IFATCA - The Controller - November 1973 by IFATCA

IFATCA JOURNAL OF AIR TRAFFIC CONTROL

The Controller in the Equipment Jungle

In this Issue: Report of the Technical Panel Discussion at the 1973 Conference Air Traffic Control Equipment and Navalds at the 1973 Paris Air Show Air Traffic Control In the United States

FRANK F URT AM MAIN

NOVEMBER 1973

VO L UM E 12

NO . 4

3 41 032

International Air Traffic:

-SAFETY FIRST Ourcontribution Â·. ATC radar systems

~Iii~ T Radar equipment of AEG -TELEFUNKEN

IFATCA

JOURNAL

AIR

TRAFFIC CONTROL

THE CONTROLLER Frankfurt am Main, November 1973

Volume 12 • No. 4

Publisher: International Federation of Air Traffic Controllers' Associations, Standing Committee II, Private Bag X 5052, Kimberley, South Africa. OHlcers of IFATCA: J-D. Manin, President, 0. H. J6nsson, Vice-President (Technical), R. Meyer, Vice-President (Professional), H. Guddat, Vice-President (Administration), T. H. Harrison, Executive Secretary, J. Gubelmann, Treasurer. Editor: G. J. de Boer, Private Bag X 5052 Kimberley, South Africa Telephone: 05 31-60 22 Publishing Company, Production, Subscription Service and Advertising Sales OHlce: Verlag W. Kramer&Co., 6 Frankfurt am Main 60, Bornheimer Landwehr 57a, Phone 43 43 25 and 49 21 69, Frankfurter Bank, No. 3-03333-9. Rate Card Nr. 2. Printed by: W. Kramer & Co., 6 Frankfurt am Main 60, Bornheimer Landwehr 57a. 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.

CONTENTS

The Controller In the Equipment Jungle ......... · · · · · · · · · · · Paris Report - ATC Equipment and Navalds at the 1973 Paris Air Show ................................. · · · · · · · · · IFR Helicopter Operation .................. · · · · · · · · · · · · · · · ·

Air Traffic Control in the United States ....... · · · · · · · · · · · · · · · Airspeed and ATC ......................... ··············· Relief for Ground Traffic Controllers ....... · · · · · · · · · · · · · · · · ·

Book Review

22 24

33 38

Letters from Readers ............... · · · · · · · · · · · · · Ground Based Collision Avoidance

News from the Federation ........... · · · · · · · · · · · · · ·

AEG-Telefunken (inside cover) Selenia Radar and Systems Divisions (page 29 and back cover) Ferranti Ltd. (inside back cover)

............................................ Maastricht U.A.C. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .

SID

Advertisers In this Issue:

.......

................................

News from Corporation Members ....... · · · · · · · · · · · · · · · · · · ·

39 41 43

Editorial The steady growth and influence of the Federation was again demonstrated in recent weeks at three events: the autumn meeting of the Board of Officers in Geneva, the 21st Congress of Aviation and Space Medicine in Munich and the Medical Symposium held in Manchester under the auspices of Geigy Pharmaceuticals Ltd. The Board Meeting was given prominence in press, television- and radio reports by Swiss and other news media, while the high degree of interest shown in the various papers dealing with human and environmental aspects of Air Traffic Control and which were presented at the Medical Conferences in Munich and Manchester, surprised even those who knew that this interest was already quite considerable.Certainly we have come a long way since IFATCA was formed in 1961, and there is every sign that the Federation will continue its upward trend in the future. And yet, we are still far from realising our main goal: true professional status for all Air Traffic Controllers wherever they may work. The up-hill climb facing us here is clearly illustrated by the disputes between Member Associations and their Authorities which have for so long now made the news headlines in certain countries, culminating even in heated debates in parliament. There are still too many people who know next to nothing about Air Traffic Control, although they should know better, and it is our task to put our case across to them in the best way we can. How far we still have to travel along this road was demonstrated at the Annual Convention of our U.S. Member Association, the Professional Air Traffic Controllers Organization in New York last May, when the U.S. Secretary of Transportation, in a message to the convention, wrote: "Even before I became Secretary of Transportation I was aware of the strategic importance of the Air Traffic Controller in maintaining the safety and efficiency of our airways. But now - as I acquire a working knowledge of ARTS Ill, NAS Stage A, and other assorted alphabetical mysteries -

appreciation of your skills and the intricacies of your operations grows daily." The Board is deeply concerned about the lack of recognition for the fully justified aspirations of Air Traffic Controllers which is still so widespread in this world of ours. Our press release in Geneva, recorded elsewhere in this issue, bears evidence of this. The Officers are doing all they can to help bring about a calmer atmosphere so necessary if negotiations for a solution of the problems are to be successful. It is not possible to say more about the Board's behind-the-scenes moves in this context. But members and well-wishers may rest assured that the Board is active, and will remain active in this connection. We really don't want these conflicts, and regret the resultant bitterness and inconvenience to travellers. Moderation and negotiation is what we are after. Those who watched our President during the press- and television interviews in Geneva, could not help but observe that the demands on him are increasing as steadily as the workload of the Federation increases. These days, as President of IFATCA. you have to have the qualities of a diplomat, the skill of a negotiator, and the memory of a computer. Jean-Daniel Monin faced twenty-five press representatives at the press conference which marked the end of the Board Meeting. A public relations job very well done. The improved image of IFATCA as a result of the success of the Reykjavik Conference, which was attended by 400 people, and the press and television coverage of the Geneva meeting, is, although gratifying, no reason for complacency. We still face that problem of how to present our case for better recognition and our justified demands for a much better deal than we are getting, in a more effective way than we are doing. Perhaps members can tell us what we should - and what we should not - do in this regard. One thing is certain: the end of the road is not, and will not be in sight, for a long time to come yet.

Mr. V. D. Hopkin \

The Board is happy to announce that Mr. V. D. Hopkin will join the editorial staff of "The controller" as Contributing Editor on "Human and Environmental Factors", and will commence duties as from the next issue (February 1974). David Hopkin, surely, needs no introduction. We all know him from contributions which have appeared from his pen in earlier issues of our journal, and from his activities on behalf of SATCRA, but perhaps even more so from his great interest in the human problems which fuce the Air Traffic Controller of today, an interest which gives rise to the papers presented and sessions chaired by David at so many international medical gatherings. Having heard so much about him from our former Editor, Walter Endlich, yet never had the pleasure of a personal meeting, I made a special trip to Munich after the Geneva Board Meeting in order to meet David. Just in time, too, as the 21st Congress of Aviation and Space Medicine was about to end. We had time for a two-hour discussion before our new editorial staff member had to dash off for another function, but I am sure that both of us will come to value our discussion in view of our work together in the future. David Hopkin will edit all material coming our way in the field of human aspects in Air Traffic Control, and he will contribute to "The Controller" personally under his own name on a regular basis. The Officers believe that we are fortunate in obtaining the services of an acknowledged international expert in this so very important field. "Stress in Air Traffic Control" is a subject which is in the news, and it is a fair bet that a lot more will be heard about this subject as time goes by. The PRO of the British Guild, Mr. Len Vass, well known to IFATCA members, very clearly put the matter into perspective recently in these words: "It is somewhat a paradox that a situation exists at present where superb and highly sophisticated air traffic control equipment costing many millions of pounds is being installed to improve the air traffic control scene generally. Yet this equipment and the safe control of aircraft still depends on human beings whose psychology, make-up and general working environment has been the subject of comparatively little investigation. There is, therefore, a very real need for much greater System study in which the Human Element itself should be examined in depth and in relation to the System and procedures and practices at all major ATC units. Modern living breeds stress in most walks of life. A controller, perhaps more than most, is only too well aware not only of his responsibilities but also of the more insidious stresses which constantly lurk in the background and which can and do occasionally place these responsibilities in jeopardy at alarmingly short notice. Occasional cold sweats and adrenolin tingles must be accepted by a controller. What must be avoided at all costs is a frequency of their occurrence beyond the norm and a net result at the end of a busy session of what is a mental, rather than physical, fatigue. There is reason to feel that such stresses nowadays are becoming more frequent in controllers. Aircrews have for many years now benefited from the work of a highly respected branch of the medical profession whose tasks are confined almost entirely to aviation medicine. Whilst it is true that some of this work also embraces air traffic control, perhaps the time has come for wider application of ATC studies within an independent sub-branch of aviation medicine. In this way, the skills of dualqualified medical personnel might better be harnessed to studies in the air traffic control field the work of which tends to be taken very much for granted, particularly by the public. It is, after all, so often the public who by and large stand to suffer the most in the event of serious error by a controller ... "

12th Annual IFATCA-Conference

The Controller in the Equipment Jungle By W. E. J. Groves

Und~r the_ theme "The Controller In the Equipment Jungle", a panel d1scuss1on under the direction of Mr. W. H. Endlich was held on Thursday, 10t~ ~ay 1973, in Hotel Loftleidir at Reykjavik, Iceland. The panel consisting of IFATCA Corporation Members, discussed new ~evelo_pments in Air Traffic Control, with slide presentations a~d f1l~s in technicolour. There was much Interest in the lively disc~ss1on and Conference participants in IFATCA '73 turned up in considerable numbers to attend the session.

Ou~ member Mr. W. E. J. Groves, has written an excellent Report regarding the proceedings at the panel discussion, and his Report foll~ws below. The Federation is indebted to Mr. Groves for producing such a comprehensive resume for the benefit of the readers of "The Controller".

With the technical work of the 1973 IFATCA Annual Conference completed by Committee B on the evening of Wednesday 9th May, the traditional Panel Session with Corporation Members was held on the morning of Thursday 10th May. Walter Endich very ably undertook the task of Chairman of the Panel and introduced its members to the audience. Mr. T. Foster (Plessey Radar), Mr. P. Jorgensen (Selenia Elettroniche lndustrie), Mr. G. Oddie (Dansk lmpulsfysik A.S.), Mr. W. Parthier (A.E.G. Telefunken), Mr. A. Pitas (ATA), Mr. R. Shipley (Cossor), Mr. D. Stoddart (Ferranti) and Mr. T. Wilson (IAL) represented the Corporation Members on the Panel. The theme of the session had been chosen to indicate the fact that the plethona of new equipment developments, all aimed at providing greater ATC System capacity to meet ever increasing traffic loadings, may well overwhelm the human controller, unless they were applied selectively. The Chairman suggested that the discussion should first look at the present situation in ATC Systems and then examine the requirements and prospects for future developments, having regard to both provider (controllers) and user (operators) interests. In considering future developments it was essential to take account of those A.T.C. services which have or soon will have sophisticated equipments and also those in lower traffic density areas which still retain an essentially procedural system. The session should examine what the industry can provide in a system context; what is required, where is it needed, how does the future controller fit into the system and what knowledge, skills and preparation does he require. An attempt should be made to indicate where the emphases and priorities should lie in future developments. For this purpose the Chairman suggested that the discussion might be subdivided into seven categories; basic inputs and sensors, data processing, presentation to controllers, decision making, confirmation of implementation and assessment of system capacity.

Inputs to the System The Chairman introduced Mr. Oddie of Dansk lmpul _ fysik who gave an illustrated presentation on a technique f 0s the automatic acquisition and display. of data to both pil 0 t sr and controllers. The system was d es1gned for terminal area use and could fulfil a valuable role in the interim period before fully developed automated data interchange systems as envisaged by the ICAO ADIS Panel, could be brough~ into operational use. Operating in the 300 MHz band, the system provided a TV type display of RvR and Met data and the presentation was confined to numeric characters only for simplicity. It incorporated an automatic air-ground data link for the relay and presentation of this data to pilots. Analysis had shown that both RvR and terminal met information could be presented in numeric form without compromising the message content. During discussion it was foreseen that eventually systems involving the automatic air-ground transfer of data would have to be integrated into some form of general purpose data link capable of handling the data transfer requirements for both A.T.C. and company operational purposes.

Basic Data Availability The data available to the A.T.C. system embraced a wide variety of inputs; AFTN flight plans, stored flight plans estimates, position reports, primary and secondary radar' Met, AIS and ATIS, as well as data on revisions and appro~ val requests. All types of data required some form of interface for the processing of the information for presentation to the controller. Such interfaces could take the form of flight data processing systems, data banks, computer links radar plot extractors, automatic hand off devices and variou~ forms of air and ground data links. Mr. Stoddart referred to the development of computer networks whereby ATC computers at Centres and airports could exchange data automatically and so reduce the current co-ordination problem. It was essential that such cross talking between computers should be facilitated and he mentioned the work being done under ICAO auspices to provide for compatability of data format. Mr. Partier described Telefunken's work for the BFS in Germany embracing a computerised system for the evaluation and transmission of flight plan data and the automatic transmission processing and strip printing function. So far the exchange of data between computers was confined to the national network but international application would come at a later stage, with the interchange of data using the

ICAO format. During discussion it was mentioned that early developments of data interchange within F.A.A. computerized centres had shown that it was possible to devise translation facilities for interchange between centres using different equipments and formats. However, all efforts were now directed towards the use of common formats.

ment of rate of climb or descent. Experience in the U.S.A. (Mr. Pitas ATA) indicated that the advent of ARTS 3 had placed a requirement on aircraft operators to ensure that their equipment was functioning properly and Mr. Shipley added that occasional excursions of height readout was usually attributable to some coding malfunction of the airborne transponder.

Radar Data Availability The Chairman said that various technical improvements in radar data availability were in progress which were of direct interest to controllers and he invited Mr. Shipley to summarise current trends. Mr. Shipley instanced the problems experienced with S.S.R. and described some of the efforts to overcome them. It was a fact of life that aerial siting for S.S.R. was often conditioned by the siting of associated primary radar aerials. In many cases this involved the location of secondary radar at airports where the siting was far from optimum, by virtue of the large reflecting surfaces presented by terminal and administrative buildings and hangars. Reflection of transmissions from the transponder gave rise to spurious returns but a solution to this problem was available, though it involved additional equipment. The accuracy of S.S.R. position determination was an area where improvements were well justified since secondary radar provides one of the most valuable sources of A.T.C. data by the association of positive identification related to position. There were well known deficiencies in the azimuth accuracy of secondary radar but current developments were aimed at providing an accuracy of 6 minutes of arc at 60 n.mls and 10 minutes of arc at 120n.mls. Interference between transponders was a third area where improvements were being sought. More airborne transponders and the fact that at higher operating altitudes equipment would respond to more interrogations all combined, together with the increasing number of ground S.S.R. facilities, to compound the over interrogation problem. Measures are in hand to restrict the number of ground stations and the development of ADSEL (Selective Addressing) in the U. K. and DABS (Discrete Address Beacon System) in the U.S.A. should araeliorate the problem. These techniques utilised computers to instruct the transmitter when to acquire information, thus restricting the arc of interrogations. To cater for the acquisition of new targets and those aircraft not equipped with selective addressing, a complete 360Â° transmission would be made at stipulated intervals, say every 3rd revolution. Considerable work had already been done on the use of secondary radar as an airground data link. A capacity of up to 1 million hits/sec. could be provided and coupled with the use of selective addressing, further refinement and development could provide in flight information additional to position, identity and Mode C altitude. During discussion a question was raised concerning the reliability of Mode c height readout and whether any technical developments were in hand to verify the height data or to eliminate errors. Controllers from Maastricht said that in their experience few cases of gross errors of altitude occurred and a subjective estimate indicated that about 95 % of height information displayed is correct. Experience at the London ATCC indicated a similar high level of reliability of height readout errors. Gross errors were easily detected whilst small excursions were difficult. No statistics were available but S.S.R. had proved a valuable tool not only in the determination of altitude but also for the assess-

Presentation of Information Processing and Display The form in which information was presented to the controller, the faith and dependence which he could place in the data displayed and the degree of training and familiarisation with new equipment were all very relevant to the discussion and the Chairman invited comment from the Panel. Mr. Jorgensen said that the display of analogue radar data was unlikely to feature in development work: new techniques would all involve digital processing and display. On cost grounds alone there was little point in starting with a primary radar data processing system. ARTS 3 developments had shown that primary and secondary radar data processing for display was as economical as early primary only systems. One of the main problems was the training of controllers and technicians in the correct handling and maintenance of the equipment. Mr. Pitas agreed that there was little point in considering primary radar only systems as a first step since all aircraft would have to carry secondary radar. Mr. Stoddart wondered whether controllers were satisfied with a purely digital processed radar display; may they not want the availability of raw radar? In a reply, the opinion was expressed that the scan converted radar displays at the London ATCC did not provide the quality nor reliability of the old CRT raw radar, though the situation was improving. Comment was also made on the undesirability of introducing new equipment and a new environment at the same time. This had caused unnecessary problems of assimilation for the controllers. Experience at Frankfurt had indicated that processed radar displays were technically satisfactory but they sometimes posed psychological problems for the controllers where inadequate familiarisation had been provided. The Chairman emphasized the importance of training for the advent of new equipments and environments as an essential means of giving operational controllers the necessary faith to accept the new situations. He instanced the case of Maastricht where, from the inception of the proj~ct, no provision was made for the remoting of radar video into the Centre. At the present time plots from two.remote radars were extracted at source, digitised and transmitted over telephone lines to the centre for processing and display and it was planned to remote the plots from two additi~nal radars to the centre by the same means. The question in~Â vitably arises, how much faith can controllers place in purely synthetic displays. The ease of the London Cent~e was somewhat different in that analogue radar data is avail~ able as a back up to the scan converted displays. The opinion of Maastricht controllers indicated general acceptance of their processed radar displays. Reliabi~ity was at least as good as previous raw radar displays which they had used and this had built up an element of faith in the new techniques. One controller at least felt that he would now find it difficult to revert to the old form of radar display and was not adversely affected by the absence of raw radar. The symbols used were small, reliable and had

an accuracy of about 11/2 miles and a separation of 5 miles between the edges of symbols could be used. Turning the discussion to the availability of secondary radar only, Mr. Foster felt that it should be used only to aid a basically procedural system. Icelandic controllers said that their use of secondary radar only had proved valuable. They used large separations, 10 miles within 100 miles of the radar head and 20 miles beyond, but this had facilitated traffic handling as compared with the 120 miles separation required in the procedural system. The radar had been used for only a relatively short period but for level changes on overflights it had proved satisfactory and of great assistance. It was likely that the system would develop towards the use of digitised secondary radar. ICAO opinion was expressed that the use of secondary radar without primary radar was likely to be restrictive in its application. Supplementary procedures for its use had been covered at Regional Meetings where IATA, for example, had taken the view that the implementation of secondary radar only should not prejudice the full provision of a primary and secondary radar system. The latter is a cooperative facility which relies upon full airborne implementation. Partial fitting can pose problems for controllers, although this was not apparently the experience in the Icelandic ATC system, presumably because the predominantly NAT traffic was fully equipped. However, there were areas where problems must arise when equipped aircraft could be separated from each other, but not from non equipped aircraft. Mr. Foster agreed with the ICAO comment and considered that, whilst the use of secondary radar by itself should be used only to supplement a basically procedural system, the availability of funds was a relevant factor. The implementation of secondary radar alone should not be delayed until funds were available for both primary and secondary radar.

