IFATCA The Controller - January 1966 by IFATCA

I FATCA JOURNAL OF Al R TRAFFIC CONTROL

In this Issue

Anal,..is of th• Procesaes involved In 1he TntCdment of Information by the Air TnlfHc Controller

The Third lntemational R&D Symposium The Approach to automating ATC In France ATCA ••• a n lnsphallon

VOLUME 5

NO . l

D 20418 F

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The picture shows a ZETFAX tronsmitter with control unit and two ZETFAX receivers in the ATC tower of a large airport.

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The ZETFAX facsimile transmission system has been successfu lly appl ied to the rapid transmission of aerodrome weath er, flight plans, and a variety of othe r aeronautical information. With the extremely reliable ZETFAX equipme nt, handwr itten data is transmitted on normal telephone lines. Utilizing their own ZETFAX receivers, airline companies o re also linked with the ZETFAX facsimile networks, which are often quite extensive. The local weather information can be provided at short intervals and without de lay by a ccredited MET observers and is thus ava ilable not only to the a ir traffic services units but a lso to airline dispatch offices.

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IFATCA JOURNAL OF AIR TRAFFIC CONTROL

THE CONTROLLER Frankfurt am Main, January/February 1966

Volume 5 · No. 1

Publisher: International Federation of Air Traffic Controllers' Associations, Cologne-Wahn Airport, Germany. Officers of IFATCA: L. N. Tekstra, President; G. W. Monk, Executive Secretary; Maurice Cerf, First Vice President; Roger Sad et, Second Vice-President; Ernest Mahieu, Hon. Secretary; Henning Throne, Treasurer; Walter Endlich, Editor. Editor: Walter H. Endlich, 3, rue Roosendael, Bruxelles-Forest, Belgique Telephone: 456248 Production and Advertising Sales Office: W.Kramer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr57a, Phone 44325, Postscheckkonto Frankfurt am Main 11727. Rate Card Nr. 2. Printed by: W.Kramer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr 57a.

CONTENTS International Symposium on Air Traffic Controller Training Maurice Cerf

Stockholm Air Traffic Control Centre inaugurated ....... ·

Fifth Annual North Atlantic and European ATC Conference

New Air Traffic Control Tower at-4.od Airport, Israel ..... ·

Analysis of the Processes involved in the Treatment of Information by the Air Traffic Controller ................. · · · · ·

J. Leplat and A. Bisseret Subscription Rate: OM 8,- per annum (in Germany). Contributors are expressing their personal points of view and opinions, which must not necessarily coincide with those of the International Federation of Air Traffic Controllers' Associations {IFATCA). IFATCA does not assume responsibility for statements made and opinions expressed, it does only accept responsibility for publishing these contributions. Contributions are welcome as are comments and criticism. No payment can be made for manuscripts submitted for publication in •The Controller·. The Editor reserves the right to make any editorial changes in manuscripts, which he believes will improve the material without altering the intended meaning. Written permission by the Editor is necessary for reprinting any part of this Journal.

Advertisers in this Issue: Cessor Electronics, Ltd. (6); The Decca Navigator Company, Ltd. (Inside Back Cover); Ekco Electronics, Ltd. (4); Dr.-lng. Hell (1); General Precision Systems, Ltd. (ll); Messe und Ausstellungs GmbH (12); The Marconi Company, Ltd. (3, 5); Plessey Radar (Back Cover); Selenia S.p.A. (8); Satco (23); Standard Elektrik Lorenz AG (2); Telefunken AG (Inside Front Cover) Picture Credit: ATCA (22); FAA (24, 25); Leplat/Bisseret (16); Villiers (35, 36, 37)

Clifford P. Burton ATCA Executive Director E.N.A.C. to move from Orly to Toulouse . . . . . . . . . . . . . . . . . . . . . . . . . . ........

The Third International Aviation R&D Symposium .. · · · · · · · ·

Tirey K. Vickers The Law and the Controller ......... · · · · · · · · · · · · · · · · ·

John G. Wilson The Approach to Automating ATC in France

Jaques Villiers 15th Session of EUROCONTROL Permanent Commission . ·

Results of the 1965 ICAO Air Navigation Conference .. · · · ·

ICAO Meetings 1966 .............. · · · · · · · · · · · · · · · · · · ·

Outstanding FAA Performance ........ · · · . · · · · · · · · · · ·

The Air Traffic Controllers' Guild of India ....... · · · · · · · · ·

Decca establishes ATC Advisory Unit in the USA .. · · · · · · · ·

Cooperation Haly/EUROCONTROL ......... · · · · · · · · · · · · ·

ATCA ... an Inspiration ....... · · · · · · · · · · · · · · · · · · · ·

Gen. William F. McKee Book Review

·····················

IFATCA Corporation Members

IFATCA Addresses and Officers

Selenia products are JNorking for safety in the air

ATCR systems and METEOR radars from SELENIA have be.e~ chosen and ar~ in operation for the Air Traffic and Weather Bureaus Authont1es of 15 Countries. It is not by chance that these highly specialized pro~ucts, oft~n connect~d into large ~y.stems, have been designed by Selenia for so many exacting users and operate m such different environmental cond1t1ons. Selenia has a staff of engineers working on the problems connected with safety in the air: all the experience acquired by years of research an~ produ~tion in the military and professional electronic field is put to good use to reach one basic goal: Keep the Air Traff1~ safe. . . . . Selenia is prepared to give a~I .kind of assistance in solving the proble~s concern mg. Air Traffic : from the study of the best system to the training of personnel, through research, design, construction and installation of corn t 1 networks, including Terminal and Air Route Contr?I . radars, . Weather radars, data handling and display syst~~se microwave links, remote control and data transm1ss1on equipment, etc. '

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International Symposium on Air Traffic Controller Training Paris, May 1965 The International Symposium on Controller Training was sponsored by the Secretaire !'Aviation Civile and organized by the Ecole Nationale de !'Aviation Civile (ENAC), the French Air Traffic Control School.

The introduction to the programme outlined the reasons for the Symposium in the following words: "The rapid progress in the technical data of air transport, the objectives of an ever increasing safety, linked with faster flow of traffic, gradually change the picture in air traffic control. These developments bring about changes in the methods of recruiting, training, and utilization of air traffic controllers. Such progress is made easier by parallel progress in the study into the controller's work as well as in the knowledge of his psychological process when implementing control techniques." Experts from different countries gave their experiences on four main topics: Problems of selection - the part played by active methods in the controller's training how to keep up the human element and technical proficiency in the air traffic controller - automation and air traffic control. In addition to this, two psychologists read a treatise: "The air traffic controller and his methods of work." The lectures were arranged in the panel form with an open discussion at the end of each session. In his opening speech, Mr. Paul Moroni, the Secretaire General a !'Aviation Civile, underlined the evolution in air transport leading to a necessary renovation of the air traffic control system, this renovation making the reappraisal of controller's training a necessity. Mr. Manuel, the Director of the Ecole Nationale de !'Aviation Civile, before introducing the different speakers, stressed the importance of adapting controllers to present conditions and of maintaining this adaptation. The first panel was chaired by Mr. Lansalot Basou, Directeur de la Navigation Aerienne. The subject under discussion was "The air traffic controller and his methods of work". Professeur Leplat (France), Chief of the Investigation and Research Service of the Psychotechnic Research and Study Centre, outlined the methods used in France to analyse the work of the controllers and the possible use of the results. The Psychotechnic Research and Study Centre has undertaken to define the functions presently performed ~y the controller, and to predict the consequences of the introductio~ of electronic computers, taking over some of these fun~tions. Professor Leplat pointed out the necessity of a co_ntinuous and systematic training for the controllers. Following the studies mentioned above, teaching programmes have been established. Mr. Bisseret of the Psychotechnic Research and Study Centre ~eported on the study conducted at Paris ACC, from which two main methods of control appear: the subs~ctor strate~y, using the geographical position of the aircraft as prime_ data, a~d the flight level strategy, using the levels occupied by aircraft in the sector. The results s~ow that the level strategy system provides greater efficiency, economy, and a better appreciation1). 'i

See page 13.

by Maurice Cerf

The second day of the Symposium started with a panel on problems of selection, with Mr. Johnsson from ICAO as the chairman. Mr. Tournadre, Director of Studies at ENAC, spoke of the French experience in the field of selection. France chose to select by academic examinations, followed by "ab initio" training. Candidates have no previous aeronautical experience. The results of this system are encouraging. The British experience was recounted by Mr. Dickinson, Chief Instructor at the British School of Air Traffic Control. Three sources of recruitment have been used so far: Candidates with aeronautical experience, from 23 to 25 years of age - assistant controllers - cadets (18 to 23 years of age). In the future, increasing reliance will be placed on the third system. Mr. Leclercq, Inspector of Air Traffic at the Belgian Regie des Voies Aeriennes, gave the Belgian views on those aptitudes necessary for a controller. He described the tests used in Beligum, which were devised after a study of what was done abroad; these were of different natures: intellectual, spatial, etc. Mr. A. A. DeRoode, Deputy Director, Current Operations at Eurocontrol, chaired the meeting on the next morning. The first speaker was Mr. Perry S. Bolyard of the Federal Aviation Agency, who had been prevented from presenting his paper on the previous day. Mr. Bolyard stressed the necessity of having strict selection criteria, to avoid a high percentage of failures during the training period. The FAA uses different kinds of tests: Numerical ability, non verbal abstract reasoning, letter sequence, space relations, air traffic problems, oral direction following. To take these tests, applicants must meet one of the following experience requirements: Facility rating, FAA certificates, instrument flight rating, or else have a bachelor's degree. Experience shows that the age of the applicants has a direct influence on the results. As anyone can guess, if applicants have passed a certain age, they are less likely to succeed the older they are. Mr. Leclercq opened the session on the next subject "The part played by active methods in controller training". In Belgium, the controller under training can be promoted to assistant controller, aerodrome controller, approach controller (procedural or radar), and area controller (procedural or radar). The training continues as the controller is promoted. The methods of training in France were explained by Mr. Lengrand, Chief of the Air Traffic Control Division at ENAC. Teaching is concrete and limited to the main points, it takes into account the lack of motivation that is found in most trainees. The course lasts nine months; 1t embraces many control activities: aerodrome, approach, en-route, and radar. Audio visual systems and simulators are used extensively, navigation flights are provided, familiarising controllers with radio telephony procedures and provid ing opportunities to visit different units and centres 1n France. The course ends with a written exorn1nation and practical tests. Mr. Lengrand then exponded on the 111-

structor training, underlining the danger of using only veteran controllers. Miss Enard (France) from the Psychotechnic Research an~ .study Centre has been engaged in a study on the trmn.rng of controllers at ENAC. Two types of training are ~rovrded: School and on the job. Miss Enard thought that ideal training should include -

standardized methods of work and training individualization of the methods active and cooperative attitude of the trainee continuous control by the trainee of his own progress.

The analysis of the controller's work can lead to programmed teaching which will improve the training considerably. For the next panel, dealing with "How to keep up the human element and technical proficiency in the air traffic controller", the chair was occupied by yours truly as delegate of IFATCA. Mr. Dickinson, after enumerating the different grades in the British air traffic control hierarchy, explained the progression in theoretical and practical training, and the use of audio-visual methods. Speaking of the instructors, Mr. Dickinson indicated that they should be selected from good and willing controllers. In the United Kingdom instructors have been especially trained for automation. Mr. Pailhas (France), Deputy Director of ENAC, spoke about the controller's training during his career. It is necessary to update his knowledge continuously so as to allow him to keep abreast of the times. Facility instructors will attend courses on performances and particularities of aircraft, on new air traffic control equipment, and rules and teaching methods. Mr. Pailhas raised the problem created by fatigue and ageing, which has not been solved so far, he thought that controllers should be given yearly tests and be allowed, when necessary, to occupy other positions where their experience can be useful. Mr. Bolyard explained the training methods utilized when, after the Colorado Grand Canyon mid-air collision occured, a large number of controllers were recruited in the United States. The applicants attended an eight week basic ATC course, before being posted to different units as assistant controllers. Training was then resumed at these units. Instructors should, according to Mr. Bolyard, have an adequate professional level, the will and aptitude to teach. During the ensueing discussion, Mr. G. M. Waller (FAA), insisted on the necessity of having young controllers, however, instructors may be older. Nevertheless, the position of instructor should never be considered as an "old folks home". In summing up this panel, Mr. Manuel considered the great variety of selection criteria described by the speakers, and he thought that basic concepts and common methods could be derived from them. There is a direct relationship between selection and training - the stricter the selection, the shorter the training and vice-versa. Some selection criteria, however, could be generally agreed upon: physical aptitude, education, and age. Mr. Manuel then concluded that aviation-related experience, although an interesting factor, is not an absolute necessity, that the lock of motivation can be palliated during the training period by odequate indoctrination, and that the applicaiion of suitable psychotechnic tests can certainly improve the selection results.

The subject "Automation and air traffic control" was first dealt with by Mr. Pa_ul Berger (European Bureau ICAO). Mr. Lansalo_t Basou charred the panel session. Mr. Berger expressed his concern about the influence that automation ~an have on the controller's psychology. Automation relieves man of all minor physical activities which are vital for his balance of mind. The logic of the machine is different from that of man, thus there must be an adaptation b~tween ~h~ ~uman being and the machine. Mr. Berger in hrs own, rnrm1table style gave the meeting some thoughts to ponder on. Mr. Lansalot Basou was of the opinion that we cannot do without automation but that "the beast has to be tamed". Automation created a number of problems in the United Kingdom, and these were enumerated by Mr. Goodyear, member of the Automatic Data Processing Section ATC Experimental Unit. Controllers have been trained a~ programmers, they were selected among those who showed special ability for mathematics. A radar data processing project is currently in progress. Mr. Goodyear also mentioned the Apollo system, which has been installed at the Prestwick ACC and is used for feeding flight plans into the ATC system. Mr. J. Villiers (France), Chief of the Centre d'Experimentation de la Navigation Aerienne, lectured on "The stud~ of the ~~nt;ollehr's fu~ction and of automation in air traffic contro . syc o og1sts have been participating in study, which lead to conclusions such as: Each controller's contribution to the tot~I efficiency of work decreases as the overall workload increases, and the unit is nearin saturation. The time allote~ becomes too limited to perm~ the use of all the data available, thus leading to an ap _ · f · 0 pa rent saturation o airspace. ne of the purposes of automation is to contribute to a better allotment of information. Automation can decrease the total workload b simplifying and organizing it, also by adjusting it to y man. . f . T h ree sources o f in ormat1on have been surveyed: flight plans, secondary radars and primary radars. At th t. · h h · · e 1me b e1ng, t e emp asrs 1s mostly directed to the study of flight plans. The electronic computer can have · . a part tn the control process, erther by analyzing flights d Iocat. . . an rng conflicts, or by taking decisioM on coordination with other centres and other controllers Mr Vill'ier' I · . · · s cone us1on was that automation helps to reduce the cont ro II er ·s manual workload and will also allow a more th h . . oroug process rng of all available data Automatr'on c b · Ie. , an e imp

me1~ted. pro~essrvelr and should be designed for the controd1er rn orh e r t~ e 1mi~ate any problem of professional an or psyc o 1ogrcal ad1ustment.

Mr. Lansalot Basou and Mr. Manuel th · . . . en summarrsed t h e proceedings. Selection criteria and trar· · h . . nrng met 0 d s vary greatly rn the different countries , but ge nera 1 t ren d s are. apparent. The Symposium highlighted the benefits derrved from close collaboration of · logists, and operating staff Performan ecengtrenseters, pdsychod. . · s con ucte to rnvest1gate the technical proficiency of t ff d . con ro 1 sta an to study the influence of restraints such as fatigue should be agreed and suitable terms should be defined At this point I should like to present I . . . . . my own cone uinteresting meeting · First , as ha s b een sm'd sions on. thrs . . b e f ore, 1t rs obvious that there are num . . . . et ous concepts f or t h e se Iect1on and training of air traffic control t ff d th t · s a 1 an _e cou~ ries represented seemed to be quite satisfied with their respective systems · Still , the Sympos1um . . ht m1g

cause the attendants to stand by for a while, considering to take into account the results of the research work described above, wherever they had been applied. Thus it should be possible to standardize criteria, of course, with due consideration of local particularities in the different countries. These local particularities could be sensed throughout the discussions and are direct consequences of the different status of air traffic control staff in the various countries. One could easily gather that, in a limited number of states, controllers are a low category of civil servants and, consequently, take no part whatsoever in the management or planning of air traffic control, leaving this to other classes of officials who, although proficient in management have no experience in active control. Elsewhere the range of positions occupied by air traffic controllers is much wider, to such an extent that some of the best can ultimately reach the planning and managerial level and take part in international discussions such as this one. The problems brought about by the introduction of automation have attracted my attention. I heard on the one hand that the human being is expected to adjust to the machine, but I was greatly relieved, on the other hand,

when an expert in automation expressly stated that automation should be designed for the controller so that no professional or psychological adjustment is required on his part. The Ecole Nationale de !'Aviation Civile should be commended for having initiated the Symposium, and I was rather proud that it took place in France. Mr. Bolyard confided to me that this was his first stay in Paris and that he greatly enjoyed strolling in the streets and down the Champs Elysees, which our American friends so curiously call the Champs. His impression was undoubtedly influenced by the fact that we were gratified with a warm and sunny weather which he believed we had permanently. I did not have the heart to inform him that the previous week had been rainy and cold; I hated shattering his dreams and, besides, our tourism can do with some enthusiastic testimonies. The attendance of several IFATCA members (wearing our badge), some of them among the speakers, was most pleasant for the IFATCA representative. It is my hope that there will be a follow up on the Symposium. Problems were set, other meetings may contribute to their solution.

AIR TRAFFIC MANAGEMENT Continued expansion has led to the creation of a new Air Traffic Control post in the

Air Traffic Management Group of General Precision System Limited. This is a rapidly expanding field of consultancy work demanding inter alia a very high level of operational capability. The aim is to provide a comprehensive consultancy service whose scope includes land, sea and air traffic management. Opportunities will be available for extensive overseas travel. The selected candidate will have a wide ATC experience and will enjoy the confidence of the practising Air Traffic Control Officers nationally and internationally. Essentially, he will be able to project his ideas and to put them on paper fluently but concisely. This is a career post, rewarding and challenging in its scope. Age about 28-35. Salary negotiable. The Company operates a contributory Pension Scheme. Applications in strict confidence to:

Mr. P. C. Haines, Manager, Air Traffic Management Group, General Precision Systems Ltd., Bilton House, 54/58 Uxbridge Road, Ealing, London W. 5

Stockholm Air Traffic Control Centre inaugurated At the end of Oktober 1965, the new Area Control Centre was officially put into operation at Stockhol m Arlanda a irport. Since March 1965 operationa l trials had been carried out at Stockholm airport with an automatic data processing system for radar information, w hi ch was developed a nd p roduced by Standard Radio and Telefon AB. Th e Stockholm Centre is the first centre in Scandinavia whe re automatic processing of radar information is being applied. The system proyides for coordination of civil and military traffic at the civi l airports Bromma and Ar landa, as we ll as severa l military bases.

