IFATCA The Controller - 4th Quarter 1985

ISSN 0010-8073

JOURNAL OF AIR T RAFFIC CONTROL.

4/85

SPECIAL ISSUE FOR CORPORATE MEMBERS BERN, SWITZERLAND

4 TH QUARTER 1985

VOLUME 24

Sfrs 5.-

..

~

Located in the heart of the Americas, Costa Rica is small in size, but huge in natural beauty. Its mountains and volcanoes, of artistic magnificence, surround San Jose, Costa Rica 's capital and most beautiful city. Nightlife in San Jose vibrates with excitement. People gather in discotheques, nightclubs, cinemas, clubs, theaters and restaurants.

But if you are looking for peace and tranquility, Costa Rica 's beaches are among the most beautiful in the world and there is one for every taste, secluded or with modern hotels, white or blacksanded, warm or cold, you may choose among hundreds of them in the Pacific or the Atlantic coasts.

Springlike climate, peaceful and quiet beaches, mountains, volcanoes, nightlife -you name it- we have it!

Ulacsa

The Airline ofCosta Rica

IFATCA JOURNAL OF AIR TRAFFIC CONTROL

THE CONTROLLER Volume 24 路 No.4

Bern, Switzerland, December, 1985

Publisher: International Federation of Air Traffic Controllers路 Associations. P.O. Box 196. CH-121 5 Geneva 1 5 Airport. Switzerland

In this issue

Officers of IFATCA: HH. Henschler. President. Lex Hendriks. Vice-President (Technical). E. Sermijn. VicePresident (Pro fessional). U. Windt. Vice-President (Administration). B. Grezet. Treasurer. P. O"Doherty.

Executive Secretary

25 Yea rs IFATCA - by Bernard ROthy

Editorial page2

Editor: A. Avgoustis 5 Athens Street 172 Nicosia. Cyprus Telephone (72) 44 87 86 Management and Advertising Sales Office: The Controller. P.O. Box 196.

CH- 12 15 Geneva 15 Airport. Switzerland H.U. Heim. Subscriptions and Publicity.

Tel. (022) 82 26 79 M . Henchoz. Accounting. Tel. (022) 92 56 82 B. Laydevant. Sales Promotion. Tel. (022) 82 79 83

A. Avgoustis writes on Air Terrori sm and its Evolution page 10

Production "Der Bund". Verlag und Druckerei AG Effingerstrasse 1. CH-300 1 Bern.

Telephone (031) 25 66 55 Subscriptions and Advertising Payments to: IFATCA/ The Controller. Union de Banques Suisses P.O. Box 23 7 CH- 12 15 Geneva Airport. Switzerland Acc. No. 602 254.MD L Subscription Rate: SFrs. 20.- per annum (4 issues). plus postage and package : Surfacemail: Europe and Mediterranean countries SFrs. 4 .20. other countries SFrs. 5.40 .

Airmail: Europe and Mediterranean countries SFrs .. 6 .20. other countries SFrs. 10.60 .

Special subscription rate for Air Traffic Controllers. ;ontributors are expr~ssing their personal points of 1ew and opinions. which .may not necessarily coincide with those ?f the lntemat1onal Federation of Air Traffic Controllers Associations (IFATCA).

IFATCA does .not assume responsibility for statements made .and opinions expressed. it does only accept respons1b1hty for publishing these contributions.

Frank Fischer writes on 'What Do We Owe the Paying Passenger'? page 11

J . Kleeman writes on 'ATC Training: Realism and Training Effectiveness ' page 73 路Evolution of the ATC Beacon System ' by C.F. Philips page 78

c.ontributions are w elcome as are comments and criticism. No payment .can.be made for manuscripts submitted for pubhca11on in "The Controller". The Editor reserves .the right to make any editorial chanaes in manuscnp!s. which he believes will improve t he material without altering the intended meaning.

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

Advertisers in this issue: Lacsa - Ferranti - M arconi - Philips - Westinghouse - Selenia Photos:

P.A. Jorgensen writes on Radars in ATC page 25 J .P. Locher writes on 'ATC System Engineering ' page 28

A.A. Archives. Hiro Tade Cartoons: M artin Germans & J. E. Tomczak THE CONTRO LLER /D ECEMBER 1985

.J

Arnold Field OB I writes on ' Plessey Displays in ATC' page 30

On 25 November 1959 there opened in Frankfurt a European meeting of a small group of Controllers路 Associations to form a European Federation of Controllers which was destined to become a few months later the core of the International Federation of Air Traffic Controllers' Associations .

Since I FATCA' s first inaugural-constitutional meeting took place in Amsterdam in October 1961 Corporate Members. a small number at first. maintained close ties with the Federation. These links become more obvious particularly at Annual Conferences when Corporate Members exhibit their ATC and field-related equipment or through article contributions and advertisements to this Journal.

THE CONTROLLER started as a European publication which established itself in its international character together with the Federation .

Corporate members and IFATCA form almost one family. It is therefore very natural that at the Federation's Annual Conferences Corporate Members conduct technica l panels and many times their proposals are adopted by the Executive Board and Member Assoc1at1ons and perhaps become IFATCA policy.

Th is issue of the Journal is the 2nd issue which is dedicated to IFATCA's si lver anniversary. It is particularly offered to Corporate Members to mark the cooperation that exists between them and IFATCA. Articles were written especially for this issue or they were technical presentations made at the 24 Annual Conference in Athens which we were asked to use instead.

A quarter century of fruitful cooperation. w ith THE CONTRO LLER always being the unique forum for the Federation's members.

25 Years IFATCA The Story of a Childhood

and Youth

by B. 0 . Ruthy. Switzerland

(Part two)

With the end of the 2nd Annual Conference the year 1 963 was by no means past for the Federation. Two very important milestones in the history of the Federation still lay ahead: In May IFATCA was for the first time invited by !CAO to send an observer to an important international conference. the RAC / OPS Divisional Meeting. The 1 st Vice-President. Maurice Cerf. attended this conference and with his French charme and souplesse put the Federation on the map. !CAO and representatives of its member states recognized that IFATCA was able to provide professional advice. more than necessary at such conferences.

In September the Board of Officers (Executive Board) appointed Geoffrey W . Monk to the post of Executive Secretary. Geoffrey. a former controller and manager in the UK National Air Traffic Services immediately started to organize the Federation· s Secretariat in an efficient and productive manner. Over the years we came to appreciate Geoffrey as a real gentleman of the old English school. always very helpful. never excited. quietly doing what had to be done. at the proper time.

Brussels !hus _the Federation was well prepared for its third Annual Conference. w hich was held at Brussels. Belgium. on 21 to 23 May. 1964. 16 ~ember Associations (only the Central African Association was unabl~ to attend) and eight non-member Assoc1at1ons ~ere represented. Jn line with the organizers of earlier conferences the Belgian Guild had done excellent work 1n the preparatory phase. The Conference took place in the Palais des Congres and was opened by the Guest of Honor. Monsieur R. Lecomte. Director General of the Belgian Regie des Voies Aeriennes. In his opening address President Tekstra put much emphasis on the fact that for the first time a representative of the International Aircrah Owners and Pilots Association (IAOPA) attended the Conference. He thought that this was very timely and appropriate aher the !CAO RAC/OPS Divisional Meeting had accepted the principle of ·extended control' (later to become ·controlled VFR'). He found that General Aviation and controllers should maintain close contact to the benefit of both groups.