Display Aspects Mr. Stoddart raised the question of the type and content of information displayed and its allocation to main and secondary displays. He wondered if it was necessary to display more than identity and Flight Level on the main display, allocating all other information to a supplementary display. A view was expressed by German military control that, particularly for Operational Air Traffic above FL 245, the call sign only was required, the rest of the information on each flight being shown elsewhere. For approach control work the display of primary radar data only was sufficient. A contrary civil controller view was expressed, requiring the addition of call sign and altitude for TMA traffic depending upon the density of traffic in the terminal area. It was also felt that functional codes for route information was also valuable for enroute traffic. In the approach region secondary radar identification was useful where traffic from two or more stacks had to be reidentified after handover from en route sectors. The answer appeared to lie in the provision by industry of all the available data, with selection facilities for the controller to choose and displays what he needs depending upon the circumstances. This must also involve the choice of what data is to be shown on the main display. At this point the Chairman observed that care must be taken to ensure that the controller was not given a complex correlation problem in relating data on the same aircraft from two displays. The view was also expressed that an analysis should be made of the types of information, the methods

of presentation and the amount of data to be displayed. Mr. Foster warned that selection processes could well turn the controller into a "selection typist", thus inducing additional workload distracting the controller from his primary task.

Organisation and Management of Traffic Flow Control The Chairman invited Mr. Pitas to summarise his paper entitled "Flow Control Concepts and Airline Operations". Mr. Pitas introduced the subject by observing that some form of Flow Control had been in operationn for many years, certainly in the U.S.A. and that its use in various forms was of necessity increasing as traffic increased. By definition the term must imply a measure of restriction but proper flow management could utilise restrictions to smooth the peaks in traffic demand whilst increasing efficiency and maintaining safety and economy. The airlines were adamant that the application of flow management techniques, Whilst very necessary, should in no way abrogate their requirement for complete freedom of operational control of their flights i. e. any Flow Control Plan must have the responsibility for flight despatch and other aspects of fleet organisation and scheduling to each individual airline. The province of flow management was not involved with the separation, Which was the function of Air Traffic Control, but should concentrate upon measures to avoid the saturation of airports and airspace. In the U.S.A. a Central Flow Control Facility is in operation with the objective of monitoring individual facility restrictions to ensure that one facility does not prejudice the overall system efficiency. "Islands" of flow control cannot be tolerated any more than "islands" of automation. Mr. Pitas referred to a list of principles in his paper, the first of which was that all operators must share equally in traffic delays; the rule of "first come first served" was no longer acceptable. The chairman observed that, arising from the paper on flow control, some form of central flow management organisation would be necessary for regions of high traffic demand. One of the prerequisites to the establishment of such a facility was an assessment of system capacity in order to determine which sectors or routes were overloaded, prior to flow management action.

Assessment of Capacity A general discussion followed from the last point concerning the need to determine the ability of airports, sectors and routes to handle the traffic offering. The point was made that the root of the problem lay at the terminals where airlines chose departure and arrival times to suit the convenience of passengers and flight interchange. Even so night curfews restricted the hours of departure and tende~ to produce traffic bunching. Some form of Flight Plan Allocation System was necessary and Germany for example had introduced such a scheme. But its efficacy was dependent upon aircraft adhering to their allocated slot times. Much could be done to improve the existing capacity of ATS systems; where acceptance rates were low, additional route structures were required. The use of procedural separation at FIR or sector boundaries was a hindrance as it restricts traffic and does not realise the full capacity potential. Continous efforts must be made to implement radar hand-offs at the boundaries. However, even if such improvements were achieved, much remained to be done in the

The President, Mr. J-D. M onin, at IFATCA '73 Technical Exhibition

the

f ield of c apac ity assessment. The c apacity of most of the major airpo rts had been determin ed and schedul in g o f d epartures and arrivals was arrang ed acco rdingly but l ittle had been achieved towards fi rm statements o f air way capacity. The U.K. had experimented with a form of secto r capac ity assessment and had gone some way i n the dete rmination of capac ity on airways li nk in g with O ceani c Ai rspace and in the rationalisation of traffi c allocation on these airways. The C hairman referred to the work in iti ated by the ICAO European Ai r Navigation Plann ing Group and its subgroup, the Ai rspace and Traffic Management Group. The latter had already embarked upon a fu ll consideration of system capacity assessmen t an d the need for a Eu ropean Flow Management Organisat ion.

Preparation and Training for new Equipments and Environments The Chai rman referred back to ea rl ier comments which had st ressed the need to ensure that a full traini ng prog ramme was carried through before contro lle rs were prese nted with new equipment techniques and operating requirements or new environments, particularly those involving a re-a llocation of functions or du ties between the members of control teams. Opinion from the U. K. indicated that co ntro llers were reaso nably well prepared for the advent of new techniques and a good deal of experience was now available on the use of simulation tech niques, to the extent that training for the in troduction of new system s is receiving considerable attention. Views expressed from Maastricht i nd icate~ t~ at the 3 day M INFAP indoctrination was enough for familrarrsation but d id not necessari ly con stitute an adequa.te preparation for full competan cy in heavy traffic periods. Fortunately the change over from previous working with primary and secondary radar at Brussels to the use of synthetic radar disp lays at Maastricht took place during a peri od of relative ly low traffic density. For the change-over from the MINFAP to the MADAP system, due

in October, 1973, c on sid erably more trai ni ng and fam iliarisation is provided.

Summa ry A lthough there was every indication that the discussion cou ld continue unabated, t he Chairman drew attention to t imescales and summarised the main points emerging from the Panel Session. a) D ialogue between controllers and system engineers was essential. T he contribution which IFATCA was able to make by b ringing active controllers and Corporat ion Members together at venues such as th is was important, but where soph isticated A.T.C. equipment was involved it was very necessary to establish a permanent dialog ue at the o utset by b ringing controllers into the design tea m. One aim should be to p rovide software specialists with an A TC backg round. b) In its deliberations on ATC matters, IFATCA must have regard to the req uirements of all regions, not j ust those of Europe and North America. For this reason, system concepts should be expressed in modular design terms to cater for logical growth as traffic i ncreases. c) Computers and data processing systems installed in ATC centres must be compati ble. d) In the traffic management fiel d in Europe maximum use must be made of available capacity by the establishment of a co-ordinated European Flow Control Organisation, to avoid the inhibiting effects of "island " of flow control with in individual European States. e) To achieve optimum benefits from future systems. operational co ntrol staff must be properly trained and prepared. With the time bordering on 1300, Walter End lich thanked th e panel members and pa rticipants from the floor for a stimulating series of presentations and discussions lasting in all for we ll over three hours.

Paris Report Major Interest in Air Traffic Control Equipment and Navaids Stronger-than-ever exhibits of ground equipment, together with plenty of interest in navaids and air traffic control, made the 1973 Paris Air Show at Le Bourget one of considerable importance to airports. French manufacturers were there in force, and Aeroport de Paris staged a big exhibit, but there was plenty of activity from other countries, notably Canada, the USA and Britain. We report below on some of the equipment featured.

Air Traffic Control and Electronics Automation is on the way for smaller terminal areas, largely as a result of the development of the mini-computer. Two companies in particular - Lockheed Electronics and Plessey Radar - were exhibiting equipment at Paris of interest to those who cannot contemplate large and expensive systems based on more sophisticated computers. Both companies were able to announce orders for their systems. Lockheed's ARTS II, developed under a $ 1,5 million contract placed by the US Federal Aviation Administration in July 1972, has now been bought by the Italian Government. It will be delivered late this year for a location which has not yet been diclosed. The sale follows a demonstration which Lockheed gave at Rome/Ciampino last autumn. ARTS 11 (ARTS stands for automated radar terminal system) has been demonstrated in a number of other countries, using local radar installations. It is also due to be shown in Moscow this year. The FAA's first installation was delivered by Lockheed last December and is under operational evaluation at Wilkes-Barre/Scranton Airport, Pennsylvania. The System incorporates Lockheed's MAC 16 mini-computer. Plessey Radar, UK, was originally co-operating with Lockheed in providing the displays for ARTS II, and hoped thereby to gain an entry to the US market. The two companies had a joint exhibit at Transpo '72 in Washington last summer. Eventually American equipment won the day and Plessey dropped out of ARTS II. The British company however is now in the field in its own right with the unveiling at the Paris Air Show of its Series 200 system. The first order for it - a $ 500,000 contract from Jersey Airport in the Channel Islands - was also announced. The competition between the two former associates for this potentially large market should prove interesting. It is difficult to compare prices without a detailed investigation of circumstances, but the price of ARTS II is given broadly as $ 500,000 to $ 1 million according to the installation. The price of Plessey's Series 200 on the other hand is stated to be from $ 300,000 for a basic system with three controller displays. The system capacity of the Series 200 is 250 radar targets. Up to six displays may be provided with each basic system.

The controller is provided with processed SSR (secondary surveillance radar) data, and primary and secondary radar are correlated. The need for the controller to translate mentally the SSR code into the callsign of the aircraft he is working is obviated by the provision of a conversion facility. The codes automatically appear as callsigns on the displays. The 14-digit label allows the displays of a callsign of up to seven digits, plus a single-digit code to show the type of airspace (for example "U" for upper airspace, "T" for transit, "C" for controlled airspace). The remainder of the label can display the flight level of the aircraft and a twodigit code for its exit point (e. g. "LL" for London). The emergency transponder codes are converted into plain language as "SOS", "RT FAIL or "HIJACK" as appropriate; these flash to attract the controller's attention. Other facilities available include a height filter, by which the controller can take a look at a horizontal "slice" of his traffic and remove from the display all aircraft operating outside the height band. To check speed and heading of an aircraft he can bring up the "history" of the target with a display of its trail for the previous five antenna revolutions. The display incorporated in the system is Plessey's Mk 8 - not a fully bright display, but well tried, with over 800 in service. Screen sizes available are 12 in (305 mm), 16 in (405 mm) or 22 in (560 mm). The system's processor is Digital Equipment Corporation's PDP 11 minicomputer. One point of possible importance to many airports is that the computer may also be used off-line for commercial computing tasks. A feature to which Plessey salesmen are giving particular emphasis is superior quality of character writing on the display. Good legibility, it is felt, reduces fatigue and the chance of mistakes by the controller. The latest series of surveillance radars from Raytheon, U.S.A., were featured on the company's stand. The ASR 808, developed by Raytheon Canada, is now being supplied to the Indian Civil Aviation Agency for installation at Madras and Calcutta. It is a dual-channel radar of mainly solidstate construction with coverage exceeding 60 nautical miles at up to 30,000 ft altitude. From Raytheon (U.S.A.) comes the PVD (plan view display), an air traffic control display developed for the U.S. Federal Aviation Administration. It was being demonstrated at Le Bourget with a simulated input from a Raytheon 704 computer. A high-resolution screen with clear alphanumeric characters is one of the features claimed for the display. The company had a second PVD unit set up in a private room in the U.S. Pavillion for technical briefings. The$ 74 million Canadian Government's JETS air traffic control project was a major talking point on a number of stands, since the outcome of the competition is likely to be announced soon. It is now believed that the successful bidder will be chosen from a short list of three - Litton Systems, Computing Devices of Canada (CDC) and CAE Electronics.

Procurement is to be in three stages, of which the first worth about $ 22 million is for seven en-route and two terminal semi-automatic control systems. The terminals involved are Montreal and Toronto. An expansion stage will then follow over a period of about 2112 years, during which more terminal units will be added. Shortly after that the third stage will be reached, with general up-grading of the software for fully automatic operation. Delivery of the first prototype system in stage one is due to be made in February 1975. The Canadian Government has put a requirement of 60 per cent Canadian content on the project. Litton claims to be the only company in the competition using all-Canadian technology. The firm is also working on an export order for the first phase of the new Mexican airspace system. CDC is competing for the JETS contract in association with Plessey Radar, U.K., whose Mk 8 display is incorporated in the CDC proposal. The current automation programme for France's three air traffic control centres incorporates the Cll 10070 computer. The ATC system, which will cover the whole of French airspace, will have seven of the computers, manufactured by compagnle lnternationale pour l'lnformatique (France). The three centres are at Orly, Bordeaux and Aix-enProvence. They will be interlinked and fed by remotely located radar covering the whole of French airspace. The Cll 10070 is general-purpose third-generation computer which makes extensive use of integrated circuitry. The company has also developed specialised air traffic control software for its Cll 10020, a smaller third-generation machine which is already in use at less busy control centres in France. The software available includes flight-plan processing programmes. Colour television displays on the stand of Compteurs Schlumberger (France) include information systems with civil aviation application. The company's Television Division has developed Arlequin, designed for the posting of information at local control centres. In particular serviceability states of various facilities and aids can be displayed on a colour television screen, and use can be made of colour codes. Input to the system is by means of a keyboard. Entirely automatic operations is a possible extension of the system. Simplicity and reliability are claimed for Arlequin, which is transistorised and of modular construction.

Nava ids Featured on the Plessey (U.K.) stand was the company's new PLAN 17/18 instrument landing system. This has just been installed at Hurn Airport, U.K., for trials by the Civil Aviation Authority and the Ministry of Defence, which are expected to begin shortly. The system is of solid-state modular construction and intended at present for operations to ICAO Cat 1 and 2 standards. The basic price is about $ 110,000 - $ 115.000. The PLAN 17/18 will eventually be developed to ICAO cat 3 standard for automatic landings and in about five years time may be in a position to replace Plessey's well known STAN 37/38 ILS. The latter, a company spokesman pointed out, is still the only ILS approved for Cat 3 operations by the U.S. Fe-

deral Aviation Administration. The installation at Washington/Dulles is on lease to the FAA from the U.K. Department of Trade and Industry. Other navaids featured by Plessey included Doppler VOA. A low-cost instrument landing system for the smaller airport has been developed by Thomson-CSF (France). The company's LS 372 is available to ICAO Cat 1 standard (but Cat 2 accuracy is claimed) at a price of between $ 66,000 and $ 88,000 according to installation. The first LS 372 was accepted by the French authorities last year and put into operation at Rodez; subsequently a government contract for six installations has been received, plus two or three orders from non-government airfields in France. Thomson-CSF's current ILS is the LS 371; a letter of intent for four Cat 2 installations of this model has recently been received from the Australian Government (a Cat 3 and a Cat 2 installation having been ordered previously). Over 65 have been sold altogether, excluding those licence-built in the U.S.A. by Texas Instruments. Basic price of the Cat 2 version is about $ 155,000, and of the Cat 3 version about $ 190,000. Both have duplicated transmitters, and the chief difference lies in the monitoring facilities provided. Thomson-CSF Cat 3 ILS is in operation at Orly, Toulouse and Bordeaux and has been selected for Roissy. The company is expecting an order for a Cat 3 installation from Vienna, and has equipment in use at Tashkent and Leningrad (though only for Cat 2 operations at present). The first of two systems ordered for Moscow is due to be installed within the next two months. Another new system from Thomson-CSF - which was the subject of demonstrations during the Paris show - is high-frequency ILS working in the C band at 5 gigaHz. Known as SYDAC, it is undergoing operational tests at Pontoise. The chief advantages claimed for SYDAC are a reduced antenna size, less sensitivity to obstacles and easier siting than conventional ILS. Use of the equipment, which will cost around $ 55,000, depends on the installation of a frequency converter in the aircraft to enable reception with the normal airborne equipment. The microwave landing system chosen for the Airtransit experimental STOL service in Canada was a feature on the stand of Philips Electronic Industries (Canada). a subsidiary of the Netherlands-based Philips group. The system is the Co-Scan, developed by the AIL Division of CutlerHammer, U.S.A. It is an interim MLS aid. It was being used in the Twin Otter demonstration at the show. set up in this instance for a 6Â° glide path. The Airtransit contract involves the supply of four ground stations and 20 airborne receivers. In the ILS field Philips Canada was featuring its PHL 7002 system, designed to meet ICAO Annex 10 recommendations for Cat 3 operations. The company has sold four to Venezuela, one to Hong Kong and one to Ankara in rec~nt months. Previously it supplied 51 units to the Canadian Government. Award of a British Government contract to Plessey Radar for an immediate start on Phase 2 of the microwave landing system (MLS) programme was announced at the Paris Show. The contract is part of the British side of international investigations into the new landing-aid technique. Eventually

standards will be adopted by ICAO, but MLS in its fully developed state is unlikely to be in general use before the early 1980s. Systems already in use based on microwave techniques are interim in nature and unsuitable as a general replacement for ILS on an international scale. The first phase of the MLS programme, completed last December, involved studies by interested member States of ICAO. The US.A., Australia and West Germany as well as Britain have responded.

tories. Plessey Radar gained access to the experience when it acquired STC's ILS business in 1971. Plessey is also working under sub-contract however on a Doppler MLS proposal put up by Hazeltine Corporation in the U.S.A., which is receiving FAA support. The work for the British Government is on an air-derived data system for azimuth and elevation angle operation in the 5 GHz and 15 GHz bands. The programme will involve full flight testing and evaluation.

The system chosen by the U.K. uses the commutated Doppler technique, and this will be the subject of the new development contract.

Singer Kearfott, exhibiting in the U.S. pavilion, produces the Talar IVc, another interim MLS, now in service in the U.S.A. and a candidate for the Federal Aviation Authority's forthcoming MLS competition.

It was evolved by the Royal Aircraft Establishment, Farnborough, and Standard Telecommunications Labora-

(Published by Courtesy of Airports International, the Official Journal of the International Civil Airport Association.)

The Coming Era for IFR Operation of Helicopters The ultimate measure of the utility of IFR certificated helicopters will be the extent to which their operations are successfully interfaced with the Air Traffic Control System.

Segregation of VTOL from CTOL Traffic A fundamental factor involved in the IFR operation of helicopters within the ATC environment is to segregate their operations from CTOL (conventional takeoff-landing) traffic. Of course, an !FR-certificated helicopter can follow the conventional routings and make a conventional instrument approach using an ILS. However, the inherent advantages of its flight characteristics are lost by so operating and the

*) GLEN A. GILBERT is known widely as the "father" of Air Traffic

Control, not only in the United States but also in many other parts of the world. From the mid-1930s on. his influence has been a major factor in the development of programs for increasing air transportation safety and efficiency, with emphasis on present and future improvements in Air Traffic Control. Mr. Gilbert was the first Director of the United States' Air Traffic Control System, which he helped to organize in 1936. Since that time he has served in a variety of roles in government, the United Nations, and, since 1957. as a private aviation consultant. He is the author of the world's first comprehensive book on ATC (Ziff-Davis, 1945), as well as numerous articles and papers on various aspects of aviation. He holds membership in many professional organizations including the Aviation/Space Writers Association; the Air Traffic Control Association and Professional Air Traffic Controllers Organization of the United States: the Canadian Air Traffic Control Association; and the International Federation of Air Traffic Controllers' Associations.

By Glen A. Gilbert *)

pilot might just as well be flying a conventional fixed-wing aircraft. On the other hand, to take advantage of the helicopter's flight characteristics, discrete routings will need to be developed covering enroute flight, terminal area operation (Âą 30 nm radius of a major airport), and approach and departure flight paths. In areas of little traffic, establishing such segregated operations may present virtually no problem, or in fact their need might not even exist. On the other hand, establishing discrete flight profiles in areas and at airports having highdensity conventional traffic volume may require thorough analysis and studies. Simulations may be needed in advance in some areas in order to develop the most effective techniques for performing the required segregation. Along these lines, the Federal Aviation Administration and the NASA-Langley Research Center have developed a program to investigate, through dynamic simulation, "the effect of STOL performance characteristics on the Air Traffic Control System and the effect of A TC System requirements on the efficient operation of STOL aircraft." (Note: Although this simulation relates specifically to STOL aircraft, the general principles insofar as helicopter operation is concerned would be essentially the same in respect to the air traffic control considerations.) The simulation is accomplished by tying the NASA-Langley Research Center STOL flight simulator into the FAA's digital air traffic control simulator at NAFEC and, through real time simulation, introducing a busy STOL operation into high density terminal area environments.

Conceptual sketch shows how three-d imensi onal RNAV corri dors can provide "overpasses" and "underpasses" for segregating IFR hel icopter operations from CTOL traffic . RNAV waypoints are used to del ineate the desired flight profiles .