Fifth Annual North Atlantic and European Air Traffic Control Conference

Parallel zur Hannover-Messe veranstaltet der Bundesverband der Deutschen Luft- und Raumfahrtindustrie e.V., Bad Godesberg, die 6.Deutsche Luftfahrtschau auf dem Flughafen Hannover. Die Ausstellung beginnt am Freitag, dem 29. April, und dauert bis zum Sonntag, dem 8. Mai 1966. Die Organisation der Deutschen Luftfahrtschau 1966 erfo lgt durch die Deutsche Messe- und Ausstellungs-AG, Hannover-Messegeliinde. Auf einer gegeni.iber den Vorjahre~ auf rund 100 OOO m2 erweiterten Ausstellungsflache geben in- und ausliindische Unternehmen der Luft- und Raumfahrtindustrie einen umfassenden Oberblick i.iber ihre Erzeugnisse. Flugzeuge und Triebwerke ziihlen ebenso zum Angebot der Deutschen Luftfahrtschau 1966 wie Erzeugnisse der Luftfahrtaus ri.istung und der Raumtahrttechnik. Zurn Ausstellungsprogramm geho ren wi~足 derum tiiglich Flugvorfi.ihrungen auf dem erwe1terten Gelande des Flughafens Hannover. Deutsche Luftfahrtschau 1966: Sie sollten dabei sein und sich von dem technischen Stand des Angebots und der Leistungsf~~igkeit der au~足 stellenden lndustriegruppen uberzeugen. Ste sind herzlich eingeladen.

Deutsche Luftfahrtschau 1966 auf dem Flughafen Hannover 29. April - 8. Mai

The fifth Annual North Atlantic and European Air Traffic Control Conference was he ld from l 6th through l 9th November 1965 in Rome Italy and was attended by civil and military representatives from Belg ium, Canada, France, Ire land, Italy, Portugal, Spain, the United Kingdom and the United States. The Italian A ir Staff hosted the Conference, with Capt. Pacetti as Project Officer. Gene ral Giovannozi, IAF Ch ief of Air Traffic Services opened the Conference, which was sponsored by the United States Air Force in Eu rope with the purpose of bringing together Air Traffic Control lers of all nations involved in hand li ng U.S. mil itary traffic in Europe. Although these working meetings were originally designed on a more limited sca le, th e response among nations ha s been so en thusiastic that it is now agreed that the interest of th e North A tla ntic and European Air Traffic Contro l Conference should be expanded to all of Europe, including civil as wel l as mi litary air traffic control. Besides participa ting in the working sessions the attenda nts visited the Rome Ai r Traffic Control Centre and the Sele nia Radar Factory. Highlight of the Conference was on l 7th November when the delegates were privileged to attend a Papa l Audience. Hi s Holin ess wished the delegates succe ss in F-X th eir deliberations.

New Air Traffic Control Tower at Lod Airport, Israel As part of the implementation of the Israel Nationa l Air Navigation Plan, a new control tower has taken up operati on in October 1965. Its construction had created many a proble m, si nce the new tower had to be bui lt on top of t he old o ne, without any interruption of air traffic services during the construction period. Israeli controllers consider th e ir new tower a nd its modern and elaborate electronic equipment as kind of a "dream come true". The National Air Navigation Plan of Israel, which has first been published in 1961 by the Department of Civi l Aviation of the Ministry of Transport, provides for the e stab lishment or modernization af the following facilities: - an integral na tional network o f a ir nav igation aids; - adequate e lectron ic landing aids at Lod Internationa l Airport, with a particular view to the requirements of jet traffic ; -

modern visual landing aids, including lan ding lights, runway markers, and ramp lighting a t Lad Airport; Ele ctric powe r systems and stand-by g e nerato rs for e me rge ncy powe r supply at Lod Airport ; new contro l towe rs a t Lod and Eilat Airports; Aero nautical Fixed Te le commun ication Syste m.

Analysis of the Processes involved in the Treatment of Information by the Air Traffic Controller by J. Leplat and A. Bisseret

The purpose of this study is to analyse an operation carried out by the air traffic controller: the detection of possible conflicts between aircraft. It is part of work which aimed at studying the effects on man of the progressive automation of the actual air traffic control system. The analysis leads to the compilation of an organigramme which sums up the process followed by the controller in his research work. A static simulation test enables the organigramme to be verified, that is to say, to establish the existence of a correspondence between the order in which the variables are examined and the difficulty of the various researches. Two typical strategies are identified starting from the order in which the variables are examined, and it is possible to establish both logically and experimentally the superiority of one them. Finally, some characteristics of a representative model could be defined. The theoretical and practical significance of these results is stressed in the conclusion. Parts of the paper were first presented at the International Symposium on Controller's Training, which was held at the Ecole Nationale de !'Aviation Civile, Paris-Orly, in May 1965. The original French version was then printed in the Bulletin d'Etudes et Recherches Psychologiques, whose Editor, Professor J. Leplat, has kindly granted permission to publish an English translation of the study in THE CONTROLLER. Acknowledgement is also extended to the Secretariat General !'Aviation Civile and the Ecole Nationale de !'Aviation Civile for their assistance, and to Messrs. M. Cerf, Paris, and J. Massie, Brussels, who have kindly provided the English translation.

Analysis of the processes involved in the treatment of information by the air traffic controller The study presented here concerns the analysis of the human functions in an air traffic control system. Before outlining precise objectives, we will place them in context. The yearly increase in the volume of air traffic is presently estimated to be 10%. Its control poses more and more difficult problems which, it has been obvious for some time, cannot be solved by solely applying ,,classical control methods. The symptons of saturation apparent in the present system have caused the "Direction de la Navigati_on Aerienne" to consider the possibilities of modern machines for the treatment of information. For the time being, this is not a question of fully automating air traffic control but of entrusting to the machine some functions formerly carried out by man, in order to ease the controllers' workload and to assist them in meeting t~e requirements of ever increasing traffic. This gradual implementation of automatic data processing is presently restrained by the requirement that it must be possible to resume manual control with traditional means should the need arise.

One of the tasks assigned to the psychologist in this conversion process was to define the functions which are carried out by the man in the present system. These functions cannot be deduced from regulations and operating instructions, which only show the objectives and the conditions of the task. They must by found by an analysis of the controllers' actual activity.. But this analysis is difficult: in the first place the operations carried out often escape notice, then they are difficult to isolate because of their frequent overlapping, for example when a decision is taken during the reception of a highly redundant message. The present paper is only related to one part of the studies carried out on this position, that part which deals with the the analysis of the activity and the search for possible conflicts. The interest of this study is two-fold: practical and theoretical. On the practical side, the knowledge of the functions actually performed by the controller and the requirements which are entailed can assist in achieving an optimum working method for this same controller, or better for the control in so far as the system and the possibilities of the electronic computer actually available are concerned. This knowledge will permit to guide the measures of automation and help to foresee the consequences of their implementation on the controller. The necessary analysis of the functions performed by the controller also has the merit of underlining some characteristics of the actual activity and to suggest useful modifications for these. On the theoretical side, the present study constitutes an example of how to analyse a rather complex intellectual activity with symbolic data. This activity which could be termed as one of categorisation or classification, will be analysed not only from its traces, that is to say the behaviour in which it is expressed, but also to provide an explanation of the processes underlying this behaviour. Thus the experiments made have no other purpose than to bring into light significant traces which will facilitate the interpretation of the activity. Particular attention will be paid to the methodological characteristics, the transposition of which could be considered for other operations of the same type. The study will be organised from different stages of the analysis since the latter constitutes the centre of the work. Thus, while trying to simplify to the greatest possible extent, it was not the intention to eliminate concrete supporting material. Some information will therefore be given on the work surveyed which will allow a better u~足 derstanding of the possibilities and limits in the analysis of conflict detection methods. Afterwards, in the light of this analysis, we will examine the complexity factors of control problems, research strategies and their effectiv~足 ness, and the way in which the traffic is represented. Finally, some conclusions will be drawn with regard to the theoretical and practical aspects of the work.

Information on the present control system Elements of the general organisation of control The flow of air traffic is assured by two types of orgcnisation: The aerodrome control towers and the area control centres; the latter taking charge of the aircraft throughout their trip. The nothern air traffic control centre (situated at Orly) controls the northern half of France. Two types of flight are possible: Visual Flight and Instrument Flight. When the aircraft captain chases the Instrument Flight Rules (and this is almost the general rule with civil aircraft) it is the ground controller who, to a great extent, takes over the responsibility for collision avoidance. The main part of the controller's activity is to ensure that there are no conflict possibilities between aircraft. The second objective, important but subordinate to the first one, is to provide for an expeditious flow of the traffic. These aims cannot be reached by using a long-term plan as in rail traffic. In fact, numerous factors contribute to upset the flight plans and to modify the estimates, in particular meteorological conditions. At present, control can only be planned a rather short time ahead (in the order of 15 to 20 minutes maximum}. The airspace is delineated by a number of electronic aids on the ground (beacons, markers, etc.) which define in the horizontal plane a number of air routes. These are also limited in the vertical plane by a base (determined by the terrain) and a top. Between these two extremes a number of flight levels have been defined. The intensity of the traffic has brought about a subdivision of the control area into sectors, each sector being entrusted to a controller who is aided by one or more assistants. Thus, in a sector, a flight is defined for the controller by the route it follows, i. e. the successive beacons to be passed by the aircraft, the flying time between the beacons, and the flight level. Every time an aircraft overflies a beacon, the pilot transmits to the controller by radio a position report which comprises: the beacon which he is passing, the time over the beacon, the next beacon, an.d the estimated time at that beacon; he also repeats his flight level. The study which is presented here will be abo~t controllers who have at their disposal only a symbolic representation (alphanumerics), it will be concerned with enroute sectors where radar is very little used (insufficient range). This type of control is known as "procedural".

Conflict detection For each aircraft crossing a sector there is a corresponding strip which contains all the information mentioned above. These strips are displayed parallel in front ot the controller, thus constituting a summarized picture of the traffic situation in the sector. By means of this display, (the controller is also provided with infor'.11ation on the type of aircraft concerned, which reveals its performance, particularly its speed) the contr?ller. has to detect possible conflictions between aircraft 1n his sector and, in order to avoid them, request the pilots to carry out appropriate manoeuvres (usually a change of level or, in the case of temporary saturation, holding over a beacon). The requirements of control are a function of the precision with which the position of aircraft and their movement can be determined at any given time. Presently these parameters can only be estimated with a certain margin

of error (besides, the aircraft are not equipped with warning devices to indicate the proximity of other aircraft). It is therefore necessary to apply sufficient separation between aircraft, taking into account all possible errors, so as to eliminate all possibilities of conflict. A set of rules has therefore been established, defining a certain number of safety standards which air traffic control is required to enforce. Let us simply say that they are presented in terms of "flying time" (the most usual standard is 10 minutes), to be maintained between two aircraft. For example, two aircraft of the same speed, flying on the same route and maintaing the same level must be separated by ten minutes. When the term "confliction risk" is used here, it should be understood to mean "two aircraft which are closer to one another than the separation standards allow". The process of conflict search is startet when un-anticipated new information appears and alters the traffic situation. Two general cases can arise: a new aircraft is introduced into the sector in level flight and an aircraft must change level. The controller must interpret that information: in conjunction with the general information he possesses in his mind (rules, particular regulations applicable to the sector, etc.); - in conjunction with the temporary information concerning the aircraft in his sector, which is displayed on the flight progress board. He is thus required to make a diagnosis (risk of confl iction or not) and when there is a risk of confliction, to work out a solution. This latter function will not be the object of the present study, which is only related to the activity of data processing, with a view to detecting a risk of confl iction.

Analysis of conflict detection methods Conflict detection can be considered as a form of categorisation. In fact, it is a question of classifying the situation which is apparent at any given time in one or another of two categories: no conflict - potential conflict. This categorisation can be conducted for the immediate or more distant future; the controller can detect the confliction at a more or less distant term, the mechanics of detection remain the same in every case. In this part of the study we will show how the process of categorisation was analysed.

First logical analysis With regard to the present air traffic control system and the regulations in force, one can determine the information necessary to achieve the desired categorisation, i. e. the classification into "conflict" or "no conflict". It is this analysis which is required by the programmer who wishes the work of conflict detection to be carried out by a machine. For example, in one of the cases which will be investigated here {new aircraft in level flight), there seem to be six variables which can occur for the determination of eventual conflicts or, to use the terminology of Bruner (1962) six attributes can serve to distinguish the situation lo be classified. These are: the level, the flight path, the longitudinal separation, the speed, the direction of flight, the lateral separation. These variables or attributes can be continuous or discontinuous. One of the characteristics that result from the activities studied is that the variables

forming the more easily explainable action and, if thus, one looses all that has been acquired by experience. It con also be feared that the subject utilizes formal elements of explanation, referring to regulations or official instructions, which were introduced when the subject was under training.

distinguish pairs of aircraft and not every individual aircraft: relative levels (two aircraft at the same level or at different levels), relative trajectories (two aircraft heading for the same beacon or not), etc. Henceforth, when we speak of variables, it will be a question of the relative variables defining the relation between two aircraft. The categorisation will be developed with the aid of a number of variables, which are not fixed. Thus the relative level, if it is different, is sufficient to classify the situation in the "no conflict" category, the same applies to the flight path phen two aircraft are heading towards different beacons. Categorisation, however, often requires that several variables are taken into consideration. Thus, a situation where two aircraft are flying at the same level, heading for the same beacon at equal speeds and separated by more than ten minutes will be classified as "no conflict". Categorisation, then, is generally effected from a combination of variables or attributes; the number of these can be as high as ten under certain circumstances. These remarks can be translated into the language of Bruner (1962) in terms of validity of the attributes. In the work analysed, the attributes have different validities to the effect that, when used alone, their probability of classifying the situation in the appropriate category varies very high in the variable "level", for example, it becomes very low for the variable "speed". This logical analysis will not be developed any further at the moment, its purpose being only to serve as an introduction to the analysis of the processes actually applied by the controller in the treatment of the information displayed on his flight progress board.

Analysis of conflict search strategies

The present analysis aims at determining the actual working methods of the controllers, in other words to establish the class of value the operator attaches to each variable and the order in which he examines them to achieve the categorisation which is the objective of the work. a) Explanation of strategies: The results of the catego-

risation do not inform us on the manner in which it was performed by the controller. To obtain information on this point, the controllers were asked to explain the steps taken. This method was often used in experimental psychology for the study of thinking during a test of the "problem solving" type. The schools of thought psychology (Wurzburg school) hove often applied it under the term "instigated introspection", (see Piaget on this subject) and Cloporede hos also used it. This method consists of asking a subject, to whom one has assigned a problem, to resolve it out loud, in order to know not only the result but also the processes involved in reaching it. There ore several criticisms of this method which are well summoriz~d by Grize and Matalon (1962). Straightowoy, there is a n~k that th~ real mechanisms may be distorted by becom.1ng conscious of them. It is not certain that people act in the same way when they see themselves acting and when their action is only orientated towards the aim of the action. The requirement to describe the action verbally creates a new situation, and it can happen that the subject is tempted to devote more importance to the telling of the easy processes and to neglect those which are more difficult to explain. It can also be asked if there is not a risk of the subject reverting to basic stages, per-

Finally, the subject gives his explanation of the reasoning carried out and it is never certain whether one corresponds to the other. In spite of these insufficiencies, this method has recently been rehabilitated by the authors (Newell and Simon, 1963) who are interested in the techniques of " simulation of thought". With these authors, we consider that it can provide useful information, especially if it is possible to evaluate the elements thus provided in a critical manner, by cross-checking them with data stemming from other sources. In the present case, this method enabled us to obtain the indications on the nature of the variables used and the order in which they were examined. Two types of questions were asked: -

the general type of question: when a new aircraft in level flight is introduced, how do you compare it with the others? Example of the interview: the controller starts to reply: "I put the strip on my flight progress board under the corresponding entry point, and if there are other aircraft under this designator, I check if any are at the same level as A".

Two variables then appear: the relative geographical position, which we called before the relative path (trajectory); the relative level each of these variables has an alternative - yes or no.

The subject is then asked: "what do you do in this case?" This process generally requires fairly lengt~y explanation. It imposes on the controller a difficult explan~足 tion since he must imagine, without the aids usually available, the different cases which can arise and the manner in which they are resolved. At a first stage, however, the information thus obtained enables us to elaborate on the problem and to establish provisional hypothesis on the further development of the processes. These results have been used to prepare the second series of interviews .. Questions refering to specific problems. Information previously obtained helped to build up a simulated working picture in a static form. A number of flight progress strips were placed in front of the subject, who was then given new strips, one by one, and asked to explain out loud for each of them the steps to be taken in order to detect potential conflicts created by the introducti~n .of an aircraft on to the sector. This situation is less artificial than the former; it corresponds to that of the controller at the time of shift change, that is to say at the time he takes over his position. Such interviews were held with many experienced controllers. b) The representation of the strategy: the organigram

The information obtained from the previous interviews constituted such a complex set, that it was necessary to present it in a clear way. The method .of r~presentation by means of an organigram appeared 1n this case to .be the most appropriate. It has often been used to describe sequential processes, notably in view of their simultat1on.

No conflict

1----- No Conflict 1-----Conflict

No Conflict

Separation atthereporting point

Conflict

No Conflict Relative Speeds

Relative Levels

Introduction of A

More accurate separation Conflict

Later Relative Paths

Possibility of conflict later when overtaking More accurate separation Conflict

Figure 1 N0

No other aircraft at the same level as A

The faster aicraft ahead

One or several (x,, x 2 , x 3 , Xn) aircraft at the same level as A

x, is proceeding to the same reporting point as A, but on a different

V, Same speed V3 The faster aircraft behind

flightpath

Ta The tracks of the two aircraft are diverging after the reporting point

T2 x, is proceeding to a different reporting point T3

The two aircraft are following the same route aft th · point er e reporting

x is on the same flightpath as A and proceeding to the same report1

ing point S,

Ample separation (> 20')

Separation grossly insufficient (< 5')

Separation approximately 10 minutes

The organigram is thus a step in the approach to the programming of the processes. The organigram is a topological method of presentation of the organisation of operations (une image topologique de !'organisation des operations) (Rosenstiehl and Ghouila-Houri, 1960). Proceeding along one branch in the direction "entrance-exit" symbolises the chronological progression of the process. Figure 1 represents an organigram established for the situation "introduction of an aircraft in level flight". Each squared block represents one operation pertaining to one of the variables mentioned above. From each block there are arrows, corresponding to the alternatives of the variable, i. e. to the different results which are possible in the process. The progression on the organigram, which is from left to right, illustrates at the same time the order in which the variables are examined.

N?te: If there. is no ~onflict with x, one recommences the process with another aircraft in the sector, x,, and the continuing until aircraft at the same level as A have been investigated

The organigram and the complexity of control problems The organigram obtained shows that the sequences o f . . data collection . illustrated by the different 1·rnes are Ionger or shorter or, in other words, that the end of a search programme (that is to say the verification or th b . . k) h e a sence appens o f a con fl 1ct ris . a shorter or fu r th er way a Iong. Thus the number of variables to examine vary accor d'mg to the problems and constitute a factor ·In th e1r · d'ff' I . . I ICU ty. Other things being equal one can mak th t' . ' e e sugges ion that a problem will be more difficult if it is located on a longer .branch. Two experiments have b een d es1gne · d ·in . . attempting to verify this hypothesis. the'ir · · I · . · princ1p e 1s th e following - the problems are built up in such a way that each corresponds to one particular branch of the organi-

gram; then they are submitted to the subjects in a laboratory, thanks to a static simulation technique which allows the measurement, for each one, of the time required for conflict search. If the preceding hypothesis is verified, one can expect to find a good correlation between the length of the branch and the search time corresponding t~ t~e problem. The rejection of this hypothesis would s1gn1fy that the organigram is wrong, this could either result .from a temporary wrong sequential organisation of variables, or from the occurrence of variables or procedures other than those under consideration.