The conference accepted three new Member Associations: Canada . Italy and

R. M . Soward. Eurocontrol. Arnold Field and Executive Secretary Geoffrey W. M onk(/. tor.) during coffee break at Brussels.

2

Uruguay. With this the Federation considerably increased the number of individual members and truly leh the boundaries of Europe behind.

Th~ main conference work was again done in two sub-committes. chaired by the Honorary Secretary. Hans Thau. (A) and Arnold Field from the U K Guild (B). In SubCommittee A the accounts for 1963 were accepted. They showed a modest excess ?f income over expenditure of £96. bringing the Reserve Fund to £953 or approximatela SFr. 12 OOO in today's ' JFATCA ~urrency'. Practically all items discussed in Sub-Committee A were m ea nt to improve the infrastructure of the Federation.

Some of the rules and By-Laws accepted to smoothen the operation of IFATCA are. even today. still valid and part of the Manual: By-Laws regarding ' undue hardship' in annual subscriptions for Member Associations: Rules of Procedure for Sub-Committees: Lay~u.t of technical papers: Dec1s1on not to establish a Standing Committee on Awards; D~cision to reestablish Standing Committee IV (Human and environmental factors. cancelled at the London conference); Schedule for the (re-)election of Officers: ~irs! discussions on a region al organ1zat1on. . Another topic . discussed at length had in the meantime become a 'stand.ard '. trfavel concessions. It was on the agend~ 0 every conference d d. . somuetdimes became ra.th!~ emo~~~~!f rons n er the experienced ·d · nold Field Sub c . gui ance of Ar. - ommrttee B pr number of items that ocessed a on ICAO' agen d a an d for which were IFATCA s was expected to establish it s posit" The primary radar procedur'on ~r policy. and accepted at this confere~s discussed large extent. still part of ce are. to a PANSRAC(Doc. 4444)toda ~he l~AO 0 I feel con trollers should b~· a ~et1mes aware of such facts when they a k ~t mo~e the Federation doing for me?" s What 1s

Two of the animators of early IFATCA conferences Alf F Luxembourg (I). and ' Morty' M ortensen. Denmark · t ~e eltes. with French controllers during lunch . · a ing shop

1

THE CONTROLLER / DECEMBER 1985

..

ATC or Air Defence.

Ferranti completes the picture.

You don't need. us to tell you about Ferranti ATC systems and sunulators, military and civil Nor about Ferranti Air Defence Systems. ¡ These h~ve bee~ around long enough to have won an mtemational reputation for performance, reliability and flexibility.

It r:ow makes sense to combine them into a totally mtegrated system so that air defence and civil/military air traffic control information can be co-ordinated in conjunction with all available sensors.

This Ferranti has now done, in its Airspace Ma1:1agemei:it.System. The advantages are obv10us: efficiency and less duplication of sensors. Savings are made in display processing,

communications and data handling equipment.

Training is made cost effective and reali~tic, when you use the modular simulator and V01ce Activated Management System.

The software plays a vital role in . everything, and here, of course, FerrantJ. is unequalled.

Contact Ferranti the leaders in C3I systems expertise, and let us ~omplete the picture.

Ferranti Computer Systems Limited, Systems Sales Department, Ty Coch Way, Cwmbran, Gwent NP44 7XX Telephone: 06333 71111 Telex:497636

FE Computer Systems

LS0 216'illJ4.,

Head table .during opening ceremony of Brussels Conference: (I. to r.) Henning Thrane. Treas.urer. Ha_ns W Thau. Honorary Secretary. Roger Sadet. 2nd Vice-President. R. Lecomte. Director General of Belgian RVA and President L.N. Tekstra.