T here are three phases to this study. The first has been completed in the form of a "Letter Report" and covers the impact of a down-town STOLport upon the ATC System. The repo rt fou nd that " because of l imited available airspace in high-density terminal areas, precise navigation , strict ATC rules and procedures will be required to ach ieve safe and efficient STOL operations." Phase Two of the study will cover, from an ATC point of view, a simulation of STOLport activity on a conventi onal airport, and simi larly Phase Th ree wi ll deal w ith STOL operation in a high-density metropolitan area. The full report is expected to be in fin al form so metime during 1973. The New Yo rk area is bei ng used as the model for this sim ulation and the resul ts w ill be of sig nifi cant va lue to act ual IFR hel icopter ope rations in that area since they would be handled pretty much as the simulated STOL operations. the esse ntial difference being in the size of the landing area actually requi red for a helicopter as contrasted to that required for a STO L ai rc raft. It is felt that using the New York area as a model for this simulation will develop basic principles that can be applied on a national scale. "By deve loping ATC System techniq ues for handling segregated V/ STOL type ai r traffic in the New York area, we can do it anywhere," says J im Dzui k of FAA's Quiet Sho rt- H au l Ai r Transpo rtation System Office (formerly known as "V/ STOL Specia l Projects Office").

Special VFR Helicopter Separation As background for th e introduction of ful l IFR helicopter operati on into the ATC System, it is important to understand the si tuation existing today with respect to .. special VFR Helicopter Separation" (Reference FAA Handbook 7110.88). Essentially, a "Special VFR" helicopter operation can be performed if the pilot is able to maintain .. visual reference to the surface and the traffic patterns. routes and reporting or h olding fixes." In such instances, ATC separation criteri a perm it minimum separation of one mile between special VFR hel icopters, although 200-ft separation may be authorized by delegating to the pilot of one of the helicopters

responsibility to "remain at least 200-ft. from the other" by visua l means. In regard to an arrivin g Spec ial VFR helicopter and an arrivi ng fixed-wing IFR aircraft executing a straight in approach, one-half mile separation may be applied by the co ntrol ler if the fixed-wi n g aircraft is less than one mile from the landing threshold, but if the fixed-wing aircraft is one mil e or more from t he landin g t h reshold , o ne-and-onehalf- mile separation is used. In the case of an arriving fixedw ing IFR aircraft executi n g a ci rcling approach or missed approach, an arriving Special VFR helicopter is separated by two miles. A long sim ilar lines as above, separation varying from o ne-half mile to two miles is appli ed in the different situations between a departing fixed-wing IFR aircraft and a Special VFR helicopter, between a departing specia l VFR helicopter and a departing fixed-wing IFR aircraft. and between an arriving fixed-wing I FR aircraft and a departing Special VFR helicopter. In the case of IFR helicopters, they currently wou ld be governed by the same separation criteria as are applied today for fixed-wing ai rc raft in te rms of IFR or rada r procedures. Since such procedures call for separation minima between CTO L aircraft of from three to five miles (sometim es more) it is obvious that the goal of independent IFR helicopter operations into and out of conventional airports as well as en route and to city-center heliports would not be attainable. Thus it would appear that significant changes in ATC separation criteria as applied to IFA helicopter operation wi ll need to be developed. It may very well be that the Spec ial VFR helicopter separation crite ria outlined above will provide a useful basis for consideration in developing new separation criteria applicable to IFA helicopter operations.

Why IFR Helicopter Operation? It might be logical to assume in some instances that more flexibility in heli copter operation is possibl e using th e Special VFR criteria t han would be permitted under IF A operations. 11

MORRISTOWN

LAGUARDIA

i-..-~,;..._;...:_--20

MILES-------1

(12mlns.)

New York Airways route structure shows application of helicopter service in high-density traffic area. For full IFR operation, vertical profiling will be needed to facilitate ATC segregation from CTOL traffic.

NEW YORK AIRWAYS HELICOPTER ROUTES

However, situations can arise where the difference in reliability of operations between those permitted under VFR and Special VFR and those which would be possible under IFR operation may be very significant. According to New York Airways' President Warren Fucinga, Special VFR got them to achieve a completion goal of about 92 O/o, but with IFR capability they would be able to achieve a completion goal of about 98 % in the relatively near future, and eventually be able to raise their completion factor to perhaps 99.6 %. Considering that in the month of July New York Airways carried over 40,000 passengers, a 6 to 7.6 O/o increase in meeting scheduled flight performance is a significant economic factor. Since the S-61 helicopters being operated by New York Airways are !FR-certificated, the problem of converting the operation on their present helicopter routes from VFR/Special VFR to IFR is entirely an air traffic control question and is now under study by NYA in cooperation with the FAA's Eastern Regional Office. Another case for "Why tFR helicopter operation?" is made by Hank Evans, Director of Aviation of the New York State Department of Environmental Conservation, flying his Bell 212 equipped with a Butler National three-dimensional area navigation (3-0 RNAV) system. Flying numerous simulated I FR flights between Albany and the 30 th St., 60th St. and Wall Street heliports, Evans is convinced that such an operation "would be completely feasible under actual IFR conditions with a high degree of scheduled reliability once our 212 is fully I FR-certificated." Although this operation conceivably could be carried out to some extent under Special VFR operation, obstacles such as mountains, rough terrain, towers, stacks, high-power lines and buildings could make such flying hazardous to say the least during marginal weather conditions. Under IFR operation on the other hand, the helicopter can be flown at safe terrain clearance altitudes throughout the entire flight. In addition to increasing flight safety, it is obvious that IFR operation greatly enhances the capability to perform flights with a very high completion factor within desired scheduling parameters. The New York State operation as simulated under IFR conditions provides a model which may very well be followed advantageously in similar situations elsewhere. The flight is performed directly from Albany via RNAV to a point in space at the intersection of the Harlem and Hudson Rivers. An instrument approach procedure is then executed at this point using the 3-0 RNAV system and descent at the 12

desired gradient (pilot selectable) is made down to the approved MDA (Minimum Descent Altitude). Upon establishing visual contact with the surface, the flight would then continue under VFR or Special VFR to the desired heliport. On the return flight, the helicopter is flown VFR/Speciat VFR from the downtown heliport to "sterile" airspace, and thence by RNAV directly back to Albany at a safe IFR altitude, landing on a helipad at the Albany airport. "Corporate VTOL IFR operations in busy metropolitan areas will soon be impacting the airspace system". forecasts Bob Richardson, Executive Director of the Helicopter Association of America. He goes on to say that IFR helicopter operations "are now becoming possible because more useful and dependable helicopters are being developed with turbine power and twin-turbine engine-out integrity." A real-life example of a corporate operators' interest in IFR helicopter usage is the program of Bill Sapp, Director of Air Transportation for Mack Truck Corporation, which was described in some detail by Dwayne Jose in an earlier issue of FLIGHT.

FAA Definitions for IFR Helicopter Operations In anticipation of the coming IFR helicopter era, the FAA promulgated an amendment to FAR 97 effective April 27, 1972, establishing several regulations specifically relating to helicopter IFR operation. One is a new definition for helicopter approaches as follows: "Point in space approach means a helicopter instrument approach procedure to a missed approach point that is more than 2,600 ft. from an associated helicopter landing area." IFR approaches to a point in space with final approach and landing under VFR/ Special VFR procedures (as per New York Stat~ pi.an) c?u~d be a combination that will find significant application within the ATC System. In the same revision to FAR 97 referred to above, the FAA introduced another new section relating to helicopters as follows: "Copter procedures means helicopter (instrument approach) procedures, with applicable minimums as prescribed in section 97.35 of this Part. Helicopters may also use other procedures prescribed in Sub-Part C of this Part and may use the Category A Minimum Descent Altitude

HEIGHT ABOVE GROUND, ft

400

200 FLIGHT PAT L.llliiiiiii;;diS:ES~==E=~BSTAC:LEI CLEAMANCE!--- d - - O

Sketched are various types of vertical gradients which may be applied as appropriate for ATC purposes to reduce noise exposure and to provide safe obstacle clearance.

(MDA) or Decision Height (OH). The required visibility minimum may be reduced to one-half the published visibility minimum for Category A aircraft, but in no case may it be reduced to less than one-quarter mile or 1,200 ft. RVR." Although the longer-range FAA/NASA simulations referred to previously are expected to produce some basic national criteria for the separation of V/STOL and CTOL IFR air traffic, the FAA has indicated a desire to cooperate immediately with any !FR-qualified helicopter operator to estaÂˇ blish the appropriate routings, approach and departure procedures and related air traffic control procedures to meet specific and individual requirements. "We want to work with the helicopter operators who desire to get into IFR operation with properly certificated aircraft," states Walt Kies, Chief of Planning Staff at FAA's ERO. "All they have to do is come up with some specific ideas as to what they want to do and then we will roll up our sleeves and sit down with them."

En Route and Terminal Area Operations While the establishment of discrete en route airspace structuring for IFR helicopter operations may be somewhat complex in the highdensity corridors and areas, this is nevertheless feasible if helicopters are equipped to follow designated RNAV routings with a high degree of accuracy. This accuracy will be required not only in the lateral and longitudinal dimensions but also in the vertical dimension (3-D RNAV) so that they may follow pre-established "overpasses" and "underpasses" relative to CTOL traffic. Since helicopter operators will want to go point-to-point to the greatest extent possible, it is obvious that extensive routing around CTOL traffic would be uneconomical, and hence the necessity for the programming for thee-dimensional RNAV route structures. Helicopters not suitably RNAV-equipped would be handled by ATC as a CTOL aircraft if flying under IFR. In terminal area operations, the various advantages of the helicopter's flight characteristics (ability to slow down readily, variable approach and climb gradients, small landing area requirements) introduce many factors which favour IFR helicopter operation in the ATC environment. The steep approach angles which can be performed by the

NORMAL APPROACHES

200

400

600

800

DISTANCE TO TOUCHDOWN, ft STEEP APPROACHES

helicopter provide a very significant advantage by reducing the amount of the airspace required for the approach flight path, as contrasted to CTOL aircraft. Fall-outs of this capability include reduced objectionable surface, noise level exposure and the ability to achieve safe obstacle clearance altitude during the approach. In some instances, "steep approaches" may be the only way that helicopters could provide service to a city-canter heliport due to other buildings and structures in the vicinity; also, the reduced noise exposure area may be essential to achieve public acceptance of a citycenter heliport operation. On the other hand, where traffic, obstruction and noise considerations aren't significant, the so-called "normal approaches" may be followed. A two-segment combination of the steep approach and normal approach profiles may be found desirable in some instances. In this procedure, a steep initial (first segment) approach would be made to a desired altitude at the desired point in space relative to the touchdown point, with subsequent transition to a normal (second segment) gradient for the final approach to hover and touch-down. Helicopter instrument approach procedures including minimums will, of course, be established, flight checked and charted by the FAA in the same way as are the instrument approach procedures for fixed-wing aircraft today.

RNAV Significance to IFR Operation The capability of the helicopter to reduce speed rapidly and if necessary fly at slowspeeds provides an exceptionally important tool to the Air Traffic Control System not available with CTOL aircraft. This capability facilitates achieving maximum utilization of the airspace by helping the controller to provide optimum sequencing and spacing ~f the individual aircraft involved in any particular traffic situation. With the proper application of three-dimension~! flight profiles and proper timing control factors, IFR helicopters may be expected to be able to operate effectively and efficiently in IFR conditions en route and to and from helipads at CTOL airports as well as to and from segregated heliports. "How easy the traffic problem", declares Grover Loening, aviation pioneer and VTOL proponent, "when the pilot with electronic aids is the master of his plane by having the

power to stop in the air if too close to obstructions or slow down in a traffic jam!". An important part of the equipment of a helicopter for IFR operation in the ATC environment will be its capability to navigate with a high degree of accuracy. This requirement has been specified by the FAA (Reference earlier quotation from Letter Report on STOL Simulation). In addition, NASA-Langley Research Center in several reports on simulated IFR operations of V/STOL aircraft in the terminal area emphasizes the need for "a precision terminal air navigation system which can be phased in with or be a part of the future final approach system." One of the airlines (American Airlines) which has conducted STOL evaluation programs in relation to the interface with the Air Traffic Control Systems. states that "the ATC System will remain incompletely equipped to solve its congestion problems" until aircraft are equipped with area navigation capability to provide the pilot with "lateral, longitudinal, vertical and time navigation information". For arriving IFR helicopter operations in a terminal area under ATC, the pilot must have the ability to be able to navigate accurately on specified and identified three-dimensional flight paths, in the same manner as en route, but with higher equipment sensitivity and resolution (generally, RNAV equipment certified for IFR operation has two modes - "en route" and "approach"). The pilot follows a designated path to arrive at the initial approach fix (IAF) at the specified initial approach altitude using his 3-D RNAV equipment for three-dimensional flight profile navigational guidance. Time of arrival at this point may or may not be an air traffic control factor, but if the aircraft is not equipped to permit the pilot to comply with a time assignment from the ground ATC System by reference to airborne equipment (4-D RNAV) the ground system may give speed control instructions to meet desired time parameters. The final approach may be carried out by reference to ground-based precision landing system, such as some of the newer microwave landing systems now being manufactured, or the final approach may be made by the pilot by reference solely to his 3-D airborne area navigation equipment. Also, a "point in space" approach may be made using 3-D RNAV, and if in visual contact with the surface at MDA (or OH), final approach and landing may be completed under Special VFR criteria. In some instances, the IFR helicopter pilot may wish to use a conventional ILS for final approach, but this introduces the exposure to being handled as a CTOL aircraft. In the climb-out and departure configuration, the IFR helicopter again offers many advantages to the ATC System. Three-dimensional RNAV flight paths can be followed to avoid conflict with or by CTOL traffic, with the capability to apply readily speed controls as may be necessary to provide time separation from CTOL or other V/STOL type traffic. As mentioned in previous articles of this series, airborne RNAV equipment of different models and configurations is now available or is being developed. However, it should be understood that to use RNAV in IFR operations (en route, in terminal areas and for instrument approaches) within the ATC environment, the airborne equipment must have a Supplemental Type Certificate (STC) issued by the FAA in 14

accordance with criteria currently set forth in Advisory Circular 90-45. At an RNAV Symposium sponsored by the FAA in January, 1972 (attendance nearly 1,500),incorporation of area navigation into the ATC System was dealt with thoroughly. FAA Administrator Jack Shaffer immediately thereafter established a government/industry Task Force and charged it with the responsibility of working out a detailed implementation action plan to make area navigation an integral part of the National Airspace System.

Outlook for Constructive Program There is no doubt but that the coming IFR era for helicopters is just around the corner. IFR capability will greatly increase their productivity. They will need to operate into and out of major airports used by conventional aircraft in such a way as to avoid any adverse interaction between the different categories of aircraft. They also should be able to operate with a high degree of regularity into and out of city-center of other heliports. Their full utility application will involve the use of many smaller airports and landing areas under instrument approach conditions. The touchdown point for a helicopter IFR approach may or may not be equipped with an electronic approach and landing guidance system. If such a system is available, landing minima will be set accordingly for an IFR approach procedure. However, most touchdown points probably will not have a local electronic landing installation. Therefore, helicopters making IFR approaches to such points will need to be equipped with suitable airborne 3-D RNAV equipment which can give them the desired capability at the location in question. The FAA will set MDA's and DH's accordingly. The Air Traffic Control System will need to look at the coming IFR helicopter era in a positive, constructive vein. Indications from FAA, both Washington and field, give evidence that this will be the case. However, helicopter IFR operations will need to be designed so as not to impose an undue or unacceptable additional workload on the controllers themselves, or resistance might be generated which would adversely affect the further development of IFR helicopter utilization in today's ATC System. Proper planning for contemplated IFR helicopter operations coupled with appropriate educational and training programs for controllers no doubt will be developed on a concerted basis by the FAA. Because of the advantageous characteristics of a properly equipped helicopter in terms of adaptability to fourdimensional control, IFR operations may be viewed with considerable favor in the ATC System in general and by controllers in particular as the volume of IFR helicopter flying builds up. The capabilities of this type of air vehicle coupled with RNAV make possible IFR operations virtually independent from CTOL's in so-called high-density traffic areas, at high-density conventional airports, and to and from heliports in city centers and at many outlying landing areas. Introduction of IFR helicopter capability will result in a concrete contribution to this country's total air transportation system. (Reprinted from FLIGHT Magazine, Journal of Business Aviation. 2700 North Haskell, Dallas, Texas.)

Air Traffic Control in the United States by Robert Emme tt Greene *

On December 17, 1903, in Kitty Hawk, North Carolina, the aviation indust ry of the United States beg an. Seven ty years later, the industry is a giant in th e business world .

â&#x20AC;˘ Robert Em m ett Greene, married, fi ve daughters, began Air Traffic Control i n Military, 1954 - - VFR Tower. 1957- 1958 Flight Service Station Communication Special ist 1958- 1968 A ir Route Traffic Control Center (Den ver) 1968-1969 Ai r Traffic Contro l Tower/ A pproach Control (Denver) 1970 Full time - - N ational Vice Pr esident Professi on al Air T raffi c Controllers Organizati on

Wh en A TC Beg an

T he basic science of Ai r Traffic Control Service in the U n ited States began in 1926 when the U .S. Government assumed con trol of the infant aviatio n industry. As t he years passed, r ules and regul at io n s were enacted by governmen t age ncies to i nsure the safety of the flying publ ic, and at the same time promote the growth of the industry itself. Unfortunately, the growth of the indu s try out distanced the ai r traffic control system th at h ad the respo nsibility of in su rin g the safe , orderly and swift movement of the traffic.

B ack in the old days . ..

