapted to suit local requirements. The aim of the basic course is to give students who have limited experience in airport and airspace planning a comprehensive grounding and appreciation of the interactions between the many components of airport and airspace operation. Efforts are concentrated on ensuring that the vocabulary of planning is fully understood and the effects of airport development on the aviation system are appreciated. Some reference is made to methods and procedures used in assessing airport capacity but this subject is dealt with more comprehensively on the advanced course. It is assumed that those under-taking the Advanced level course already have some experience and wish to improve their knowledge.

The emphasis is on airport and airspace design for the optimisation of capacity and the techniques used in the assessment of capacity. The applications are directed towards the development of existing airports and in the establishment of new airports.

Airports and their Control Towers (3)

-"' ,

Control T ower, Lyon-Satolas Airport, with the Concorde passing over.

43

Lyon-Sato Ias On April 20 1975, Lyon's brand new international airport opened to serve the Rhone-Alpes region of south-eastern France. Situated some 24 km (15 miles) from the major industrial city of Lyon, the 1976 Conference venue of our Federation, it has replaced, for airline traffic, the already saturated airport of Lyon/Bron which however continues to serve general aviation. It is the ambition of Satolas to become a major international gateway, relieving pressure on Paris and promoting regional development.

The city of Lyon is out to restore its former status as a financial and economic centre, and during the past ten years Lyon has begun to attract back some of the financial authority which existed in the city in a former age. It is reasoned that if a provincial city or its surrounding area is to attract the headquarters of national and international companies, a really good airport is essential, and in Satolas the regional authorities of Rhone-Alpes believe they now have such a facility.

Satolas serves a region which is already economically and industrially the most important outside Paris. The population of the Rhone-Alpes region is almost five million, and the ratio of industrial to agricultural employment is higher than in other regions of France. Faced with the anticipated saturation of Bron Airport, and the difficulty of expanding it (it lies fairly close to the city), planning began in the late 1960s for a successor, not before time considering that in 1974 Bron handled 1.25 million air transport passengers, considered to be above its tolerable ceiling, and already tending to discourage traffic to the benefit of Paris and also such centres as Baste and Milan, not far away. Moreover, the passenger traffic in the first quarter of 1975 was 13 per cent up on the same period of the year before - a growth rate well above the European average, .EÂľJd mainly accounted for by a 22 per cent upward swing in the number of international passengers.

In looking for a suitable site, three main criteria were applied: accessibility, satisfaction of all technical critera, and situation in an area of low population density. Detailed studies of three areas were made, and Satolas was selected. As for road communications, the site lies near and has been connected to the A 43 Lyon-Chambery autoroute, which, in Lyon, connects with the main artery between Paris and Marseille. New autoroutes due to be completed betweeen now and 1980 will link the airport with Geneva and Grenoble, and improve communications in the direction of Paris and Marseille. Possibilities for rail links have also been studied; one notion is to extend the new Lyon Metro - under construction - to the airport, and another is to take a spur from the Lyon-Grenoble main line into the airport. Satolas is served by a 20-minute-interval bus service. The amount of noise disturbance to residents in the area is claimed to have fallen considerably with the transfer of operations from the old airport, and it is intended that Satolas should remain free of a night-time curfew.

The airport commenced operations with only one 4,000 m (13,100 ft) runway, aligned north-south to reduce nuisance factors to a minimum and to suit prevailing Rhone Valley winds, but will eventually have three runways of 4,000 m length enabling Satolas to handle some 100 aircraft movements an hour. The airport can now handle 3 million passengers annually, but in 1980 will be capable of processing 6 million passengers per year, and freight handling capacity will increase from the 5,900 tons handled 44

.

in 1974 to 50,000 tons in 5 or 6 years' time. As with any new airport, Satolas is expected to lose some fr 10-11 million (roughly $ 2 million) during its first year of operation, including capital charges, but the break-even point is expected to be reached in 1980.

The linear concept of the passenger term~nal results in concourses which are reasonably intimate in scale; their appearance has been enlivened by the imaginative use of bold colours, predominantly orange and green. A central building containing offices, shops, restaurants and a four-star hotel is flanked on either side by terminal wings. eventually to be semicircular in shape but of which only part has been built in the first stage of development. It will take 5 to 7 years to complete future extensions which will double the size of the southern airport wing and treble the northern wing. Public car parks have space for 2,400 vehicles. The minimum walking distance from the accessroad kerb to check-in is a mere 17 m (58 ft). The minimum distance from the kerb to the door of the aircraft is 70 m (230 ft). Passenger handling - arrivals and departures is conducted on a single level. A special area has been allocated to the processing of general aviation passengers.