Description of the procedure The controller is faced with a traffic situation shown on a flight progress board similar to that with which he normally works. However, this situation is fixed, i. e. throughout the experiment the time remains the same. It is, to a certain extent, the time of shift change. The situation presented to the controller is free from any potential conflict. The problems are shown, as in actual conditions, on flight progress strips; either new aircraft to join the traffic, or aircraft who wish to change their level. The problems are presented to the test persons one by one. For each one the controller must study his traffic picture in order to determine whether or not the problem aircraft interferes with one or several aircraft in the setor. He is only given the task of diagnosis (possible conflict or not), therefore he does not have to worry about the eventual solution. The time required for this diagnosis is measured and the result recorded. As soon as one problem is solved, the corresponding flight progress strip is removed, so that it no longer interferes with the situation and the next problem can be presented.

The method of static simulation In the actual working environment, the function of conflict search is practised under difficult conditions, resulting from an accumulation of many varied activities, the most essential of which are the reception and transmission of information by several means (radio, telephone, television, direct speech). Under these conditions measurement is not practicable. It is difficult to isolate the function to be studied from the rest of the activity, in as much as it is characterised by the fact that there are only few obvious indications in the behaviour pattern. For the same reason a dynamic work simulation does not appear desirable. It seems to have the advantage over the actual situation insofar as it can be programmed at will, but this advantage is only apparent. Practically, in fact, the subjects, by not taking similar decisions, change a situation that was initially identical in such a way that finally the comparative anlysis of the steps and the results becomes impossible. The method used here, i. e. the static simulation, allows - the elimination of all aspects of work which do not enter into the function studied and therefore the isolation and measurement of only this function; - placing the subjects in strictly identical situations; - the experiments to be short and relatively easy to be carried out.

Table 1

The first experiment and its results Nine problems were taken from the organigram corresponding to the conflict search possibility in the case of a new aircraft joining the sector in level flight. Fourteen controllers were tested twice with an interval of one month beween tests. The order of the problems was changed haphazardly for each of the subjects; however from one test to the other the same subject was given the nine problems in the same order. The search times thus obtained have been the object of an analysis of variance of which the results are given in table 1.

Analysis of the variations of the time required for conflict detection Degree of freedom

Sources of variation

Mean squares

Between subjects Between qualifications Subjects/qua Iificatians

Between problems Between the four classes of problems Problems/class

23,32 ••

73,93 25,01 •• 2,03 N.S.

184,84 7,89

3 5

9,16 •• 5,96 •• 3,71 ••

29,06 80,80 13,54

3 10

F (1)

32,04 ••

101,58

Between sessions Interactions session :-: subjects session X problems Problems X subjects session X problems

104 104

subjects

Total

229

Total

251

(1)

• ,01

<a< ,05

••

,001

N.S.

1,53 N.S. l,02 N.S. l,25 N.S.

4,87 3,25 3,98 3,17

3,64

,05

a) It can be stated that none of the interactions envisaged are statistically significant: the second test therefore does not modify greatly the classifications of the controllers or the problems. Besides, the order of difficulty of the problems does not change with the qualifications of the controllers. b) The differences between individuals are very great. The qualifications have an importance and have statistical significance in the variation between individuals., yet without exhausting this source of variation. c) The problems, which as a whole differ greatly, have been grouped into four classes, according to the length of time required for the conflict search. This factor accounts for the source of inter-problem variations. There is a close relationship between this classification of problems and that given by the organigram. Some of the anomalies which have been noted do not figure in the organigram, but certain faults in the conception of the problem in this first test are indicated. In fact, it is difficult to work out actual problems whose only difference depends on which branch they are located. Other sources of variation can interfere and contribute to the ease or difficulty of extracting the information. Thus it takes longer to calculate a time difference when it passes the hour: for example the interval between 1157 and 1207 is more difficult to calculate than the interval between 1200 and 1210. In addition, one notices that for the same number of variables, which are differing from one to another, the correlations between the time, and the length of the branches is mediocre. This can be explained by the fact that the necessary operations to obtain the values of the different varibles do not have the same complexity and, therefore, influence quite differently the time required for conflict search. Subsequently it would be useful to plan experiments suitable to determine adequately the time of the different operations in an exact way and to analyse these operations.

Second experiment and its results Taking these results into account, a ~econd experiment was carried out, based more systematically on the problem of validating the organigram. It was based on problems of level change. Twenty six controllers participated

Table

Average times required for conflict delt:clion in the five classes defined in accordance with the organigram

Classes

Average time in seconds

Table

Mean squares

subjects problems classes of prublems problem/classes

250 285

Total

I Va

17,26

20,96

Analysis of variations pertaining to the individual times (after logarithmic transformation) of 26 test persons for ll given problems

Residual

fl)

Ill

6,35

Source of variation Between Between Between Between

in this experiment which, with regard to the results of the first, required no duplication. The eleven problems used correspond to the eleven branches of the organigram, arranged in such a way that short problems being integrated in the long ones. The following classification was taken from the organigram: Class I - One variable sufficient to solve the problem (relative level), - Two variables sufficent (relative level, geClass II neral trajectory), Class Ill - Three variables are neccessary (relative level, general route, relative position of the aircraft according to reports over beacons), Class IV - Four variables are necessary. (The first three and the time separation between two aircraft obtained by a simple calculation.), Class IVa - Four variables are necessary. (The first three and the time separation between two aircraft but this being obtained by a more complex calculation). It can be seen that classes IV and IVa are at the same level with regard to the number of variables. They differ in the complexity of the operation necessary to obtain the values of the variable. This can be used on the future study of the organigram on the level of elementary operations. Table 2 gives the mean time for each class. Table 3 indicates the results of the analysis of variance with regard to the individual results (after logarithmic transformation}. Class I and class Ill do not differ and even show the times arranged in an order opposite to what the hypothesis lead to expect. The phenomenen can be explained by the fact that the controllers (or to be more exact a percentage of them) had not used this possibility of rapid diagnosis possible with only 2 variables; they added for confirmation (in the case of no confliction existing) one test to the other: The geographical position related to the beacons. If classes I~ and 111 are grouped in the same category, it can be considered that the hypothesis received elements of confirmation from this experiment, since the search times agree with the lengthes of the branches of the organigram.

,001

N.S "<. ,05

43,647 66,634 151,296 10,192 7,030

F (1) 6,208.

9,478. 14,844. l,449 N.S.

The organigram and the efficiency of the system It has already been seen before that one of the important aspects of the processes represented by the organ igram rests in the order of examination of the different parameters. Logical analysis shows, and the organigrams of the controllers confirm, that between certain variables, order is necessary (for example, it is necessary to ensure that two aircraft are heading for the same beacon before calculatin~ their separation on this beacon) but that, for other v?riables a certain freedom of flexibility exists in the choice of the order of examination. Thus, for the same type of problem, different strategies were used by the controllers and give rise to different organigrams. Practically, it was found that two main types of strategies were used which differed in the choice of the first variable used and consequently in the rest of the processes. This choice does not only influence the order of variables, but also the general structure of the processes. The most common system which we shall call "subsector" first of all considered the variable "relative geographic position"; the controller splits his sector into several geographical designators and groups together the flight progress strips of the aircraft who are, at a given moment, in the same "Sub-sector" (In the case of the given sector having several points of route convergence). The controller in this case, carries out a division of work in the time: he compares (according to the other variables) the "problem aircraft" with each of the groups of aircraft successively. A second strategy, not so commonly used, consists of firstly comparing "relative level". The controller arranges his strips "by level" and his comparisons are carried out directly on all the aircraft on his sector. On posing the problem of the relative efficiency of these two systems, considering the double objective of control (safety and expedition) one is lead to distinguish three conditions of this efficiency which concern: 1. The excatitude: Each diagnosis must be certain (not probable). 2. The speed: It has been said that the other tasks of the controller often put him in conditions of severe stress. Lastly the forecast: That is to say, the term of the diagnosis, considering that it is desirable that, in a given sector, the risks of confliction are seen as early as possible. This being submitted, it seems that two distinguishing factors can be related to the efficiency of the system: the validity of the variables and the sequential organisation of the process.

1. Analysis according to the validity of the variables. A valid variable will be one in which one of the values is decisive, that is to say, one which in itself allows a situation to be classed in the category "conflict" or "no confliction". Logically the optimum strategy is that which from the outset highlights the valid variables and among them those whose decisive values have the highest probability. This strategy, in maximising the chances of only using the necessary variables, reduces the mean time required for the whole of the diagnosis.

Let us now consider the two current strategies which were mentioned above, from the point of view of the two variables which distinguished them. Being given a problem-aircraft A., the variable "relative level" can have two values. -

N, -

No -

There exists one (or several) other aircraft at the same level (or at a level which may interfere). There is no other aircraft at the same level.

The variable "relative route" can also be reduced to two values:

t, -

to -

There exists one (or several) aircraft whose route has, at least, one common point with that of A. No other aircraft having a common point with

A. It can be seen that N 0 and T0 are two decisive values since when the variable level or the variable route have this value, the diagnosis can be immediate by means of only one variable. Now, in the absence of precise statistical information, it seems that it can be assured without a possibility of important error, that the probability of Nn/A is greater than that of to/A. Note:

Probability that the variable #relative level" takes the value N .. when on aircraft A involves a conflict detection.

This could be expected, for one knows that in most sectors the number of levels used is more important than the number of possible converging points and, furlhermore, that an aircraft crossing a sector uses fewer different levels (normally one) than it is overflying converging points. Thus this type of analysis permits the conclusion that the "level strategy" is the most economical: it minimises the mean number of variables to be examined.

2. The organisation of the process in the time. The choise of the first variable also has a bearing on the sequential structure of the continuation of the process. The "level strategy" implies that the process is applied at once and directly on all the aircraft (" extraxtion" of the aircraft which are at the same level as A then with each of them comparison according to the other variables). On the other hand with the "sub-sector" strategy, the controller repeats the same process several times succesively for each sub-sector (extraction of the aircraft which are in the same sub-sector as A. - among them, extraction of those at the same level - on each of these, comparisons according to the other variables then, taking the requirement of traffic prediction into account, the same thing for the aircraft in the next sub-sector). It will be seen that with the strategy level, the traffic prediction influences the whole of the sector while with the "sub-sector strategy", there is a tendency to be more localised. Moreover, this can be shown materialistically: on the display by levels the strips of two aircraft are automatically side by side while on the "sub-sector" display they can be in different groups of strips and even totally separated by all the other strips. Thus the hypothesis to be verified will be that the "level strategy" is the most efficient, as well as from the point of view of speed of diagnosis as from the qualitative point of view of the term of this diagnosis and, consequently, in its property to be final, for the whole of the sector.

Experiment and results To test this hypothesis one experiment has been carried out in a static simulation. a} The problems. Seventeen different traffic situations (and therefore 17 strip displays) were prepared, each one corresponding to a problem. Each situation was identical as to the num.ber of aircraft (12), in the setting out of the geographical dispositions of the aircraft and in the occupation of the levels. The problems were of different types and varied in particular on the question whet~er the aircraft .which,, was in conflict with the problem aircraft A. was in a subsector" near or far from that of A. (prevision of conflict in the short or long term). b} Experimental design. Two independant groups of 9 subjects took the experiment in two differing conditions: the subjects of one group worked with a classification by "sub-sector" that is to say with their usual method; the other group composed equal1 of controllers normally using the same classification, made to use the classification by levels. Before the experiment the 9 subjects of each group underwent the same control test composed of 4 problems to be resolved on a display organised by the control~er.s thems:lves. The results of the two groups did not stat1st1cally differ; they therefore can be considered as of equivalent levels.

~ere

c} Practical conditions. The subjects of the two groups carried out the same task in the following manner: For each new problem t~e situation is similar to shift change time. The problem strip was given to the subject for a rapid examination. Then the corresponding strip display board was uncovered. The t .1me measur ed was that between the appearance of the display and the diagnosis. The seventeen problems were thus succesively presented during the same session. d) Results.

Speed of diagnosis and strategy The mean time in seconds for the solving of a P~,oble~ was, in seconds, respectively 14 seconds for the . level system and 19.06 for the "sub-sector" system. The two times are significantly different (ci< .02). The . controllers using t h e "I eve I" st r ategy were therefore quicker than the others. This result is even more remarkable as these controllers were under the disadvantage of using a method of classification not familiar to them. . o f t h e "I eve I" st ra tegy received a .supThis superiority . .in t h e f ac t that the mean times lementary confirmation were of resolution of eac h o f t h e seven teen problems . d roup using this metho th f systematically shorter or e g bi ) than for the other (with the exception of one pro em .

Prediction of future problems In order to test the hypothesis concerning the ease of tra ff .1c pre d.1c t"1on in the "level" strategy, ten problems

were taken in which there were no immediate conflictions, but on a future beacon of the flight path of the problem aircraft. For these problems, the number of times where the controllers of the two groups had not mentioned the existence of this confliction risk in the long term was considered. The non-parametric tests, to which it is obliged to resort to with such data, are little sensitive and do not reveal any difference of statistical significance. However, the important arithmetical differences tend to confirm our hypothesis: Out of 90 diagnosises (10 problems X 9 subjects) one notes that the long-term prediction is missing 13 times in the "sub-sector" group, and only 2 times in the "level" group. Summarizing, one can conclude, from the total of the, results, that the "level" strategy not only renders itself as the quickest, but also the more favourable with respect to the prediction (as from the time at which a problem is presented, for instance by the introduction of a new aircraft) of all conflict possibilities, including the remotest.

The organigram and the traffic display The organigram shows the variables necessary for the conflict search and the order in which they are examined. Obviously it does not tell us how the operator extracts the information of interest to him, however it permits us to analyse this last point and it helps us to better understand the processes which are really brought into action during the work. At the time of relief, the controller is obliged to extract all necessary informations from the flight progress strips, but after a certain time the survey shows that he can resolve certain problems without referring to his flight progress board. It seems, therefore, that he memorises certain aspects of the situation in order to build up a schematic representation of the latter, a representation which avoids his permanent referring to the flight progress board. It was deemed of interest to study the characteristics of that representation, of that model on which the controller elaborates and which he updates at certain times. The experience which is going to be presented here constitutes nothing but a first step towards the study of that problem. The analysis of the characteristics of the model of the prevailing situation is not easy. A direct interrogation of the controller to find out, for example, which details of the traffic situation he remembers is difficult in practice and, furthermore, too artificial. It appeared that a better method would consist of deducing the characteristics of that representation from the way the controller solved certain problems without reference to the flight progress board.

Principle and procedure of the experiment For this purpose the method of static simulation has again been utilized, but in a different manner. The controller was asked to study, within the period of time necessary, a traffic situation displayed on a flight progress board arranged by himself. When the controller stated to be well familiar with the situation, the board was covered and a problem was presented. The controller was then invited to give his diagnosis: conflict or no conflict. When he was not in a position to furnish a reply he was asked

to specify the information he was lacking. The number of strips on the board was 14, and 7 problems were successively introduced to the existing situation. The 8 test persons were not required to solve the problems with a certain rapidity. The purpose of this preliminary experiments was to compile certain information on which the hypothesis on the characteristics of a model of representation can be based. Thys hipothesis would finally have to be proven in a more systematic manner.

Results and conclusion of the experiment From the results of the 56 tests (7 problems X 8 subjects) one notes that in 87% of the cases the variable "level" is known and in 60% of the cases the level and the position (with reference to a navigational aid) are memorised without error. On the other hand, the values of the other variables, particularly the time over a fix, the types of aircraft and the relative speeds are rarely remembered. Thus the controller remembered always the first variables of the organigram. His traffic picture was essentially based on the level and the geographical position. These two variables would allow him to make an initial sorting without reference to the flight progress board, the latter he did not consult but for the aircraft which his first sorting did not classify among the "non-conflict" strategy. After identifying these aircraft on the board, the controller then continued with each of these according to the pattern indicated in the organigram. These remarks must later be more precisely defined, and it would hence be important to undertake a study of the dynamic characteristics of the model, in attempting to analyse how its pattern changes as a function of data on the flight progress which are provided to the controllers by the pilots.

Conclusion On the theoretical basis the study indicates the advantage of a detailed investigation of the processes involved. Even if one accepts some of the criticism as being justified, which might be held against the method governing the construction of the organigram, the latter would find sufficient justification from the benefit derived in the overall analysis of the problem. Associated with a method of static simulation, the organigram does in effect permit to define the situations introduced to the subject - the stimuli - and it also helps to interpret the behaviour observed - the responses. ~ certain validation of the method illustrated by the organrgram could furthermore be seen in the results, without them being completely satisfactory for the organigram applied here, nevertheless providing important elements of confirmation. Finally, the importance of strategy was made obvious in this complex task. Also in this respect the organigram facilitates better understanding of that s!rategy and through it certain charactersitics of the organrsa-

tion of work. By way of the study of representation, which has not really progressed beyond the introduction, one enters even further into the analysis of characteristics of genuine human data processing. That subject would merit a special study of its own, but one can underline that here, too, the hypothesis on the method of extracting information from the flight progress board, such as illustrated by the organigram, permits to better understand and to better locate in the total process the model by which the subject summarises the information already available and in which he incorporates the supplementary data which are necessary for the solution of certain problems. One of the advantages of this work was to conduct it with the cooperation with qualified operators, thanks to them the initial training period, which often puts very provisional adjustment mechanisms into the game, could be rapidly surpassed. The stability of the individual results obtained by the static simulation, as well as the rather strong correlation with the level of the professional experience are factors in favour of this method. From a practical viewpoint, the results of the study can be exploited in several ways. The most immediate application concerns the field of training. It would consist of utilizing the organigram as working aid (Wulff and Bery, 1962), the students would be trained systematically to resolve the prob!ems by reference to the steps indicated in the organigram. Furthermore, the static simulation itself could be used at the beginning of the training. In addition, the economical procedures could be taught when training is conducted, rather than having to be discovered - and they aren't always - by experience. The process indicated here may be compared to certain methods proposed by Rimoldi (1963) in the course of studies concerning the analysis of complex mental functions. As regards the organisation of work and the utilisation of resources provided by modern means of data processing and display, the study permits to clearly put the problem of information coding and to indicate some conditions of its investigation. Certain operations of the controller are being illustrated by a model or a system of representation, some essential characteristics of which have been generally described; it will also be important that the way of coding the information provided corresponds with the system of representation. In particular any integration of existing principles with a view to facilitate the task of the controllers must be compatible with the type of model of representation used by the latter. If one considers that the model depends to a large extent on the nature of information treatment, one can therefore conclude that all research on the method of information presentation is inseparable from an investigation of the methods of treatment of that data by the operators. One can also imagine that a global method of comparison between the systems of presentation would be quite insufficient. One has seen that the variables applied in the organigrammes are relative ones, which are themselves the result of a previous treatment of elementary variables (for instance speaking of the same level or a different level implies that an operation of comparison has already been made). At each "knot" of the organigram could hence figure a sub-programme, corresponding to the operations

required for the determination of the values of the variable. One could, therefore, establi sh the hypothesis that one way of assis ting the operator, without taking away from him the advantage of being abl e to master the s ituation through the know ledge of the different variables, would consist o f fu rnish ing him directly the data correspoinding to the in fo rmation at these "knots ".

Bibliography Brune r, J .-5. - Goodnow, J .-J. ing . New York, J . Wiley.

Austin, G.-A. (1 962): A study of thfok-

Grize, J .-B. - Motolon, B. (1962): Introduction a une elude experimentole et formelle du roisonnement noturel. In lmplicotion, formolisotion e t logique noture lle. Poris P.U.F., pp. 9-68. Newell, A. - Simon, H.-A. (1963) : Computers in Psychology in Hondbook of Mothemoticol Psychology, New York, J . Wiley. Pioget, J . (1947): Lo Psychologie de !' Intell igence. Paris, A. Colin.