. .. and this is where we are to-day

There have been many studies performed in an effort to continually improve the system; howeve r, the process has been one of start and stop rather than continual. Few people involved in aviation today will argue that the system is not more human than machine. Even with the adven t of c omputers, the proj ected percentage of invo lvement w ill rem ai n more human than machine, for many years. 10,000 Airports

In the United States, nearly every seco nd around the clock thro ughout the year, two aircraft take off and land. There are approximately 10,000 airports in the U.S. varying in s ize from such complexes as Chicago O'Hare to s mall rural single grass strips. Between 400 and 500 of the 10,000 have control towers . Of these , approximately 125 have surveillance radar and more t han 250 have instrument landing systems. Additionally, there are about 30 air route t raffi c co ntrol Ce nters that move the t raffic between termin als. Two T ypes of Separation

The ATC system in the U.S. today is composed of two types of separation - VFR and IFR. VFR is the "see an d be seen " concept wh ich has been in existence since man 16

has been flying; the pilot is responsible to avo id other aircraft. The other type is IFR (instrument flight rules) whereby the contro ller has the responsibility to separate aircraft which he is controlling. Unfortunately, when the two concepts become intertwined, as often occurs in terminal areas, the system occasionally fails to function. Th e net result sometimes being a midair coll ision, or at best a situation that jeopardizes safety. Speed Dictates Need For Positive Separation in High Altitude Stratum

With the dramatic change in aircraft design. speed, and fligh,t configuration over the past decade, the "o l d" VFR concept is no longer a safe standard by which to separate aircraft. There has been an ever-increas ing pressure being brought to bear to provide "positive separat ion " by ground controllers and equipment. The "postive" separation concept began in the early sixties in the higher al titude st ratum, along se lected transcontinental airways. Gradually, the program was expanded to include more airways until finally all airspace at 24,000 feet and above was positive control. In the late 1960's, the altitude was lo w ered to 18,000 feet and is projected to be lowered to 10,000. The " positi ve separation " standards have generated an enormous i ncre-

we are con tinually striving to make it the safest A T C System

ase in wo rkload and responsi b ility o n an already understaffed con troller fo rce. Positive Control Concep t Spreads to Terminals Afte r severa l mi dair c oll isions in the late 1960's, it became quite apparen t that the "positive separation" stan dards should be imp lemen ted at select large airports, i. e. A tlan ta , New York , Los Angeles, and Washington, D. C. The theo ry was to al low the jet type aircraft to make a h igh angle app roach from t he h ighest altitude possible , at the last approach fix , and have departing jet traffic c limb at a sharp angle to an altitude within which slower, no n-jet aircraft - no rmally - do not operate. Coupled wi th the " keep them high " concept was the designation o f select arrival and departure corridors and restri cted areas where aircraft were not permitted to fly, unless they were under the d irection of a cont rol fac ility. Finally, al l arriving VFR traffic had to be safely sequenced by radar controllers with arriving inst rument traffic fo r landing. Previous ly, the tower cab controller sequenced the traffic visually rather than having the radar room work al l arriving traffic . Enormous Volume Growth i n 60's During the period from 1963 to 1969, there was an en ormous growth in traffic volume within the system. Th e

growth was caused by the n umber of ne w ai rcraft enterin g the system and t he " time u ti lization " or " quick turn around " time of the ai rcraft themselves. Wh ile the growth was occu rring i n the industry, the ATC system was being handicapped b y an austere econom ic program w ith in the Federal Aviation Administrat ion . 1963-1 967 : No Co nt rolle rs Hired The auste rity period of 1963-1967 saw virtually no new development (train ee) controlle rs h i red. The result of the nohire p o li cy was a critical shortage of qualified controllers beginning in 1967- 1968. In order to compensate tor the shortage, most controllers were req uired to work 6-day-work weeks for months on end , with no relief in sight, with many working a 10-hour day. The dramatic increase in volume, t he shortage of personne l and the increased work week began to take its toll. Work Action " Spotlights " Problems In the spring of 1970, many American controllers remained away from work in a demonstration of d issatisfac t ion with t he sho rtage of controllers, the !ack of adequate equipment, the absence of modern equipmen t, and the i nadeq uacy of the FAA academy training p rogram for new contro ll ers.

Action Brings Change in the Air Traffic System Following the demonstration and disruption in service, a metamorphosis began within the Air Traffic Service in the U.S. Several thousand developmental controllers were hired, (today there is still a shortage of approximately 1000 positions} the training program at the FAA Academy was completely revised, the government awarded multi-million dollar contracts to improve radio-radar equipment, and maximum effort was given to speed up the installation schedule of computer equipment. Additionally, a new national flow control procedure was implemented to meter the volume of traffic that could enter the system at any given time. From that time, there has been a much greater consideration of controller input in equipment design and procedure formulation. And finally, there has been a definite improvement in the "employee awareness" responsibility within the FAA. Classroom Training at FAA Academy ATC in the United States is a "young man's" profession, as it is in most countries. It all began back in the 1930's with the low frequency range and "on the job training" working an occasional airplane in and out of airports in the New York area. Today, the FAA Academy complex in Oklahoma City covers thousands of acres, including an airport. The ATC program consists of nine weeks of classroom instruction and laboratory work with the latest equipment in audiovisual aids, where the student demonstrates his non-radar control ability. A radar training program is presently underway, utilizing radar instructors on a temporary loan basis from control facilities throughout the country. The program will be improved upon with the installation of advanced radar simulators, coupled with computers. O. J. T. Continues in Facilities

Upon completion of the academy course, the student is returned to the center or tower facility where he entered on duty to continue his progression with "On the Job Training" under the direct supervision of an "instructor-controller". Depending on facility complexity, i. e. volume of traffic, runways, radar vs. non-radar facility, the time required to become a fully certified controller can vary from several months to 3 112 years. Control Positions

Most towers in the U.S. are staffed on a twenty-four hour schedule. There are some, because of reduced traffic volume during the evening and early morning hours, operating from 6:00 a. m. to Midnight. The normal control positions in the tower cab are local: controlling arriving and departing traffic. Ground control: responsible for traffic movement on the airport area. Clearance delivery: receives and issues 1.F.R. clearances and flight plans. In the area of supervision, there is a "team leader" that is the immediate supervisor of the controllers on duty and an assistant chief that is responsible for the watch functions. Additionally, there is a deputy chief and a facility chief. Depending on the complexity of the facility, there will often be a training supervisor, computer supervisor and even procedure supervisors.

For the most part, the team leader is the only supervisor actively engaged in controlling traffic. In many instances, the team leader position has become an administrative function and the operational job duties have become a controller function. In the Air Traffic Control Centers, the developmental stage begins with the Flight Data Assistant (receives flight plans and enters information into the computer). It is in this job position that the trainee begins his controller training; normally six months to one year after entering on duty. Upon completion of the classroom training at Oklahoma City, the student is assigned to a facility instructor, who administers the "on the job training" to the student. The control positions in centers are interphone: responsible for flight progress strips, non-radar separation, clearances and instruction and alerting the radar controller of pending conflictions in traffic flow. The radar controller: issues control instructions to traffic he is in radar contact with; Position Coordinator: assists in communications between interphone controller and radar controller - gives and receives all radar handoffs and is normally responsible for the total operation of the control sector. Control centers are divided into geographical sectors. The sectors are again divided by altitude stratum. As an example, a low altitude sector will vary in size from 50 miles wide to 200 miles wide, and include all airspace from the ground to 24,000 feet. A corresponding high altitude sector of the same geographical description will control the traffic from 24,000 and above. Most centers have established ultrahigh altitude sectors that control all traffic above 45,000 feet. Control area, complexity and traffic volume dictate the number of controllers required for each facility. Tower compliments vary from half a dozen controllers to 150. Centers vary from 50 to 700. The grade structure (pay) for certified controllers ranges from $ 12,000.00 to $ 23,000.00, depending on facility traffic count and length of service. The facility classification standards applied today to determine pay have been criticized severely by practically every segment of the controller ranks. The FAA has been encouraged to develop a more equitable system encompassing not only traffic count, but airport layout, terrain, type of traffic and communication, and coordination required to move the traffic. Certification Is Only Beginning Once fully certified, the individual is under a period of scrutinized general supervision where "everyone" keeps an eye on him until he demonstrates that he has, indeed, developed the "technique" necessary to become an integral part of the total operation. Promotions The progression up the ladder to a supervisory position or laterally into the computer-programmer function depends on several factors, but primarily on personality, aptitude, potential, and demonstrated ability. Certainly there are instances where "round pegs" are placed in "square holes"; however, the practice is gradually becoming the exception rather than the rule. It is apparent in too many instances in bygone days that some individuals were promoted by default - no competition. Did you have that problem in your country? Today, we are encouraged by the signs of change.

Aerial view of the Aeronautical Center, located on Will Rogers World Airport, Oklahoma City. The Academy is a division of the Aeronautical Center, the Air Traffic Training Branch a part of the FAA Academy

Edward Murray, a Terminal instructor from Milwau kee Tower, conducting a class i n the Ground Control phase of training

En route radar laboratory used for teaching radar identification techniques. handoff procedures, vectoring, and speed control. Students spend two weeks of the nineweek course in this laboratory.

Behind the scene

U.S. Controllers Like to Move

Most air traffic control centers are iden tical in design, both exterior and interior.

The Ai r Traffi c Controll e r in the U.S. is, for the m ost part, a very mob ile ind ivid ua l ; likes to move from o ne facility to anot her . A con tro lle r i n L as Vegas, Nevada might transfer to Los Angeles a few hundred miles away, or he might transfer to Newark, N ew Je rsey Tower, two thousand m iles away.

Some terminal facil ities have found it adve n tageo us to install horizontal radar sopes rather than the uprig h t.

The difference in con trol facilities withi n the system is quite extensive. From the ,.old vintage" tower at Payne, Wash ington to the newer modes of Boeing Field, the control procedures remai n basically the same. Only the controller technique and local procedures require change.

T he admin istrative function within large fac ilities, because of the number of control lers, will often require many add itional supervisors or support personnel. Keeping track of the many navigation components within a center area or the status of radio and radar equipment often requires

Th e con trol eq uipment is iden tical nationa lly wi th cen te rs utilizing horizontal radar scopes and te rm inal radar fac i l ities working primarily with " uprights".

Another demonstration . . .

What's the status of your faci li ty?

ma ny m an-hours. The status board o f the N ew York C enter is shown w ith th e various equipm en t components.

Initial Probl em s of Computer Cause Excessive Delay In is the computer room associated w ith the Common IFR Room se rvi ng the New Yo rk area airports. Th e total computer in stallatio n prog ram is several years behind schedule, prima rily due to initial difficulties in programming the system. Afte r two or three programming efforts that fai led , it was real ized that the programmers themselves must have an ATC backg round in o rder to understand the total interlaced function of computers in Air Traffic Control. A background in programming alone was not sufficient to establish the prog ram. Now that the prog ram is established , experience has overcome many previous obstacles and all programmers need not have an ATC background.

Next Decade Pro j ected to Repeat 60's There is a sayin g that "the past is prologue ", from the past we can see th e future. In some respec ts the statement is a falacy. Howeve r. all too often it is proof positive. Experts, both in the private and public sector, predict a n enormous growth in air traffic volume over the next ten years. With the advent of the jumbo jets, there will most certainly be tremendous problems surrounding ai rport l ayout, design , and traffic patterns. not to mention the exten sive problems of ground transportation and passenger ha ndling. Controlle rs' Responsibility is International in Scope The ever-inc reasing speed of aircraft makes Air Traffic Control more of an international science than a nati onal profession. Th e speed, in essence, makes all controllers colleagues on a daily working basis.

A job action by con t rollers in any major coun try sends c o nce ntri c circles of economic an d traffic co ngestion problems rippl ing throughout the aviat ion world. Seeking solutions to the worki n g environmental prob lems of all controllers must be shared equally by al l other controllers. Just as improvements and advances in equipment and p rocedures should be mutually exchanged by all countries. IFATCA is the vehi cle by which al l controllers can rea lize a n d appreciate an ever-improving worl dwide A TC System. The United States is largest, but it is not necessarily the best A T C Syste m . We are conti nu ally s trivi ng to make it th e safest.

The Trfumph of the Robot " Ladies and g e ntl em en. this is your compu ter speaking . Welcome aboard F lig h t XYZ 401 from New York to Los Angeles. We are now cru ising at 39.000 feet, o u r airspeed is 600 statute miles per hou r, and we will land in Los Angeles at 10.05 p.m. As this is a fully-automated , computer-controlled operation. we will be landing irrespective of weather. but for your information it is overcast in Los Angeles and the temperature is 75 . May both I and my ground-based colleague wish you a p leasan t tr ip." A rid icu lously improbable dream (nightmare?) of the future? Scarc e ly! A s we are all aware. fully-automated unmanned flight o f both the conventional an d space varieties is a cu rrent reality. When the day comes that the groun d computer tal ks merely to its airborne brother. not o n ly the pilot will be unemployed , so pe rhaps it behoves us to consu lt with IFATCA, if not to f igh t against technological redu ndancy, then to make su re we both occupy the sunny side of Skid Row ! (From the November 1973 IFALPA News Bu l letin)

Airspeed and ATC What is airspeed? What does it relate to? What is the difference between True Airspeed (TAS) and Indicated Airspeed (IAS)? How about Groundspeed of the evermysterious Mach number? These are some of the important questions posed by many radar controllers as they tabor to effect necessary speed adjustments in an effort to reduce all these widely divergent variables into a common denominator of constant relative groundspeed. To emphasise this point, the radar controller does not really care how fast or slow given aircraft are proceeding, so long as there is not other traffic involved. In fact, the faster the speed the better we like it, since the time on the sector frequency will be reduced and total demand on the sector will be lessened. The controller is, however, most interested in maintaining a constant relative groundspeedinterval between two or more arriving, departing, or enroute aircraft when the traffic situation demands an orderly flow of traffic and a specific interval between radar targets. The alternatives - most of us agree - are chaos, frequency congestion and sector or controller saturation. If the radar controller is to retain full command of the situation he must use a definite means to meter and control the traffic flow into his sector. To accomplish this function he must successfully and efficiently apply speed adjustment and control, which in turn requires that he be thoroughly familiar with various airspeeds and their interrelationship. Many of us with flying experience have fair knowledge of airspeeds. Some of us acquired this basic knowledge while on the job, by the trial and error method. Practically none of us were exposed to formal and standardized training in the science of airspeeds or speed control techniques. Yet all of us, faced daily with ever-growing loads of air traffic, were forced to deal with and gradually increase control of speeds flown by modern aircraft in our ATC system. Today, skillful use of speed control is an indispensible and frequently employed tool of the radar controller. It is a fact of I ife.

By A. J. Kulikowski Miami Center

C. Equivalent Airspeed (EAS) is the airspeed indicator reading corrected for position error, instrument error, and for compressible flow for the particular altitude. EAS is equal to CAS at sea level in standard atmosphere (59° at 29.92). D. True Airspeed (TAS) is the speed of the airplane relative to undisturbed air; or to put it more simply, EAS corrected for altitude and temperature. TAS is the airspeed filed in the flight plan and shown on the flight progress strip. Again, CAS, EAS and TAS are equal at sea level in standard atmosphere at 59° F (15° C) and 29.92. E. Groundspeed (GS) is the true airspeed corrected for wind. This is the speed of the airplane over the surface as seen by the controller on the radarscope, or displayed in the alphanumeric data block by the automated tracking equipment. This is obviously the speed which must remain constant if the interval between any two aircraft is to be maintained. F. Mach Number is the ratio of aircraft True Airspeed (TAS) to the speed of sound at altitude. It may be expressed as a percentage of speed of sound at altitude; for example at Mach. 82, the aircraft moves through the air at 82 percent of the soundspeed at that level. This is a useful speed for the application of longitudinal separation in terms of time or distance, and is a required item in ICAO flight plans used in oceanic control.

A. Indicated Airspeed (IAS) is the direct airspeed indicator reading in the cockpit, without correction for airspeed indicator, position or compressibility errors. This is the speed used by the controllers, as required by the ATP manual, to effect speed adjustment. As a rule of thumb, IAS decreases at a rate of about 1-1-1/:z percent per 1,000 feet of altitude, or about six to seven knots per 1,000 feet for most turbojets in use today. It is the most important of the various airspeeds as far a controller is concerned.

It becomes, quite apparent from the above that none of the various airspeeds are constant, because among other things they are affected by altitude. The only time speed can remain constant is when all the conditions are constant (which is practically never). One can also easily deduce that from a practical point of view the controller will not be directly concerned with GAS, TAS or EAS; he should, however, have a clear understanding as to what they mean. Indicated Airspeed (IAS) and Mach number are very important, and are frequently used to produce equal spacing between given radar targets. It is imperative that the controller has clear perception of these speeds. He must know that any two or more aircraft in his sector at the same altitude and headings maintaining identical IAS/Mach, will have identical groundspeeds; that climb at constant IAS will produce an increasing Mach number with altitude and changing groundspeed; that turbojets climb at a given IAS until reaching climb Mach, then fly at that Mach until at cruise altitude; and conversely descend at cruise Mach until reaching descent IAS where indicated airspeed becomes primary; and finally, that Mach number is not used at lower altitudes (where pressure is dense) but is used as a primary indicator above FL 240.

B. Calibrated Airspeed (GAS) is the airspeed indicator reading corrected for position and instrument errors. It is the same as the true indicated airspeed (TIAS) previously used. GAS usually is identical, or very close, to IAS when the aircraft is in cruise configuration.

Knowing all this, it then becomes obvious that in order for any two or more aircraft to proceed at the identical groundspeed and thereby maintain a constant interval, the altitude/flight level must remain the same or be changing simultaneously. To state it more briefly one must control altitude in order to control relative speed between aircraft.

In an effort to better understand the various airspeeds and how they are influenced by different factors, let us review some of the basic facts:

IAS/TAS Relationships for Various Mach Numbers and Flight Levels

.76 FL430 209/438 FL410 222/438 FL390 234/438 FL:370 247/438 FL350 259/438 F'L)30 268/443 FL310 280/445 FL290 294/450 FL280 300/452 F'L270 307/455 FL260 313/456 FL250 320/458 FL240 326/460 FL230 333/462 FL220 340/464 FL210 346/465 FL200 353/467 FL190 360/469 FL180 367/471 FL170 374/473 FL160 381/475 FL140 388/477 FLl O 396/479 FL130 403/480 FL120 411/482 FL110 418/484 FLlOO 425/485

.78 216/450 229/450 242/450 253/450 265/450 2??/454 288/457 302/462 909/464 315/467 322/468 329/470 335/472 342/474 349/475 356/477 363/479 370/482 378/484 384/485 392/487 399/489 407/491 414/493 4?1/495 429/497 437/498

.80 223/462 235/462 248/462 260/462 272/462 285/465 297/469 310/474 316/476 324/478 331/480 ))8/482 345/484 352/486 359/488 366/490 373/492 380/494 387/496 395/498 402/499 410/501 418/503 425/505 443/507 4 1/509 450/511

.82 229/473 243/473 255/473 267/473 280/473 293/477 305/481 318/485 325/487 343/490 3 0/492 347/494 354/495 361/497 368/499 376/502 383/504 390/506 398/508 405/510 413/512 420/514 428/516 436/518 444/520 452/522 461/524

lASJTAS* *Al:>ove are the average figuresJ

.84 235/485 249/485 262/485 274/485 287/485 300/488 314/493 327/497 335/499 343/503 349/504 356/505 363/507 370/510 377/512 385/514 393/516 401/518 408/520 417/522 424/524 432/527 440/529 448/531 456/533 464/535 472/537

.86 242/495 255/495 269/495 ?82/495 295/495 308/500 322/504 337/509 344/511

351~14

358 515 365/517 373/519 381/522 388/524 396/526 403/528 411/531 418/533 426~35

434 537 441/539 448/541 457/543 466/545 475/547 483/549

289 507

.90 257/518 270/518 283/518 297/518

316 512 330/516 345/520 353/523 360/526 367/528 374/530 382/532 390/534 397/537 405/539 412/541 421/543 430/545 437/,547 445/549 453/551 460/553 469/555

324?s23 338 528 353/532 361/535 368/537 376/539 38u/542 392/544 400/546 408/548 415/551 423/553 432/555 440/557 448/559 456/561 464/563 472/565 480/567

487 559 495/562

498 572 508/575

.88 250/507 264/507

276~07

303~07

310~18

478~57 .489~70

.92 265/530 277/530 290Js30 304 530 319/530 328/535 346/540 362/544 370/547 378/550 386/552 393/554 401/556 409/558 417/561 426/563 434/565 441/567 448/569 456/572 465/573 474/575 482/577 491/579 500/581 509/583 518/585

.94 273/542 284/542

.96 278~53

292 553 306/553 319?53 326 542 334 553 340/546 350/558 352/551 365/564 371/556 380/568 379/559 388/570 387/561 396/573 395/564 404/575 403/566 413/578 411/568 421/580 419/570 429/583 428/573 438/585 436/575 445/587 444/577 452/589 452/579 461/591 459/581 470/593 466/583 477/595 475/585 486/597 484/587 495/599 492/589 505/601 501/591 5141,603 511/593 523/605 520/595 532/608 530/598 541/610 298~42 312~42

speeds will vary slightly with changes in temperature and pressure.