A control centre in the central building incorporates transparent walls, allowing the public to watch staff at work. From here the Swiss Autophon passenger information display system, with its T-VT 6000 display terminar and computer, is operated; gates are allocated to aircraft; baggage channels are activitated; police, customs and other services are informed. The centre includes a monitoring console and displays for lighting, air conditioning, etc. The freight centre and mail terminal is situated to the south of the main terminal area, and to the north are the fire station, control tower and meteorological office.

Air navigation and Air Traffic Control services are, in France, ¡the responsibility of STNA (Service Technique de la Navigation Aerienne). Operations to Cat 3a (150 m visibility and 50 ft decision height) are authorised. The ILS equipment has been provided by one of IFATCA's Corporation Members, Thomson-CSF. The TMA surveillance radar on the south side of the airport, with a range of about 100 n.m. (identical to those installed at Orly, Roissy-Charles de Gaulle and Toulouse airports) and in use since before Satolas was built, is being used for Approach Control purposes. The unsatisfactory data renewal, which arises from the fact that it is difficult to reconcile the automatic processing of secondary radar data with the use of antennas rotating at a high speed, plus an alleged unreliability of returns within about six n.m. of the runway notably on the approach axis towards the north - ascribed to the configuration of the Satolas site and to the presence of a high level of permanent echoes have not enhanced the system in the eyes of air traffic controllers. But management feels that after a period of routine use, these defects in the detection will be less strongly felt by the controllers, while - management says - it is possible to adapt the ATC procedures to make the best use of the radar coverage that exists.

Your Chance to try for the 1976 writing award for the best article published In THE CONTROLLER. Entries must be received on or before the 1st September 1976.

Scope: all original artlcles relating to ATC, not exceeding 4000 words. Only Air Traffic Controllers are eligible for the yearly writing award. Start writing nowt

Welcome to new IFATCA Corporation Members Gustav A. Ring A/S, Oslo, Norway Gustav A. Ring A/S, manufacturers of high-technology electronic systems operate plants in Norway and West Germany. Continuous research and development, advanced technology and modern manufacturing methods have been combined in the production of RING-MASTER direct speech systems, SCANRING alarm and surveillance systems, ACD automatic call distribution systems and GAREX telecommunications control equipment. These product lines are exported. to more than forty-five countries throughout the world.

In Norway, representing a number of the world's leading manufacturers, Gustav A. Ring A/S is one of the largest and strongest sales and service organisations in electronics, telecommunications, data processing, office equipment and related systems.

To us as air traffic controllers, the GAREX system holds most interest. A complete GAREX system integrates the communications control of radio channels, external telephone lines and intercom between controllers, giving each controller access to all facilities by means of consolemounted control panels. The GAREX programme includes systems adaptable to requirements ranging from those of smaller domestic airfields to the most sophisticated systems needed at large international airports. This flexibility, and the fact that GAREX systems offer an integrated solution to all communications control requirements in airport towers and radar rooms, has resulted in installations in more than 40 airports throughout the world. In situations where a specification cannot be met from the standard GAREX range, custom-designed systems can be made available. A well-staffed R & D department deals with all enquiries, be they the development of special sys~em~ or requests for assistance in the planning of communications control centres at new airports.

The standard GAREX-5 system is installed at all civil airports in Norway and at several international and domestic airports elsewhere in Europe, Asia and South America.

GAREX-5 is a modular system with a communications control capacity per standard panel of: Radio Panel: 10 radio channels Telephone Panel: 20 telephone lines Intercom Panel: 12 intercom lines between GAREX-5 controllers.

Due to the modular concept of GAREX-5, this system can easily be adapted to varying requirements such as number of control positions, radio channels, telephone and intercom lines.

The company has recently been awarded a contract to provide a new communications control system for Schiphol (Amsterdam) Airport by the Netherlands Civil Aviation Authority. This new system will serve 60 controllers and because of the complex operational procedure laid down will be computer controlled. In including computers for control purposes of its GAREX systems. the company is moving into a new generation of communications control systems.