Other subjects discussed. some of which were on the work program for many yea rs. were:

~~~-~orr;mitte~ B in s~ssion. At the head table (I. to r.) Roper Ch "! · nd Vice-President. Ernest Mahieu. Committee Vicea"man. and Arnold r"'1, 'e'd .

1 • • Chal(man.

After several addresses by guests and observers. and the President's Final Address. Andre Maziers proposed to adjourn the 3rd Annual Conference. The proposal was duly seconded and carried with ma ~hanks to the organizing committee f ny JOb well done. or a Judging from the December 19 64 issue of the IFATCA Circular the period after the Brussel~ conference was very busy for the Fe~er~t1'?n . ! he Executive Board tried to ob.tain inv1tat1on.s from ICAO to several meetings but received no. or evasive response. It was learned informally that ~ome members of the Council had obiected. that..controllers were (in most countne~) civil servants and as such could not possibly voice opinions that were not shared by their Government. It took quite a number of years to gradually overcome these objections. ~ne item of interest in the above Circular 1s th~ . report. ~n a S~mposi um held by the British Airline Pilots Association (BALPA) on the theme ' Navigation . Communication and Air Traffic Control - the Next Ten Years' . It is funny to read the Chairman' s summing up of this lively event 2 1 yea rs later:

b) Improved comm unication. initially by extended range V HF supplemented by RD (radioteletype) in regions of denser traffic; c) lr;iproved long range commun ication f'.1ther by a VH F relay system or. more likely, coded HF t elegraphy data links; d) A self-contained navigation aid backed up and up-dated by long- and shortrange ground reference area coverage navigation systems; e) ~ead-up and head-down displays of '~Proved instrumentation for the pilots: f) Increased use of comput ers to reduce tork load on controllers and pilots.· f t also shows that it is very difficult to To~esee t he tec hnological development. .e members of ICAO's Special Com~~~~)on Fut~~e Air Navigation Systems h · on w ich IFATCA is represent ed d a~e noheasy task in this respect. trying to e ine t e development of . . . services over th air nav1gat1on . . e next 25 years.

Du~ing thi s summer of 1 964 the Board of Officers also undertook t . administrative and technicalo improve the of the Federat ion A k. management ing was held in Lon;~r ~eg~oupdmeetsidered th e results of .its okar con. . wor at the autumn Officers Meeting. One of the proposals accepted was to extend the 4th Annual Conference to three consec utive days.

Simultaneous use of parallel runways (UK Guild).

Air I ground data links (UK Guild).

Closed circuit television (Belgian Guild) Analysis of requirement for better radar (Netherlands' Guild).

Appraisal of radar equipment for air traffic control (Netherlands' Guild).

Integrated civil I military air traffic control (German Association).

The Final Plenary was held as a ·Public Meeting' in which a considerable number of national and international dignitaries participated . The first speaker was Mr. K. Delaure. Attache for Aviation. speaking on behalf of the Belgian Minister of Communications. Among ot her things he said 'You are faced with an increasing complexity of problems created by the evolution of aircraft. increased traffic numbers and aircraft speed . The solutions to be found will only flou rish if tech nical means and methods of control are uniform. if contacts between those who "invent" and those who "execute" are established and if the latter. who normally work in the ' ft was thought that th e following were shadow. get an opportunity to follow the development of techniques that will be at needed: their disposal in operations.· a) Identity and altitude encoded tra nsponders: In his reply Tek sa id 'You wi ll realize that our young organization still meets with considerable difficulties as none of us had any experience in managing an international body when the Federation was inaugurated two and a half years ago. We are doing our best to reach a sufficient standard for effectively achieving our objects. Taking into account the fact that all our work is spare-time activity. our progress can only be slow.· The reports of Sub-Committees A and B were then read and accepted. To get in pace with the new rules for the election of offic ers the 1 st Vice-President. the Honorary Secretary and the Treasurer were re-elected for one year. whilst the President the 2nd Vice-President and the Group of delegates board1~g the Airspeed Ambassador aircraft for a Decca d Treasurer were re-elected for two years. stration flight at Brussels a"port. emon4

THE CONTROLLER / DECEMBER 1985

Vienna This Conference was held on 13 to 15 April. 1965. in the Vienna Intercontinental Hotel. True to its reputation Austria welcomed the delegates from 1 8 Member Associations and seven non-member associations in style . The environment made available for conference was excellent: Herbert Brandstetter. President of the Austrian ATCA and his organizing committee again did everything to ensure a smooth operation of the event. Some of the delegates started wo ndering where we would end if every host of an Annual Conference outdid the preceding conference at this pace.

In the course of 1964 the New Zealand ATCA had been accepted as Member Association by mail ballot. The Vienna Conference accepted two additional members: Venezuela and Yugoslavia. It is worth mentioning th at at this time the Federation also already had thirteen ·Corporation Members' (today Corporate Members). and was proud of the fact.

Tirey K. Vickers of the US A TCA takes a close look at a group of Schrammeln musicians at Kloster Neubrunn.

President Tek Tekstra

The Austrian Minister of Transport and Power. Mr. Otto Probst. unfortunately was unable to attend the Opening Ceremony due to other committments. This. however did. not prevent him from inviting those delegates who had already arrived the evening before the Opening ~eremony to a reception and delivering his address on this occasion! .

Sub-Committees A and B were_again chaired by Hans Thau and Arnold Field. In A the Treasurer could again report a modest (or not so modest at our 1964 standards) excess of income over expenditure of £5 5 2. This was brought about by a very tight budget control by the Officers and the fact that the German Association .. wh.o at that time were in charge of publishing The Controller' had returned £ 100 to the Treasurer . They said 'The Controller' was covering its costs. they therefore did not need the contribution . The accounts were. of course. accepted with acclaim.

The Executive Secretary had to report to Conference that he would not be able to continue in this function for both the Federation and the British Guild. as the workTHE CONTROLLER / DECEMBER 1985

load was too great. The Guild announced it hoped 10 appoint a separate Executive Secretary so that Geoffrey could cont inue to serve the Federation. This offer was gladly accepted. . .

The policy decided earlier that .every Member Association should su ~scri_b e to as many copies of 'The ~ontrollJ;lr as_it had members in good standing was again discussed at length. A majority of MAs had found it impossible to comply with t~~ Resolution. It was therefore change.d t_o 1t shall be the aim of Member Assoc1at1ons to distribute one copy ?f the Journal to each individual member . Even today only a few MAs have reached the aim .

Vienna was the first time th~t the subject o f a permanent secretariat for t he Federation was discussed. It was to come up at many of the subsequent conferences. The result however was always the same. as today: the necessaiy funds were not available and Members did ~ot. see a chance to raise the annual subscriptions to the extent necessary to achieve this goal.

Between the Brussels and Vienna Conference SC IV - Environmental and Human Factors in ATC. taken care of by the Irish Association. had distributed a comprehensive questionnaire on working conditions in the MAs' countries. A number of replies had been received . The Conference decided that. once the replies had been assessed. a ·report should be prepared recommending cert ain minimum standards for environmental condition s if these conditio.ns ha~e. a direct bearing on the safety of air traffic . The quest ionnaire and the replies of members later provided the nucleus of IFATCA' s Information Handbook(IH B). Des Eglington of the Irish Assoc1at1 on and his group did a good job.

The Conference also accepted a draft of the I FATCA Manual ·Administration and Policy'. a predecessor of today's IFATCA Manual. The Honorary Secretary was asked to maintain this document .

Discussion was continued on the subject of Regional Organization. Austria.

Canada. New Zealand and Uruguay were asked to nominate Regiona l Liaison Officers to maintain contact w ith non-member associations in their areas.

One point that was discussed several times at early IFATCA Conferences was the subject of an International ATC University. Jacob Wachtel. of the Israel ATCA. had forwarded a proposal that the Federation should encourage the establishment of such an institution. Although there was much sympathy for the idea delegates had some doubt whether this was in fact realist ically possible. Jacob was ·authorized to use the name and authority of IFATCA in carrying out his research into the feasibility of a University of ATC'.