In the table shown here I have attempted to present graphically to the reader the changing relationship of Mach number and altitude vs indicated/true airspeed (IAS/TAS). The figures are approximate and subject to slight change with variation of temperature and pressure. The simple rule of thumb still remains; at the average turbojet speed range the IAS increases/decreases at about 6K to 7K per 1,000 feet. It really works. Now, I realize that all this talk about airspeeds and our involvement in speed control and adjustment resulting from the controller's attempt to meter the traffic flow in an orderly manner meets with a lot of opposition as well as criticism by the pilots and the aviation industry. This is understandable and to be expected, but it doesn't help us. Some users and the American Transport Association (ATA) say: don't slow down - we will take our chances at holding, if need be (hoping that holding and delays will not materialize). The pilots and ALPA do not want the controller in the cockpit trying to fly the airplane from the ground. We agree. Yet, ATA and ALPA expect the controllers to bring in all that ever increasing traffic to the airports safely, expeditiously, orderly and with minimum possible delay! This is fine, but how in the world is the controller expected to perform this miracle? With one airplane or for that matter with any number of airplanes properly spaced and separated, there is no problem. The job gets done by itself while the controller can just sit back and watch the airplanes go by. Very easy and nobody complains ,everybody is happy. Well, we all know things are not just this simple. The traffic has a tendency to come and go in bunches. Convenient departure times, popular arrival times, competitive scheduling, etc., are causing peaks of heavy traffic and airport saturation. How then are we going to cope with this demand on the system and pressure on the controller, yet minimize holding delays for the users as well as remove or at least reduce the controller's presence in the cockpit?

The answer seems to be pointing towards compromise, with users (pilots) actively participating in, instead of being passively subject to the control of air traffic. Specifically, the need for active pilot participation in the control of air traffic is in the arrival and departure phase. With this in mind I am suggesting that the departure and arrival profiles flown by the vast majority of turbojets be standardized in terms of sÂˇpeeds (IAS/Mach) flown. This is to say that ALPA, ATA, FAA and other interested groups should have a meeting of the minds, to develop typical climb/descent profiles that are within aircraft limitations and can be flown by most if not all airplanes in our turbojet inventory. Experience indicates that standard speeds of about 300K IAS/.78 Mach in climb and around Mach .78/300K IAS in descent are well within normal performance envelope of most turbojets in use today. The arrival profile should also be standard in terms of vertical speed (rate of descent) to be used. Triple the altitude formula, as used now by some carriers, may be adopted. It simply means that arriving aircraft would commence normal descent at a point from the destination airport which is equal to altitude X 3 in nautical miles. For an aircraft at FL310 this would be 93 NM away. produce an average groundspeed of about 350K (considering reduction to 250K below 10,000), about six miles per minute, result in descent rates of about 2,000 feet per minute or 300 feet per mile, and take 16 to 18 minutes to accomplish. This formula may be modified to employ outer/ feeder fixes together with normal crossing altitudes as a point from which standard profile should be measured. This standard departure and descent profile should be only a procedural requirement, to be modified or eliminated whenever possible, at the discretion of the controller. if the traffic situation does .not warrant such restrictions.

Issuance of clearance to climb/descend at pilot's discretion would automatically delete profile restrictions and permit the pilot to fly the indicated and vertical speed of his choosing. Speeds below 10,000 MSL in the terminal areas would remain as at present and subject to control as necessary for purpose of sequencing and the job appears to be easier with the advent of ARTS and groundspeed readout capability. It is interesting to note that 80 percent to 90 percent of the pilots, when asked to express their views on speed control, indicated that a reasonable speed adjustment is much preferable to excessive vectoring and holding. It seems quite logical then to allow the pilot to control his own speed during most phases of flight by flying the standard profile, thus actively contributing to the control of air

traffic, and letting the controller out of the cockpit. We all know and appreciate the fact that it is far more enjoyable to the controller, and infinitely more so welcomed by the pilot, if the control clearances delete rather than impose restrictions to freedom of flight. It is so much easier to say "descend at pilot's discretion", instead of .. reduce to ... ". In conclusion, I am firmly convinced the radar controller must have intimate knowledge of airspeeds and their interrelationship. He must skillfully apply this knowledge, and achieve a desired spacing and metering of air traffic, with minimum inconvenience or delay to the users. And finally, he must demonstrate his expertise in the field, so as to evoke active cooperation by the pilots and earn the professional recognition he deserves. (Reprinted from the Journal of ATC)

Relief for Ground Traffic Controllers New Design Concepts from the Netherlands Offers Promise for Both Medium and Large Airports The application of modern techniques to airport surface control systems is anachronistic. Despite the very great gains achieved during the last three decades in avionics, navaids and other electronic support systems. comparatively little progress has been made in improving aircraft ground traffic control. One relatively sophisticated system is under development for trial use at Kennedy International Airport in New York, co-sponsored by the FAA and the Port Authority of New York and New Jersey. True, there the need has been recognized, but this, the first, is geared to solve particular problems at Kennedy. And. on a worldwide basis, progress has been even slower. The International Civil Aviation Organization, through its Visual Aids Panel, not long ago included taxiing guidance systems on a conference agenda but deferred action by recommending that a new special group be established to look into such systems for Category Ill operations and high traffic density situations. The result, then. is that this subject will not receive consideration on an international basis until late 1973. However, during that ICAO visual aids meeting, a new contender. Philips Airport Equipment Group (The Netherlands). did come forward to make a presentation of a low cost and seemingly practical design proposal for an airport ground movement control system. Essentially, it combines computer monitoring, situation displays and taxiway movement detectors to direct sequenced green center-line lights and red stop lights for the guidance of ground traffic. All operations would be subject to human control and override. Albert L. Bloemendaal, marketing representative from the Philips Group's Airport Traffic Systems division, stres-

By Charles D. Lafond

ses that the need for taxiing guidance is not just at times of low visibility but also in periods of peak traffic. "Taxiing aircraft create a demand which on many occasions is beyond the capability of the available equipment". he declares. At such times, he points out, safety depends greatly on the skill and alertness of the tower operator. Yet, it is in just such situations that ground control radio frequencies become saturated, voice contact becomes erratic and confused, traffic movement bogs down and controllers experience high stress. It is then, says Bloemendaal that the pressure builds on the controller as he faces a dilemma caused by his mandates to maintain safety and to maintain traffic flow. In the end, the result is predictable: the imposition of time-wasting taxiing and aircraft holds. There are many major airports throughout Europe and North America serving both general commercial aviation that are approaching a limit during peak periods on ground traffic handling. For some, says Bloemendaal, their physical confines are such that neither taxiway nor runway capacities can be extended. Complicating this problem is the advent of lower operating minima. Add poor weather and the situation worsens. Under such conditions, there appear to be only two solutions: Restrict traffic or optimize ground movement control for all weather conditions without impending safety, he declares. Even in periods of moderately inclement weather coupled with heavy traffic, ground operations become troublesome. Studies have shown that the critical points in airport taxi patterns are crossings and junctions. These tend to decrease capacity because of the natural tendency of pilots to reduce speed, particularly when they are not familiar with the layout or when diminished visibility impairs recognition of familiar landmarks or available visual aids. Summing it all up, Bloemendaal asserts that too often "optimization of taxiways and aprons is achieved by improvisation rather than by precalculation".

__ . . . .

Provisional Time Table SUNDAY May 19, 1974 Arrival of Participants in Israel Registration MONDAY May 20, 1974 Registration Official Opening Working Sessions

13th Annual Conference of the International Federation of Air Traffic Controllers' Associations

TUESDAY May 21, 1974 Working Sessions Reception by the Mayor of Bat Yam Night Tour of Old Yafo WEDNESDAY May 22, 1974 Working Sessions Evening

THURSDAY May 23, 1974 Technical Presentation Final Sessions Evening

Dear Colleague, Corporation Member and Yisitor, We have the pleasure to inform you that the 13th IFATCA Conference will be held in Isreal in May 1974. We shall do our utmost to continue the tradition of previous conferences and trust that the coming one in Israel will be a great success. We hope to have many guests from all over the world. By attending the conference in Israel, you will have the opportunity to visit this country and to experience the beauty of its landscape, the variety of its people, its historical past and its archaeological findings as well as its present dynamic development. We very much look forward to having you with us in 1974.

Israeli Folklore Evening

Banquet

FRIDAY May 24, 1974 Excursion Tour Evening

"Meet the Israeli at Home" Home Hospitality

General Information Location The Pan American Hotel, Bat Yam (near Tel Aviv) Official Language English Registration fees (per person) Participants Accompanying Persons

$20,$12,-

These fees cover: Participation in the Professional Sessions Receptions Secretariat 13th Annual IFATCA Conference P. 0. Box 16271 Tel Aviv, Israel Ladies' Program

Sincerely yours, Willy Katz President Air Traffic Controllers' Association of Israel

In addition to the general social activities to which t~e accompanying ladies are invited, a diversified progra~. will be arranged for them during session time, including an Arts and Crafts" tour, visits to a kibbutz and Women's Army Base. Climate May is one of the nicest months in Israel. It is pleasantly warm during the day and cool at night. Average temperatures for May are: Centigrade Fahrenheit 15.2-24.6 59.36-76.64 Tel Aviv 15.1-24.6 59.18-79.52 Jerusalem 22.2-35.5 71.96-95.90 Eilat

A primary objective of a taxi control system must be the maintenance of a regular flow of aircraft. Therefore, in the Philips design, the selection of a complete taxi route becomes paramount and all other predicted mov~ments must be considered. Unlike the control of other kinds of traffic, aircraft route selection is not determined by the pilot but by the controller of all the traffic. Therefore, there must be specific delegation of command for ground direction and, of equal importance, there must evolve a faith in both the method and the means of ground direction. The design of a ground movement control system, says Bloemendaal, must assure a capability to the controller for direction of traffic over the best possible predetermined routes and assure that at all times he is in command of the total situation. Moreover, his control functions must be performed with the lowest practicable personal workload. For the pilot, directive signals or instructions must assure confidence by giving him an unmistakable route and one free from unexpected interference by any other traffic. Conversely, should another aircraft have priority at an intersection, directions to either slow down his aircraft or stop must be absolutely clear at all times. The approach taken by Philips, says Bloemendaal, is one that provides guidance in forms already familiar to pilot and to controller - through centerline lighting and display board or screen. Moreover, the system offers a control flexibility, adjustable for both good weather and bad, assuring safe separation under different conditions and different ground speeds.

as the system movement sensor. Its cost is relatively low, it requires no maintenance and the concept of operation is uncomplicated. When a vehicle passes over a loop, which is embedded in the taxiway surface, a change in electrical inductance occurs. This change is readily detectable and is easily assimilated into system logic. To assure continued reliability and to prevent ambiguity, detectors are paired, but are separated by a distance of about 60 meters. Developers claim this prevents double detection of the same vehicle, allows a capability for determining speed and provides reliable directional information. The selection of 60 meters assures the applicability of any pair for the detection of any aircraft. In operation, two modes may be employed: one for maximum capacity assures a separation of 150 meters for following aircraft; a low visibility mode provides a 300meter separation between aircraft. The 150-meter block length was selected because within this distance any aircraft taxiing at a speed of 40 knots can be brought to a full stop at an acceptable deceleration rate (e. g., a Boeing 747 moving at this speed can be stopped within the block length at a rate of no more than 1.9 m/sec.2 or less than 0.2 Gs). Also, for safety and assuming a worst-case situation, the first block length of each runway may have to be some 345 meters to allow for a high speed turnoff of up to 80 knots and a deceleration rate of no more than 2.5 m/sec. 2. The point is, according to Philips' research, the recommended block length of 150 meters is not necessarily a hard fixed value; it sometimes may be altered depending on the actual situation and thus the block may be shorter at junctions or longer at run-up points.

Two other points that must be considered and allowed for in the system design, he asserts, are the entry and exit of authorized motor vehicles and the assurance of disclosure to the controller of the presence of unauthorized vehicles on aprons or taxiways. Philips' proposed system design employs centerline lights of sufficient intensity to permit safe taxiing in visibilities down to 100 meters. The taxiway area is divided into blocks of at least 150 meters, considered the minimum safe separation between taxiing aircraft. Provision is made, however, to move back or alter the last block boundary to accomodate a large number of queuing aircraft near the run-up area.

As a result, provision is made to recognize these, towed aircraft, and emergency vehicles. And, for the latter, provision also can be made for their guidance should the need exist.

Each block in the taxiway is bounded by a pair of inductive loop detectors and a single bar of red lights imbedded across the runway (Both centerline lights and the red lights are of similar construction). The loop detectors in a number of sequential blocks are connected to an "outstation" that controls the switching of lights and continuously checks by internal logic the status of each block as to its condition, either "free" or "occupied". All the outstations are connected together for the transmission of data to a control desk at the tower and each outstation receives commands from the control desk. Depending on airport need or to provide a growth factor, Philips' design permits a two-phase equipment installation. The first or basic system requires manual route selection on a display board with direct transmission of command signals to the various outstations. The second phase or complete system makes use of a central data processor. Thus. a computer would perform optimal routing and drive a video-type situation display providing aircraft identification and position. Because of its proven reliability in other applications, Philips researchers selected the inductive loop detector

To accommodate service and emergency equipment, a special vehicle transponder (called VETAG) has been developed as well as interrogators, to be located at the outstations. Each transponder emits a unique code, identifying a specific vehicle. By using the loop detectors as antennas for the automatic two-way transmissions, vehicle identification can be made relatively foolproof at very low cost, Bloemendaal disclosed. Procedures for handling incoming and outgoing aircraft, as far as the controller is concerned, are slightly different. Depending on the type of aircraft and weather, who makes the turn-off selection and the decision on the entry point into the system for incoming aircraft may vary. However, for outgoing aircraft the controller determines the entry point. When an incoming aircraft leaves the runway in accordance with ground control direction, lead-in lights of other turn-offs are extinguished. If the turn-off point selection is up to pilot decision, all lead-in lights are switched on. As the aircraft enters the taxiway area, it passes over a detector; immediately thereafter, the lead-in lights are switched off and the red crossbar lights at the entry point are switched on, blocking this section to following traffic.

By the nature of the detection system, any vehicle movement on a taxiway will be recognized and at least the control desk would be alerted to the entry of an unauthorized vehicle. But, it was also realized by designers that some special accommodation would be required for maintenance and service vehicles.

Simultaneously, the entry is reco rded visually on the d isplay at the co ntrol desk. The controller then selects the best route and activates appropriate switches if the system is manual. If under computer control, the controller cranks into the system ai rcraft position , identification and destination (identity and destination could already be preset in the system). The cont rolle r checks the proposed route on display and then directs the computer to execute guidance. To the pilot, either procedure resu lts in the same visual di rect ion. He will see the green centerline ligh ts switch on over a portio n of the route directly in front of him. An d, as he moves forward, green lights conti nue to turn on ahead as those behind switch off. At crossings and junctions, the red crossbars protect the route against the unauthorized entry of other vehicles and the same holds true for following traffic within the established separation limits.

IFATCA' 75 MELBOURNE

On approaching the apron, procedures may vary with individual airpo rts. Thus, if the apron layout permits it, a line of steady green lights might be employed leading to a common p osition from which aircraft could be directed by a stand guiding element. For the ou tgoin g aircraft (in the manual system) entry point into the system and the best route are provided by the con troll er at the time of pilot request for taxi clearance. In a Phase II syste m, this data may be preprogrammed and the controller merely inputs airc raft identity into the compu ter. Whe n an aircraft reaches the run-up area, th e pilot may be informed that control has been tran sferred thro ugh use o f a flashing last red crossbar. O r, in a queuing situation , the last crossbar may be successively moved back as each airc raft is acco modated and co ntrol is transferred. A va ri ety of features already are being considered by Ph ili ps for use in th e system to handle special situatio ns. Oth ers could readi ly be added, accordin g to Bloemendaal. Fo r example, should an ai rcraft not follow direction and pass ove r a lighted red cross bar, center-lin e li ghts ahead o f that ai rc raft would begin to flash. A simil ar approach would be used to a lert an unauthorized motor vehicle enterin g th e system. A t the sa me time, a warning light would alert the contro l desk; should he consider the situation an emergency, th e cont rol ler cou ld activate a switch th at overrides all previ ous co mmand s within the system, lighting all red cro ssbars and bringing all traffic to a halt. At peak periods when the system goes into its maximum capac ity m ode, o ne b lock imm ed iately ahead o f th e taxii ng aircraft is conside red occupied: the second block ahead wil l have its cen terline lights on and is reg arded as ,, rese rved " . Thi s space rese rvation, however. is intended as a provisional occupancy that ca n be altered to accommodate another aircra ft assuming a higher priority. This could occur if one ai rc raft is travelling at a consistently higher rate, overtakes the first aircraft on a paralle l taxiway and will reach a junction to crossover or turn well ahead of the other aircraft previous ly reserving that blocked s pace. As a result, the centerline lights in that block would be extinguished and the crossbar red lights switched on at the block entrance. Th is procedu re perm its a pilot space to adj ust speed to varying c irc umstances whi le at the same time permitting the controll er o r compute r to red esig nate priorities according to th e traffi c situatio n. Bloemendaal stresses that a pri ncipal attribute of the Phi lips d es ign is th at both pi lot and con troller have an

Civil Ai r Operations Officers' Association of Australia P. 0. Box 789F, MELBOURNE, 3001 PHONE : 67 5661

impression when using this system that procedures are similar to those used now. Yet, both are relieved of unnecessary voice communications. Early Philips studies showed that a majority of pilots polled prefer lights that roll-on rather than a static line. Also, there was an admitted natural tendency of pilots to slow down while taxiing whenever there was an uncertainty concerning the position of other aircraft. Bloemendaal feels that pilot confidence will result from the experience of

following a "freelane". In turn, this should expedite taxi procedure and aircraft movement, he declares. Of importance to airport officials are the cost aspects of such a system. Bloemendaal asserts that if one accepts the inevitability of centerline lights on the taxiways of most airports in the future, then the installation of the additional equipment for movement control would be relatively modest - particularly if both are introduced at the same time. (Airport World)

SID

By Capt. Bernard Wohl

Is the Standard Instrument Departure Being Used as it was Intended?