Summarizing, th e analysis, rende ring more explicitly the mechan isms brought into action by the controller, permits to bette r und e rstand the functions he pe rforms in the system. It co n al so he lp to improve the actua l working condition s in order to render the exercise of the functions more easily and more efficiently, and also to prepare modifications to the present system and to pre dict its val ue.

Rimoldi , H.-J.-A. (1963): Processus de d ecision e t fonclions men tales complexes. Rev. Psychol. oppliquee, 13, 65-82.

Clifford P. Burton appointed ATCA Executive Director

The French Civil Aviation Academy to move to Toulouse

Rosens tieh l, P. Pa ris, Dunod.

Ghouilo -Houri, A. (1960): Les Choix economiques.

Wu lff, J.-J. - Berry, P.-C. (1962): Aids to Job Performance. In Psycho路 logical Principles in system d evelopment. New York, Holt Rinehart o nd Winston, pp. 273-299. X.. ... (1964): Automotisotion du Contrale de lo circulation oerienne. Choix d'un nouveau colculote ur pour le C.C.R. Nord -Centre d 'experi路 menlolion de lo navigation oerienne. Rapport interne.

The French Ecole Notionole d e !'Aviation Civile (E.N.A.C.) w ill move from Paris Orly airport to Toulouse where a vast a e rospace complex is und e r construction . An exh ib itio n of mock-ups of the new E.N.A.C. facilities was rece ntly presented at Orly. The opening cere mony took place o n Ja nuary 24th, in the presence of Mr. Lonso lot Bosou, Directeur de lo Naviga tio n Aerienne, and high ranking civi l aviation personalities. Th e transfer of th e Ecole Nat ion ole de l'Av iotion Civil e from Orly to Toulouse is port of a decentral ization p rog ramme introduced by the French Government. Vi ce President Maurice Cerf represented IFATCA at th e opening ce remony. M.

IFATCA Annual Conference, Rome

The U.S. Air Troffic Control Association has appoi nte d Clifford P. Burton as Executive Director recently, whe n he retired from FAA where he he ld the position of Deputy Director, Air Traffic Services. This is Mr. Burtons seco nd tour as Exec ut ive Directo r of the ATCA, havi ng he ld the position from April 1956 until September 1958, during the formative stages of the Assoc iation. 22

Th e Fifth Annual Confere nce of IFATCA wi ll be held from 18th to 2l s~ Apr il 1966 in the Palazzo dei Congressi, E.U. R., Rome. It is organized by the Associozione Nozionole Assistentic Controllori dello Civi l Novigozione Aerea Ita lia, under th e chairmans hip of Mr. Corio Tuzzi. Fu rther information may be obtaine d by th e Confere nce Secretary, Dr. Enzo Buongiorno, via G. B. Ma rtini 6, Rome, Italy, or by th e IFATCA Executive Secretary, Mr. G . W . Monk.

SATCO

AUTOMATIC AIR TRAFFIC CONTROL SYSTEM

-,"'"' fligh t progr ess ch eck

conflict r e so lution

coo rdin at io n

conflict search

radar, weapon control, data handling, air traffic control systems N .V. HOLLANDS£ SIGNAALAPPARATEN HENGELO THE NETHERLANDS

The Third International Aviation

Scope The scene was Atlantic City's huge and ancient Haddon Holl Hotel, and the dote was November 1- 3, 1965. Sponsored by the Federal Aviation Agency, the Third International Aviation Research and Development Symposium attracted 125 people from 27 foreign countries, plus a floating audience of about 375 Americans. The theme of the meeting, "Automation in Air Traffic Control " led into what was virtually a world-wide progress re;ort on ATC automation philosophies, plans, and programs. An impressive array of speakers described the automation programs of Eurocontrol, France, Germany, Japan, the Net herlands, the United Kingdom, and the United States. During the afternoons, visitors tou red the various laboratories of the nearby Notional Aviation Facilities Experimental Center to see for themse lves how NAS, the US program, is shaping up.

System Comparisons To keep score on the similarities and differences between the various system approaches which were described du~ing the symposium, we mode a rough summary of the salient features of each system. This data appears in Tobie l . All of these systems apply to air route traffic control. In mos t coses, the automation of terminal area control functions will hove to come later. In ~II systems which will use digitized target tracking, SSR wrll be the preferred data source; however primary radar :-"'ill be r~toined as a supplementary sourc:, to track unequipped aircraft and to provide continuous target tracking durin g SSR fodeouts. B. W. Oakley of the Roya l Rodar Estoblishn:ient (RRE) stated that 5% of the transponder returns 1n the UK ore lost, mainly because of antenna shadowing during turns.

Jon Smit, Hollondse Signoolopporoten; Dr. jur. Kori E. Ka r. wo rth , Deutsche Lufthansa AG; Hons Giesecke, FAA NAFEC (I . tor.)

R & D Symposium by Tirey K. Vickers

Why Automation?

Seated one Day at the Organ

Seve ral s peakers reported that a primary goal of the ir automation efforts was to be able ultima tely to reduce the number of ARTC sectors. There ore a lready 452 sectors in th e US. System costs for display equipment and fo r controlle r and maintenance manpower ore roughly proportional to th e number of sectors. Thi s provi des a strong economic incentive to reduce the numbe r of sectors a s much as possible. Such a reduction should help to reduce the inter-sector coordination workload.

Most speakers agreed that the primary problem in ATC automation today is the man/ machine interface or input/ output prob lem, which includes all the difficulties that are generated by g iving the controller a vast array o f pushbuttons and keyboards instead of a pencil. J. Vil lie rs of Fron ce calls this factor the "induced workl oad", and points out that if automation is to pay off, the task benefits must greatly exceed the task loads induced by automation itself. Mr. Vill iers hos found in his wo rk with CAUTRA, th e French ATC automation program, that there ore relative ly few tasks which the computer con tackle fo r the system, without depending to some de gree on a deci sion or act ion by a human co ntroller. Th is, he said, is the reason why ATC automation has not yet given such spectacular results a s automation in other fieldsâ&#x20AC;˘).

Hopeful ly, automation may permit sectors lo be enlarged ge ographically, by reducing the amount of controller workload pe r aircraft, particularly in the functions of data a cquisi tion, processi ng , distr ibut ion, d isplay, and coordination. Loter, automation is expected to e xtend into th e functions o f conflict prediction and resolution.

Harvey Schwarz, Decca Navigato r Company, Ltd. ; Tirey K. Vikkers, the author of this article; B. D. Po rker, Decca N ovigolor Com pony, Ltd. ; Joe Bartling , Air Line Pilo ts Associat ion. (I. tor.)

See poge 27.

On the other hand, none of the speakers wanted to replace the human controller by a core memory. Both Mattew Rosenshine of Cornell University (US) and Stanley Seltzer of the Air Transport Association (US) pointed out the fallacy of designing an all-automatic super-system with a human monitor - and then expecting the human to be able to take over the situation when the equipment fails. Jan Smit of HSA (Netherlands) stated, as a result of his long experience with the SATCO system, that automation requires not only the adaptation of equipment to ATC, but the adaptation of the human controller to automation.

of the "touch display" concept invented by Eric Johnson of the RRE. This concept may represent a very important breakthrough in solving the man/machine input/output problem previously described. Functionally, the touch display works a little like the FAA's category/function selector (as used in the ARTS and SPAN systems) except that the number of functions or data elements which can be selected successively from a touch display is virtually unlimited. You make the selections simply by pointing to what you want. The display is a CRT with a plastic overlay. Embedded in this overlay is a coarsely-spaced grid of very thin wires, aligned vertically and horizontally. Each crossover point is the junction of an individual balanced bridge circuit which becomes temporarily unbalanced whenever the controller touches his finger to that point on the overlay. The x-y coordinates of this junction point ore then sensed by the computer. In operation, a ~et of selectable data elements is presented on the CRT, m alphanumeric form. Each element on the CRT is positioned to line up with a different junction point on the wire grid. When you put your finger on the element you want, the computer instantly displays the secon~ set of selectable items on the CRT. When you point to the item you want .here, the third set magically appears; and so on. Mea~while, all the elements which you have selected appear in .a row, for verification. When you see that your message 1s complete and correct, you touch an "action" element and the message is squirted electronically into the computer. Very fast and flexible, the touch display should offer excellent possibilities in combination with other tabul or pictorial ATC displays. As the amount of data which a~ controller can comprehend simultaneously is limited the system might be designed around the idea of givin~ the controller access to any data he wants, but sequentially

Displays

It is apparent from Table 1, that there is a definite trend away from flight progress strips, and toward the display of tabular flight data on cathode ray tube (CRT) indicators. Once the basic flight data is digitized, it can be manipulated by the computer in many wondrous ways. For example, the UK Ministry of Aviation has come up with a height-versus-time indicator called a planning probe display. This somewhat abstract presentation indicates the predicted relationships, in terms of fore-and-aft time separation, between the selected aircraft and any other route traffic at the same, and adjacent, altitudes within the sector. The selected aircraft is symbolized at the center of the display. Potentially conflicting targets at all three altitude levels are identified. Their position symbols appear at the appropriate levels, referenced to a fore-and-aft time scale which extends across the top of the display. In our opinion, the most significant news to come out of the entire symposium was the offhand announcement

System Summary

Table 1

ATC System Functions E"co'掳"tcol

Digitized Target Tracking Primary & Secondary Radar Computer processing of Flight Plans, Data Distribution, Keyboard updating,

France

Ge<ma"y

Japan

United Kingdom

Netheda"d'I Domestic

I Oceanic

x x

USA

x x

Coordination

Strip printing

CRT Display: Tagged Targets

Tabular Data

x x

x x x

Conflict Prediction Conflict Resolution

--路

Legend: X

.=c

yes,

mechanical boards,

1 = first stage,

2 = later stage

x 2

(one "page" at a time). The controller could use specific aircraft identifications, altitudes, fixes, or times, as indices, to select what he wants when he wants it. Conceivably, this sequential display concept could greatly reduce the space requirements for ARTCC facilities.

After Automation, What? Perhaps the next step after complete automation will be a radical new concept which we call Anthropomation. It is defined as the process of giving back to the human, the jobs which automation should never have taken over in the first place. Seriously, though, after three days on the automation frontier at Atlantic City, we began to wonder how far automation will actually go in solving tomorrow's ATC problems. It seems to us that automating today's ATC system is a little bit like automating a single-track railroad. Surely it will increase system capacity, but the resulting increase in traffic demand may simply push us faster toward the ultimate barrier - the lack of multiple traffic lanes and runways to permit independent streams of traffic flow for large numbers of aircraft, simultaneously. Twice during the symposium, J. D. Smith of United Air Lines tried to start a discussion along these lines, by point-

ing out that a recent UAL computer study indicates that several US airports will have to handle 180 to 230 operations per hour, by 1975. J. D. did not get very far, as the panel members deemed that this was a local (US) problem, and not a subject for international discussion. Such traffic rates will obviously demand much more than automated data processing and displays. It is fairly certain that they will require area-coverage navigation, to provide closely-spaced free-flowing traffic lanes feeding multiple approach paths to multiple parallel runways. We might also hope that a good percentage of these operations will be made by STOL or VTOL aircraft. One or two of the far-out thinkers at the symposium timidly mentioned the subject of CAS (Collision Avoidance Systems), which might permit pilots to take over a portion of the staggering separation workload of future systems. In this concept, the flow patterns would be organized by ATC, and pilots would use their CAS to maintain separation from the aircraft ahead. With multiple traffic lanes, aircraft could be segregated by speed category; a whole chain of same-speed aircraft using CAS could flow through the system with little more controller workload than a single aircraft, today. We feel that it isn't too early for people to be thinking about, and developing, these concepts.

The Law and the Controller The air traffic controller in any country needs no convincing that he carries enormous responsibility for the safety of human life. What he is never quite so sure about, is the extent of his legal liability, should he fall victim to a human failing and make a mistake, or just forget something, and subsequently an accident actually happens. It is an area where there are no precedents, and little material to research from. It is an area which is further complicated by the fact that control boundaries cannot be drawn through control problems and, as a result, in ma.ny pa:ts of the world control boundaries do not coincide with national boundaries. Because of the existence of such legally inconvenient facts, which are dictated solely b.y the practical nature of operational application in this fluid, air traffic control environment of ours, there definitely seems to be a need to establish a basis for every controller's responsibility and liability, and also to define the conditions governing the jurisdiction wherin he can be held to account. The logical instrument for such a definition in our so very international profession is, of course, an ICAO recommendation, and work to this end is already in hand. This article does not attempt to anticipate any such work, but merely to ask, from the controller's point of view, some of the questions which must be answered. I think it needs to be made clear, initially, that the prime result of any such ICAO recommenda'.ion~, even whilst still in draft form, would be an exam1nat1on, by each member country, of its position with respect to the recommendations. For many countries this would prob-

by John G. Wilson

ably be the first time that a policy in this area had been put into words. Whether the final action resulted in concurrence in principle, or in a notification of differences, the net effect would be that all controllers would know where they stood, and the ground rules for international cases would have been established. The present circumstances are, in many instances, unsatisfactory because of their uncertainty, and unresolved because there have been, luckily, no test cases, except in a totally domestic environment. Consequently, as things stand at the moment, a very hazy area exists, which a major test case in international circumstances would only further confuse, since it would have to make its rules as it went along, and would obviously represent, in the final analysis, only the agreed policy and procedures of the two countries concerned. Such agreement, such "case law", might very well not prove acceptable in the courts of two other countries, having perhaps different prece路 dents, or statutory provisions, in the fundamental concept of legal responsibilities and liabilities. There are several circumstances which must be carefully considered by any body framing general recommendations. Firstly, we must consider the controller's general liability, whether in domestic or international conditions. In the civil area there seem to be three instances; the jurisdiction where the employer is completely liable for the employee's "torts and malfeasances", which frees the

employee from the prospect of civil suit; the jurisdiction where this applies, but the employee has subsequently made a personal decision, and thus opens himself to civil liability - this seems to be negated by the fact that the controller is always specifically authorized, by regulation, to exercise judgement and make decisions, thus returning to the employer the liability for the results; and the jurisdiction where the defence of "just carrying out my duties" is not acceptable, and the human employee has a civil liability along with the employer. Of these three, it seems entirely reasonable for the controller to expect statutory freedom from such civil liability, if he is required, by regulation, to exercise judgement and make decisions in the normal course of his work. This would not prevent an employer from taking administrative disciplinary action, where a case had found the employer liable for a controller's bad decision. Secondly, we must consider the criminal implifications of gross irresponsibility or negligence. Once again we have a cho;ce of circumstances, the jurisdiction which has a statutory provision of criminal irresponsibility or negligence; and the jurisdiction which has not. For many controllers in many countries, to attach a criminal label to negligence or irresponsibility, however gross, would be to create a sword of Damocles, and on these grounds it would seem desirable to free the controller from this type of criminal liability. It is, however, an area whose wording in recommendation would have to be most carefully and thoughfully considered; and, even then, it would be one where a number of differences, representing national criminal codes, would undoubtedly be filed. Nevertheless a statement of desirable intent, in the form of a recommendation in this area, should be made. Having considered the general circumstances, we now have to look at the international scene, which is by no means so clear cut. In every connotation here, two questions have to be answered - the regulations applicable to, and governing, the controller's decision; and the jurisdiction to which the controller may be held accountable. We have several types of circumstance which may occur; in the first place there is that of the internationally created agency - typically Eurocontrol - where the situation may well arise of a controller of one nationality, sitting in a second country, and controlling traffic over a third country. Jn this case there is no argument over the applicable regulations, and the only question is that of the responsible jurisdiction. In the second place, we have the situation of bilateral agreements, which result in control boundaries not coincident with national boundaries usually in the interests of commonsense, practical, control efficiency - and lead to aircraft over the sovereign skies of one country being controlled by controllers of the second country sitting in that second country, with the further possibility that the regulations and standards of each country may differ in some important respect. On top of this additional complications may be introduced by a controller of one country releasing control of a specific flight, in the interests of expediency, at a point other than even the agreed control boundary. A typical example of a complex inter'.11ixture of this nature is shown by the southwestern portion of Toronto Centre's area. Canada, in this part of the world, juts into the USA, and the result is that two of Toronto's sectors lie in between two of Cleveland's sectors for the purposes of the NW/SE traffic flow. The agreed control boundary

is not, and cannot possibly be, the national boundary and results in Cleveland having exclusive control over a large part of the Canadian skies; in fact, further to the southwest, there are some Canadian airways completely within American airspace. To aggravate the situation, traffic is often climbing from, or descending to airfields located close to the boundary, which results in the necessity of releasing control of specific traffic prior to the boundary. To add fuel to the fire, Canadian and American regulations and standards are by no means compatible; vertical separation between FL250 and FL290 is not the same; radar separation applicable to an aircraft in the same geographical position, may be different depending on who is controlling it from where; American regulations permit VFR on top, Canadian regulations do not; Canada requires controlled VFR on airways above 9500 ft, the U.S. does not; these are the major differences, and they are quite enough! In practice, the operation proceeds in a most smooth and cooperative fashion, but to try and resolve an incident or accident occuring within such a mixture is guaranteed to give any court a headache. When these insta~ces are examined thoughtfully, it seems clear that a simple and fundamental recommendation should be a requirement that the applicable regulations and standards should be written into any international agreement, whether bilateral or multilateral in the same way as the "law" of a contact is written tnto international commercial agreements. However, the specific instance of a controller releasing control of a particular flight at a.point.other than the agreed transfer point, is another consideration. In these circumstances, is the receiving controller fully responsible for the flight and able to apply the standards of his own jurisdiction, or is he only the agent of the releasing controller until the formal control boundary in crossed? It seems reasonable to accept the releasing controller's authority to modify the control boundary in occasional circumstances - he is, in any case, the agent of his employer, and this would be just one more application of his authoritiy to use judgement and discretion. In this case, the receiving controller would be fully responsible for the flight and able to apply the standards of his ju~isdiction at the transfer point or time. The recommendations, then, in the specific circumstances of specially c~ordinated transfers of control, should be that . the applicable regulations become th ose of t_he receiving agency at the transfer of control point or time. Which leaves only the question of the jurisdiction to which the controller should be answerable · It is , h owever, . a logical continuan~e of what I have already written to come to the conclusion that, if these thoughts are accepted, the controller needs only to be responsible in the courts of the country which licenses h 1 'm . The c ase o f ·in t er-

natio~ally create~ agencies is somewhat different, and here 1t seems sensible that the jurisdiction should be written into the basic administrative and regulatory provisions of the agency, with each controller accepting these as a contractural condition of employment. As . can be · f actory, . seen '. the prese n t s1·t ua t.ion ·1s unsatis especially in the international field. So far there have been no_ ma~or _incidents or accidents having air traffic cont~ol . 1m_pl1cat1on~, but with the generally increasing traffic, 1t 1s beco_m1ng more of a statistical probability every day. In the interests of justice, the controller's liability and jurisdiction need to be defined.

The Approach to Automating ATC in France

by J. Villiers Chef du Centre d'Experimentation de la Navigation Aerienne

The fol_lowing study has been presented by M. J. Villiers at the Third _International Aviation Research and Development Symposium, Atlantic City, November 1965. It is reprinted with kind permission of the author and the Federal Aviation Agency.