Under ·Any other business· it was recommended ' that the Austrian and Yugoslavian Associations cooperate in pro~ucing a model Membership Card for ind1v1dual members which records both membership of the national associations and of IFATCA. and submit their proposals to the Elective Officers' (Executive Board).

In Sub-Committee 8 Terrain Clearance gave rise to considerable discussion regardi_n g controller I pilot relationship. A working paper on the subject was referred to SC 1. The Standing Committee was asked to cooperate with IFALPA and IAOPA in o~der to make further study on the points of pilot I controller relationship.

A paper on Supersonic Transport (SST) was accepted as basic document for further study. SC I was asked to continue its resea rch into that matter. It should be noted in this respect that at that time States had not yet decided to prohibit supersonic flight over their territories.

Most controllers were very eager to learn more of the operational characteristics of SST in order to assess its impact on day-today ATC. Committee B then proposed 'that IFATCA recommends the implementation of (Automatic Terminal Information Service [ATIS]) broadcast of routine ~TS information at airports where a reduction

5

in the load on ATC RTF channels is desirable.'

The Committee decided to remove the subjects of ·Bright Radar Displays' and 'The Future of 10-cm Radar' from the working program and instead init iate a study on ' Radar Displays and Requirements'.

La st. but not least. it was proposed to Plenary 'that IFATCA. in close cooperation with IFALPA and IAOPA take up a study of RTF phraseologies in order to prepare proposals to be made to ICAO'.

The final plenary accepted the reports of Sub-Committees A and B. It then decided that the 5th Annual Conference was to be held in Rome. Italy.

The 1 st Vice-President. Maurice Cerf. and the Editor. Walter Endlich. were reelected for two yea rs . Ernest Mahieu (Germany) was elected as new Honorary Secretary. Hans Thau. who had been poste.d by his national administration to be his nation's representative on the ICAO Air Navigation Commission in Montreal. unfortunately had to take his leave. In thanking him for his excellent work in the Federation President Tekstra said 'without Hans Thau there would not have been an IFATCA! If ATC has gained in international stature in these last years. it has for a great deal been due to his enthusiasm. optimism. and driving spirit. I am sure to speak on behalf of all Directors and Officers. when I thank him sincerely for his part in the foundation of IFATCA.' The IFATCA Scroll of Honour did not exist at that time.

Hans should really have been the firsl recipient of this Scroll for all he had done in setting up the Fede~ation.

There followed nine speakers. representing international organizations. corporate members and non- or new member associations. One of these speakers. Mr. S. Scripcaru. from the Romanian ATCA had asked to address the meeting in French.

Ted McClusky volunteered to interpret into English . When he had finished an unnamed delegate called 'Mr. President. can we now have the translation from Scottish?'

One of the nine speakers at the Final Plenary was Tirey K. Vickers of the US ATCA. for many delegates an old friend.

Tirey informed that his association was not in a position to become a full member of the Federation for financial reasons. but had applied to become a Corporate M~m­ ber. ' It enables IFATCA to become a little more international. and it gives ATCA a very good reason to become a little more professional. Needless to say. we look forward to the day when we can achieve full membership in IFATCA. · Contacts between IFATCA and the US ATCA had of course been established long ago. At that time annual ~ubscriptions.of the Federation were a fixed per capita amount. the sliding scale had not been invented yet. For ATCA as an organization subscriptions would therefore have been a large amount although for the individual US controller the subscription was very small indeed. Unfortunately. ATCA never achieved full membership in the Federation.

Tirey's remarks were received with delight by delegates. Tek Tekstra thanked him and said that the application for Corporate Membership had been gratefully accepteo by the Officers. He pointed out that this was a milestone in the history of IFATCA. and he did not think I FATCA could be considered completely international until ATCA became an affiliated member.

ATCA at that time was the only organization representing a majority of US controllers.

On the social side there were several very noteworthy events. One of them was an evening at Kloster Neubrunn where. down in th e cellar. dinner was served more or less next to the wine barrels. Bob Shipley. representative of one of the Corporate Members gave a brief lecture in physics. when he showed that vine can flow upwards. too. The other one was a Heurigenabend at Grinzing where delegates and guests got ample opportunity to taste the ' Heurigen' (wine of last vintage) and found it very palatable.

I

Bob Shipley proving (once more) that liquids can flow upwards - if you know the trick.

6

Rome Rom e was another new experience.

Delegates from 1 8 Member Associations gathered at the Palazzo dei Congressi.

EUR. Rome. Italy. on Monday. 1 8 April.

1966. The novelty of this conference was that most delegates stayed in hotels in the north of the city while the Palazzo dei Congressi is in the south. A bus service by the Italian Airlorce picked up delegates in the morning and brought them back in the evening. Thus we got every opportunity to see something of the city and - most of all - study the behavior of Italian car drivers.

In several hair-raising situations the only one that 'kept his hair on' was the airlorce bus driver.

The Palazzo dei Congressi main conference room was much too large for the number of people attending the Opening Plenary; we fel t somehow lost in it. The ceremony started at 7 p.m .. followed by a 'get-together' rece ption. The reason was to give delegates two full working days for discussions in sub-committees.

Again a few highlights of conference work should be mentioned: Sub-Committee A had to learn that the Honorary Secretary elected at the Vienna Conference. Ernest Mahieu . had to resign at very short notice for private reasons.

The accounts were accepted as well as the budget for 1 9 6 6 I 6 7. Th e latter contained an increase in sa lary for the Executive Secretary to £950 per year. For the first t ime delegates were faced with the necessity to increase annual subscriptions. Directors were asked to consider the matter w it h their associations and report back to the Officers by 31 August. It was also proposed to express gratitude and appreciation to Treasurer Henning Thrane for his devoted service.

The subject of an international loss-oflicense insurance for air traffic controllers was discussed at length. Th e Swiss.ATCA was asked to investig ate the need. 1f any, for such a scheme within the IFATCA membership. If a need was found to exist. the association was to investigate the market to ascertain what it had to offer from the international point of view.

It was t hen proposed t o Plenary that. with effect from 1 January 1967. IFATCA should ta ke over the overall responsibili ty for administration and finance in respect of the journal 'The Controller' . A vote of sincere thanks was extended to the German association for having carried the burden of publishing and subsidizing the iournal during IFATCA's formative years ..

Sub-Committee B delved deep into the problems of IFR separation minima. It proposed to Plenary: that separation minima for world-wi~e application should be incorporated in Annex 11 (instead of PANS-RAC) and given the status of Standards; that ICAO should be asked to define more clearly the track separation minima specified for VOR and NOB and t o indicate whether the separation to be used is for both diverging and converging tracks: that MAs should approach their national authorities with the object of removing the application of I FR separTHE CONTROLLER / DE CEM BER 1985

ation based on ·dead reckoning' navigation as soon as possible in the interest of safety.

It was further proposed to Plenary that the Federation should approach IFALPA with a view of participating in a Study Group on the requirement for an Area Navigation Aid for submission to ICAO. One outstanding - and so far unique event in IFATCA history was the attendance of most delegates at the Papal Audience in St. Peters. Vatican City. on Wednesday. 20 April. 1966. Although there "Ye:re many groups with thousands of part1c1pants. Pope Paul VI in his words of welcome addressed the controllers. praised them for their arduous. highly responsible work and wished the Conference success.

At the end of the Audience the Officers had the opportunity to exchange a few words with the Pontifex Maximus.

0~ Thursday morning. a Panel Discu~s1on was held with representatives of !h~ Corp~rate Members on the subject of ~1r Traffic Control Displays'. Questions discussed were experience with secondary radar (SSA) and problems encountered ~antenna sh~dowi.ng). Mode C accuracy. r.a.d.ar substitutes (e.g. data link). capab1llt1es and reliability of narrow-band (radar) re~oting and bright displays. Today these sub1ects seem rather comonplace but at that time only very few controllers had worked with SSA and were keen to learn more about it.

The Final Plenary convened Thursday in th!3 late afternoon. Reports of Sub-Com-. mittees A and B were accepted with minor ar:iendments. Herbert Brandstetter. Austria. was elected Honorary Secretary and Bernhard Ruthy. Switzerland. was elected Treasurer.