An Acronym meaning "Standard Instrument Departure", SID is defined in the Airman's Information Manual as a preplanned coded Air Traffic Control IFR departure routing, preprinted for pilot use in graphic and textual or textual form only and has been established at certain airports to simplify clearance delivery procedures. It would appear that one of the real benefits of SID departures would be in the alerting of the pilot (of high performance aircraft in particular) as to what routing can be expected to comply with immediately after takeoff. This would preclude him from having to display the standard en route or local area chart, and as some pilots do, clip, paste or insert it into some crevice in the instrument panel. Because of the size of these charts, they present something of a challenge to the pilot as to where best to place them for quick reference. (I work for an airline that is kind enough to install small permanent clipboards for use by both the pilot and the copilot, to hold en route and approach charts). Airlines, business aviation and general aviation spend a lot of money obtaining and maintaining currency of SID data. Pilots diligently devote time inserting this material in their en route and terminal flight manual. Dispatch and operations personnel have modified their flight forms and trained their personnel to properly process and handle the requirements dictated by a SID request. Air traffic personnel are uniform and precise in including the coded SID when applicable in the predeparture clearance issued to the pilot; in most cases prior to the time he starts his taxi to the active departure runway. A typical SID requires some degree of studying and orientation. Kennedy lnt'I. has seven of them. San Francisco has nine in use. Rochester, N. Y. has one, which seems logical as it is in an area not too congested. But on the other hand, St. Louis lnt'I., which is situated in a fairly high density airport area and with many more aircraft movements, and located near the hub of the transcontinental, regional and local airways (all crisscrossing each other), had no published SID as of this writing. Honolulu Airport has nine SIDs. Chicago's O'Hare, the world's busiest, has one common SID departure for all runways. Let's consider how a SID can work as seen from the cockpit. We'll asume the pilot and copilot have just received their abbreviated airway clearance. (We will consider an aircraft at JFK. departing for a Caribbean destination.) The pilot has filed and received a clearance: "You are cleared

to San Juan via Jones Beach Three Departure and then flight plan route." Both pilots take out their Jones Beach Three SID chart and study it. They set their altitude reminder to the first altitude restriction, tune in the appropriate VOR frequency and set in the proper radials for altitude crossing and heading change cues. They discuss what data will be depicted on whose flight instruments depending on which pilot will be making the takeoff. Usually the pilot not making the takeoff will repeat the SID departure procedure to the other just prior to taking position on the runway to eliminate any misinterpretation. Picture, if you will, these two pilots shortly after becoming airborne, with their minds and reflexes programmed to execute a Jones Beach Three Departure as directed. Imagine the consternation when they suddenly receive the following change in clearance: "Turn left to a heading of 180Â° for radar vectors and climb to and maintain 5,000 ft." All the effort and time spent in preparation for the SID seems for naught and on some occasions is quite frustrating. This aggravating occurrence is not a rare or occasional happening. On the contrary, it is more the norm than the rarity. The initially conceived concept of SIDs was to: Reduce radio telephone verbiage. Simplify transmission of terminal departure procedures. Expedite departure traffic by the development of SID routes. Reduce cockpit workload thereby enhancing flight safety. The air traffic controller is the only one who has the big picture in front of him at any given time, observing the aircraft and the total traffic situation as it then exists. And there is no question but that the controller is doing his best, what with the equipment and know-how he has available to him. SIDs at the outset appeared to be a good approach to the problem of relieving some of the workload from both the controller and the pilot. But when we think of Nandi Airport on Fiji Island with four SIDs, and (again) the world's busiest airport with one SID - and the many clearance changes after takeoffs, issued by departure controllers at many airports - we begin to think twice. Maybe the SID concept deserves to be re-evaluated as to its merit and effectiveness, and as to whether it is really being used as it was intended. (Airport World}

Maastricht U.A.C. First European Air Traffic Control Centre By Dr.-lng. Hansjiirgen Frhr. von VILLIEZ Director of the U.A.C. Maastricht

Why European Air Traffic Control? The work directed towards the setting-up of a supranational air traffic control system is understandably still little known to the public at large: even many for whom the aircraft is a customary means of transport know little about what goes on behind the scenes to ensure the safety of air traffic. More than ten years ago six countries (Belgium, the Federal Republic of Germany, France, the United Kingdom, Luxembourg and the Netherlands) decided to work together to promote the safety of air traffic on a European basis and for this purpose they set up the Eurocontrol Agency. In 1965 the Republic of Ireland acceded to the Eurocontrol Convention, and at present Spain is seeking membership of Eurocontrol. In addition, agreements for close technical cooperation have been concluded with other European States and with the FAA of the U.S.A. The demands on an effective air traffic control system both today and in the foreseeable future are determined mainly by a high overall volume of air traffic and by the requirements of the different airspace users which in some respects are extremely varied. The differences between civil and military air traffic frequently give rise to incompatible demands; this is especially so in very confined airspace, such as our particular region. Although as recently as 15 years ago it was easy to separate these two types of airspace users on account of the very different performance characteristics of the aircraft in question, this is no longer possible today. Since the introduction of civil jet aircraft (1958) the higher flight levels above 20.000 ft (~ 6.000 m) are even preferred particularly on account of the more economical operation of jet engines at these levels. The 20.000 ft boundary line between upper and lower airspace has since lost its practical and operational justification. I mention this because Eurocontrol was made responsible for the upper airspace. since it is mainly here that fast cross-frontier jet aircraft operates. If we consider the usual cruising speeds flown today, i.e. approximately 850 Kilometres per hour, in relation to the geographical distances of the route segments in European airspace - and in particular the airspace of the BENELUX countries and the FRG viewed along its eastwest axis - it becomes clear that a control system must extend beyond national frontiers if it is to meet the present and future requirements of air traffic. This fact, which was first discussed in 1958, finally resulted in the Eurocontrol Convention relating to Cooperation for the Safety of Air Navigation. This was signed in 1960 by the above-mentioned founder States and formed the keystone of a European air traffic control system. With this simplified account one must not, however, lose sight of the fact that for the States in question economic considerations have played a part and will certainly continue to do so. Finally, it should be noted that the capital expenditure required for a modern control centre

with an ATC system geared to the future is in the region of DM 120 million; this represents a financial burden which can be more easily borne by a group of States than by a single State.

The Eurocontrol Centre at Maastricht The operational objective is an air traffic control system providing positive control for all flights in the upper airspace of the BENELUX-North Germany region with a minimum of restrictions. To this end the Maastricht Control Centre will offer air traffic services, irrespective of weather conditions, for all airspace users complying with the rules laid down by 1.C.A.O. (International Civil Aviation Organisation). This category of airspace user is designated General Air Traffic (GAT) in contradistinction to military flights not complying with l.C.A.O. rules (Operational Air Traffic = OAT). However, the competent bodies are already taking steps to ensure that the control of OAT by military services can also be effected from the Maastricht Centre in due course. The existing airspace structure (sectorisation) is determined by a network of airways and the traffic along these airways, i.e. the work load generated for the sector control team by the traffic volume. The increase in the capacity of the overall system is to be achieved by two means: a) division of the work into a planning and an executive control function with a view to the extensive conflict-free planning of traffic flow so that only a small number of cases that cannot be dealt with in this way or unforeseen traffic situations are left to be solved by executive control; b) extensive use of a powerful data processing system which collects and stores all the information required for traffic control and provides a synthetic picture of the air traffic situation. This system makes all the necessary calculations and comparisions and distributes the results in such a way that each air traffic controller has the right data displayed to him at the right time at the right place. (This system, which is supplemented by comprehensive data display equipment, is called MADAP (Maastricht Automatic Data Processing and Display System). Setting aside the large number of aeronautical/navigational and meteorological data inputs, the main data sources may be said to be the following: Flight plans, which must be filed for all intended IFR flights prior to take-off and Radar, radar data being transmitted from one or more radarstations to the Centre, thus providing a picture of the current traffic situation at any time.

It goes without saying that provision must be made for radio links between controllers and pilots for the trans-

EUROCONTROL M a astrich t A ir T raffic Con tr ol Cen tre.

mi ssion and c o nf irma tion o f control instruct ions, as we l l as teleco mm unica tion s (tele x-telep ho ne) fo r the exchange o f data b etwee n co ntro l ce ntres. If w e take a c loser look at the process ing o f data fro m th e t wo m ain sou rces mentioned ab ove, it will b e c lear t hat the f irst op eration al phase (MADA P A) alread y o ffe rs a wide rang e o f functions.

Flight Plan Processing T his sta rts w ith logical and syntactical ch eck ing of the in c o mi n g d ata, which are first of all sto red . A sc reenin g opera tion fol lows to extract the in formation w hich is o f sig nificance for the M aastr icht Cen tre. Whe n flight plan data are ac tivated the ai rcraft's c all sig n is displayed to the first contro l ler res pon sible for the fl ight, a reply code e nabl in g rap id and re liab le identificatio n of the radar echoes is assigne d to the airc raft con ce rned, and the flight progress str ips are printed for all the secto rs affected on the fl ig ht in q uestion. In ad di tion, the messages fo r the mil itary ATC units op erati ng in the same control area are compiled an d au tomatically transmi tted. A lso o f great importance is th e ca lc ulation of the flight path and the associated ti mes for each flight, taki ng i nto accou nt the airc raft performa nce characteristics and t he preva iling me teoro logical co nditions. The results e nable c ontin uou s compar isio n with the ai rcraft posi tion as transmi tted by radar as well as extrapo l atio n of the remainder of the ro ute to be flown w ith the associated times. which is also extremely useful for detecting potentia l confl ict situat io ns.

Radar Data Processing Th is beg ins practical ly on th e radar site. The signals from the p ri m a ry and seco ndary radars are subjected to d ig ital target detection, after which target messages are co mp iled by a com pute r. T hese messages are then transmitted o ver te lephone or data lines to the Maastricht Centre . Coverage for th e a i rspac e over t he BENELUX countries is provid ed by the B russels and Lee rdam radar stations , the latter b ei n g si tuated in the centre of the Netherlands. These facili ties are d upl icated to e nsure the necessary operational rel iabi l ity. Depe ndable coverage of the north German airsp ace w il l be provided by the Bremen and Hann over radar stations. In t he Cen tre's MADAP (computer) system each target echo is fi rst of all t racked per individual radar. T he val ue of this track i ng l ies ma i nly in the conti nu ity of the flight path, and in th e case of primary radar targ ets it facilitates maintenance of t h e aircraft's identity. For aircraft equipped with t ransp onders and able to transmit an individual code thi s tracking is triggered automatically, but for al l other ta rgets it has to be initiated manually. In orde r to precl ude any confusion when an ai rcraft passes from the area of coverage of one radar into that of the adjacent radar a multi-radar track ing program is available - an important facility where the coverage areas ove rlap. T his makes it possible for t he optimum section of the overall p ictu re of the air traffic situation to be selected at t he radar con trol ler pos it ion , irrespective of the coverage of the individual radar stations. In addition, the aircraft identity is maintai ned and the various errors are smoothed

EUROCONTRO L A i r Traffic Control Officers at work.

Ph o tos A EG-T elefunken

Flight plan and radar info rmation are c orrel ated autom atic ally in the MADAP system in so far as the targe t ca n be un ambiguou sly assoc iated with the re levant flight plan by means of an individu al (4 d igit) rad ar reply code. Th is is mostly the c ase. Th e oth er cases can b e coo rdina ted manually. Any emergencies b e tween the actual position o f the airc raft (determ ined by radar) and th e positio n as co ntinuously calculated on the b asis o f the flig h t pl an are therefore sp eedily detected . Acco rding to th e extent o f th e deviation observed, the n ec essary amendments to th e fl ight plan are e ffected either automa ti cally o r by the con trolle r respo nsible; the latter proced ure is applied to en sure tha t every m ajor co rrection rece ives the c ontroll er' s undivid ed attention.

Present and Future

An i mpo rtant featu re of the M ADA P system is the representation of the air posit ion in synthetic f orm on graphic display screen s. O ur photo shows such a graphic air picture ... w ith the aid of which movements in air space can be followed c ontinually

Th e system o utl ined above is in op era tion since 1 Oc tob e r 1973. It is being used initially fo r air traffi c control in th e upper a irsp ace ove r Belgi um and Luxe mbo urg. Th e n e xt importan t step towards extend ing th is C entre's area o f responsibil ity is p lanned for early 1974 w ith th e takeove r of ai r tra ffic services in the uppe r ai rspace o ve r No rthe rn Ger m any (th e upper ai rspace ove r the So uth ern p art o f th e FRG w il l b e co n trol led wi th effect from 1976 by the Euroco n trol Cent re a t Karls ruhe). Another important dec is ion provid es fo r th e co-location of the c iv il and milita ry ai r traff ic services fo r the North German upper airspace a t the M aast ri cht Cent re . The target date for this is 1 Octo be r 1975. Subsequ ently, th e Cent re is to assume respo nsibil ity fo r th e upper airspace over the Ne the rlands. The develop ment of th is fi rst Eu rop ea n ai r traffic control centre in l ine w it h the pol iti c al decision s take n to date w ill then b e complete. The German ver sion of th is arti c le was first published in the June 1973 i ssue o f EUROPA VERKEH A

News from the Federation Recent Press Releases and Announcements The following press release was issued by the Board of Officers at their meeting in Geneva on 17September1973: "IFATCA is in contact with the German Ministry of Transport and the Verband Deutscher Flugleiter and sincerely regrets that there has been no solution to the present problem. It is unfortunate that the Controllers have not achieved professional recognition and that, so far as we understand, they have not been invited by the Aviation Ministry to discuss vital matters of the profession. The proposals of an Expert Committee established by the German Government to examine the problems within their ATC system (e.g. Schlieker Committee) in 1971, have not been realized and until some definite steps are made to accomplish this, there can be no progress on either side. IFATCA suggests that the whole question be reviewed immediately with open mindedness with the object of restoring normal Air Navigation facilities in Germany thereby relieving the pressure on controllers in neighbouring countries". The following is the text of an announcement by the Canadian Association, released on August 15 1973: "The National Executive of the Canadian Air Traffic Control Association Inc. views the recent action of the Israeli Government in forcing down an international airliner as an incident which demands the strongest possible protest by all air traffic controllers. In light of the position taken on this subject by the International Federation (IFATCA) at several annual conferences and re-emphasized in Iceland only last spring, the Executive considers that IFATCA should do what is possible within the limitations imposed on controllers to publicize its condemnation of this illegal action by a national Government. Accordingly, the Executive proposed to the National Council, which voted unanimously, that CATCA recommend to IFATCA that it notify the Israeli Government that by their action they have forfeited the honour of hosting IFATCA '74, which should be re-scheduled for another location. At the same time, a press release was issued by the National Office announcing CATCA's position and its recommendation to IFATCA. It should be noted that no criticism of the Israeli Association is intended or implied. However, the Council considers that, however inconsequential such action may be to the Israeli Government, it may serve as an indication of the Federation's unity in pursuit of its published aims." The following Telex was received from the Israeli Association on the 23rd August, addressed to the Executive Secretary: "The Air Traffic Controllers Association of Israel, being a member of the International Federation of Air Traffic Controllers Associations does not support actions like the one taken place on August 10th 1973. This Association has taken part in discussions concerning actions of sabotage or air piracy in the skies land vigorously opposed them. The position taken on this subject by the International Federation at several Annual Conferences and in May this year in Iceland is that every

Member Association should do what is possible within the limitations imposed on air traffic controllers to publicize its contempt of such acts and to protest such action. The Israeli Association could not have prevented the action taken on August 10th, in spite of its vehement opposition and policy adopted. This press release should be circulated to all 38 Member Associations by the Secretary." Editor's Note: The Executive Board of IFATCA, during its meeting in Geneva from 17-19 September 1973, has carefully considered the various representations submitted by a number of Member Associations, both for and against the holding of the next Annual Conference in Israel. The representations included a telegram from the Hungarian Association strongly opposing the venue of the 1974 Conference, which was handed to the Officers while they were examining the issue. The Board decided to go ahead with the holding of the 1974 Conference in Tel Aviv, as it was constitutionally not possible to alter a decision which was confirmed twice by the representatives of Member Associations at successive Annual Conferences. The Professional Air Traffic Controllers Organization issued this news release from its Washington, D. C., Offices, on the 2nd August 1973: .,The President of the Professional Air Traffic Controllers Organization (PATCO), John Leyden, today called for the reinstallation of PAR (Precision Approach Radar) at every major Tower in the United States. This comes as a direct result of the crash of a Delta DC 9 airliner, July 31, at Boston Logan Airport, which resulted in the death of 88 passengers. PAR radar gives the monitoring controller precise altitude and course information in the Tower until virtually the moment the aircraft touches ground. If such radar had been operational at Logan, controllers probably could have been alerted to the fact that the aircraft was in trouble and thus they might have been able to avoid the crash. Although initial findings indicate that there was no air traffic controller error involved in any way in the accident, PATCO has dispatched one of its accident investigation specialists, Eastern Region Vice President John Lapine, to the accident scene. Lapine will serve on the National Transportation Safety Board investigating team which is looking into the accident, of which there was only one survivor. Newspaper reports of the incident indicate there was a ten minute lapse of time before notification was made that the aircraft had actually crashed. Leyden explained that from their position in the Tower, controllers could not actually see the aircraft landing, since the airport was fogbound, and the aircraft was not displayed on the Tower radar. The controllers, therefore, had no way of visually knowing that the aircraft had not made a safe landing. PATCO is on record for the past four years of attempting to get PAR back. Other airplane accidents which have occurred might possibly have been avoided had this radar been in use; the most notable was the crash of the Japanese Airline DC-8 into the San Francisco Bay three years ago. If this radar were operational, controllers would be in a position to monitor each aircraft's entire approach to the 33

The Meeting of the Executive Board: from the left : Messrs. Guddat. de Boer, Harrison. Monin. Meyer. Gubelmann and J6nsson.

airport and more specifically, i n bad weather if they observed an aircraft off course o r at an unsafe landing altitude, a verbal warning could be issued to the pilot immediately and he could then take the necessary corrective action. PATCO represents all of the more than 15,000 air traffic controllers w h o monitor virtually all ai rcraft flying in thi s country."

Meeting of the Board of Officers, Geneva, 17- 19 September 1973 All Officers and the Editor were present when the Meeting opened under the chairmanship of President J eanDaniel Monin at 8.30 a. m. on the 17th September 1973. The work of the Standing Committees, in particular, was minutely examined and the beneficial effect of the changes in the framework of the Executive Board, recently adopted. soon became apparent when each Vice-President in turn was asked to account for the work done by these Committees s ince the Reykjavik Conference. In one instance. where it appeared that the Committee in question had become bogged down. ways and means were discussed to lift the Comm ittee out of the morass. The Officers examined such questions as : the representations made by the Hungarian , Canadian , Netherlands, South African . Surinam . and other Associations regarding the venue of the 1974 Conference : Reports submitted by the Regi ona l Liaison Officers : the disputes in which some Member Associations were involved w ith their National Authorities . a number of issues arising from the Reykjavik

Conference ; l iaison w ith Corporation M em bers ; preparations which are in hand for the organising of th e 1974 Conference ; IFATCA to make some effo rt to influence those States which have not yet ratified the Tokyo, Hague and Montreal Conventions ; nominations for the el ectio n of the Board o f Officers; co-operation with International Organizati ons (ICAO , ILO, IFALPA, IATA, IACA, IANC, WEAAP, IAASM, SATCRA); and a long list of other issues. The full minutes of the meeting have been distributed by the Execut ive Secreta ry to al l Member Assoc iations in the usual way. During the meeting, one press re lea se was issued (on the dispute between the German Assoc iat ion and its National Autho rity): par t of one of the sess io ns was telev ised by the Swiss Television Service ; radio- and press coverage and interviews we re recorded by a number of news med ia. and a press conference was held afte r the meeting ended on the 19th September . The Offi cers are indebted for the hospitality extended to them by Rad io-Suisse , Swissair, the Swiss Association. and Mr. and Mrs. J-D. Monin. Finances and the well scatte red hometowns of the members of the Executive permit only two meetings a year apart - of course - from ou r Annua l Conference, but it is felt that in spite of the low frequency of meetings, good progress is maintained in the running o f the Federation. The Board is grateful for the help given by the Icelandi c and South African Administrations which enabled Vice-President 0 . J on sson and the Editor to attend the meeting. The Sp ring meeting of the Executive will take place in Budapest from 6-8 March 1974.

[C13~13.!J±:f 9 C1=3~1~

PROBLEMES

ContrOleurs , ·aer1ens >· : :. , · dans le 111onde entier .