The first international conference on the automation of ATC dates back to 1961, when the EUMED Meeting of the ICAO was held in Paris; the fact that this Meeting gave birth, some time later, to the ICAO Air Traffic Control Automation Panel (ATCAP) was not the least of its merits. At this early stage, the many ideas which were put forth were ample proof that people in charge felt that modern methods of data processing might well be applied to solve the difficulties that ATC had to face because of a continuous exhaustion of air traffic. ' Five years later, when those early ideas had been tested by hard facts, it was found that they had gained considerable ground. . Of course, a~tom~tion is being applied, and will continue to be applied, in many centres but one must admit that it has not yet radically modifi:d the structures and proc~sses of ATC. Nor is there evidence, supported by practical, actual size experiments, that automation will, tod.ay any more than in 1959, inaugurate a foreseeable, fru1tf~I, deep transformation of the ATC system. This could only be met with pessimism or scepticism if one underestimated the great complexity of operational, ~uman and technical problems involved by the introduction of automation in this ATC field. If operational applications are not very spectacular as yet, research work in this field has contributed a more subtle knowledge of ATC as a data processing system and a better estimate of the difficulties involved in the relationship of man and machine in this delicate field. At the same time, original equipments were developed and manufactured (digitizers and radar decoders; tabular displays etc.) while computers made progress which could not have been dreamt of only a few years ago. It has now become possible to conceive systems which, even though they have not yet been put to the test, are meant to undergo live operation and meet its final judgment. A lot has already been done in many countries, and France hopes having contributed at least a little in these achievements. As research and experiments continued to be carried on in France, automation was beginning to be put to practical use, as soon as 1962, at the main French ATCC (that of Orly), when the calculation and printing of strips came into operation. This very first step of the automating process is well known to all: to describe it once more together with its results would contribute little to the Symposium. As far as the more advanced steps of automation are concerned, today we only have at our disposal stud~es, analysis and preparatory experiments, as well as a design whose progressive installation and operation bring its daily share of problems which, when they are solved, will be of strictly historical interest.

Thus, for lack of working resu Its based on an effective exploitation of leading techniques in ATC automation, we'll have to be content with a description of the basic steps which enabled us to conceive a system which 1s meant both for research work and operational use.

Air Traffic Control System: A Real Time Data Processing System Basically, the Air Traffic Control System is a re a I time data processing system. Analyzing this system as such is convenient and constructive both for the manual system and for the system under process of automating. Compared to other information handling systems, this systems shows a number of marked characterisitics of its own. The very first original constraint is that time in the system may be termed an absolute time, that is, there is practically no degree of freedom in the acquisition and processing speed of the information involved: the system must keep up with the traffic, which is, of course, what circumstances make it. Time allowance for fresh information that will crop up in a quasi-random way is extremely restricted, which means that it will be hardly possible to soften this constraint by use of waiting queues. The Air Traffic Control System is an original example of a working party the members of which cooperate in real time on a number of e s sent i a 11 y i n t e I I e c tu a I ta s k s . Each particular problem to be solved is comparatively simple, but it must be handled within a very short time indeed, which means short spells of extremely intense brain work. Now, this brain work is of a highly diversified kind, and it is only the astonishing capacity of adjustment to new circumstances shown by the individual with the proper training that makes it possible. In spite of some very fine achievements, often at the cost of unfortunate stress and nervous strain, there comes a time when a breaking-point is reached and when it becomes necessary, as traffic increases, to intensify more and more the division of labour. This division of labour can be brought about either through a reduction of each particular elementary control volume (sectorisation), or by sharing out within each sector the different tasks involved on the basis of their respective characteristics (procedural control, radar control, coordination etc.). We all very well know that the benefit of this crumbling of tasks is quite out of proportion to the extent of the sharing itself; as a matter of fact, the resolution of every particular problem requires consideration of data which is not directly accessible any longer. The rapid increase of tasks caused by this scattering of the information cuts down the effective contribution of the individual to the data handling collective task while initiating a chain reaction of increasingly divided work.

It follows that, when a given density of traffic is reached 1 t h e a m o u n t o f t i m e d e v o t e d to d a ta pro c e s s in g is too s ma 11, and all the available data cannot be made good use of any more. In many cases, an apparent saturation of air space is but a byeffect of the abovementioned phenomenon. Thus, automation is, potentially at least, the means. of getting out of this deadlock. After all, the data processing capacity of modern computers is practically boundless, and such computers should therefore ~~ able to ma~e ~p for the limited data processing capabrlrty of the brains in an inadequately coordinated team of controllers. However, the problem is not any simpler than attempting to speed up a walker's pace on rough and broken ground by means of a racing car. Of course, both the walker and the machine enjoy th~ir own specific advantages, but those can hardly be associated at all times. The racing car could undoubtedly be put to good use on smooth ground, but .carrying it on ro~gh ground might prove a bit tricky at :rmes, an~ on.e mrght find oneself eventually obliged to dispense wrth rt. Air Traffic Control has much in common with that rough ground on which it is difficult t~ entrus!, in real time that is, both man and the machine wrth multiple and overlap~ . t k As long as man is still a part of the whole busrh b ·d rng as s. ness, the automated ATC system wil I only ~e a rr sys t em ·rn w h·ch 1 man , at his brightest and his maximum of competence, will be expected to share with a c~mputer · ·rn r eal time - the job of data collection and - again,

processing. . Thus, compared to other real. time d~t~ handlrn~ sys t ems, su eh a Co nfiguration is decidedly orrgrnal, and brt is attended with a number of extremely complex pro Iems. . This is precisely why automation has not yet given, as far as ATC is concerned, such spectacular results as were obtained in other fields. Analysis shows that there is no clear-cut bound~ry between that share of the data handling process which onef can b e use f u II Y handled by the computer ·and the t which can only be entrusted to man at a given sage o automation. . · h · It .1s ex t reme Iy d'rff.rcult , then , to opt1m1ze. t e ass1gn. the machine of their respective ment to b ot h man an d . f b th · b es t achievements o o · . parts .rn vrew o f securing It' has often been thought that computers were to relieve the controllers from their "clerical tasks''. so th~t they could devote their whole time to controlling tas s proper. . . . f . reality is This is carrying simplrficatron a brt too or· much more complex than that. . . The ATC tasks cannot be easily drvrded into so-called marginal and basic tasks. h 'fi ·t On the contrary, a thorough analysis of t e s~b~cl.'t rcr ~ . .. of the various act1v1t1es w h're h 0 re the responsr r 1 Y o t the controllers .rs nee d e d ·rn or d er to find out, what h . par the new data processing and data display tee nrl~ues . Onet rea might play in relation to every one of them ·bi k rzes, I ven no e as s can then, that some highly comp ex or ·~bs both straightforbe rapidly automated, whrle other I ' d d ward and commonplace but particularly well ad apte tof . . . stay manua I at an advance stage o man .s action, mrghr

automation. tl)en tha t the ma in problem would be to try It seem S , , . h 'th th and reduce the over a I I task whrc rests wr e

controllers as a body, in order to start reversing the process of an increasingly divided work among a growing number of controllers and assistants; it may be hoped that this will help make the most of all information existing in the system and to defer the time when saturation point for the system is reached.

Minimization of the overall manual Task The investigation of automation and a thorough, careful analysis of each one of the basic tasks which lie on the controllers are obviously joint issues. It follows that the various problems which arise at each particular stage fall within the field of the human sciences. This philosophy is at the root of all the research work which is being carried out in France in this field, and I must say that controllers, technicians and experts in labour psychotechnics have been working together in a spirit of frank, complete and fruitful cooperation. Since what we had in view was to cut down as much as possible the overall tasks which is still incumbent on human work, we endeavoured to trace and analyse all the tasks that could possibly be handled by the computer. We very soon found out that there are very few tasks that the computer can tackle for the system without the controllers giving some degree of help or without their taking some sort of action. The first rather obvious difficulty one comes up against is that the computer cannot create the basic information and that there are some sources of information which it cannot access without some kind of human intervention (reporting of aircraft positions on VHF, issued clearances etc ... ). Though less obvious, there is another stumbling-block which is just as big with consequences. If the controllers are still retained in the system and if we cannot go on right now to a complete automation, it can only mean that, for the time being at least, we cannot make without the versatility of mind of the controller in situations which would require a very complex computer program, provided such a program could be worked out at all, which would not be the case in many instances. Now, if a controller can adapt himself rather quickly to new and changing situations, it is no easy task to have him assisted by a computer which is by no means equally versatile. Moreover, a controller is always free to decide how and when he will tackle each particular problem, so that it would be a contradiction in terms to expect that the computer would always present the controller, without his asking for it, all the appropriate information he needs at any given time, and this information only. Now, overburdening the controller under a mass of uncontrolled information would not be much help either, and what is more, it obviously would not pay. As a result, if automation might considerably reduce the overall task of the controllers, it is plain that it will eventually result in a number of new additional tasks which are unheard of in a manual syst:m: these tasks we shall call "induced tasks". The actual benefit gained through automation can be

figured out by subtracting the induced tasks from the task benefit: g 1 = task benefit - (minus) induced tasks The case of the production of strips is of special interest since this operation might well be carried out without apparition of any induced tasks at all. Because of this favorable characteristic, stripping was systematically selected as phase one of most automation schemes and it went into service without causing major difficulties. On the other hand, those limited experiments which were carried out in order to combine automation and control processes more intimately, have shown that one can never be quite sure that the gs balance will be positive. Searching investigation of the tasks involved shows that automation cannot be put to practical use at a profit unless induced tasks are kept to a strict minimum, and unless the controller is effectively assisted by the computer in the execution of the said tasks. Successful operation of the system will result from a positive difference between the tasks saved by automation and the residual induced tasks: g 2 = task benfit - residual induced task Thus, step by step, one is led to a far more advanced stage of automation than was first thought necessary. The importance attached to such concerns is one of the most striking characteristics of the work which is carried out in France in this field. For each function, it has been attempted to minimize the overall task and to allow for a minimum of induced tasks. A key that is not to be pressed by a controller any more, a designation operation (rolling-ball or light gun) which can be dispensed with, a piece of information which is displayed as conveniently as possible with regard to the intellectual work of the controllers, those are so many limited victories which, taken as a whole, might help bring nearer the final success of automation. As we can neither go into the details of the resear~h work which has been done in this field, nor make a list of the analyses and experiments which are still to be undertaken, we shall have to be content with a general survey of the main options which have been chosen in France in order to enter that narrow gate which might open up, some day, on full scale automation. For the sake of clarity, ATC tasks have been classified under three headings: - data acquisition - data integration and data spreading - traffic display and analysis.

Data Acquisition The raw information which is needed for spotting present and future positions of aircraft proceeds from several primary sources, every one of which gives only a p~r足 tion of the necessary data. The medium involved varies with each source: telegraphic signals for flight pl?ns or weather forecast; spoken messages for telephonic and radiotelephonic calls; written messages; video-fre~uency signals for the radar supplemented by digital coding for the secondary radar.' In some centres which I could name, people are by no means shy of using ballistics a me?ns of conveying written information on a material medium (throwing of strips from one control position to another).

The task of decoding and shaping up this information for controlling purposes depends on the specific requirements attached to each particular source of information. Generally speaking, one might say that, in any given centre, practically every vis i b I e (or "audible") task is related to some extent to the acquisition, decoding or distribution of the information involved. No wonder, then, if those tasks are enough to limit the extension of control centres. It is both logical and desirable to attempt to feed the ba!;ic information into the computer in order to have it then processed for the benefit of the controllers. Modern techniques allow for that kind of thing, especially when dealing with information about Flight Plans, the Secondary Radar and the Primary Radar. Flight Plan Processing The Flight Plan left by the pilot or the Company previous to take-off contains all elements pertaining to this particular flight and enables to trace the flight in advance, from a time origin i.e. the scheduled time for departure. Basic information contained in the flight plan is very rarely subject to subsequent modification, except for the time of departure itself. Automatically generated strips on reception of messages from the Aeronautical Fixed Service Network (AFTN) stand as a first, comparatively simple step toward automation. In the present state of international standards, such an operation still requires a human link, since the code used for Fixed Service messages is not yet frt for direct input into the computer (1 ). However, personnel in charge of transcoding those messages act as a passive, independent, intermediate link and they have no share whatsoever in the selfsaturation which we mentioned. Now, on a more general plane, we may say that the Flight Plan which is filed by the pilot at the airport makes it possible to embark on a comprehensive calculation of flights, with emphasis on the calculation of flight times between fixes. Such calculations ore comparatively accurate since forecast meteorological winds are taken into account. Among the various data which will make it possible to update the flight, take-off time or time of entry into the controlled zone play a particular part; knowledge of those times enables one to "initiate" the flights and to deduce easily the absolute passage times over successive fixes. This information is obtained at the time being from the airport or the previous centres by telephone. For sophisticated stages of automation, it is essential that this information should be fed into the computers. Subsequent information obtained through a succession of position reports given by the pilot from air to ground, are somewhat different in essence. Practically, such information is only essential to the control operation insofar as the forecast based on the Flight Plan that was initialised, and then completed with additional information from other sources, cannot permanently and adequately define the positions of the planes. It will not a:ways be possible to do without these reports, but it does not follow that the information involved will systematically be subject to automatic processing. There lies one of the trickiest problems of automation, (1) The new flight plan form which has been studied and proposed by ATCAP is on the point of being accepted

VHF air-to-ground voice communicatio~ being .an adequate means for man to use, since there 1s no ma1or p~obÂ lem for him to decipher, make use of, and feed into storage (2) this particular information. o~ the other h~nd, this source of information is not fit for direct automation. Therefore feeding such data into the computer would mean a p~rticularly severe automation ind.uced task. There follows that one can only think of making use of such information in the computer, insofar as it has been first ascertained that the benefit derived for the controllers from the processing of this data by mea.ns of the com~uÂ ter, will far outweigh the sum total of induced tasks involved. We are dealing here with a key problem. As f~r us, this type of information is the only one that w~ w~n t systematically attempt to enter into the computer, in view of its inherent manual link. On the other hand, we shall see, in dealing with some specific operations (_such as transfers) that the controllers will have to fee? into the computer certain information related to the flights, and that the updating of flight plans will be a valuable by-product of those transfer operations. The controller will take a part in the data input in proportion to the rapidity with which other sources ~f information will have been subject to both an effective and efficient automation. Such sources of information are rich with promising prospects of direct automation, that is, without the controller taking any part. Secondary Radar Automatic Processing

The feeding (and processing) into a computer of the Secondary Radar data appears as a process which though very complex, difficult, and expensive is highly susceptible of success. This source of information can be used as input for the computer without the controllers having. a hand in it, which makes it at the present time of exceptional value. It will therefore be soon automatised (3). Most attractive improvements will follow, as planes are gradually being equipped. Primary Radar Automatic Processing

The case of the primary radar is mor.e co~plex. As ~ matter of fact, though information contained in each Primary Radar recurrence is indeed, in itsel_f, unfit for any direct use the same information, when displayed on the after-gloV:ing layers of the cathode screens, is extremely well suited for immediate interpretation. As a matter of fact, after-glow will ensure, with astounding simplicity: - grouping of Radar echoes into "plots" (a.II the echoes from a particular target, as obtained during recurrences during one and the same passage of the beam) grouping of the "plots" thus obtained into tracks (gr~up of plots concerning one and the same t?rget ~unng successive antenna rotations), together with a display of the speed vector. Conversely, the same results can be obtained ~y means of computers only at the cost of great complexity, espe. II Âˇ the presence of adverse noise (thermodynamic c1a y 1n " ,, ) noise, residual ground and cloud clutter, ange 1s .... {2)

Through

(3)

In 1966, at the Orly A TCC.

manual modifrcotion of the strip.

That it is why it is desirable to integrate, and then to spread this elementary information so that the data needed by every one concerned to carry on his particular task might be made available to him at the most favourable time, while unnecessary information that would only distract his attention is excluded. Tasks which are related to the spreading of information within a centre are often improperly termed "coordination tasks". Within a manual system, this kind of operation calls for a great variety of tasks which are the heavier as there is more division of labour (on a functional and sector basis). It stands to reason that each controller must be in a position to resort, if needs be, to other sources of information than those he can directly access. The various parts which make up what we might well call a jigsaw ~u~zle a~e scattered among the different work posts, and 1t 1s ?es1~able that some of them, or rather, significant combinations of several of them, should be simultaneously displayed at various places. Provided that primary information has been recorded into its data storages, a computer is particularly well fitted for automatic display to each controller of such integrated information as he may need at any given time.

Traffic Display and Analysis We have shown how the elementary data needed for knowledge of present and future positions of each pa rt i c u I a r f I i g h t, could be acquired, integrated and spread among all concerned. To pass on to the controlling operation proper, it remains for each controller to analyse a g r o u p .of trajectories in order to investigate their mutual interference, so that flight clearances might be issued accordingly. . Because of this s~aring of the various tasks (on a functr~nal or sector ba~1s), ~raffic analysis is by no means limited to the one s1tuat1on which is the responsibility of one given controller. The controller must make sure thanks to a close coo r di nation, that his decisions will meet the requi.rements of other controllers who might be conc~rned, s1multaneo~sly or at some later time, by the same flight. The complexity and the density of the data needed for a thorough knowledge of the traffic (four dimensions numerous planes, various trajectories etc.) make it impos~ sible for a controller to keep permanently in mind a dynamic picture of that part of the whole traffic which is his responsi~ility,. not to mention the traffic which might interfere with his own, at once or in the near future. Such a mental picture could not be comprehended in a human mind, and there is, of course, no other practical means of making .up for this inadequate perception. . The pr.oper attitude, then, is to resort to partial images with varying degrees of sharpness and limited number of parameters. For ease of analysis, we shall compare this problem to the case of an observer whose field of vision would be far outranged by the scenery he is watching. In order to keep an eye on the whole scenery, this observer can c~ll in .the aid o.f his "para-visual" field which will provide him w1~h a sa!1sfactory, .though blurred, image, in case something of interest arises outside his normal field of vision. Now, on the oth~r ha~d, he might sweep the whole range of the scenery using his average axis of vision thus picturing to himself more sharply, though at the c~st of

greater efforts, the landscape in its entirety. Lastly, supposing that something of outstanding interest should happen to be sighted, the eye will focus on it so as to transmit to the brain as sharp an image as possible. The comprehensive image formed in the mind of the controller of that part of the traffic which he cannot visualize as a whole is somewhat similar to that of the ocular vision insofar as it calls in images with varying degrees of sharpness as well. However, far from being a d i re c t v is i o n, this comprehensive image of the traffic is more of a "traffic pattern" which is built up, so to speak, from the various data at hand. Coarse as it may be, this "built" image will take heavy toll on the intellectual capacities of the controllers, since they are continually obliged to build up those mental images in order to watch over their traffic and keep a sharp eye for such situations as might deserve more careful analysis or immediate action even. This kind of intellectual activity, which can be extremely intense at times, often escapes analysis since it is an extremely swift phenomenon of an all but automatic nature. Though it may be slight in terms of time, such a task will use up a considerable amount of controller energy, the loss of which will be the more exacting as other tasks related to the conveying of information will keep interfering. Moreover, because of this, the controller will develop a sense of insecurity since he can never be quite sure that he has been exact enough in carrying out his watch or that some important event has not slipped his notice. The computer could take an active part in this supervision task. With the information at its disposal, it can investigate the traffic, at short, regular, intervals, so as to take the necessary action, if any is needed, or suggest it to the controller. The amount of automation that can be brought into such operations is a function of the degree of automation reached by the system or, more precisely, of the nature and the accuracy of the data which have been fed into the computer. Thus, using the comparatively crude information at its disposal, namely the Flight Plan broadcasted by the AFTN and supplement by a preliminary updating at the time ~f arrival of planes into the Control Area, the computer will be in a position to sweep systematically the whole range of active traffic, so as to be able to: - anticipate the density of traffic in each particular sec. 路 t'ion of tor, so that measures of conservation (opt1m1za available staff distribution; flow control) can be taken well in advance. give warning to a controller that he is to pass on a plane (or a piece of information) to another contr.oller: safety margins concerning selection of this particular time will be the narrower as the data known to the computer is the more accurate. . . ready the coordination messages with the information at its disposal in such a way that the controller's onl.y job will be to confirm those messages, a~d, if needs be, to correct some of their elements, but. with?ut having to enter the whole message ?r concerning himself with the problem of dispatching them to those whom they concern (an example of the active part !hat can be taken by the computer in matters of coordination).

automatically dispatch such messages; ensure as full as possible a time independence for tasks which are the responsibility of the controllers involved; monitor transfer negociations until they are completed. An actual size experiment of this stage of automation will take place at the Orly ATCC some time in 1966.