M One of the guest speakers was r ..H.M. Koemans (Netherlands) representing IAOPA. He made some very critical re~arks about the position of IFATCA regarding General Aviation. He thought t~at the Federation put too much emphasis on those procedures that accommo~ated t~e airlines and not enough on those ?r GA. We only say that nobody has more nQhts than somebody else. and that solutions to existing problems can only be found.by ~utual efforts of cooperation and c~ordmat1on_. and never by pressure of any kind. We. claim that our air(space) is empty, even in the US .. .' . President Tekstra did not enter into details of relations between IFATCA and IAOPA in his final address. Talking about th!3 proposed reduction of lateral separation standards on the North Atlantic routes he too~ sides with IFALPA who opposed the project. He said 'if pilots whom we ~erve ~re concerned about an element of air traffic control flight safety. then we equally share their concern.· Tek considered the Rome Conference a success. 'The lively discussions have shown that we are learning the trade.· He thanked the Italian Association for hosting the conference and called upon Carlo Tuzzi to propose the adjournment of the 6th IFATCA Conference.

Geneva

Next came Geneva. Daniel Manin.

President of Swiss ATCA welcomed delTHE CONTROLLER/DECEMBER 1985

egates on 17 April 1967. 'We are delight- resentation (i.e. voting power) should be given to larger Associations. No coned to host the conference at a time when the Federation has overcome "infant's ill- clusions were arrived at but Canada was invited to submit a formal working paper nesses".' The Geneva Intercontinental on the subject to the next conference.

Hotel provided an excellent background Sub-Committee B. again chaired by for the conference.

During the Opening Plenary. 19 MAs Arnold Field. first discussed the presentation of technical policy. It was decided were represented. three were unable to attend or had not yet arrived and two new that policy should be provided in the form of amendments to existing ICAO Annexes members were accepted: Iran and Rhoand other documents. Delegates of the desia (formerly part of the East African Federation to international conferences Association). could then insert IFATCA policy in the apDr. W. Guldimann. Director of the Fedpropriate ICAO documents ('facing ~age:') eral Office for Civil Aviation and well known and thus always have current policy in throughout the world for his work as avihand when discussing ATC issues. ation lawyer. conveyed regards and best Next. and discussed in detail. were wishes of the Swiss Government. He ICAO IFR separation minima. It was propointed out that his Government was very posed to plenary: interested in all questions pertaining to that I FATCA consider it dangerous to aviation in general and the air navigation apply the new minima . specifi~d in services in particular. The Government put PANS-RAC (Doc. 4444) in relation ~o much emphasis on medium and long-term Track Separation when one or both airplanning to enable the air traffic services to craft are approaching a VOR o~ _NOB provide their services under optimal conunless accurate ·distance to run inforditions. mation is available; Work started again Tuesday morning in that when tracks are separated by ~on­ Sub-Committees A and B. Sub-Committee siderably more than the angles detailed A was chaired by D.J. (Des) Eglington. in PANS-RAC. ICAO should specify an Ireland. Your reporter got his first opporabsolute minimum distance at which tunity to present reports on annual acaircraft may be considered to be latcounts (which passed easily) and budgets erally separated; (which were discussed at length). It was that before introduction by a State of proposed to plenary that the annual sublongitudinal separation mini~a ba~ed scription should be increased from 10 to on distance. sufficient operational trials 1 2 shillings per year with effect from should be conducted to ascertain ac1 January 1968. ceptable OME minimum separation Another decision of tl:le Geneva confercriteria. and that the effect of such proence was that the Treasurer should always cedures on RTF loading should be present two budgets: one for the current carefully watched; year and a provisional budget for the that where OM E readings are used by following year.

ATC for the provision of longitudinal During discussion of the report of the separation it is desirable that the same chairman of SC IV (Environmental and ·on track' OM E station be used by both Human Factors in ATC). Mr. Dunandofthe aircraft concerned. whenever pracInternational Labour Office (ILO). Geneva. ticable; addressed delegates. He explained the that ICAO should be asked to provide function of the ILO with particular refermore guidance as to how t<:> _determine ence to the Inland Transport Committee whether aircraft on spec1f1ed tracks and its concern with environmental facshould be separated on ·same I retors. He said the ILO would offer help in ciprocal' tracks or on crossing tracks. studies of these subjects. The chairman Some of these resolutions are current thanked Mr. Dunand for his interesting text in PANS-RAC today. to some of the address and it was agreed that close conquestions no answer has been given but tact with ILO should be maintained by National Administrations have had to SC IV and the Executive Secretary. specify their 'interpretation' in their own A progress report showing that the ATC Instructions.

Executive Board had compiled all material Another subject was the issuance of for production of the IFATCA Manual was clearances to maintain VMC while climbaccepted. Directors asked the Officers to ing or descending to IFR flights. The macomplete work and publish the Manual during the course of 1967. Geoffrey_ Mc:>nk jority of delegates was of the opinion that such clearances should only be issued had indeed done a very comprehensive JOb at the specific request of pilots; in submitting a draft layout. This was la_ter the aim of IFATCA is the total elimindiscussed in detail at the autumn meeting ation of VMC clearances to IFR flights of the Officers and I agreed to type the first and that this elimination should be issue of the Manual. This became a permanent job. Luckily today with word ~ro­ achieved progressively. cessors being available for the processing Next on the agenda was civil I military of amendments things have become much coordination. Wolfgang Goebel. on behalf easier. of the German Association. presented the At the same time came the first paper and started a lively discuss~on. It amendment to the Constitution. Unfor- was found - once more - that circumtunately the conference report does not stances varied so much in the different specify what the changes were. countries that it was difficult to arrive at mutually applicable policy. In the end it One point should be mentioned that came up under ·Any other business': The was decided that yet another questionnaire should be sent out to MAs in order to Canadian ATCA asked that increased rep7

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get more information on procedures applied in t he MA' s countries.

When Tek Tekstra called the Final Plenary to order. 20 M ember Associations were present (one delegation only arrived aher the close of the conference!).

Des submitted Sub-Committee A's report which was accepted with minor amendments. J .R. (Dick) Campbell of Canada was elected 1 st Vice-President and joined the Officers on the platform.

The retiring Maurice Cerf was presented with a silver flagon as a token of the Federation's appreciation. That was. of course. not the last we saw of Maurice as w ill be seen.

Sub-Committee B's report. presented

by Arnold in his usual masterly fashion. was accepted. too. Arnold. who was also chairman of SC I. said that he was very grateful for the amount of work done by Member Associations in preparation for the conference. and the fact that on one item he had to give his cast ing vote was some indication of the considerable discussion that had taken place.

Then followed nine addresses to conference by guest speakers. among them Mr. N.G. Ehrnroot h from the United Nations. Mr. G. Dunand from the ILO. Mr. A. Azzaoui from ICAO. Mr. A.M . Waldin from FAA. som e from other National Administrations and from pilots' organizations.

The President then thanked all those who had contributed to the success of the conference. and. in particular Daniel Monin and the members of the Swiss ATCA. After the Final Plenary delegates were invited to a Fondue Party in the outskirts of Geneva. This melted cheese dish can only be prepared immediately before it is served. For some 200 guests this. of course. took some time. Waiting was made supportable by a few drinks. By the time the chesse arrived. participants were already in good humor. And - as t hey say in fondue commercials this dish even increases good humor. In other words. it was a very animated and memorable evening.

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·,:.. -: ;:· ~. :/._,~r_. ;:. ...

Humor from Poland by J E. Tomczak (Warsaw Ace)

Cub Pilots Invited to 'A Sentimental Journey' Wh~t promises to be one ge~t single-model airplane

of the larfly-ins is being pla nned for summer 1986.

8

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The subject is the Piper Cub. still the generic name for all general aviation airplanes despite nearly 30 years of industry attempts to co nvi nce the world otherwise.