(ML) - Le Comlte exeeutif d e I'IFATCA (Federation internationale des associations de eontrolenrs du trafic aerien). reuni a Geneve depuis Jund! pour examiner Jes problcmes qai se posent dans le . monde aux controleurs aeriens, a termme ses travaux bier. En debut d 'apres-midl, nne foule de Journallstes attendait le president de l'IFATCA, le Genevois Jean-Daniel Monln, pour connaitre l'issue de ces travaux, marquant ainsi l'inter et que la seeurlte nerlenne suscite dans le public· Gageons qu'ils ont etc dei;;us, car rien de scnsationnel n'a filtre de ces travaux. L'IFATCA est une f eder ation d'associations professionnelles qui, si elle ne represente • que " 12 OOO controleurs sur Jes 50 OOO ou 60 OOO qui travaillent dans le monde, n'en est pas moins unique et seule r epresentative. Son role est de promouvoir Ja profession et de chercher a obtenir. d a ns tous Jes pays, la reconnaissance d es particularites de celte act!vite par !'adoption d'un slatut special. alors qu'actuellement, Jes conlr6ieu rs ·s ont le plus sou ven t assimi!es a des employes de la fonction pub!ique, sa ns q_';'alifications ni r esponsabilites particuheres (on a ete jusqu'a Jes comparer a des gardes-barrieres ). L'IFATCA n'est certes pas un !auteur de greves, mais au contra ire un organisme qui r echerche, par l'inst a uration de dialogues. a Jes prevenir, pour que ses objectifs premiers (securite et regularite du trafic) soient realises. II etait done difficile pour le comite executif de l'IFATCA de prendre position sur Jes confllts passes et presents et c'est pourquoi ce n'est qu'avec une extreme p ru de nce qu'un communique a ete redige, relatlf ll la situation en Allemagne. OU la greve du zele s'tHernise, provoqua nt de graves perturbations. L'IFATCA deplore q ue Jes conclusions, deposees par une commission d'experts ins tituee en 1971 par le gouvernement de la RFA, n 'aient toujours pas ete s uivies d'effets et r ecommande que tout le probleme soit immediatcment repris, dans le but de restaurer une situation normale en Allemagne et dans les pays limitrophes forcement touches par le mouvement des controleurs a llema nds. L'IFATCA a note avec satisfaction qu'a Ja suite des nombreuses et vigoureuses critiques emises au printemps dernier lors de !'a pplication du fameu x pla n Clement Marot, subs t!tuanl un controle aerien militaire au contr6le civil,

Jes autorites frani;;aises ont radicalement m odifie ce plan, dont Jes imperfections etaient criantes et dont on ne salt toujours pas s'll porte la responsabilite de la catastrophe de Nantes. Sur le plan suf.sse, a dit M. Monin, ou !'accord de palx du travail a ete denonce par Jes controleurs pour la fin de l'annee. l'espoir est r eel de voir Jes problemes se resoudre par un arbitrage, une tranche discussion ayant pu s'instaurer entre Jes controleurs et leur patron, Radio Suisse SA. En bref, ii taut retenir encore de !'expose de M· Monin que si des revendica-

Reunis

a Geneve pour des questions importantes

Les controleurs aeriens ne veulent plus etre pris

pour des gardes-barrieres ! Employes d es gouvernements, souvent confondus avec Jes condu cteurs de locomoti\'es ou Jes gardes-barrieres ou meme avec Ies pllotes de llgne. C'est ainsi que se presente nt, avec un 1>eu d 'amertume, les controleurs aericns. Pourtant cette profession est tres difficile et elle meriterait d'etre reconnue comme telle. C 'es t !'impression qui ressort d e la conferen ce d e presse qu'a t enue mercredi apres-midi le comite executif d e l a Federation internatio nale des controleurs du trafic aerie n. Ce d ernier etait en e ffet reuni a Geneve d epuis trois jours afin de discuter d es problemes actuels d e la profession. Tout n e va pas tres bien dans le meilleur des m ondes : greve du zele en Allemagne, menaces e n Suisse pour ne citer que Jes principaux problemes.

Les controleurs du ciel ont fait le point

<< DEFENDRE LA PROFESSION>> Le comi te executif de la F ed er ation internationalc des associations de contro!eurs aer iens (IFACTA) vient de sieger pendant trois jours a Geneve. Lors de cette seance de comile, Jes travaux furent diriges par un Suisse, M. J ean-Daniel Monin, president de Ja Federation. ll a rappele a !'issue de ces travau x q ue la Federation reunit quelque 12 OOO controleurs aeriens de 38 pays. 11 mon l ra la part importantc qui est celle de ces controleurs dans la secu ri te aerienne. Toutefois, dans la majorite des pa.vs. Jes contr6leurs ne sont pas reconnus officiellement. Parfois, ils sont des fonctionn aires gouvernementaux ou affilies (comme dans notre pays). Aussi la F ed eration a-telle comme objectif principal de faire

tions apparaissent sporadiquement i;;a et Ja, revelant Jes problemes, c'es t le monde entier qui est concerne car ce n'est pas par des mesures a !'echelon national que les difficultes nees de l'accroissement prodigieux du trafic pourront etre aplanies. Un jour v iendra peut- etre ou Jes m ethodes et moyens seront normalises dans le monde entier. Mais ce n'est pas pour demain. D 'ici la, Jes problemes croitront en m em e temps que le trafic et si Jes solutions tardent trop, l'aeronautique se trouvera devant une impasse au moins aussi alarmante que la crise naissante du petrole.

reconnaitre officiellement la p rofes~i on . En Suisse, ii faut etre en possession d 'une maturite federale, ou son equivalent, avant de suivre une formation de quatre ans. Les quatre buts essentiels de la profess ion sont : assurer la securi te aeriC'nne ; promouvoir la regularite du trafic aerien ; maintenir le ni veau q ualilalif des membres ; defendre la profession. En ce sens, on tend, actuellemen t. a ohtenir une diminution du nombre d'heures de travail. G. G.

En ce qul concerne la Suisse, l'objet du litige est l'abaissement de !'age de la r etraite et, en relation avec cette reve ndication, le relevement des salaires. Les negociations durant depuis quatre ans sans resuitat, les controleurs suisses ont denonce la convention de paix du travail qu'ils ont a.vec Radio Suisse, Ieur employeur, avec effet a fin decembre. Ils pensent neaomoinS a rriver a un resuitat avant cette date. En ce qui concerne l'Allemagne, l~s controleurs n'arrivent pas obteror d'etre r econnus professionnellement par les autorites et ces dernieres ne veulent pas discuter des principaUX problemes de le ur metier. La situation semble done sans issue, ce qui ne facilite pas le travail des con troleurs des pays voisins de l' Allemagne sur lesquels une partie du trafic aerien est detourne. Il est interessant de rappeler que pour les contr6le urs aeriens la que~ tion salutaire n'est qu' une petite part-1e des revendications, la principale etant le fait d'etre reconnu comme une profession a part. J .-C. P.

The ~ e et i ng of the ixecutive Board was given ex t ensive cov erage in the Swiss l r ess

The Work that goes on behind the Scenes Most members probably know little about the way in which the day-to-day affairs of the Federation are being looked after and how the Officers keep contact with each other, and it is therefore timely to throw the spotlight on the question which is so often asked: what goes on behind the scenes? Is it really possible to run the Federation effectively when its executives are spread right around the globe? The answer, of course, is in the affirmative, and with the exception of the contact between the President and the Executive Secretary, who occasionally talk to each other on the telephone when a matter crops up which requires immediate attention on the part of the Executive Secretary, all other contact is done by letter. With airmail connections as good as they are, letters between the Officers rarely take more than four days and in many cases less; the average time for a letter from the Editor in South Africa to the Executive Secretary in Scotland takes three days. By using "express airmail" it is possible to cut this time down to two to two and a half days. Copies of all letters written by the Officers, or important letters which are received by them, are sent to the President, who is therefore at all times aware of everything that goes on within the Federation. About twice a month, the President writes a circular letter which he sends to all Officers and the Editor. In his letter, after giving a brief overall picture of the Federation's latest spheres of action, he addresses each member of the Board in turn and examines the recent activities of the Officers and the Editor in detail, adding his own comments and suggestions or directives as the case may be. In this way, all members of the Board keep up-to-date with what his colleagues are doing. The President's circular letters are studied closely by the Officers, in particular where they mention their own field of operation, and it is probably true to say that - upon receipt - the Officers first read the portion which deals with their own activities before turning to the rest of the President's comments. Apart from the President, the other Officers, in particular the Administrative Vice-President, on occasion also send similar circular letters to their colleagues, usually starting by giving an outline of their own work first, followed by a brief report on their liaison with the others. The only Officer not sharing in this work is the Executive Secretary, but Mr. Harrison already writes letters and circulates news received by him to the Board members several times a week, at times almost daily. so there is no point in sending circular letters as well. The question may be asked: is the work-load so heavy that all this intensive contact is necessary? The reply is "yes". and perhaps the best illustration of the extent of the work-load is the fact, that when the President returned from his summer vacation last August. he found twenty letters and other communications awaiting his return and requiring his attention. containing two hundred pages. The Executive Secretary's work-load defies most members' imagination. Mr. Harrison very often works a twelve- to fourteen hour day. and he is totally occupied by the affairs of the Federation right through the working week, including Saturdays and Sundays. His correspondence, commitments and tasks on behalf of IFATCA increase steadily. Those who are in a position to call on Mr. Harrison at his home would be well advised to do so. and those who do will 36

have a very informative and enlightening hour or so examining the spaces where the Executive Secretary has managed to store the vast archives, files and other matters which form part of IFATCA's history. How his family puts up with it, is a matter of constant wonder. The whole task has grown into an enormous burden for one man to undertake, and it is only a matter of time, and not a very long time. before another hand will be absolutely needed. Contact between the Executive Secretary and the Editor is especially close. The exchange of news, articles for the Journal and the Circular, everything that comes to hand which will interest members, goes on practically daily. Both officials are continually on the look out how they can make use of the information they receive in the best possible way. Members who spend effort, time and sometimes money to forward contributions, views, ideas, etc. to the Federation can rest assured that no worthwhile contribution will be filed away unused. Everything that comes to hand and is judged to be of interest to members, will be circulated in some way or other. This pledge is given unreservedly. The Technical Vice-President is probably the most travelled Officer of IFATCA. In the course of his duties he attends meetings of other Organisations such as IFALPA, and Mrs. Jonsson has very quickly found out what it means to be an IFATCA Vice-President's wife. Since the Reykjavik meeting, where OJ was elected, she hasn't seen a great deal of her husband. Another Officer whose duties have increased is Mr. Guddat. The distance between the Editor and the publishing house causes some problems, but Mr. Guddat - as the Vice-President directly responsible - has ably stepped in to tie up loose ends with the result that the previous issue of "THE CONTROLLER" (the first after a break of many months) appeared on time as planned.

It cannot be said that the Federation stands still between Annual Conferences. If there are still some who think this way, perhaps the above outline will help to put things into a clearer perspective.

Excursion through Southern Iceland Many of the guests and delegates who attended the 12th Annual Conference of the Federation at Reykjavik in May this year, stayed on for another day to take part in an excursion through a part of Southern Iceland organised by ICEATCA, the Host Association. As in the case of the Conference itself, the excursion was superbly organised in the efficient Icelandic manner which Conference participants had by now come to accept as normal. En route to a small place called "Eden" where a luncheon was awaiting the party, the guiding stars of ICEATCA suddenly decided that it was now enough and that the time had come to throw a spanner in the otherwise well oiled works. One of the coaches carrying the party through picturesque valleys and over fast flowing streams came to a stop in one of these uninvitingly cold looking waterways, and no amount of pushing and pulling could induce the coach to continue on its journey. Our former Editor Walter Endlich, true to Editor's tradition and streams ahead of the newly elected holder of this office, most efficiently succeeded in capturing the scene for readers of the journal. Members who took part in the excursion will no doubt value the reproduction of the fotographs in this edition.

One of the coaches carrying the excursion party is we ll and tru ly bogged down

The o ther coach comes to the rescue but the line sn aps and we are back to square one

Help arrives in the form of a farm tractor, and the party is soon on its way again

Cover Design for "The Controller" The Board acknowledges with thanks receipt of a number of designs for a new cover page for "The Controller", which have been submitted by a number of Associations and individual members. The designs were examined during the autumn meeting of the Officers in Geneva, but no decision was made, and the competition is still wide open. Further entries will therefore be gratefully received. May be it will eventually be necessary to get some professional advice on this matter, but it would be nice if an original idea from one of our members could be adopted.

From the CA TCA Newsletter, September 1973

We have contacted the Ministry of Transport and requested a NOTAM advising pilots to let the arrival controller know well in advance if a landing clearance with less than a certain number of miles behind a departing "heavy" is not acceptable. Both the Canadian Airline Pilots Association and the American Airline Pilots Association have also been requested to help prevent such unexpected "go-arounds", which can play havoc with the arrival controller's approach sequence. Nevertheless, we can expect an increase in requests by pilots for provision of separation between their landing aircraft and a departing "heavy" jet, but we certainly hope such requests will be made known to the controller before the landing aircraft, as has happened, is by the marker inbound and the "heavy" has started its take-off roll.

Wake Turbulence and The Heavies In some recent instances airline pilots have refused to accept a landing clearance when using the same runway as a departing "heavy" jet when less than 5 NM separation existed. When questioned, pilots referred to the crash of a DC 9 landing behind a DC 10 on a touch-and-go at Fort Worth, Texas, U.S.A., last year, and revealed that they were under the impression that the DC 10 was taking off on initial departure and not after a touch-and-go. The cause of this accident was determined to be the wake turbulence caused by the DC 10 on the landing final approach portion of the touch-and-go.

Iceland Air Traffic Controllers won't obey Order REYKJAVIK - Iceland's air traffic controllers yesterday refused to obey a Government order not to give flight control instructions to British Nimrod reconnaissance aircraft. A spokesman for the controllers said stopping contact with the British planes would be a violation of international rules and would constitute a severe danger to civil aviation in Iceland. Communications Minister Bjorn Jonsson, who ordered the ban as part of Iceland's cod war with Britain, said he was astonished at the controller's refusal. (Globe and Mail, 15/9/73)

Letters from Readers Subscription for "The Controller" Many thanks for sending me a copy of your IFATCA Circular which I found interesting and very readable. I was glad to read that "The Controller" is to be published again and hope to take out an office subscription. Presumably we will be told how to do this through the medium of the U.K. Guild Bulletin or similar? - D.W.H. Davies, Head of Service, EUROCONTROL Regional Service for Ireland and the United Kingdom. The Board considered the matter of a subscription service for "The Controller" at their recent Geneva meeting. W.e.f. the 1st January 1974, a year's subscription will cost OM 10.-, and individual copies OM 3.- each. Orders can be placed with S.C. II, or with the Publishing House of W. Kramer & Co., Frankfurt, or with any of the Officers of the Federation. Subscriptions are payable in advance, and invoices for individually ordered copies are sent out after the Journal has been despatched. - Ed.

IFATCA Technical Working Papers May I. please, suggest that IFATCA consider to print all their current technical working papers to be available for

sale at small cost, e.g. $ 5.-, to ATC and Non-ATC parties interested in the Air Traffic Controller's opinion. The papers could be in the form of a brochure. I think that there could be quite a number of potential buyers, who, not knowing of individual papers or not wanting to deal with individual papers, would be interested to get a more over-all view of IFATCA's ideas on the different technical subjects. - Frank W. Fischer. The Board of Officers discussed this matter at their meeting in Geneva last September. Mr. Fischer's suggestion carries merit and the Board is appreciative of the thought behind it. However, in the absence of an adequate market survey, the financial implications for the Federation could be very unfavourable in the light of the present-day high cost of printing and distribution. "The Controller". "IFATCA Circular" and "Newsletter" already tax the finances of IFATCA greatly, and it is not possible to add to these costs by embarking on another venture which might prove unprofitable. In any event, individuals who want to order specific copies of working papers can do so through the Executive Secretary, and all Member Associations hold copies of every IFATCA working paper which has seen the light of day. Under the circumstances, the Board regrets that it can not undertake this project. - Ed.

Ground Based Collision Avoidance By Willard C. Meilander*)

Much discussion has taken place, many papers have been written, and many systems devised and tested for an Airborne Collision Avoidance system (ACAS). The techniques involved are either passive or active, noncooperative, or cooperative. Conclusions have been drawn that only the cooperative systems will offer a good chance of providing sufficient avoidance information for the pilot. In the case of ground based Collision Avoidance Systems (GCAS), much less has been written. The techniques are less discussed, and the requirements seem to be less well defined. In fact it seems that the criteria for acceptable performance are substantially different than in the airborne ACAS. The real problem for both GCAS and ACAS seems to be ~ne of maintaining assured separation. Separation standards are defined for radar surveillance of controlled traffic. However, separation standards for VFR/IFR and VFR/ VFR traffic are not established. This paper suggests that criteria used for the Knoxville experiments on GCAS be considered also for the terminal environment. These criteria, based on radar position and Mode C altitude, include three types of conflicts and a warning time, which will permit avoidance action to be effected. The conflict types are: 1. Less than three miles lateral and less than 500 feet altitude separation or unknown altitude separation during the prediction interval, between controlled aircraft. 2. Less than 1 mile lateral separation during the prediction interval between controlled and uncontrolled aircraft. Altitude separation is unknown. 3. Less than 1 mile lateral and less than 500 feet altitude separation during the prediction interval between controlled and uncontrolled aircraft. The GCAS requirement is threefold: 1. To provide detection of intrusion into the above separation distances. 2. Determine a satisfactory resolution of the situation. 3.

Provide the information in sufficient time that proper action can be taken.

From the air traffic controller's point of view, desirable characteristics of a GCAS are: 1. All potential collisions are detected in sufficient time for proper corrective action. 2. False alarms are minimized or nonexistent.

In meeting these requirements it is necessary that the system develop the tracks for all aircraft within the region being controlled. These tracks must be available whether the aircraft are equipped with transponders or not; i. e., both primary and secondary radar information must be used for tracking. Track drop must be reduced to near zero. Tracking, then, becomes very important for conflict prediction. Some of the significant considerations in tracking are: 1. Tracking should be provided in 3 dimensions whenever possible. 2. The velocity vector (on which prediction should be as precise as possible.

is based)

3. Manoeuvres, both horizontal and vertical, should be detected as soon as possible. 4. Track drop and swap should be minimized.

Tracking Three dimensional tracking is essential for detection of conflict with a minimum false alarm rate. Several tracking schemes can be considered. Tracking in radar coordinates (rho, theta) provided a relatively simple means of correlating radar data With track data. Velocity is maintained in terms of range and azimuth rates. These must be converted into ground coordinates to obtained ground speed. Further the rates change very rapidly as the aircraft approaches the antenna. Aircraft at the same range and azimuth may have significant lateral separation because of differing altitudes. Tracking in ground system coordinates overcomes, to a certain extent, the difficulties encountered in the radar coordinate tracker. Two approaches to ground coordinate or X, Y tracking can be considered. One in which the radar slant range is considered to be the ground range and one in which true ground range is developed. Most systems in use today are of the first type. The difficulties in this approach are similar to those encountered in the Rho-theta tracker. The indicated ground speed X. Y changes as the aircraft approaches the antenna and approaches zero when the aircraft is directly over the radar. The error in velocity adversely affects correction prediction of future position. Like the Rho-theta tracker, considerable lateral separation in the ground plane can exist between two aircraft that have the same indicated X. Y position because of differences in altitude.

3. Suggested resolution manoeuvres are: a. Accurate and safe. b. Minimize stress on the aircraft and passengers. c. Minimize changes in flight plan of controlled traffic.

True ground plane tracking uses altitude information to correct the slant range measurement to ground range. Thus. true lateral separation can be obtained.

*) W.C. Meilander is technical director for ATC systems at Goodyear Aerospace Corporation. He has been active in collision avoidance systems studies for the past ten years, and was responsible for the recently completed work on ground based CAS at Knoxville, Tenn. His background includes 30 years of experience in development of shipboard and aircraft fire-control systems and analog and digital components and systems. He is currently responsible for the development of applications of associative processing techniques.