In addition to standard and specially designed communications control systems, custom-designed consoles are

delivered world-wide for towers and radar rooms; for example, at Yesilkoy Airport in Istanbul, a GAREX-5 system and ATC consoles for 26 controller positions are being installed. But aviation is not the only field of operation, and the GAREX-5 system has also been installed at many large fire stations in both Sweden and Britain. Police Headquarters in Oslo are equipped with a modified system, as are those in Dublin and all main police stations in New Zealand's major cities. Specially designed GAREX systems have been delivered to the air forces in Norway, Brazil, Singapore and the United States as well as to the Swedish and Norwegian armies.

Prototypes of the GAREX-6 system have been delivered to the U.S. Air Force as the communications control system in the AN/TPN-19 programme (an advanced mobile landing system which we are still planning to describe in a future issue of this journal - Ed.). GAREX-6 is designed, produced and documented in full accordance with military specifications. 58 stationary landline switching systems, GAREX-20 (AN/G TC-28), have also been delivered to the U.S. Air Force for installation at bases in the U.S. and abroad. GAREX-8 and -10 are mini-systems used in mobile units in the Swedish and Norwegian armies. One outstanding feature of the GAREX-8 system is that in case of an emergency, all major communication functions can be remotely controlled over a four-lead cable from a remote control panel.

In summary, the overall GAREX programme offers a wide range of communications control systems covering most requirements.

The Mitre Corporation, McLean, Virginia, U.S.A. This ¡newcomer to the IFATCA family is primarily a system planning, engineering and integration organisation specialising in the field of information systems and their related technology. Since its incorporation, Mitre has been providing this type of expertise to national, state and local governments and to other organisations serving the public interest. The total corporation staff size is 2,000. More than 1,000 of these people are professional scientists and engineers representing a broad mixture of managerial and technical skills.

Formed in 1958 at the request of the U.S. Government, Mitre maintains permanent offices in Bedford. Massachusetts. and Mclean, Virginia. while field offices are located elsewhere in the United States and abroad.

At its inception, Mitre's orientation was principally towards defense work, although its services included support of non-military programs, notably those of FAA. Today, Mitre serves numerous civil agencies. When an agency has a requirement for technical advice, the central question to be answered is whether or not the technical organisation it considers has the internal technical competence and system engineering experience required for the programs.

Mitre believes that its diversified experience in civil system problems makes it a most qualified organisation to satisfy this need, and that its work with the Federal Aviation Ad-

45

ministration, Environmental Protection Agency, Departme~t ¡ce Office of Science and Technology, Federal Ra1lo f J us t I A .. road Administration, Urban Mass Transportation .. dmm~stration, National Science Foundation, and othe.rs contributes to a unique background and experience m syst_em engineering. Where a government a~ency has. a requirement for technical assistance or advice regarding system engineering management and do~s not its~lf have the ~taff to perform these functions on a timely basis, organisations such as Mitre can be an excellent source of assistance.

I

â&#x20AC;˘

Mitre is a non-profit organisation working sol~ly in t~e public interest. It does not formally compete with prof1tseeking companies, nor does it accept contracts from them. Mitre is precluded by the U.S. Government from entering into hardware production. The Corporation operates independently both of government and of industry, and can focus its resources on solutions to problems that are beyond the limited jurisdictions of government _lab~ratories or too complex and unwieldy to attract profit-orientated industry. Free from pressure to show a profit and with. no vested interest in products or system components, Mitre brings to its clients objectivity as well as technical competence. It avoids formal competition with profit-seeking firms, and protects sponsor planning and contractor proprietary information.

Work on Air Traffic Control problems occupies the energies of more than one-third of the technical staff of Mitre's Washington Operations. The facility is located in the Westgate Research Park, Mclean, Virginia, ten miles from downtown Washington, D.C. The modern, fully equipped complex contains extensive computer, office, labora-

tory, library, and conference facilities. In addition, t~e Washington technical staff of approximately 500 professionals, drawn from a wide variety of disciplines, constitute a resource of unusual depth and versatility.