The organizers of ·A Sentin:iental Journey' are putting together. in cooperation with t he National Cub Club. a Piper Cub fly-in at a place that Cub owners call Mecca b ut the rest of the world ca lls Lock Haven. Pennsylvania. where the Cub was built . The purpose. according to organizers of the event. is to 'celebrate the dream of William T. Piper w ho placed flying wi thin the grasp of t he average man ·.

The fly-in will be held at William T. Piper Memorial Airport. adjacent to the old Cub factory. on July 13 to 19.

1986 . It will include fl ight contests. displays. pilot seminars. a flea m arket and other events .

THE CONTROLLER / DECEM BER 1985

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ASTRID offers 2 sizes of display unit, 3 different screen phosphors and 3 system configurations with a mix of sensor inputs.

ASTRID provides all the radar and SSR processing facilities which are now standard in air traffic control RDP systems. Further optional facilities are available.

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A WHOLE NEW GENERATION OF THINKING.

Air Terrorism and its Evolution

by Andreas Avgoustis. the Editor

The tragic o utcome of the hi-jacked B 73 7 of Egypt Air on 26 November 1985 is unfortunately an addition to the list of recent terrorist activities directed against Civil Aviation.

An Air India jumbo jet with more than 300 people on board was lost in the Atlantic in June this year. apparently blown up by a bomb planted on board the aircraft by terrorists .

Three other aircraft were hijacked

by Lebanese terrorists earlier the ~ame month . An unfortunate experience which puts men. women and childre~ to the limits of their mental and physical endurance. A dramatic adventure that involves hundreds of people not knowing when and how all this will end. An adventure of the man. the woman or the child who leaves home one morning to learn about fear under threat of death.

Would all these terrifying acts create any doubts in your minds as to t~e degree of safety that exists in the air?

Apparently yes. Are you r doubts founded on sou nd grounds? I will s~y again and emphatica lly. yes. ~ut w.111 you put off a business or a holiday tnp abroad because of these fears? The answer is obviously no. The chances that a bomb will be planted on the aircraft that you will fly or that it will be hijacked are certainly very remote.

When airlines were first being founded some 60 years ago. flying was a fairly simple if somewhat unpredictable business . The pioneer aviators dusted off their biplanes and carried off their intrepid passengers for short daylight hops whenever the weather permitted. No one gave thought to such matters as air piracy.

The situation has since changed.

The nature of hijacking itself has also c hanged. Initially. hijacking was represented by the side trip to Havana and was joked about by passengers. governments and the business alike .

No one. of course. considers hijacking today as a matter to be treated lightly.

Terrorism is no new phenomenon to any country. There are many types and examples of terrorism that one could cite from history but they pale into insignificance when compared to 10

the nature and style of international terrorism in the form of hijacking. Perhaps. you may contend. terrorism is a

A.Avgoustis

sign of our times for we live in a world riddled with strife and violence. It is a phenomenon that knows no borders. respects no laws - domestic or international. It is an evil that has left no nation in the world untaunted.

The political terrorists have appea red on the scene just as the ransom seeker. Civi l Aviation has become a prime target of all those who seek to draw world attention to their cause. Passengers and airlines alike have in the meantime become the innocent victims of this terrori st activity. The most important turning point to the nature of hijackings was what is ca lled the Labour Day weekend of 1 9 70 when 5 large jet aircraft including a jumbo. were hijacked and after being taken to the Jordan desert were blown up.

Air terrorism is in the strictest sense a problem of international dimensions. Its genesis lies in the peculiar mixture of cold war politics with the unique technology of commercia l jet travel.

The jet aircraft in flight is externally a symbol of prestige and prowess. Internally it is vulnerable. The air terrorist

ostensibly acts against pilots and crew; but the primary coercion is against the lives and safety of passengers. Passengers are repeatedly exposed to potential physical harm du ring hijackings not only from hijackers but also from security personnel who may use counterforce as a deterrent.

Having said all this. let us examine the methods used and measures taken to combat hijackings and perhaps see how effective these have been . so far.

At considerable costs. governments and airlin e operators have implemented strict security measures as for example the pre-boarding screening system to prevent t~e hijack~r from taking arms onto the aircraft; airborne armed guards are still u~ed by ~ome airlines; national and international laws imposing heavy pe n altie~ on hijackers: international cooperation ~nd concerted action against states which are offered as sanctuaries to the hija ckers are aims which materialized ~n the very recent past: to be more illustrative. let us recall also a few of the countermeasures taken against the air pirates and what one might call the war of the pirates. .

You will all remember the danng Israeli airborne comma ndo attack on Entebbe in 1976 which in effect triggered other countries t? move from passive to offensive tactics. T.he Germans copying the Entebbe raid. successfully executed a commando attack and released the passengers of the Lufthansa flight who were h ~ld hostag es in Mogadishu .. Somalia.

Many countries have trained and equipped special units !hat are able to fo llow and attack the ai r pirates wherever they may seek sanctuary. A.II these means and methods were primarily directed at prevent ing air pirate acts. .

However. complete prevention. as we all have witnessed these last few months. has not been achieved . Admittedly they were eliminated to a considerable degree.

It is possible that hijackings may be stopped altogether if state~. apply strict and heavy penalties to h1Jackers and offer no safe haven to them .

Truly. in recent years the number of sanctua ri es for air pirates has shru~ k considerably but as long as ther~ is one country in wh ich they ca n find refuge this crime wi ll contin~e.

Cold war politics still remain an obstacle in resolving the problem . No one can reasonably see the day when the hijacker wi ll be arrested and punished by any state. It is unfortunately. a statement of fact that for exam ple the USA will react differently from the Soviet Union to an escaping Russian seeking political asylum .

TH E CONTROLLER / DECEMBER 1985

What Do We Owe the Paying Passenger?

by Frank W. Fischer President International Advisory Group -Air Navigation Services

I represent your Corporate Member ANSA. ANSA stands for International Advisory Group Air Navigation Services.

We are not manufacturers.

Therefore. thi s is not a t echnical presentation .

I myself am a consultant an air traffic controll er and a pilot. ¡ .Now, it is a known fact that human beings com e in different versions. For the ~a ke of my presentation. please consider yourselves as being air tr.a ~sportation providers. that means airli ne managers. civil aviation directors. airport operators. air traffic controllers. pilots. and the like.

I myself wi ll be the payi ng passenger.

Why? B~ca u se the passengers are part of the air tra~ sportation system . But they are an active part of it only for the moment, when they pay for their ticket.

Thereafter they are condemned to be passive.

Some of them guess th at there is a !ransportation system and believe in its proper functioning at all times and therefore rela x. Others do not and are often frightened . . Now. what do all of you do to justify thi s belief and What do you owe me the paying passenger? ' The answer is simple : Respect!

But all too often. I. as a paying passenger. lack your respect . This respect. that to m e. is pronounced as Safe Transport.

Let me tell you what I think you owe me. for the fa re that I paid. My fare. w hic h creates the demand for your professions and pays for most of your sa laries.

You owe me safe transport from A to Bat any time. beca use the safety of my life tota lly depends upon your proper functioning . And I, therefore. define safe transport as:.

THE CONTROLLER / DECEMBER 1985

Frank Fischer

'The transportation of my body in an aircraft that has been certified to be and is airworthy, that is being maintained and operated on the ground and in the air in accordance with all existing national and international regul ations of ICAO and of the variou s national authorities whose territories are overflown; that is being operated in controlled airspace and provided air traffi c control service. which means standard separation from other aircra ft without endangering my life at all times! ' From my point of view. this should not be diffic ult. It should be normal and not worth mentioning. because I am not looking for adventure.

Anything else, to me. is not safe transport!

Let me give you a few facts and thoughts.

The passenger of today does not plainly believe a pilot. w ho always blames ATC for his departure delay.