Utmost care has been taken to ensure a positive g2 balance of the tasks involved, and provided that our hopes are not disappointed this stage should then go into operation. Note that the updating of flights by the controllers in view of operations for the transfer of aircraft will provide the computer with information which it might put to use for computing and displaying subsequent, more precise, transfer, propositions messages. When a more advanced stage of automation is reached, the more elaborate (4) information contained in the computer's data storages will make it possible for it to play a still more constructive part for the benefit of the controller. Progressiveness in the participation of the computer to the control itself will be achieved. At first it will be attempted to display the integrated information with a view to minimize the strain imposed on controllers to "build" their mental picture of the traffic; research work in the field of psychotechnics as well as experiments on the selection of such displays will be a considerable help for definition of new displays susceptible of effectively reducing the overall task, without generating, as they are analysed, filtered and shaped up by the controller, an induced task that would cancel out the gains. At a still more advanced stage, the computer might be required to assemble and classify information, so as to keep to a minimum the effort put forth by the controller in investigating conflicts (e. g., by listing together information touching aircraft that are likely to interfere). We can now foresee the times when it will be possible to have the computer share in the analysis of the traffic and its systematic sweeping, thus relieving the controller of a task which he carries out only at the cost of a constant, unremitting strain. Provided that every useful information is recorded in the computer data storages, warning can be given by the computer to the controller of any problem that might justify his taking an action or some refinement of his analysis. When the ultimate stage of automation is reached, such a function will gradually turn into a conflict investigation. It seems conflict solving will then only be a particular case of the search for conflicts since the former operation is nothing more than a search for conflicts which is applied to a computed solution in order to test its validity, and then compare between possible solutions. Letting ourselves be carried away by logics and, perhaps, imagination as well, we have just evoked the times when automatic systems will play a prominent part in control processes. But the ultimate stages of automation are another matter. They will imply a radical improvement of data acquisition methods together with the implementing of a system of an all but absolute reliability. However, it stands to reason that there will be room for many intermediate steps between the preliminary pha(4) Especially information from the Secondary Radar and from the updating of Flight Plans that is carried out with coordination opera路 lions.

ses and the more sophisticated stages reached at the culmination of the whole process, and that the development of the scheme will be no rev o I u t ion but more of an e v o I u t ion a r y process instead. Automation will be continuously applied as a method for organising the work of the controllers. ~n order. to make the most of man's extraordinary capac1t1es - which no computer will ever match - while attempting to entrust the computer with the tasks that it obviously does better than man. We may then regard automation as an evolutive cess of such nature that as it will reduce the overall which rests on the con~rollers, it will at the same make it possible for the available information to be

protask time pro-

cessed more thoroughly.

The Methods used in France for introducing Automation in Air Traffic Control The experience gained during the past few years, ha~e convinced us that it is practically impossible to ascertain that an ATC automated system will stand the test of operation without resorting to full scale experiments within actual environment. Careful analysis, limited experiments are of essential value for designing such systems, though it has only bee~ of a negative kind so far, i. e., such analyses and experiments only made it possible to reject ill-adapted approaches, erroneous or over-simplified solutions. Such results are essential when considered as general basis for a new system, but they are by no means suitable if one is to go into the details of the system or, even more so, if it is desired to make sure that the selected solutions won't disappoint the designer's expectations. Nevertheless, there comes a time when methods must be selected and when a computer must be acquired and set up together with its specialized peripheral equipme~t. A detailed drafting of the operational procedures involved is a long and delicate process; specifying, aquiring and setting up the hardware will take a minimum of two years. Programs production is already started during hardware generation, but it will have to be carried on even after the computers have been set up, because of continual hardware and software interplay. Supposing that this operation takes place under the best possible conditions, an operational means fit for experimentation and ready for use will only be available three or four years after selection of the basic options for the system. Meanwhile, the system can still be further analyzed so that the decisions taken when the computer was first selected can be altered accordingly, but, actually it is only when the whole system is in a running condition that proof will be given that basic options were correct. As it is an extremely complex problem with countless implications, experience will soon reveal, no matter how careful the initial analysis may have been, that the system will have to be modified to some extent. Feeding-back of the experience gained is then initiated and will continue for a long period of time, due to the high response time constant of the system (testing time, progromming or hardware configuration alteration time). This iterative process for the improvement of the system can result in an increasingly adequate understanding of the problems involved, but it is hardly likely to lead to a final and durable solution. The rapid evolution of the

basic data of the ATC problem (ever increasing traffic, changes in aircraft performances etc.) are enough to exclude the possibility that such hopes might soon materialize. There follows that, even if proof could be given, in the laboratory that the new system will be of operational value, three more years will still be needed to evolve an equipment susceptible of coming into real operation notwithstanding the fact that both the problems involved and the techniques will meanwhile continue to develop. Besides, the installation of an entirely new system within a given centre cannot possibly be effected at a moments notice. Owing to the very essence of the control centres 1 evolution can only be progressive, step by step, and "nontraumatising" so that each stage might be beneficial to the control centre as a whole. No matter what confidence is placed in the preliminary experiments which are carried out under simulated conditions, it remains that, sooner or later, there will be no escaping slow and toilsome experiments under actual conditions. It thus appeared that the best way of giving conclusive proof of the new system's validity at a comparatively early stage, was to proceed outright to a step operation of the system as its various elements become available. It was then decided to set up the necessary means of automation at the Orly ATCC, since it was to be modernized first. The evolutionary system that was set up to serve that specific purpose is meant both a s a n e x p e r i m e n ta I a n d as a n operation a I s.y stem. Whenever the occasion arises, any new function, any new method for data display or data input are put to the test on control positions which are operated in parallel with the true positions. . E.ve~y new stag~ that is so experimented and perfected w1th1n its true environment, immediately comes into operation, thus providing for a better functioning of the centre and serving, so to speak, as a stepping-stone towards more advanced stages which, in their turn, will make for more progress still. The R and D in the field of automation for the ATC were organized accordingly, and the limited means available in France had to be adapted to the conditions imposed by the policy that had been embarked on. To this end, a small but closely-knit team has been set up whose vocation covers every branch of involved knowledge i~cluding human, technical and operational factors. The various .steps of the whole process from the designing to the starting of the operation of the system including hardware specification, procedures definition, software production and testing are all the responsibility of this team. As its activities are carried out in the vicinity of the control centre, a good many controllers and other members of the staff can join in and take a hand in the scheme. Close cooperation with the control centre at all stages makes _it possible for engineers and psychologists to anolyze with care the workings of the control operation and to get used to the "operational environment", while controlle:s can get acquainted with the new data processing techniques, potentialities, learn how to use them and generally share in the practical approach to each particular stage.

Mutual understanding and a common desire to bring to a successful end a common enterprise are the most favorable conditions for a successful issue of an extremely complex problem. Generally speaking, it has been attempted to lay down such flexible organization which seems most likely to minimize as much as possible response time to those technical, operational, human and social problems which keep cropping up randomly from the time when the system is first conceived until it is completed and ready for service. The Equipment

Utmost care was taken, in choosing specifications, to ensure maximum versatility for the system so that it can adjust itself to new conditions, since basic concepts are bound to undergo deep changes as experiments make progress. The computer's configuration has been arranged into two main similar group of units; the first one is intended for operational service and for processing of new functions, while the second one is used as a back-up system for the first in case of breakdown, and for programming and experimentation purposes most of the time. The very same configuration had proved satisfactory when applied to the first computers (IBM 650 RAMAC) that were used at the Orly ATCC (in 1962); those computers had made it possible to proceed to the calculation and the printing of strips on the operational group of units, while controller-to-computer "interface" as well as radar-flight plan correlation techniques were debugged on the back-up-system - which was connected to the STRIDA II Air Defense System.

Owing to the extension of the functions to be automatised, it was soon found necessary to acquire computers with greater processing capabilities as well as specific 110 features for each control console. Like the preceding ones, these new computers are being rented. The configuration consists of IBM 7040 computers connected to 7740 I/O multiplexors - equipped with 1050 peripheral units - and attached, either directly or through those units, to the different specific input/output features, as shown in Figure 1. Figure 2 is the block diagram of the two systems where one is used for immediate back-up of the priority system; information which is needed to restart the program without omission or error in case of emergency use of the back-up system is periodically recorded, under normal conditions, on magnetic tape units. There is no need to describe the computers involved, as their main characteristics are well known to all. Broadly speaking, the compulsions imposed to the system are essentially due to the severity of its "real time" running conditions and to its multiple simultaneous input/ output devices. As it must be operated under conditions of almost absolute safety and continuity, one is faced with additional difficulties, not usually met with in other systems. The time which elapses in the system is wholly dependent on the computer internal clock which is set by the Universal Time (Greenwich Time). Moreover, it results from our limited experience that, for the time being, Primary Radar Tracking is not by itself safe enough in any condition and then still requires manual monitoring, i.e. induced tasks; the amount of resulting task benefit, if any, in the ATC environment is not yet known. Primary

Secondary Radar

Rodar

D1g1llzer decoder

Digitizer decoder Primary Radar

Secondary

Primary Radar

Secondary Radar

Radar

Flight pion input

other proceSSOl"S (Germany. )

Long distance landlines to other Air Traffic control center and important control Towers

7040/ 7740

Remote Printing d the -Flight stripsâ&#x20AC;˘

~adar

tracking and tracks flight plan correlabon

identical input I output

UJj_jE_J

kayboard

messages cathodic display

CONTROLLER CONSOLE Figure 1

Radar

scope

keyboard

messagus cathodic display

COORDINATION

â&#x20AC;˘Flight strip' printer

CONSOLE

GENERAL DESIGN OF THE SYSTEM

One might think, then, that digitizing the information from the Primary Radar is not particularly desirable. As a matter of fact, bringing the Primary Radar into the computer's operation is likely to improve the. qualitiy of the cathodic display (and to allow Radar remoting), though 't main advantage lies with the capacity of the computer Is . . I . d f for processing such information in re at1on to ata rom other elementary sources. Speaking on a more general plane, any automatic treatment of elementary information for the benfrt of the ontroller will be the more desirable as the intermediate will be in digital code, thus allowing for .a simultaneous information of the computer. The latter 1s thus readied for sharing in other traffic control tasks which will be dealt with later on.

Overlap and priority levels were ordered according to the contents, origin and function within the System, of the corresponding information. Use of a multiplexor with its own data handling capabilities ensured a high degree of flexibility for the system's design, since the input/output were either attached to the direct input of the main computer or as the case may be, connected through the multiplexor. The diagram in Figure 3 shows the essentials of this distribution. As soon as the types and configurations of the computers were selected, it was then possible to go into the details of the specific input/output features, according to the selected operational and technical concepts.

~rocessing

Thanks to the experience gained in using radar signal digitizers, it was possible to conceive a new equipment that was better fitted to adjust itself automatically to such unfavorable conditions as clutter of all kinds. It was the Compagnie Generale de Telegraphie Sans Fil (C.S.F.) that was entrusted with this task which covers both the analog and the digital processing of the primary and secondary radars videos.

Integration and Spreading of Elementary Information Each elementary information about a given flight (Flight Plan, weather forecast, radar etc.) would not be sufficient in itself to carry out the control.

Switchover design

Tape Switching

direct data c:haMel r1

unit record

central processing unit 2

Central processing unit I

Radar data ...,.tch

removable disk files

ccmmuni cation control unit I

communication control unit 2

TTY Switch

--------r-路 -

l~-----

local input switch

remote hne s switch

1Figure 2

Controllers' Lines Switch

I __ J

unit record

Special keyboards (IBM FRANCE) were evolved that would make data entry into the computer by the controllers as easy (or rather as little uneasy!) as possible according to methods which had already been put to the test when computers were first brought into the centre. Such input operations were made as simple as possible by allowing the computer to take as active a part as possible in all keyboard handling procedures. In order to secure maximum flecibility, monitoring by the computer is programmed (but not cabled). No use will be made of alphabetic keys by the controllers. It was the Societe Nouvelle d'Electronique (S.N.E., a subsidiary of Compagnie Francoise THOMSON-HOUSTON) which was entrusted with the task of developing the cathode display devices. The same type of position decoder and character generator allows for display of characters both on a message visualizer and on the cathode ray tube meant for display of the raw and/or synthetic image from the radar. The cathode ray tubes used to serve both purposes are conventional long afterglow

(P 19 Layer) tubes. The controllers will be able to move designation marks, using rolling-balls and light-guns. At first, the cathode scopes which are being used at the moment will be retained, but they are shortly to be replaced with scopes with a faster moving cathode beam (40 MS for sweeping 90% of the diameter; 80 MS for writing a 10 characters message) which are being developed; these new scopes will make it possible to improve the display on the same image of the raw video from the radar with the appropriate after-glow and of a synthetic video without troublesome flicker. The position accuracy of the beam will be within 1 %0. Thanks to the great flexibility of design of this equipment, it will be possible to provide displays to the controllers in such a way that they can be easily modified by means of an action on the programs. The type of information to be displayed to the controllers at each stage of automation, can also be investigated and experienced upon in all kinds of different ways. Lastly, Societe IBM FRANCE has evolved in its labora-

OPERATIONAL

CENTRAL data channel A

SYSTEM

data channel B

PROCESSING UNIT

information bus

1t--.....------..----....,......-

card reader punch magnvhc tapes data channel C high- s~d printer

Radar data

teletype input I output

local low- spHd data input -----------------+!

remote communications

communication

Controllers' keyboards & strip-printers

control

unit

disk fr le

to remote

Figure 3

Air Traffic Control Centers ( AIX. BORDEAUX ) , Control Towers

ett:

:.r;

tories at LA GAUDE a special printer meant for printing of strips in the vicinity of the control positions. Strips will be printed on pre-cut paper with two character sizes and two colours for the paper. The new computers took over in March 1965 without any interruption of the printing of the strips in the centre. Delivery of the special peripheral units for the primary and secondary radars data input into the computer, as well as for equipping the 17 control sectors in the Centre, will be staggered, and ought to be completed by the end of Spring in 1966. Meanwhile, prototypes of each subset will be technically adjusted to the computer, while programming is carried out together with the first limited experiments. The controllers consoles are being modified to meet the requirements of this new equipment.

The Task:; assigned to the new System The name of CAUTRA was retained for the new system, as it is nothing more than an extension of the program that was launched with the help of its less advanced namesake. This name bears testimony of the importance attached to the solution of problems related to what we call in French "Coordination AUtomatique du TRafic Aerien". Thanks to this new system, it was possible to extend the benefit of strip calculation and printing from the centralized computer to the other two French ATCCs (Bordeaux was equipped in August 1965; AIX-EN-PROVENCE is being equipped). Information derived from flight plans is automatically dispatched in an appropriate form to all other organizations which might be interested. An automatic link with the computer at the FRANKFURT Centre (Germany) is to be established in the near future. Every one of these new functions that are more intricately bound to the control process will gradually come into operation as experiments proceed which is to begin in 1966. These additional functions which are taken to be priority functions, are related to: -

inter-sector procedural coordination (without a radar)

as was summarily stated before; -

secondary radar handling (automatic active decoding with direct display of codes and levels on the radar scopes; use of individual codes and automatic tracking of aircraft fitted with limited code capability transponders);

integration of secondary radar processing with flight plan processing and inter-sector coordination (direct automatic display of aircraft call-signals in alphameric characters; automatic updating of flight plans by the secondary radar). All these functions will be handled by one of the 7040-

7740 units. When free from maintenance, programming or backup tasks, the second system will be used for scientific, technical and operational research purposes as regards p r i mar y radar tracks acquisition and tracking; the data processing capability which is needed to serve this particu!ar purp~se, is simil.ar to that which is required for priority functions, thus 1ustifying the selection of such an organization. Additional experiments could be carried out with the EUROCONTROL simulator which is being set up at BRETIGNY, as soon as it will offer corresponding possibilities.

Conclusion Let us trust that these endeavours will contribute to the rese.arch work that is being done on the problem of automating ATC, and that they will provide for a progressive uneventful evolution of the French Centres towards mar~ and more automation. Thanks to automation, we expect that, henceforth, the task of the controllers will be carried out in the only suitable atmosphere, that is, one of calm and serenity thus enabling everyone to work to the best of his a bi lit/ without either upsetting his balance of mind or endangering his health. One may hope, too, that ATC will not constitute the bottleneck of a.ir transportation as it is growing according to the e:onom1c and cultural expansion. Keeping up at all times, as we have done with the experiments and practical real1'sat'ions w h.1ch' are carne · d out in other countries, proved both extremely interesting and highly beneficial. In any case the ATCAP ·11 h 'bi , w1 ave . ma d e 1t. poss1 e for experts from d'iff t t · . . eren coun ries engaged in s1mrlar research-work to fo rm cor d.10 I an d f ru1·t ful contacts. On all occasion, whether it be in MONTREAL or elsewhere, problems related to the ultimate end and to the methods of automation 1 ·n ATC h a d b een d'1scusse d between these experts who by the t I ' way, are ex reme y happy to see that a great many of th tt d. . . em are a en ing

this Th~rd R a~d D Symposium devoted by the FAA to their favourite sub1ect.

*** l 4th Session of EUROCONTROL Permanent Commission The Eurocontrol Permanent Commission held its XIVth Session in Brussels on 28th January 1966 under the presidency of Mr. Edgard PISANI, Ministre de l'Equipement of the French Republic who has succeeded Mr. Marc JACQUET and the vice-presidency of Mr. Frederick MULLEY, Minister of Aviation of the United Kingdom who succeeded Mr. Roy JENKINS. The discussion took place in a broad spirit of collaborc1tion and made it poss1bie to prepare the directives to be given to the Agency for the coming years at a mo-

ment when is enter·ing a new p h ase. Th e . . its development . Comm1ss1on specified particularly th a t no t'1ona or regio. 1 nal plans should be drawn up ·1n co b t h . mmon e ween eac State or region and the Agency wh· h . b . . , 1c w1 11 a 1so e respons1 ble for their co-ordination. The Agency. was charged to study th e common stan d ards for technical equipment likely to b d ·h b . e use e1t er y Agency or by the national air traff· t I · the . 1c con ro services standardization and st reng th en th e .in order. to promote . . international pos1t1on of European indu t s ry. EUR

Resuits of the ICAO Air Navigation Conference, Montreal 1965 Actions which will add to the safety and reliability of air transportation - including the establishment of a date after which the carriage of flight data recorders by all sizable turbo-jet and turbo-probeller aeroplanes will be compulsory - have been recommended by the. International Civil Aviation Organization's Fourth Air Navigation Conference, which completed its 3 1 /2-week meeting early in December 1965. These recommendations must now be considered by the ICAO Air Navigation Commission and approved by the ICAO Council before they come into effect. Included in the words of the Conference, which was attended by representatives of 40 of the Organization's 110 members States, one non-member State and seven international organizations, were the following:

Fuel and Oil Reserves The Conference specified the fuel and oil reserves which must be carried on each flight by all turbo-jet aeroplanes. The amounts vary depending upon the nature of the flights: in general they consist of sufficient quantities to fly to the destination aerodrome, plus enough extra to fly to the alternate aerodrome specified in the flight plan or - if no alternate is specified - to cruise for an additional two hours. In addition, reserves must also be provided to allow these aeroplanes to fly for 30 minutes at holding speed at an altitude of 450 metres (1500 feet) above the destination aerodrome, and to cover a missed approach and other operational, air traffic control and meteorological contingencies.