Some examples of Mitre's activities are: Upgraded Third Generation ATC System Concepts and Design: preparation for FAA of a baseline design document for R & D relating to ATC in the late 1970's and 1980's; Advanced Air Traffic Management Systems: examination of alternative ATC system design for the post-1990 time period; Traffic Handling Requirements: development of standard traffic models (e.g. Los Angeles Basin-1982) against which proposed subsystems (e.g. airborne collision avoidance system) and ATC procedures can be analysed; Airport Capacity: analysis of capacity limitations and delays at major airports; Close-Spaced Parallel Runways: development of operational procedures and subsystem requirements for independent IFR operation of parallel runways; Environmental Aspects: analyses of the interrelation of operating procedures and aircraft mix on airport noise and emissions and the impact of noise at specific airport locations; etc. etc. In the field of ATC automation, Mitre participates on such projects as Automated IFR Control; Controller Productivity; ATC Controller Equipment; Flow Control; Oceanic Automation; and many others. The company is involved in studies which include: Collision Analysis; Conflict Alert; Ground Proximity Warning; Intermittent Positive Control (IPC); and Cost-Effectiveness of Collision Avoidance Systems (CAS). Further projects concern Navigation, Communication and Landing Systems: and many others, too numerous to mention in this brief outline.

The Pilot's Point of View ATC System Design Which Way Should It Go? This is not another learned thesis on the complex subject of ATC System Design, but merely an attempt to present the alternative design principles in simple (even over-simplified) layman's terms.

We all know that today's ATC systems, like Topsy, have "just g rowed". These systems vary in detai I according to the operational environments for which they are responsible but, in essence, they rely on the flight plan for traffic planning and either radar or pilots' reports for position and separation. Inevitably, therefore, such ATC systems are a compromise between planned operation and ad hoe separation. As with all compromises, nobody is really satisfied, and least of all the user.

With the rapid advance in technology, means are now becoming available to modernise ATC systems drastically.

Navigation and communications are being automated, airborne collision avoidance systems are under evaluation, new micro-wave instrument landing systems are within reach, the satellite is just over the horizon, SSR surveillance techniques are being developed and, above all, powerful computers are now at hand to automate many of the routine ATC functions and to correlate flight progress with flight 46

plan. The time has come, in fact, for major decisions to be taken with regard to the design of ATC systems which will be capable of handling the expected type and density of air traffic until the end of the century.

Basically, there are three options open to the ATC system design planner. These are: 1. He can stick to the present concept, using the new technology to improve its various aspects.

2. He can go for a system of virtually full (strategic) control, in which airspace "slots" are allotted to all aircraft and ATC intervention is limited to incidental deviations from planned operation. This will require pre-planned multiple track and profile structures, the installation in all aircraft of SSR transponders and air-ground data link, accurate 4-dimensional navigation equipment, and the allocation of airspace designated for the positive control of all traffic at all times.

3. He can go for a system of maximum freedom of operation, wherein ATC intervention is limited to potential conflict situations. This will require all aircraft to carry a discrete address beacon transponder, with the ability to receive automated ATC communications, and a suitable means of displaying these communications. For full pilot participation, airborne proximity warning and collision avoidance equipment, suitable traffic situation display and station-keeping devices, will also be necessary.

.......

I

All these concepts have advantages and disadvantages.

System 1 has the advantage that it is evolutionary, i. e. no revolutionary change is required to today's traditional pattern of ATC; it has the disadvantage that it perpetuates the drawbacks and shortcomings of the present system, not the least of which is the invidious division of responsibility between the pilot and the controller in the "grey area" of navigation and separation. System 2 has all but one of the advantages of a railway operation (the aircraft cannot stop at signals, however) and allows the pilot to concentrate on flying his aircraft without today's separation and communications problems; it has the disadvantage that it restricts commercial and individual freedom to operate at desired times, and is certain to be fantastically costly. The great advantage of system 3 is that of operational freedom to all users, but its disadvantage lies in the sad truism that, however random the en-route operation might be, sooner or later aircraft have to be separated and sequenced for landing.

So, which way should the system go?

The U.S.A. is planning to go for something like system 3 with its Intermittent Positive Control concept, but retains control on the ground. An eminent pilot/controller group in the U. K. is advocating somethjng like system 2 {parts of the recommendations made by this group are serialised in this journal - Ed.); so is Eurocontrol. National administrations otherwise tend to follow the system 1 concept.

Within IFALPA, a brave attempt is being made to reach an answer to the question of preferred system principles.

It is a daunting task, particularly so as opinions are polarised in line with the differing operational philosophies of pilots as developed by their operational environments. It

could also be a fruitless task, as it is certain that the ruling consideration will be the costs involved, especially if these are to be recovered from the airlines. System 1 must score heavily on this point.