Tracking in altitude is essential to minimize false alarms. Altitude rate must be developed. It is just as important as ground velocity in conflict prediction. This can be seen by considering 2 aircraft on a collision course in the ground plane, but separated 6000' in altitude. If one is climbing at 3000'/minute and the other descending at the same rate. they will collide in one minute. What seemed a very safe

condition one minute ago based on altitude separation alone is not really safe. Fortunately, altitude rate developed from Mode C data is very good. Experience in the Knoxville program indicates that statistical 1 sigma altitude rate errors of less than 200'/minute can be achieved. Two approaches to improve sensor accuracy and thus better tracking involve the use of existing multiple radars. In the simpler technique three range measurements are used to obtain by trigonometry a single position report. This report virtually eliminates errors due to azimuth uncertainty. The second technique produces even better accuracy by using both the range and azimuth measurements from 2 or more radar sites. A further advantage of either of the methods is that a measure of altitude on nonMode C equipped aircraft is obtained. The accuracy of altitude information increases when the aircraft is higher and when it is closer to the radar sites. While the allowance for altitude measurement error in this method is much greater than for Mode C derived data, the information can achieve substantial reduction in false alarm rate. A significant advantage of this multi-sensor approach is the redundancy of information available. Thus, the likelihood of missing a report on any scan becomes very small. This approach also practically eliminates the secondary beacon tracks due to reflection and ring around. Another point of interest is the fact that many high density regions have multiple radars in today's systems but do not use the information available. Voluminous radar data is received and a lot of it is discarded. It's been discarded because the computing capacity to use it has not been available until now. To sum up the subject of tracking: 1. Three dimensional tracking seems to be a requirement in today's denser areas. 2. Better sensor accuracy will produce more accurate and reliable track information. 3. The use of both primary and secondary returns will result in more reliable tracks. 4.

Multi-sensor systems provide redundancy of information, greater accuracy, altitude information for non-Mode C traffic, and virtual elimination of false tracks.

Another significant factor in conflict detection is the projection of flight when the aircraft is turning. Techniques are available for use in tracking algorithms which detect aircraft turns. However, the detection occurs after the turn has started. The time for this detection is a function of turn rate, and is more rapid for faster turns# Since the aircraft track is more uncertain when the aircraft is turning, the projection volume must be increased in the direction of the turn to be certain that a potential collision is always detected.

Conflict Resolution When a collision situation is detected a number of options to its resolution are possible. In nearly all instances the controller will be able to communicate only with the controlled aircraft involved. Thus, the resolution must be based on some manoeuvre of this aircraft, and must consider the current operating characteristics of the aircraft. Further considerations of the manoeuvre must be the effect on passengers, and most importantly the effect with relation to other aircraft in the vicinity. Thus, the resolution manoeuvre should: 1. Avoid the collision. 2. Minimize effect on passengers. 3. Minimize changes in flight plan. 4. Avoid creation of future collision situations. 5. Be readily performed.

Display The collision situation after evaluation. by the computer must be clearly displayed to the controller. The display must point out the aircraft in conflict and the data block of the controlled aircraft must contain the suggested resolution manoeuvre. The controller has the option of issuing the suggested manoeuvre, or because of his greater knowledge of the situation issuing an alternative, or doing nothing.

Conclusions

Conflict Detection Potential collision is detected by projecting the velocity vector of each aircraft from its present position for some time into the future. The projection volume must be in 3 dimensions and must include inherent errors in the track data due to sensor errors and to the characteristics of the tracking algorithms. The projection of each aircraft is checked against the similar projection of every other near aircraft to determine if potential conflict exists. The projection time for the aircraft into the future is a function of response time. This time is made of controller response time, communication time, pilot response time, aircraft reaction time, and computer processing and display time. It is highly desirable that this time be a minimum so that the projected volume of airspace for each aircraft is minimized. On the other hand. time must be sufficient so that all the necessary action can be carried out with certainly.

Methods for performing the ground based collision avoidance function have been described. Many of these procedures have already been demonstrated by Goodyear Aerospace either as part of the Knoxville experiments or at the TRANSPO exposition at Dulles International Airport. The TRANSPO demonstration involved up to 400 live and simulated tracks. Performance was judged to be entirely satisfactory for Air Traffic Control use. Development of improved tracking algorithms to further improve the conflict prediction and resolution performance is proceeding as part of Goodyear Aerospace's continuing program of improving the performance of ground based collision avoidance systems. (A presentation made during the technical program conducted at the Air Traffic Control Association's 17th Annual Meeting in Chicago. This paper and 29 other technical articles are contained in "Future Air Traffic Control - Renovation or Innovation?" which can be purchased from the Air Traffic Control Association, Inc., Suite 409 ARBA Building, 525 School Street, S. W. Washington, D. C. 20024. Price $ 3.00)

A Special Review of a very Special Book Air Traffic Control: The Uncrowded Sky by Glen A. Gilbert In the first book since World War II to deal with this increasingly important subject, Glen A. Gilbert sets forth the past, the present, and the future outlook of the System in the United States and its global effects. Of the three transportation media, two - surface and subsurface - have limited or finite capacity and, as a consequence, are in serious trouble in many respects. But the third - airspace - has Infinite capacity if we know how to use it effectively. This is the main premise of Gilbert's book, as he describes developments of ATC from its beginnings in the mid1930s to the present. Comprising the System are the air traffic controllers and the pilots, along with supporting elements such as the airports, aircraft, rules and procedures, navigation aids and related ground and airborne equipment. One of the most significant elements to affect the future use of airspace is the type of air vehicles which will be part of the ATC System. Conventional, fixed-wing aircraft will be augmented by aircraft having the capability for short takeoff and landing, as well as vertical takeoff and landing. As a result, greatly expanded air service will be possible within urban areas, from city-center to city-center, and from smaller communities and rural areas. Ecological problems from noise impact will be solved. A dynamic challenge for the 1970s and beyond is to convert the unlimited potential of airspace into a transportation capability that truly can be called the "uncrowded sky". The Author puts it like this: "'Transportation - a key factor affecting social and economic progress - poses a major challenge for the 1970s and beyond. Of the three transportation media, two - surface and subsurface - have their severe limitations, but the third - airspace - has infinite capacity if we know how to use it effectively. It is the system that is crowded - not the atrspace." A number of well-known aviation personalities have already commented on Mr. Gilbert's book. Robert J. Serling, Aviation writer and author of Loud and Clear and The PreÂˇ sldent's Plane is Missing, says: "Not only a valuable book but a vitally essential one, fascinating in its expertise and incredibly thorough. Mr. Gilbert has dealt with a subject that has long needed a work of this kind, and it promises to become a classic reference in an area almost totally ignored by aviation writers in the past." George E. Haddaway, Publisher Flight Journal of Executive Aviation, has this comment: "The Gilbert book will be a landmark volume as the standard guide on the subject ... We recommend that all air travellers familiarize themselves with the many complexities of air traffic control problems and technical solutions involved ... Will be understood by laymen and technicians alike." From Robert W. Simpson, Director, Flight Transportation Laboratory Department of Aeronautics and Astronautics Massachusetts Institute of Technology, we quote: "This book is an excellent introduction for engineers entering

the world of ATC who need an explanation of terms, concepts, and ATC systems. The Institute will use this book as a reference text in our program in Flight Transportation. It provides a historical perspective on the development of our system of air traffic control, and a sense of the current situation which would otherwise require extensive reading." Grover Loenlng, Aviation pioneer and noted aircraft designer puts it in these words: "Glen Gilbert's specialty in being the outstanding expert and designer of air traffic systems in the Western World makes his treatise on Air Traffic Control all the more important." John Leyden, President of the Professional Air Traffic Controllers Organisation, has read an advance edition of the book, and wrote a letter to Gilbert commending it. "As President of PATCO and as a former controller, I find it highly informative, but more importantly, one of the best historical chronologies ever written about the Air Traffic Control System. It breaks down to layman's terms the complex and ofttimes difficult technical developments which began with the development of the air traffic control system in the Mid-Thirties to the present highly technical and partially automated system which is upon us. It identifies and significantly answers the challenge which will directly affect the future use of airspace which will impact not only on controllers and pilots, but the most important individual in the system - the air traveller. I highly recommend its reading for all who have any connection with air travel."

Editor's Comments These days, when a person wants some more information on a profession, trade or occupation, he simply walks into a bookshop and buys a text-book on the subject, which is usually written in straightforward terms, understandable to the layman. During our recent discussion in Munich, David Hopkin stressed that there is a definite need for a good, up-to-date text-book on Air Traffic Control. More and more people are becoming interested in our profession; for some of those who took part in the recent Medical Symposiums in Munich and Manchester, where the stress factor in A.T.C. was widely discussed and examined, a text-book would have been just the thing to bring them more up-to-date on our profession. One or two books have been on the market for some time, in the United States for example, but they cannot be considered "text-books" in the real sense. A proper text-book should find a ready market in the international aviation world, and probably further afield too. In our continuing fight for true recognition of the profession of Air Traffic Control, a good text-book, expertly written, attractively produced and efficiently marketed, could be a powerful instrument in our hands. Gilbert's new book, therefore, comes at a time when the dearth of other books on ATC is woefully evident and underscored by its publication. ÂˇHis book belongs on the shelf of every library and should be readily available to all students of the profession.

Every controller would b~ interested in Chapter IV which deals exclusively with "The Human Element". Gilbert outlines the training and rigours of our work. Among his comments: "Because of constantly increasing pressure, the controller very frequently finds that his health, both mental and physical, has become adversely affected." Gilbert's book also makes extensive use of illustrations to bring home many complex subjects discussed. The 4colour illustration on\ page 27 is fascinating. It shows a variety of aeroplanes in the sky around an airport, each in its own "box" of airspace. In this way, it is shown how the controller provides three dimensional separation, so that each aircraft carries with it its own collision avoidance box, which must be visualized and carried in the memory of the controller involved. Another drawing of traffic patterns at New York (page 20) presents a terrifying illustration of how complex a problem the controller faces in high density operations. The 128-page book contains 183 black-and-white illustrations and seven colour plates. The contents are: Foreword, Introduction, Glossary, and the following chapters:

I II Ill IV V VI VII VIII IX X XI XII

Behind the Scenes How It All Began The Users The Human Element Basic Procedures Radar Automation Navigation Aircraft Airports Collision Avoidance Only the Beginning

Acknowledgements. Its price is $ 12.50. Glen A. Gilbert's book is published by the Smithsonian Institution Press, and is distributed in the United States and Canada by George Braziller, Inc., One Park Avenue, New York, N. Y. 10016, and distributed throughout the rest of the world by Feffer and Simons, Inc., 31 Union Square West, New York, N. Y. 10003.

For the Controller's Shelf The Sound of the Air "The Sound of the Air" is a record, first produced in 1971, since then a second improved issue has been put on the market. This radio-telephony example in English is not only intended to assist all those who are training to become instrument rated pilots, but will also be helpful to all other categories of pilots as well as to any one else who is interested in Air Traffic Control. In this example, illustrating an IFR flight from Nurnberg to Cologne-Bonn with LEARJET D-ICAR, several simulated instrument- and radar approaches are made, and international and customary ICAO standard phraseologies and terms are used throughout the recording. In order to provide a better understanding of pronunciation, spelling and terms being used, the complete text is included in the record-album. The whole flight and the various approaches into Cologne-Bonn can be followed with the aid of approach- and other charts, specially included for this purpose. For a better and more interesting illustration, the back-ground noises in the cockpit of the LEARJET are actual recordings made under operational conditions. You will hear Captain Bernhard Joklitschke and co-pilot Franz Langenberger make all the checks needed, before and after starting engines, before and after take-off, as well as those checks performed during the landing procedure. The initiators of the record have been Mr. A. Scholz, air traffic controller at Nurnberg Airport and Mr. B. Joklitschke, flight captain and chief of AERODIENST NORNBERG GMBH. The record has been announced and described in various aeronautical publications, and is sold by several German aeronautical publishing houses at a sales price of OM 35.-. 42

A Worthwhile ATC Reference ATCA's 17th Annual Technical Presentations, a compilation of the presentations made at the Air Traffic Control Association's 17th Annual Technical Program in Chicago in October 1972, makes an excellent reference for anyone interested in the future of air traffic control. The theme of the program was "Future Air Traffic Control - Renovation or Innovation?" The presentations were well balanced between industry concepts of air traffic control, a roundup of the U.S. Air Force systems of the 1980's, the changing role of the air traffic controller, and the need for good airport planning. There is also an excellent comparison of the various airborne and ground-based collision avoidance systems as proposed by the industry experts. The presentations, made by some of the top experts in the ATC field, provide the reader with an outstanding volume of reference material on the air traffic control systems, present and future. Whether or not you attended the technical program, you will want this worthwhile volume for your ATC library. It can be obtained by sending a cheque or money order for$ 3.00 to: Air Traffic Control Association, Inc., Suite 409, 525 School Street, S.W., Washington, D.C. 20024.

Esso Air World Vol 25 No. 6 1973 Esso Air World Vol. 25 No. 6 of 1973, in the series "Know your International Aviation Organisations", contains an excellent article which describes the story of IFATCA since the Federation was formed more than twelve years ago. A foreword by President Jean-Daniel Manin introduces the subject, and a photograph of the President is featured with the text.

We recommend this edition of Esso Ai r World to every one who wants to use the material contained in the article to enlighten those around him, in plain language and simple terms, of the aspirations and achievements of IFATCA. Member Associations should consider publishi ng an article along these lines in their national Public Service Associations' Jou rn als or Newslette rs, which should go a long way to inform people within the Public Service of our existence. This will undoubtedly enhance the standing of the Air Traffic Controllers within the environment of that Service. Let us know in due course what you have done in th is co nnection ?

IEEE Spec ial Issue on Aeronautical Communications Another excellent reference publication on Aeronautical Communications and Air Traffic Control is now available throug h the Institute of Electrical and Electro nic Engineers, Inc. IEEE's May 1973 issue, Vol. COM-21, No. 5, is a real winner for those who are not only interested in the history and background on various aspects of the air traffic con-

trol system but also wish to find out what the future holds in store for ATC. The efforts of IEEE Guest Editors Sherman Karp, George G. Harou les, and Leslie Klein hav~ resulted in a remarkable compilation of expertise from the world of aviation, communications, and air traffic control. Beginning w ith an overview of the role of Communicatio ns Systems in Air Traffic Management by senior people in the Department of Transportation, the publication is divided into several sections: Operating and Planned Systems, covering system requirements and descriptions of the cu rrent operational system and planned improvements; Panel Papers, giving various airspace users' views on air traffic control system p lanning; Advanced T echnology, devoted to co mmunications- related technology that can be envisioned as contribut ing to th e desig n of future ATC systems; and a fin al section containing "concise papers" dealing with ae ronautical communications. The publication is available in microfi che or printed form from IEEE at $ 12.00 a copy tor non-members of IEEE. Send your cheque or money order to: T he Institute of Electrical and Electronic Engineers, Inc., 345 East 47th Street, New York, N. Y. 10017. It is well worth the price.

News from Corporation Members AEG-TELEF U N KEN meets the Press New SRE-LL 1 Radar Antenna in Operation During a Press Conference held on 26 September 1973 in Kaisers lau tern, West Germany, AEG-TE LEFUNKEN anno unced details of the SRE-LL 1 Radar System and, in concert with th e German Department of Air Navigation Services presentations were given on ATC projects in Germ any, radar derived inform ation, and simul ation in ATC. SRE-LL 1 is an L-band medium-range surveilla nce radar with a max imum coverage of 150 NM, and a height scan of 60.000 ft. In order to obtain a better target data rate th is antenna is eq uipped with a back-to-back antenna system (i. e. J anus antenna). Some 40 journalists had the oppo rtunity of participating in a well o rganized meeting and sight seeing to ur th rough the new ly installed fac ilities at the hill site " Ptalzer Wald " . The Pfalzer Wald SRE-LL 1 is the second system in operation in Germany today. Plan ned are a total of 6 SRE- LL 1 systems to guarantee multiple radar coverage of the German ai rspace. T he Regio nal Ai r Traffic Control Centres planned for location at Bremen, Dusse ldorf, Frankfu rt/Main and Muni ch wi ll be provided wit h SRE-LL 1 derived information. A spec ial d ata acquisition system based on primary and secondary rada r information will provide Air Traffic Contro l with hig hly accurate and reliable air traffic data.

Antenna and Maintenance Building of the Pfiilzer Wald SRE-LL 1 Radar System

Corporation Members of the International Federation of Air Traffic Controllers' Associations AEG-Telefunken,_Ulm/Donau, Germany Air Vision Industries, Inc., Montreal, Canada The Air Transport Association, Washington D. C., U.S.A. Wolfgang Assmann GmbH., Bad Homburg v. d. H., Germany Cossor Radar and Electronics Limited, Harlow, England Dansk lmpulsfysik A. S., Holte, Denmark The Decca Navigator Company Limited, London, England Ferranti Limited, Bracknell, Berks., England Glen A. Gilbert & Associates, Washington D. C., U.S.A. International Aeradio Limited, Southall, Middlesex, England Jeppesen & Co. GmbH., Frankfurt, Germany The Marconi Radar Systems Limited, Chelmsford, Essex, England N. V. Hollandse Signaalapparaten, Hengelo, Netherlands The Plessey Company Limited, Weybridge, Surrey, England Racal-Thermionic Limited, Southampton, England Selenia - lndustrie Elettroniche Associate S. p. A. Rome, Italy The Solartron Electronic Group Limited, Farnborough, Hants., England Stansaab Elektronik AB, Jarfalla, Sweden Thomson - CSF, Paris, France

The International Federation of Air Traffic Controllers' Associations would like to invite all corporations, organizations, and institutions interested in and concerned with the maintenance and promotion of safety in air traffic to join their organization as Corporation Members. Corporation Members support the aims of the Federation by supplying the Federation with technical information and by means of an annual subscription. The Federation's international journal "The Controller" is offered as a platform for the discussion of technical and procedural developments in the field of air traffic control.

1t's the world of air traffi~ control. W e' ve been in it sin ce the ' fi fties and have designed both operational systems _and simulators fo r rram mg and evaluation. Our program m ers talk to con trollers a lot a nd ge t to know their problems. They learn not only what information a controller wants but how he wants it presented . T ake t he situation today. M ore advanced equip m ent m eans that more and more information is coming in, and a controller n eeds help in sort ing the w h eat from the chaff. So we're automating air traffic

control . . ..processing the d a ta so that the controller 1s freed from a flo od of detai l but can receive early warning of the development of conflict situations a nd cahn t h en conce n trate on resolving 'th em w 11c 1eavm g t11e system to monitor all tha t's gomg sm ooth ly. It 's all helping to create th e c<;m dirion s that will be essential for t he high speed, high volume jet travel of the seventies. Ferranti arc at th e heart o f it. Ferranti Ltd., Digital System s Division Bracknell, Berkshire,England, RG 12

lRA

Canada - Ferranti-Packard Limited, Industry Street, T oronto 15, Ontario. U .S.A. - Ferranti Electric Inc., East Bethpage Road, Plainview, New York I 1803.

air traffic control for the seventies.

FERRANTI DS32 2

selenia air traffic control systems Selenia offers very advance~ equipment for Air Traffic Control, including:

e e e e e e

ATC RADARS BROAD BAND AND NARROW BAND LINKS DIGITAL DISPLAY SUBSYSTEMS COMPUTERS PRIMARY AND SECONDARY RADAR EXTRACTORS SIMULATORS AND DIGITAL INTERFACE EQUIPMENT

together with wide experience in :

e e e

SYSTEM DESIGN SYSTEM IMPLEMENTATION AND INTEGRATION LOGISTIC SUPPORT.