Carriage of Survival Equipment

Long Distance Navigation Aids

The decision was made that the present ICAO standard for the carriage of a portable radio transmitter operating on medium and high frequencies (MF/HF) should be replaced by one requiring each long-range overwater flight to carry at least two survival radio equipments operating on both 121.5 and 243 megacycles per second in the very-high-frequency (VHF) band. The Conference was of the opinion that modern light weight VHF survival equipment was easier to operate by unskilled persons and that many more aircraft would be able to pick up VHF transmissions than could pick up MF/HF broadcasts. Noting that the ICAO standards make no provision for the carriage of life-saving equipment ot provide against the contingency of a ditching when taking off or landing at an aerodrome close to a large expanse of water, the meeting agreed upon a requirement for the carriage of life-jackets or equivalent individual flotation devices when taking off or landing at any aerodrome where, in the opinion of the aircraft's State of Registry, there would be a likelihood of a ditching. The regulations requiring the carri?g.e aboard aeroplanes of life-jackets and life-rafts were s1'.111larly reviewed and updated to meet current operating practices and to provide the public with greater protec-

The rapid development of aids to air navigation made it necessary for the Conference to rewrite the existing statement of operational requirements for long-distance navigation. This new statement recognizes, among other things, that the navigation system must be suitable for use in all aircraft types which may require the service and that the system must be capable of providing service over all the used airspace of the world, irrespective of time, weather, altitude and terrain.

tion.

Flight Data Recorders The Conference noted that automatic flight data recorders are a valuable tool in accident investigation to provide information as to the cause, and thus to reduce the possibility of a recurrence. As there is no existing international rule covering the matter, it is recommended that in future it should be made compulsory for a turbine-engine-powered aeroplane above a maximum certificated take-off weight of 5,700 kg (12,500 lbs.) to carry a recorder, preferably in the aft section of the aeroplane in an area such as the vertical stablizer or tail cone in order to simplify its recovery after an accident. The requirement for flight data recorder carriage will apply to all turbo-jet aeroplanes after 1 January 1968, and to all turbo-propeller aeroplanes after 1 January 1970. The Conference also approved a specification to require all passenger-carrying pressurized aeroplanes to be equipped with weather radar for the early detection of thunderstorms and the like.

Two requirements for navigational capability were recognized, one of which is to conduct a flight safely and economically between two places, the other, of growing significance, is to meet the needs of air traffic services, including those concerned with search and rescue operations. The required level of performance for long-distance operation is therefore not constant throughout the world, as the necessary position and tracking accuracy is a function of the density of traffic in each air traffic services area - which density itself is subject to change with time. The Conference concluded that there is no present requirement for a world standard station referenced aid (an aid depending either upon ground or satellite stations); in the future such a need may arise, but this is by no means certain. There also appears to be no need for international standardization of self-contained aids, provided that these meet agreed requirements for accuracy and reliability both for aircraft navigation and for air traffic separation over such critical areas as the North Atlantic where need for lateral separation between aircraft of 60 nautical miles has been envisaged, based on current traffic forecasts.

Review of ICAO Standards and Procedures Apart from the above, the Conference carried out a major review of two important ICAO documents: Annex 6 (International Standards and Recommended Practices on Aircraft Operations) and Procedures for Air Navigation Services-Operations (PANS-OPS). Numerous amendments were proposed to Annex 6. These were concerned with the safe carriage of dangerous goods, establishmenl路 of aerodrome weather minima. regulations governing the availability of oxygen supplies for both passengers and crew, adequate pre-flight pre-

paration and the taking into account of the adverse effects imposed on performance by snow, slush, ice and water on the runways. New regulations regarding shoulder harnesses for crew members, carriage of fire extinguishers, aeroplane radio requirements, and the composition and qualifications of air crews were also considered. The qualifications demanded of Flight Operations Officers were reviewed and a new chapter was added to ensure that cabin attendants should have the necessary competence and capabilities. Because of all the changes which have already taken place or will take place shortly in operating techniques, revision of PANS-OPS proved to be the Conference's most exhausting task. The role played by radar was recognized. The gradual approach of all-weather operations was kept in mind: provisions were made to develop safe obstacle clearance limits to flt in with the higher approach speeds of modern aeroplanes and the lower weather minima involved in these operations and recommendations were put foreword to make more precise the establishment of the necessary radio equipment, aerodrome and weather criteria upon which all-weather landings will depend. A review was also carried out of the communication technique by which pilots and air traffic controllers talk directly to one another. Another item considered by the Conference was the application of ICAO operations standards to general aviation (in this case, all civil international air transport operations not for remuneration or hire). Henceforth the interests of this fast-gowing element of civil aviation will be considered to a greater extent. ICAO

Schedule of ICAO Meetings for 1966 Fifth European-Mediterranean Regional Air Navigation Meeting.

Geneva 1 - 26 February

Special ICAO Meeting on the Limits of Liability for Passengers under the Warsaw Convention and the Hague Protocol.

1 - 15 February

Montreal

Air Traffic Control Automation Panel Fifth Meeting.

Montreal 28 February approx 19 March

Legal Subcommittee on the Rome Convention.

Oxford 24 March - 5 April

Aeronautical Information Services, Aeronautical Charts (AIS/MAP) Divisional Meeting.

Montreal 13 April - 7 May

Communication/Operational Practices Divisional Meeting.

Conference on Charges for Airports and Route Air Navigation Facilities.

Montreal 4 October 7 November Montreal

15 November 5 December*

Fourth Caribbean Regional Air Navigation Meeting.

Region 22 November 17 December*

Tentative.

*** Outstanding FAA Performance in Power Failure General McKee had high praise for the "outstanding performance" of FAA employees during the massive power failure which occurred over a 80,000 sq. mile area of the northeastern U.S. and Canada, on the evening of November 9. Occurring during the peak early evening air traffic period, the power failure began in the Niagara Falls-St. Lawrence Seaway Complex. Eletrical power failure in upper New York State and over much of Ontario resulted. But that was only the beginning of a hectic six to twelve hours for FAA employees and residents of the afflicted area. The Niagara Fol ls-St. Lawrence system is tied i.nto a power system which links most of northeastern U.S. through a national power grid system. In theory, power failure in one locality should be overcome thro~gh pow~r drawn from the "pool" of surrounding localities. In this case , however , the Niagara Falls-St. Lawrence complex . . h was a major contributor and user of electric power in t e joint system. Its failure caused a severe drain on surrou~d足 ing areas and eventually, like a house of cards, the entire system collapsed. With the New York City-Boston megalopolis failure ot 5:25 p. m., nearly 30 million people in New York, Massachusetts Connecticut Rhode Island, and parts of adjoining st~tes and Can~da were affected.

Three FAA air route traffic control centers New York, Boston and Cleveland - were directly affected by the power failure. All three switched to standby power units and were "back on the air" almost immediately. But navigation aids and radar systems were slower in returning to normal. The New York and Boston terminal areas were most severely affected since most of the field lighting and airport navigational aids, including radars, relied on "second-source" commercial power for back-up. More than 100 flight diversions were reported in the New York area. Most of them went to Philadelphia or Newark. Many others diverted to smaller terminals throughout the area.

Ingenuity was the key Thanks to the ingenuity of pilots, controllers and communications and maintenance personnel, as well as good weather and a _beautiful bright moon, the power failure was handled_ without any serious incidents. Many stories c~u!d be writ~en - of controllers working from parked 01rl1ner cockpits to communicate with airborne aircraft of impromptu rerouting of aircraft, ingenious handlin~ of ground c~mmunicati~ns, and lash-ups of emergency power and I 1ghts. The idea of safety and service was exemplified by all concerned.

La Guardia arrivals and departures proceeded under VFR clearances. Chief E. E. Skaggs of La Guardia Tower estimated that delays were of "no more than ten minutes" for the duration of the power failure. But, he added, "We could have handled a lot more if it had been necessary." At Boston, lights on one runway were restored in less than an hour. Meanwhile, "beakon" lights had been spread out along another runway for use in case emergency landings became necessary. They were never needed. Boston Tower controllers alertly "taped" all information for the ATIS (automatic terminal information broadcast). Fortunately, the Boston VORTAC, over which ATIS broadcasts are transmitted, was equipped with a standby power unit and had quickly resumed normal operation. Thus, pilots in the Boston area were never "in-the-dark" even though the lights were out. Knowing that there are limits to human ingenuity and good weather, the Administrator has directed Agency heads to begin at once the necessary actions for installing FAA-operated backup power generating equipment at critical air traffic control and navigation facilities. Several airline leaders have praised FAA for air traffic controllers' handling of flights during the blackout.

W. A. Patterson, board chairman of United Airlines, wrote FAA Administrator William F. McKee that the "magnificent performance" of the controllers prevented "complete chaos". Pan American Airways Board Chairman Juan T. Trippe told the Administrator "the resourcefulness and ingenuity with which FAA personnel established alternate means of communications with these aircraft ... " was a major factor in the safe, uneventful arrival of them at alternate airports". Croydon H. Hartley, Director, international marketing for Douglas Aircraft said the controllers "rose to heights of brilliance in re-routing hundreds of flights". American Airlines President Marion Sadler joined the host of airline and aviation executives who have expressed thanks for FAA emergency services during the recent East Coast blackout. In a letter to Administrator McKee, Sadler said, "The prompt action by your Air Traffic Center certainly averted what could have become a real crisis on the East Coast". He also expressed his company's pleasure on hearing the announcement that the Agency has made available standby electrical generators for installation at LaGuardia and Kennedy Airports. FAA

*** The Air Traffic Controller's Guild of India The First Annual Convention of the Air Traffic Controller's Guild was recently held at Safdarjang Airport, New Delhi, with Shritmati Vijayalakshmi Pandit, Hon. Member of Parliament, being the Chief Guest. The Convention mainly dealt with organisational matters an a good period of time was devoted to establishin~ Guild policy. Shri. A. K. Sarkar, President of the New Delhi Branch of the Guild, summarized its objectives in the following address to the Public Meeting, which was held at the Delhi Flying Club: -

Madam Pandit, our patrons, well wishers and fellow members of the Guild: It is a great privilege and pride for me this even'.ng to welcome you all on the historic occasion of the First Annual Convention of the Guild. I am particularly grateful to Madam Pandit our Chief Guest, for sparing her valuable time to add;ess this gathering on this occasion. Madam Pandit needs no introduction to you. She was one of our foremost freedom fighters. She has brought fame and glory to our country not only as our Ambassador in different countries but also as the first lady who became the President of the United Nations General Assembly. I am particularly encouraged by the kind presence of such an eminent personality in the international sphere be.souse of the vital role aviation plays in international relations. The development of air transport has, as it were, reduced the size of the world and brought the nations closer together. Every one of us is aware of the present situation which requires the skies to be used as high-ways of international goodwill and prosperity. At the same time, how-

ever, it must also be the realm of wings protecting the peace of the world. Thus, today the air transport plays a distinctive role in peace and war. Introduction of this new and lusty means of travel-the air transport- is well within our memory. Yet, it is amazing that such tremendous progress should have been made within a space of 40 years. In our country, the real fillip to air transport came after the second World War, which coincided with our post independence era. Remarkable progress has been achieved in the field of air transport during this brief period. Today, Indian aircraft operate scheduled services from various routes by day and by night, and beyond frontiers of India, interlinking every Indian city and town of note. Not only that, India occupies a key position in the aviation map of the world and airlines from almost all countries of the world come to India or fly in transit across India. lnspite of this phenomenal growth we have been able to achieve a record of safety of which we can reasonably be proud. No doubt, this has been possible due to the skill and dedication of our pilots who have won fame in all corners of the world. But the contribution of our air traffic controllers is also by no means small. They have already earned well deserved commendation from men of eminence in the field of aviation like Shri J. R. D. Tata. The profession of air traffic controllers derives its importance from the objects of air traffic control service, which, in short, is to safeguard and expedite air traffic. The International Civil Aviation Organisation has brought in uniformity in standards and procedures with regard to air navigation, control and safety of aircraft. Air traffic control plays a vital role in achieving this safety. The jet age has put additional burden on air traffic controllers. Today due to speed it is not possible for the pilot to navigate and avoid collision by following the well known old adage of see and be seen. An aircraft has to

be under the positive control of an air traffic control unit who helps him by giving essential information regarding traffic, meteorological conditions and safe levels to fly. In adverse weather the pilot is helped to navigate and land by air controllers who have to make use of special electronic and radar aids. Thus, air traffic control today has become a highly specialised job. The speed and precision are the two most important things that are required of an Air Traffic Controller. The service can now only be executed effectively by individuals having a keen interest in aviation, one which forms the basis of their dedication to the profession. The foundation of the Air Traffic Controllers' Guild was a natural outcome of the common objects of the profession. The principle of co-operation in technical professional matters affecting air traffic cntrol necessitated the establishment of such an organisation, the fundamental object of our Guild being the furtherance of safe and efficient air navigation through the promotion of air traffic control. You may not be aware there is already an International Federation of Air Traffic Controllers' Association and many of the Air Traffic Controllers' Associations of the advanced countries in the field of aviation are already members of this International Federation. The Federation is already contributing towards the improvement of the technical aspects of air traffic control and they are even taking part in the proceedings of the International Civil Aviation Organisation which is a specialised agency of the United Nations. We, in India, also hope to play an increasing role in the advancement of the profession through our Guild. To sum up, our main venture is to bring about a sense of dedication, a sense of devotion and a sense of pride in the profession - a profession which plays such a vital role in this age of advancement. We are on the threshold of Supersonic Transport and so the Air Traffic Controllers will have to play a much more increasing role in years to come. It is, therefore, necessary for us to prepare for the coming events. We are sure that the Government is alive to the problems and they will do their best. But, we,

as individuals and members of a profession, also have a part to play. We are a professional body mainly concerned with technical aspect of the profession, but, in a field as complex as the Air Traffic Control, the dividing line between safety and technical conditions on the one hand and conditions of employment on the other, must of necessity be imprecise and one does not have to be particularly partisan to appreciate that such matters can, and very often do have a vital impact on safety in the air. A person called upon to give such split second decision naturally have to keep himself mentally and physically alert. Thus the element of fatigue has a direct bearing on our ultimate objective, i. e. safety, and professional body like our Guild cannot afford to be blind to this aspect. I am deeply convinced that human life cannot be played with and that responsible Governments have the inescapable duty of giving adequate protection. For this reason, I consider it essential that relations between the employer and their air traffic controllers should always be as cordial as possible and it should be ensured that these unselfish servants should be given facilities which afford at least a satisfactory standard of living, since officers who work reluctantly or with ill-will on such a vital job will never provide an assurance of success either to their users or to the employers. However, by this I do not mean to say that the employers (i. e. the Government in this case) are not alive to their problems. In fact, I understand that the question of reorganization of the profession is already engaging the attention of the Government. Such reorganization is essential to keep pace with the rapid advancement. But any scheme of reorganization, if it is not to be divorced from reality, has to take advantage of the current experience gained by men who are actually working the system. The Guild will only be too happy to place at the disposal of the Government the benefit of the experience gained by its members i~ th!s country and also experience gained by similar bodies in other advanced countries. P.

*** DECCA establishes ATC Advisory Unit in USA

Cooperation Italy I EUROCONTROL

Decca Navigator System, Inc., has announced the establishment of an Air Traffic Control Advisory Unit, to be based in Washington, D. C. The function of the new unit will be to generate and test applications of area navigation and data link concepts for air traffic control operations. Director of the new unit is Tirey K. Vickers, who has been associated with air traffic control continuously since 1937. A former air traffic controller, Mr. Vickers pioneered the application of operations research techniques to a'.r traffic control in 1949, and was in charge of the ATC simulation program at the CAA/FAA Technical Develo~足 ment Center from 1951 to 1959. Prior to joining Decca this month, he spent six and a half years as a Senior Systems Engineer with the Hazeltine Corporation. Mr. Vickers is a Councilor in The Traffic Control Association and is known internationally as the author of numerous technical reports and magazine articles on air traffic control.

An agreement for co-operation will be signed in Rome on 20th January 1966, between the Italian Aeronautical Administration represented by General D. A. Massimo GIOVANNOZZI and the European Organization for the Safety Air Navigation, EUROCONTROL, repesented by its Director General, Mr. Rene BULIN.

The purpose of this agreement is to facilitate reciprocal exchanges of information relating to air traffic control operations and also meetings of experts, with a view to increasing the efficiency of their respective efforts in this field. After the three Scandinavian countries, the United States and Switzerland, Italy will be the sixth country to conclude an agreement for co-operation with EUROCONTROL. EUR