From the pilot's point of view, once flight safety is guaranteed, the key question would appear to be the extent to which he should participate in the collision av oidance element of ATC. In the present ATC system (system 1), he monitors the service by listening to Rrr communications of other aircraft; in system 2, his participation would be virtually zero; and in system 3, with airborne APWl/ACAS (Airborne Proximity Warning Indicator/Airborne Collision Avoidance System) and TSO (Traffic Situation Display), and station-keeping devices, he would be actively involved in resolving potential conflict situations.

Will the answer be yet another compromise?

(V. H. King in "IFALPA Bulletin")

Wake Turbulence

FAA is carrying out a study at Chicago O' Hare International of the feasibility of reducing the separation of aircraft making IFR landings when wind conditions lessen the wake vortex danger. The agency is also testing at John F. Kennedy International, New York, to determine whether vortex conditions can be predicted up to 15 minutes in advance.

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

The high standard achieved and maintained by our instructional staff of experienced controllers is one of the many reasons for IAL being selected by these authorities. Flexibility and economy are added attractions. Courses can be tailored to meet individual requirements. incorporating national ATC legislation if necessary. At competitive prices. All the courses are approved by the UK Civil Aviatio n Authority and recognised by ICAO. We o ffer three standard coursesAerodrome and Approach Control .

Area (Ai rways) Control and Surveillance Radar Control . We also offer other courses such as an Ab lnitio course. an A IS course. as well as Special Courses which can be designed to simulate any ATC environment.

For further details about the College and course vacancies. please contact The Administrator. IAL College of Air Traffic Services. Oxford A irport.

Ki dlington. Oxford OXS 1 SH . England .

Telephone : Kidl ington 6 168

Im

College of Air Traffic Services

47

News from the Federation IFATCA's 15th Annual Conference, Lyon, France, 26-30 April, 1975 The Lyon Conference, now only weeks away, promises to be another memorable event in the history of the Federation. The French organising committee under APCA's President Gorin has done everything to make sure that the heavy programme will be carried out as planned. Since it is the 15th Conference, some special features are incorporated, such as the plan to bring to Lyon those former officers who at one stage or other have managed the Federation between the period IFATCA was founded in 1962 and the present time, and the forthcoming Conference will therefore be a Federation reunion in the truest sense. The former stalwarts will no doubt add additional colour, and it will be interesting to hear how they view the Federation as it functions today.

The preparation for the Lyon Conference began in earnest on the 22nd September last year when both the APCA- and IFATCA Board officers assembled in the Conference city to hold their respective autumn meetings.

After completing its usual customary thorough and wideranging review of all aspects of the Federation's activities, the IFATCA officers were taken on a tour of Lyon and were given the opportunity to view the spacious Congress Hall, set against the background of beautiful city gardens and France's second biggest river. We came away impressed with the Conference site, the charm of old-world Lyon itself and with the dynamic determination of the organising Association to make IFATCA '76 another resounding success.

At a well-attended press function at Lyon's new Satolas Airport at the time, Presidents Gorin and Monin elaborated on some aspects of the work by their respective organisations in the field of aviation safety, and used the opportunity to give advance details of the arrangements beirig made for, and the scope of, IFATCA's 15th Annual Conference which would be held in the City of Lyon the following year. Thanks to this and other widespread publicity since then, it looks as if we can expect a record attendance. IFATCA members in particular are urged to come along in great numbers because this will be a special Conference, and we would like to see many ladies as well

as the French have spared no effort to make the ladies¡ programme as attractive as possible. If you don't come, you will regret it tater on when you listen to the experiences of your colleagues who did attend. That's the way it goes each time.

Obituary It is with sorrow that we have to report that Mr. J. D. (Tommy) Thomas died on Saturday, 13th December 1975, aged 55 years. Born in London, England, he went to Rhodesia during World War II as a Navigation Instructor, Royal Air Force, Bulawayo. He joined the Rhodesian Civil Aviation Authority in 1948 as a Controller and was appointed Principal ATCO in 1971. He was an active member of the Professional and Technical Officers' Association and appointed President of the Public Services Association also in 1971.

The first mention of Tommy with regard to IFATCA was in the Report of the 1963 Annual Conferences in THE CONTROLLER as the representative of the Central African ATC Association which withdrew in 1964. Tommy attended all IFATCA Conferences from 1967 onwards excepting Melbourne 1975 when Rhodesia were excluded for political reasons. Tommy represented Rhodesia after they were accepted by IFATCA and became Chairman of Committee A in 1970 at the Montreal Conference. He again became Chairman of a Sub-Committee in Athens (1971) and also chaired Committee C in Dublin (1972) and Reykjavik (1973). Tommy was First Vice-President of IFATCA from 1971-1973.