Al so. nowadays. passengers are much more interested in reaching their destination safely. than in free champagne onboard or the outside air temperature. It always seems to be minus 56 degrees anyhow.

He. however. is becoming very interested in a pilot's traffic informa-

tion radio broadcast on another possibly conflicting flight while over Africa and in his airplane's flight through uncontrolled airspace.

He also doesn't want to be endangered by ad hoe provisions of air traffic control service by the military to his civil flight in times of industrial unrest and strike.

Further. I refuse to believe in the aircraft industry's reluctant attitude on installing an urgency radio override receiver in every aircraft. so that also my aircraft can be reached bX controllers everywhere and at any time.

At the same time. I am more than astonished about the lack of air I ground and ground / ground communication equipment in many countries. If we cannot talk to each other. how shall we coordinate our intentions at 500 to 800 miles per hour?

The same applies to so-called language barriers between contrc:illers or between controllers and pilots.

Simply fire the incapable and ~ire the capable. and pay them appropna~ely: I am also not interested at all in airline company regulations_ that al~ow the conduct of a flight in marginal conditions and I consider it ve~ risky by airlines and aviation authorities to allow visual or VMC approaches on IFR flights at destination. beca~se all too often I can see the uncoor~1nated pile-up of IFR flights on final. fighting for airspace to maneuver. .

And then . when I listen to the daily airline propaganda of super-safe flying, 1 cannot believe that the _use of standard ATC phraseology is not mandatory for pilots.

I also doubt the completeness and correctness of many preflig~t preparations due to the often lacking provision of up-to-date. correct an_d conclusive aeronautical information to aircrews by aviation authorities.

I also do not believe in the u.nsur~ separation between known . aircra. only under the provision of air t~affi~ advisory service or FIS. I believe in ~ir traf'.i~ control servic.e to IFR fligh~rs~ pos1t1ve controlled airspace only. ther is a four-letter word to me.

I therefore ask all of you to ra f; delay me, than to endanger my sa e h. 1 see flight.

Believe me in telling you a11 t is. f the require'ment for the exi~ten~~ ~I controller and pilot associations countries of this world. bec?us~ the~ at least guarantee the publicati~~ 0 problems to be solved: becau~e 1t. is a duty of the professi on~! organizat ion~ to fight for required improvements. and I shall support you! .

The traveller. nowadays. is aware of the fact that he moves through constantly changing environments 11

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during the course of only one flight different environments of culture. religion. mentality. motivation. welfare respectively poverty, and technology, in crossing national borders almost hourly.

This traveller. therefore often takes it for granted that his international flight is being handled in a uniform manner according to international standard by ATC units on the ground. who are equally capable to his proficient flight crew.

The fact is. there is no uniform application of agreed ATC standards; and as we all know. the innocent passenger's impression is a big lie.

This is why I also wish to see the control of flights in international airspace be performed by internationally manned multi-national ATC units; be it ICAO. Eurocontrol. or whoever. I then would feel much more comfortable. because this has the good smell of forced coordination. regulation and standardization.

12

FOR ~IN\~G pu~PQSE5 •••••.

And finally, I hate pilot/ controller controversies. because to me. you are all in the same boat.

Air transportation providers. for whatever reasons you might have for any improper functioning, I. the paying passenger. do not care. because you and I. as insiders. know of your obligation and of many more other ways of unsafe air transport.

I. the paying passenger. also do not care. who of you is to blame for incidents and accidents; no. I just don't want them to happen. And I only do care that all of you do your best to avoid them. And the utmost. to my understanding, still is not being done.

I am one out of many million.

And as a paying passenger I insist on better treatment safety-wise. Remember some of the accidents that were caused by human failure.

Just recently at Bilbao. and on Mount Erebus. due to wrong navigation; Zagreb. due to managerial system

failure and controller malfunction; Nantes, due to military presumption; Tenerife and, Madrid, in fog and due to pilot error; Sachalin, due to lack of communication and coordination; Grand Canyon, due to lack of rules and regulations.

To me, the real list seems almost endless and I am scared.

And still, flight safety records are being made up by passenger kilometers flown versus the number of accidents. instead of the number of flights versus incidents.

Therefore. please remember that I am not only a blip on your radar scope or a flight number on your flight progress strip, a paid ticket or the reason for a delayed departure or a figure in the accident file.

No. I am like you and wish to reach home alive.

Controllers, pilots, airline managers. aviation directors! Please do not forget that also you have to fly once in a while and that also your life is at stake.

Also. most of you here in this room know that near mid-air collisions do not only go into the hundreds worldwide. but into the thousands!

So. do not only talk about problems; Solve them!

Also. I. the paying passenger. do not care for politics in your business, because I cannot see any borders. I also know that not all of you can be responsible for everything. but all of you together are always responsible for all my safety.

So, if you know about a problem. tell it. Don't hide and accept things that are dangerous to me. Refuse incorrect and unsafe action. Apply available technology and use available equipment.

For. to me. todays's air transport is still not safe enough. unnecessarily, because technology is available and all the required equipment is on the market.

The risks involved in present day operations are still much too high and are invisible to the travelling public, which cannot see nor change them.

IFATCA. IFALPA. IATA ICAO and all of you together can! So. ~o and stop risky operations and impose change. Otherwise. I shall blame and claim.

And if you do not have the power to change this situation. you certainly have the authority. Authority goes with responsibility. Having the responsibility requires you to always provide a safe service to me.

My group stands ready to assist all of you in reaching this goal.

THE CONTROLLER/DECEMBER 1985

ATC Training: Realism and Training Effectiveness

by John Kleeman (of Scicon

Limited)

Introduction

A This p~per presents some ideas on TC t raining . The main thrust of the argument concerns area and approach radar control. though much of wh.a~ I have to say applies to other training too . .

Whereas theoretical and classroom ~o.r~ has. a. major rol e to play in ATC a i~ ing. it is widely accepted that the ;nai~ route to learning ATC is by exens1ve practica l experience. There are t~ree ma!n ways of gaining this ~xpt~ence; firstly controlling of airs~a t 1 ~ ?Perationa l conditions under safeervi ~ ion - which has possible ty ri sks and other problems¡ sec ond ly control on real equi pm~nt of apircr~ft flying solely to g ive controllers .ract1ce - which is extremely expensive¡ d . ¡ a nd t h'1rdly the use of computers;iven radar simulators to give udl e~ts practice without the use of rea aircraft.

It 1 . . s the purpose of this paper to c ons1der what are some of the im~~l~a~t criteria for designing and h cting a radar simulator system and tw at are the likely trends for th e fuure. f R ose o adar Simulators The purpose of a radar simulator ~Ystem is to train. in conjuncti on with instructors. student controllers.

Although some simulators are used for at.her purposes. for example eva lua.t1on. the prime purpose of most simulators is to train. th It is a c.o mmon step to assume that late n:iost impor~a~t aspect of a simuit or is how realistic 1t 1s. i.e . how well in models the real ~TC situation . Since many ~ases a simulator is used to replace live control for training it wou ld seem that the more closel.y a b s 1mulator resembl es live control the etter it can repla ce it.

However. the purpose of the live control and of the simulator is to train and there are a number of other factors which are perhaps more important than rea lism as far as tra ining is concerned .

Purp

TH E CONTRO LLER / DECEMBER 1985

Air traffic control display systems vary widely from soph isticated processed systems to simple raw radar displays. Yet for controllers using all displays there are common core skills involving understanding a changing radar picture and issuing sensible instructions to aircraft. Although display systems require practice to use properly. the important thing all controllers have to learn is how to decide what to say to aircraft- ski lls like deciding how to sequence several aircraft onto a runway. This is the most important th ing that practical train ing can teach .