AiCA ... an Inspiration"

by Gen. William F. McKee FAA Administrator

FAA Administrator Gen. William F. McKee delivered this principal address at the Administrator's Banquet during ATCA's 1965 Annual Convention in Los Angeles. We are reprinting an extract of this address with kind permisEd. sion of the Air Traffic Control Association. I have long known and have long had a high regard for FAA's Air Traffic Control Service. This acquaintanceship began many years before last July when I was appointed your Administrator. I have now had three months of direct contact with your mission and your operations and this brief personal knowledge has served only to increase that original respect. You have, consequently, been much on my mind. To begin, I want to report to you on some new machines and the men and problems involved in the orderly, safe guidance of aircraft in flight. The past year saw the introduction for the first time of advanced electronic equipment - common digitizers, computers, and alpha-numeric generators - into two of our facilities, the Atlanta Tower and the Indianapolis Center. Our success with this new equipment has confirmed some of our expectations for the new semiautomated program which we know as the first stage of the National Airspace System. We are beginning our introduction of this new system at our Jacksonville Center, and work is proceeding on schedule. All the hardware is either on the scene or on order. We have high hopes for this new semi-automatic program. It will include the altitude reporting and aircraft identification functions being tested in Atlanta and Indianapolis. At the same time it will automate all the routine non-controlling functions. This powerful tool will assist you in your search for more precise and more secure control of aircraft. Not all improvements have been confined to the tools of the controller. We have been equally concerned about the comfort and efficiency of the controllers' working area. The past year saw the commissioning of the first eight of our new standard design towers - with their cabs functionally designed for controllers. At the same time, our research engineers are examining the IFR room - redesigning it for improved light, sight, acoustics and arrangements. Perhaps the most meaningful turn of the past year, however, was initiated by you men here tonight .. 路 All of us who have had any connection with aviation have long known of the sense of duty and inherent pride that has been characteristic of the members of FAA's air traffic service. We have come to expect only excellence - both excellence of performance and excellence of spirit. We were however, still very much impressed by recent decisions of your Air Traffic Control Association. That a group of federal employees should band together to devote their energies in improving their craft ... serves as an inspiration for all of us. For my part, let me say I shall be happy to work with you, support your programs and encourage your efforts. So shall all members of my staff. Such cooperation can only result in improved air traffic service. This working together, I might add, has already begun. We have already met with ATCA officers in Washington and we

found the discussion most useful. In addition, the forerunner of this new ATCA approach - the Controllers Procedures Committee - has been most productive. Members of the Committee came to Washington in March with nearly 300 recommendations. These suggestions on how to improve our practices - coming from the men who know the problems directly - represent, in the best sense of the word, progress in the science of air traffic control. This burst of activity underscores the truly significant development of the past decade of progress - the realization by all parties concerned that air traffic control is a unique function requiring unique skills, equipment, and unique support. And requiring above all else - a unique breed of men. And such men we have evidently found. Progress shall be no less of a keyword in the decade ahead. We face the demands of adapting to the new automated equipment, the extra demand of more service required by the constantly expanding aviation industry, and the demands of change from the introduction of the new V/STOL and supersonic aircraft. Our supersonic transport program goes well. We have moved into an 18 month accelerated design stage which will see the manufacture of hardware. Each engine manufacturer will build and test three full-scale engines, and the airframe manufacturer will also build and test certain sections of their airframe. We believe, at this stage, we have the technological capacity to build this airplane. And we are further convinced we shall have an aircraft that will operate at a seat mile cost equal to that of present jets. Our schedule calls for this SST to be 1n commercial operation at the end of this decade. Now we begin this decade with certain changes in the pattern. President Johnson has decreed - and none can dispute the common sense of this proposal - that waste be eliminated; that the obsolescent programme the wasteful activities - the inefficient operations - be removed. I must tell you I mean to follow the President's orders to the best of my ability. This need for holding the line on expenditures coming at a time of new and additional demands for our services means we shall be looking to increased controller productivity. At present, we have a little more than 18,000 emp!oyees in our air traffic service. This work force, to meet the expected additional workload, will have to increase productivity about frve percent in the coming year. This is an average. In reality, more will be required of some and, others, already at peak, will not be affected. I promise you here and now that we shall ask of no man more than he can be expected to handle with in the I irnits of safety and ability. Furthermore, we shall bend every effort to provide you with new equipment and procedures to aid you in meeting this challenge. It is unfortunate, perhaps, that this period of stringency should follow so quickly the past l 0 years of boorntown growth of our air traffic service. The comparison leads to distortion. In realdy. there is ahead no falling off nor

offer very much of a future. One of you, for example, has risen to the rank of Deputy Administrator of the Agency. Another is Director of Air Traffic Service, and so is his deputy. Another is Director of our Southern Region. These are just a few examples. I would hope that this prospect for individual growth enters into your career planning. It is - for the individual - a valid point of view. We, too, are concerned with this future of yours - as are the officers of your Association. We both are at work seeking the answers to our particular personnel situation - this combination of a common age level of our controllers and productivity limits placed on them by the peculiar nature of their jobs. Three factors in this difficult personnel equation bear mentioning ... the problem is not immediate ... it is not a recurring problem ... but most important of all - the officials of both FAA and your Association are determined to resolve this situation in the most equitable manner possible. We have already forwarded our recommendation for early retirement to the Cabinet Committee on Federal Staff Retirement Systems. This group is concerned with all government retirement programs and will report its findings on controllers' early retirement as well as on other systems late this year. We are also looking into retraining and reassignment plans. The reasonable expectation would be that this problem will be resolved not by a single approach but rather by a number and variety of solutions. Early retirement retraining and reassignment promotions and normal attrition. We can, however, be certain of one thing. Answers will be found. The problems carry a top level priority. Now there is one other new element in the air traffic scene - a new blip on the scope that may affect the pattern ... The presence of a new administrator. Our task - in its simplest and most direct sense - is to put to work the will of the Congress as expressed in the Federal Aviation Act of 1958. I urge you all to read again the provision of that mandate. There runs through it the recurring theme of safety and service. These are our reasons for being. We hove, indeed, no other. It is imperative, therefore, that we realize our internal way of doing things is but a means. A recent incident indicates we might tend to overlook the proper and all important end result of safety and service. A malfunctioning radar antenna recently necessitated replacement at one of the nation's busiest air terminals. For a variety of reasons, the users of our system were not notified of the shutdown the day it actually occurred. Unfortunately, fine weather predicted for that day did not materialize. This combination of low ceiling and

poor visibility combined with the absence of the shutdown airport surveillance radar severely penalized the carriers. The delays and diversions of flight cost them a total of

s 450,000.

Now this oversight, fortunately, is a rare occurrence. But basic to the many reasons that brought about this incident was our overlooking the ultimate purpose of service to the aviation public. For my part - my way of guiding and administering the resources of the Federal Aviation Agency to the ends that the Congress has directed us - shall be to fight to the limit for the funds, equipment, and the manpower to enable us to do this task. I shall however, be just as persuasive and just as determined in arguing against and removing that which is not necessary. I think if I were to single out the quality I seek most in those who work with me, it would be the requirement that they find satisfaction in their jobs. If you can take your coat off the hook at night with the honest feeling you've turned in a good day's work and found it worthwhile, that's good enough for me ... but don't be deceived. The suggestion that you derive satisfaction from your job is, in truth, a harsh dictum. We are each of us our own sternest critic. We can fool many, but no ma~ deceives himself. To those among you who have achieved positions of leadership and authority, I say be bold. You know your mission, your men, and your operations better than anyone else. If you find something wrong, speak up. If you know a better way of doing things, sound off. There is need, in these days of the systems approach and so-called human engineering, for the man of conviction and spirit. There is need in this era of the organization for daring and courage. I cannot stress our emphasis on the human factor to 0 much. We can prov1'd e the machines; we can engineer the system, a~d .ea~ lay out the elaborate pert charts. But the machine 1s in itself helpless. The system is inert. And the ~ert cha~t is only an elaborate calendar. I have been cont1nously impressed by the truism that the succe SS O f . the manager rises and falls in accordance with the ·11 and spirit of those .with whom he works · I have , acco r d'wi 1ng-

v.:e

ly, .m.oved ~ur assistant .administrator for personnel and training up into my own '":1mediate staff reporting directly to me. At the heart of the 1ob of running any organization is a proper awareness and concern for people. In many respect.s, the head of an agency must be his own personnel. officer. I hope, therefore, that as a result of this elevation of our personnel function, it will be clear th t · ·11 b h d · · a rt ~' e t e ~ m1nrstrat~r, rather than a subordinate official, who will be making decisions concerning agency personnel ~otters. In my book, the organization is flne but morale 1s everything. '

***

BOOKS Assoziative Spcicherung (Associative memories in ATC) by Dr. Eike Jessen, published 1965 by Friedrich Vieweg & Sohn, Brounschweig. 43 pages DIN A4 Ill, including 21 pictures; DM 9,80.

The book is subdivided into 10 chapters which, commencing with pre- and early history of flight, deal equally in detail with balloon and ai:s~ip flight, the remarkable aviation development in the twenties and thirties, th~ t:"'o world wars, with VTOL and supersonic aircraft, with general av1at1on and with space flight. Each chapter is prefaced by an introductory part, outlining the major

Digital processing of flight pion information in air traffic control mainly consists of handling long data lists. The amount of logical work is restricted. Typical examples are: storage of new flight plans, cancellation of old ones, comparison with the real position of aircraft, conflict detection, etc. Most of theses actions con be reduced to simple functions of comparison.

even~s in the particular era, their background history, and their interrelations. Highlights ore illustrated on double (fold) pages (here the excellent aircraft type sketches by Gert W. Heumann deserve particular mention). An interesting feature of this publication is a compilation of true anecdotes, provided by many famous aviation personalities, ranging from Sir Geoffrey de Hovillond to astronaut John Glenn

Present day general purpose computers normally perform such a task by sequencing through all or part of the memory until the logical operation hos been achieved. This way of processing is time-consuming, the I ist being treated word by word. A more problem-oriented solution is lo compare a data word or a part of it with the entire contents of the memory.

Without doubt, "Die Fliegerei" is one of the most. pleasant and interesting aviation publications which hove recently appeared on the Germon bookmorket, outstanding not only as regards the text, but also for the many photos and sketches, the excellent lay-out, and the careful printing. EH

The logical operation has then to be performed within the memory location which meets the logical criterion. This memory location becomes active and produces an individua I output which has to be sensed and decoded in order to obtain its address.

Handbuch der angcwandten lmpulstechnik

Such "content addressable memories" are coming into use now. Occasionally they are called associative memories or search memories. Eike Jessen describes an associative memory concept which is specifically adopted to the requirements of ATC flight pion processing. All basis ATC operations in on automated system may be performed for 4096 words of 61 bits each. A total number of about 680 flight plans may be handled, if we take into account an average of six reporting points per flight. The device is supposed to consist of normal computer elements - that is to soy a 2Mc/s logical and magnetic core elements using one core per bit. The outstanding feature of this associative memory is the possibility to compare whether a value is higher or lower (other known associative memories perform only coincidence). At the same time as this function is executed another part of the word - identity for example - may be compared in order to obtain coincidence. Microprogramming facilities will give some flexibility for extended performance. • Assoziolive Speicherung" is recommended reading for specialists who ore active in the field of ATCA automation, particularly system planners.

Die Fliegerei by Arthur Gordon, translated and adapted from the English by Georg Hensel. Sketches by Gerl W. Heumann. 416 pages, including about 600 black/white and colour pictures, bibliography, and a comprehensive index. Format 21,5>'.28 cm, ~loth binding, 84,- DM; published by Bertelsmonn Verlog, Gutersloh, FRG. "Die Fliegerei" is the Germon version of Arthur Gordon's "History of Flight", which was published by the American Publishing Compan.y, Inc., New York. It is, indeed, a comprehensive review of that ever exiting venture aviation, from early man's first wishful desire to fly lo the breathtaking space missions of American and Russian astronauts. Almost two centuries ago such dauntless men as Montgolfiere left terro firma to conquer briefly the air, but it is still within living memory that Orville and Wilbur Wright made their first flight in a power driven aeroplane. The progress of aviation since the first flights of Otto Lilienthal and the Wright brothers is nothing short of spectacular. Today the aircraft holds a paramount position as rapid transport media, its effect on wide spheres of our life are considerable - and its "success" as a war machine has been terrifying. And yet, there is no respite, no end to its development apparent. Already man has opened the door to infinity. Space and time are shrinking, conservative terms of dimensions barely apply to "Mariner" and other interstellar missions. Today, the launching of a new satellite is no sensation at all; ii already needs two manned spaceships meeting in orbit, or an astronaut leaving his capsule and floating about in space to make front page headlines. Faced with such marvellous achievements one tends lo forget at times the tremendous efforts, ingenuity, and sacrifices which were necessary to realize this ever existing dream of man-flying. "Die Fliegerei" is a true record of this progress. 600 unique pictures, many of which published for the first time in Germany, combined with detailed text sections provide a representative and documentary cross-section of aviation history.

by Dr. Helmut Roschlou. 496 pages with 753 pictures, 8°, clothbinding, 66,- DM. Published October 1965 by R. v. Deckers Verlog, G. Schenck, Homburg, Berlin, Bann. In many engineering fields, particularly in electronics and avionics, pulse systems ploy a dominating role, One of the major tools of the air traffic controller, radar, is based on it, as well as a variety of air navigation systems and, to on ever increasing extent, automatic data processing. Recognising the gap which exists between the highly specialised literature available in individual fields of pulse techniques and their application and the demand for a general textbook which allows the overage engineer with solid basic knowledge to find his way through fairly advanced systems. Dr. Roschlou has undertaken to compile a compendium on pulse techniques, of value alike to the advanced student, the service engineer, and all those looking for a suitable basis to more specialised studies. Author and publishing house deserve thanks for this venture, which must not hove been on easy one. The problem was to produce a single volume publication not only of interest but of use to a variety of readers with differing levels of qualifications and experience. This difficult task would seem to hove been accomplished with some success, the author taking care to provide an adequate statement of fundamental principles lo serve as a revision or instruction, before proceeding to eloborote upon the ensuing detailed practical applications. The first of the six chapters of the handbook deals with the principles (for instance the discussion of noise, frequency and width, modulation systems, optimum channel utilization, etc.), the ledge of which is a prerequirement for the full understanding of systems.

basic bandknowpulse

The author hos deliberately avoided going into the last mathematical derivation, but this does not lessen the handbook's value, it underlines, on the contrary, its character as a practical, field-orientated working aid. Chapter 2 deals with components. Here, too, the author hos al· tempted lo provide a solid basis before proceeding to the description of the components, used in electronic circuits, by elaborating on the electron and its behaviour in metal conductors, semiconductors, high vacuum, gases, and in electrical and magnetic fields. Then follows a comprehensice investigation of the electronic "building bricks", begining with such classical components as condensors, coils, resistors, and including also cavities and waveguides, semiconductors, ferrite elements, delay lines, scan converters, parametric- and molecular amplifiers. The further chapters treat with pulse circuits (3), the application of pulse techniques in communications (4), and measuring systems (5), the latter including pulse navigation, fault detection in communication· and power systems, digital measuring, and the application of pulse measuring in physical research. Chapter 6 is devoted to the application of pulse systems in electronic data processing. The handbook is supplemented by an extensive bibliography and particularly useful - a bilingual index in German and English The "Handbuch der angewandten lmpulstechnik" is primarily intended for engineering and research personnel, but without doubt it will also be of value to operational staff who are interested to obtain a more detailed knowledge about the "black boxes" which they arc using daily. System planners and those concerned with the establishmenl of new ATS units will find it a useful reference. EH

Corporation Members of the International Federation of Air Traffic Controllers' Associations The Air Traffic Control Association, Washington D. C., U.S.A. Cessor Radar and Electronics Limited, Harlow, England The Decca Navigator Company Limited, London ELLIOTT Bros. Ltd., London Hazeltine Corporation, Little Neck, N. Y., USA IBM World Trade Europe Corporation, Paris, France ITT Europe Corporation, Brussels, Belgium The Marconi Company Limited Radar Division Chelmsford, Essex, England N.V. Hollandse Signaalapparaten Hengelo, Netherlands Philips Electronics, Netherlands Selenia - lndustrie Elettroniche Associate S. p. A. Rome, Italy The Solartron Electronic Group, Ltd. Farnborough, Honts., England Telefunken AG, Ulm/Donau, Germany Texas Instruments Inc., Dallas 22, Texas, USA Whittaker Corporation, North Hollywood, California, USA The International Federation of Air Traffic Controllers' Associations .would like to invite all corporations, organizations, and institutions interested in and concerne~ with the maintenance and promotion of safety in air traffic to join their organization as Corporation Members. Corporation Members support the aims of the ~e~eration by sup~lyi,ng. the Federation with technical information and by means of an annual subscription. The F~derat1on 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. For further information on Corporation Membership please contact Mr. Ernest Mahieu, Honorary Secretary, IFATCA, Cologne-Wahn Airport, Germany.

1J'lhe ~nternational Federation of Air Traffic Controllers Associations Addresses and Officers Secretary Treasurer

AUSTRIA

Heikki Nevaste Aimo Happonen

Austrian Air Traffic Controllers Association Vienna Airport, Austria President First Vice-President Second Vice-President Secretary Deputy Secretary Treasurer

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

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

A. Maziers

R. Sadet R. Tamigniaux R. Maitre 0. Haesevoets

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

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

Francis Zamith Maurice Cerf J. M. Lefranc Jean Flament J. Lesueur J. Bocard R. Philipeau

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

W. Kassebohm H. Guddat M. Bahr H. W. Kremer P. Storm H. Prell J. Gartz

GREECE DENMARK Danish Air Traffic Controllers Association Copenhagen Airport - Kastrup Denmark Henning Throne Chairman H. Dall Vice-Chairman J. Thilo Secretary P. Bressam Treasurer

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

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

FINLAND Association of Finnish Air Traffic Control Officers Suomen Lennonjohtajien Yhdistys r.y. Air Traffic Control Helsinki Lento Finland Chairman Vice-Chairman

Fred. Lehto Jussi Saini

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

Valdimar Olafson Jens A. Gudmundsson Einar Einarsson Guolaugur Kristinsson

IRELAND

SWEDEN

Irish Air Traffic Control Officers Association Aeronautical Section O'Connel Bridge House Dublin 2, Ireland

Swedish Air Traffic Controllers Association Luftvartsverket Bromma 10, Sweden

President Vice-President Secretary Treasurer

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

Chairman Secretary Treasurer

E. Dahlstedt B. Hinnerson C. A. Starkman

SWITZERLAND IS RAEL Air Traffic Controllers Association of Israel

P. 0. B. 33 Lod Airport, Israel Chairman

Jacob Wachtel

ITALY

Chairman

Bernhard Ruthy

UNITED KINGDOM

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

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

C. Tuzzi

L. Belluci

Guild of Air Traffic Control Officers 14, South Street Park Lane London W 1, England Master Executive Secretary Treasurer

N. Alcock Mr. Rimmer E. Bradshaw

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

Alfred Feltes Andre Klein J.P. Kimmes

NETHERLANDS Netherlands Guild of Air Traffic Controllers Amsterdam-Schiphol Airport Netherlands President Vice-President Secretary Treasurer Member Member

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

NEW ZEALAND Air Traffic Control Association Dept. of Civil Aviation, 8th Floor, Dept. Bldgs. Stout Street Wellington, New Zealand Hon. Secretary

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

U. Pallares J. Beder M. Puchkoff

VENEZUELA Asociacion Nacional Tecnicos Tronsito Aereo Venezuela Avenida Andres Bello, Local 7 8129 Caracas, Venezuela President Vice-President Secretaries

Treasurer Vocals

Dr. Carlos G. Osorio Manuel A. Rivera Prof. Vicent Smart R. Salazar J. Blanco Villanueva Miss Amelia Lara F. Arturo R. Gil Alfonso Parra

R. G. Roberts

YUGOSLAVIA NORWAY Lufttraflkkledelsens Forening Box 135 Lysaker, Norway Chairman Secretary Treasurer

F.Oie P. W. Pedersen A. Torres

Jugoslovensko Udruzenje Kontrolora Letenja Direkeija Za Civilnu Vazdusnu Plovidbu Novi Beograd Lenjinov Balevar 2 Yugoslavia President Secretary

I. Sirola A. Stefanovic

ROUGHLY

ISN'T

GOODENOUG

•••

Jet fleets cost millions to buy and to o perate. Minor deviations from optimum flight paths mea n ever larg er economic penalties. Rou ghly isn't good enough. Only the most accurate, reliable and co mprehen sive navigation system is good enough-and Decca/Harco is such a system. It pro vides the pilot automatically with compound navi gation al info rmat io n derived from both self-co ntained an d ground reference aids. Computation is automated and manipulation is minimal, greatly r ed ucing th e pi lot's work load at a ti me w hen oth er

... '

.. . '

inst ru m entation is increasing. D ecca Omnitrac- world's most advanced airborne computer-controls th e airc raf t's navigati onal requirements, wh ile on th e ground t he D ecca D ata Link continuou sly relays to A TC all in-flight informatio n from co-operating aircraf t. With Decca/ Harco comp lex traffi c pattern s can be f lown with maximum efficiency and minimum delay, ensuring the best, most economi c, use of air-space.

) DECCA· HARCO DOESTHE JOB PRECISELY

The Decca Nav1qato1 Com11any L1m1tucl London

VERSATILE

PLESSEY AR-1 NOW COMING INTO WORLDWIDE OPERATION meets all civil and military terminal-area, approach and S.R.E. requirements

ISLE OF MAN AIRPORT One of three AR-1 installati ons scheduled for Bulgaria in 1966

One of the many installatio ns being supplied to the Royal A i r Force

The Plessey AR-1 air surveillance radar has already been ordered by 9 countries. AR-1 provides: 17ermlnal-area Surveillance Approach Control Radar Sequencing Control e_arallel-runway Approach Control \:.!Utbound Control from Take-off G Ci:.A. Surveillance Element P ,p I. Approaches Fighter Recovery Survelllance of Low-flying Local Traffic

(Ronald sway) t For installation early in 1966

P lessey Radar Li mited Davis Road, Chessington, Surrey, England Telephone: LOWer Hook 5222 Telex: 262329 Cables: Plessey Chesslngton

PLESSEY RADAR PLESSEY ELECTRONICS GROUP

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