The first mention of Tommy's illness was made in the August 1971 CIRCULAR. In spite of the depressing nature of his illness Tommy produced his STUDY ON THE SELECTION AND TRAINING OF AIR TRAFFIC CONTROLLERS, with particular reference to Rhodesia in February 1975. This research gained him a Degree of Education and he was actively planning a second volume before the end. Tommy was a truly remarkably cheerful person whose diplomacy and leadership will be greatly missed by the Federation and his countless controller friends around the world. His example will activate us all in our aspirations for professional recognition for which he was an ardent enthusiast.

From the President, and throughout the membership of the Federation, the heartfelt condolence of everyone go to Mrs. Betty Thomas and family in their loss which we all share.

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Publications Review Airports and the Environment

by Alan Stratford, published by Macmillan, price £ 5.95.

This is a book not only for the planning specialist but very much of eminently readable general Interest to anyone wishing to know more of the lesser-known aspects of the airport environment.

It Is a thoroughly well-explained study of air transport development and Its impact on the social and economic well-being of the community. The contribution of _Aviation to the national economy is well documented and explained in simple terms. It is pleasing to note that the author deals with the aviation and other Industrial assets provided by the spin-off from advanced technology applied in Concorde and Apollo projects in particular, which is refreshing considering the somewhat tiresome tirades of those who constantly berate them.

Aircraft noise, of course, receives considerable study and the reader Is left in no doubt about either the problems affecting the man-in-the-street or those of the aircrews above him and the sincerity of the many efforts to surmount them. The increasing trends of community agitation get a thorough investigation all round and, indeed, a warning against ill-considered "aggro" ·of the kind applied by the residents around Chicago-Midway In recent times. The warning is implied in an IATA Report relating to successful agitation by the public which stopped Jets from using the airport. When. subsequently, the Midway area became economically depressed, another pressure group - probably containing the same members as the original - demanded that jet aircraft be routed back to Midway.

This succeeded and, paradoxically, further pressures are on the Midway management to increase rather than decrease jet movements. on the subject of noise abatement procedures, Alan Stratford is of the opinion that it is very undesirable that power reduction should be resorted to as the prime means of noise reduction for the benefit of near-airport communities. He explains that these communities gain In many compensatory ways at the expense of the more widely dispersed folk who suffer from forward-spread noise when aircraft then climb from altitudes much lower than they would otherwise be in the event of normal climb being permitted. Jet engine noise and the characteristics of the sonic boom are particularly well explained in a most agreeable simple manner. The final chapter discusses the whole main subject in relation to the 1980s.

Air Traffic Control Is referred to as indeed one would expect.

However, it is recommended to members as a valuable study of an reference to a subject which affects all air traffic controllers and likely to continue to do so for many years yet.

(LSV In "Transmit")

The Selection and Training of Air Traffic Controllers

by J. D. Thomas, P. 0. Box 1789, Salisbury, Rhodesia.

Although this comprehensive study has particular reference to Rhodesia, and the findings must therefore be treated cautiously, every one interested in the field of selection and training of air traffic controllers will find much f~od for thoug~t when absorbing the levance of the data upon which the selection of ATC trainees is re sed and dealt with in Mr. Thomas's study. Selection is not an basy process, and those responsible for selection often have to ea ke decisions based on inadequate or unreliable information. ma In the study, a thorough investigation has been made into the flowing objectives: (a) to establish the effectiveness of the CSC fo nude test battery as a predictor of ATC training performance; 8 ~ \ 0 determine the adequacy of the minimum qualifying standards ~b pect of aptitude test performance, age, education and physical in r~~ron· (c) to examine the role played by training in the selec1 ~on ~oc~ss; (d) to establish the reliability of each Individual test ~ion p csc battery. The writer takes us from a review of the ATC in th~ and a full description of the air traffic controller's special fu~~t~on to an examination of the main methods of selection; the ab1litie~. ethod and the objective method. The subject of aptisubjective ~ tures largely in the study and an evaluation is made tude test~ earcal computations test, the spatial perception test, the of the anth~e ~- actions' test, the abstract reasoning test, the direccomplex or~ irt st and the ATC problems test. Minimum qualifytional headings ere. set as well as standards in respect of age. ing te~t scor:s ~ysical · conditions. A special chapter is devoted education a~ p of lower and U9Per age limits for acceptance as to a comparison . controller trainees in 18 countries.

Naturally, qualification standards also feature largely. As to the training of controllers, Mr. Thomas goes deeply into the ATC Cadet Course, the assessment of cadets, and an interesting description is given of the profile of the ideal ATC Cadet.

The consequent findings of the study suggest that the CSC aptitude test battery possesses a limited ability to predict ATC training performance. As for the adequacy of the minimum qualifying standards regarding aptitude tests, age and education, the findings support the continued use of the existing minimum requirements.

In respect of the examination of the role of training in the selection process, this examination revealed that training itself is an efficient screening device, while a study of assessment reports indicated areas of possible deficiency which are of interest to the ATC Selection Panel. Lastly, the individual aptitude tests appear to be reliable measuring instruments.

GdB

One Way To Solve The IFATCA/IATA Deadlock?

A California student has placed an advertisement in the San Francisco Chronicle offering to pay any airline stewardess $ 1500 a year in return for her hand in marriage. She wlll never need to see him or live with him. as his sole aim is to secure the special concessional rates enjoyed by the spouses of airline employees.

A New Concept o' Operations Six Air Force Weather forecasters and one civilian forecaster have assumed duty at Kansas City ATC Centre. They are working with Centre controllers to provide weather assistance to pilots transiting the Kansas City Centre Area.

The new concept of operations, which will be on a test basis for the first year, will encompass weather monitoring and interpretation of weather data from radar and PIREPS to provide Centre controllers with current hazardous weather advisories. If this test is successful, weather service from all ARTCCs may become standard practice.

A Few Moments In a Controller's Day He came home early that evening. It was a good day because he was on a regular shift, able to eat a normal dinner at seven p.m. Next week he would be on the 3 to 11 p.m. shift, and see his children only briefly in the morning. He should take his wife out more often, he thought. but somehow the time they could be together is brief and quickly eaten up with other matters.

The phone rang, and it was his brother on the line.

"Look, I've decided to go ahead with that real estate business. It's your last chance to get into it."

"Give me a day or two to think it over", he answered.

It was a subject his brother. who was doing very well. often brought up. They could become partners and he might have a lot more security and money than now. True. he often did gripe about the job. There was a long way to go in working cond!tions. But then he had been controlling aircraft for a very long time. It was the thing he enjoyed most doing. It was also a job he was darned good at.

He walked over to the window to look out at the placid landscape for a few moments. Times before he had thought of .getting out. He always came back to the same decision.

There was nothing else he would be satisfied doing.

He wasn't a hero by any means. But he knew how important his work was, and he knew how goed he was at it.

He was glad his brother had called, however; he felt more relaxed. It was great to belong to a great profession.

(PATCO Journal)

49

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Corporation Members of the International Federation of Air Traffic Controllers' Associations AEG-Telefunken, Ulm/Donau, Germany Air Vision Industries, Inc., Montreal, Canada ASS MANN GMBH, Bad Homburg v. d. H., Germany CAE Electronics Ltd., Montreal, Quebec, Canada Cossor Radar and Electronics Limited, Harlow, England Dansk lmpulsfysik A. S., Holte, Denmark Ferranti Limited, Bracknell, Berks., England Ground Aid Group, Esbjerg, Denmark International Air Carrier Association Geneva, Switzerland International Aeradio Limited, Southall, Middlesex, England Jeppesen & Co. GmbH., Frankfurt, Germany Lockheed Electronics Company, Inc., Plainfield, N. J., U.S.A. The Marconi Radar Systems Limited, Chelmsford, Essex, 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 Gustav A. Ring Company, Oslo 3, Norway Selenia - lndustrie Elettroniche Associate S. p. A. Rome, Italy Sofreavia, Paris, France Software Sciences Ltd., Farnborough, Hampshire, England Space Research Corporation, Inc. Quebec, Canada The Solartron Electronic Group Limited, Farnborough, Hants., England Stansaab Elektronik AB, Jarfalla, Sweden Thomson - CSF, Paris, France The International Federation of Air Traffic Controllers' Associations would like to invite all corporations, organizations. and institutions interested in and concerned with the maintenance and promotion of safety in air traffic to join their organization as Corporation Members.

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