A comparison with pilots is appropriate . The difficult tasks as a pilot are not so much planning what to do but actually doing it. how to take off. etc .. the difficult tasks as a controller are not doing things (controlling the display. R/ T procedure) but planning what to do. Thus if a pilot has an emergency he needs to know how to move his controls in the right way. whereas if a controller has an emergency he needs to be able to give sensible directions. An aircraft simulator

for a pilot needs to be very realistic as the pilot needs to learn to do things right. whereas a radar simulator for a controller needs to teach thinking rather than doing skills.

Other important aspects of a radar simulator are what instructor features are available to allow the instructor to use the simulator effectively (for example replay I debrief features). and - allied to this -what student training features there are. Computers can do a lot more than passively simulate and a good simulator should have training features which aid the learning process.

What really matters in a radar simulator is how well it can be used to train ATC - or how effective it is at training . Thus training effectiveness should be the key measure of the qua lity of a radar simulator" I would contend that although realism provides an important contribution to training effectiveness. it is only one of a number of factors. Sections 3 and 4 of this paper expand on this ..

Given that train ing effectiveness does measure the quality of radar simulators. it is then appropriate to consider the costs of various levels of t raining effectiveness and how technology can best be harnessed t?wards training effectiveness. ~ect1on 5 elaborates on this and Section 6 offers some thoughts on the future.

Appropriate Realism Consider the following scenario.

The radar display systems at .an ATC centre are being replaced w1t.h new equipment. The body of experienced controllers need to be trained to u~e the new equipment. If a simulator is

John Kleeman delivering his paper at 24th IFATCA Annual Conference in Athens.

13

being used for this training. then clearly the simulator must realistically model the new equipment and probably the most important thing about the simulator is its level of realism.

Now consider the case of a student undergoing initial training. He needs to be trained in. for example. conflict detection and avoidance - the ability to detect whether two aircraft are going to conflict and issuing the necessary commands to avoid the conflict. If a simulator is being used for this training then the student must see a radar picture and be able to issue commands but there is no need for a high degree of realism in the equipment; indeed a very realistic (and complicated) display system could easily distract and hinder training.

In the first case the training effectiveness of a simulator correlates closely with its realism; in the second case realism is unimportant and the simulator's training effectiveness will be more affected by factors like the clarity of the display and the training features available. Thus the level of realism required depends on the type of training task and. for any given task. there is an appropriate level of realism to optimize training effectiveness. Below this level training effectiveness will be reduced and above it training effectiveness is perhaps not seriously affected.

Since a high level of realism can be very expensive. it can be important to examine very carefully the level of training effectiveness required before deciding the level of realism required.

An interesting case to consider is the radar sweep. Where controllers are to be trained to use analogue displays. the most realistic simulator will show a radar sweep identical to the real display. A less realistic simulator would not show a physical sweep but would update the aircraft blips once per radar revolution and supply appropriately fading backtracks.

The radar sweep does not have many practical operational uses - it exists on analogue displays simply because that is the way radar works.

For a controller it is something he soon learns to ignore: for a student it is a distraction which gives nothing to help him in understanding the radar picture: on the contrary it is a definite hindrance to such understanding.

Whereas obviously the controller does have to learn to cope with a sweep at some stage. there does seem a strong argument for teaching large parts of ATC without a sweep.

Scicon have installed such a sweep-less system at International Aeradios (IAL) School in Bath. UK. 14

Students and Instructors are extremely pleased with the high level of clarity; experienced controllers looking at the system frequently come away thinking that the display is very good - but surely there is something wrong somewhere! Only after being told do they actually realize there is no sweep.

Of course. modern processed ATC displays have no sweep anyway, but the principles apply in any case.

Essentially training may well be more effective on a clear and simple radar picture where important principles are more obvious than on a realistic but cluttered picture on which it is less easy to understand aircraft positional relationships.

Training Features Training features on a radar simulator are features which offer capabilities not available in the real world which can be used to enhance training. This paper does not attempt to cover all possible training features. but merely to indicate what sorts of things can be done. Three examples are given below.

Track Histories With a computer-generated radar display it is very easy to superimpose computer images on a radar picture.

One feature we have found very valuable is for the computer to display at any time the track histories of aircraft - lines drawn to join-up the past positions of aircraft. This feature allows an instant view of where aircraft have been and is particularly useful in small exercises where the track histories are easily viewed.

Conflict Detection and Reporting Maintaining separation is one of the key parts of ATC and it is very easy to program a computer to detect conflicts in a simulator. Then either messages can be dis~layed informing the student or supervisor of the conflict or circles can be drawn around the conflicting aircraft. If circles of radius half the minimum allowed separation (2 % miles for a 5 mile limit) are drawn. then the conflict is graphically illustrated showing the student exactly what has happened.

Replay One of the most useful training features is the ability to replay an exercise for debriefing. In an ideal situation. after a long term exercise. each student should be debriefed by an instructor on his own. He would be able to look at the radar picture he saw previously. skipping through to the points in the exercise the instructor

wanted to talk about. At crucial points the student could take over control of the replay and redo critical parts of the exercise.

Features like these are clearly useful to have on a radar simulator - providing they can be effectively controlled by the instructor. Certainly a simulator with such features is. all other things being equal. better than one without and it may well be that such features can. if properly used. dramatically increase training effectiveness.

Cost Factors Radar simulators tend to be extremely expensive. Because of this. simulators are usually very heavily used and simulator time is often in short supply. Historically radar simulators have tended to comprise actual operational radar displays driven by computers using a considerable amount of complex electronics.

However. recent technological advances in computing can offer radical cost savings for radar simulation.

Firstly the use of high-resolution graphics displays in all sorts of other fields- computer aided design. video games. etc .. - has led to the availability on the commercial market of low cost computer-driven graphics displays. These mass produced products can be used in radar simulators at huge cost savings over using specially built displays. These cost savings apply especially if the level of realism considered appropriate to the training task is less than 100%.

The most important advance is more fundamental. A computer system (and this includes a radar simulator) consists of hardware and software. Hardware is the physical electronic equipment - tubes. computers. keyboards. etc. Software is the instructions that drive the computer and cause it to execute the functions it should do. A computer is a general purpose tool and the software decides whether it should simulate ATC. allow word processing or run accounts.

In the past computer hardware has strongly limited the quantity of software a system can have. Recent developments in computer hardware have made systems with large memories capable of holding huge amounts of software very cheap. The amount of software and thus the amount of functions the computer can perform is limited now by the length of time it takes to create the software.

A typical feature often performed by hardware on simulators is the creation of a videomap. Transparent videomap overlays are inserted into THE CONTROLLER/DECEMBER 1985

special hardware which puts the v1deomap onto the simulated radar P.icture. In a software solution, the v1deomap would be entered into the c~mputer and stored on magnetic disk; the .computer would then generate the v1deomap on the radar picture by software.

Irrespective of the advantages to the user of each method, the hardwar~ method involves costly physical equipment whereas the software meth~d requires only complex com~yter instructions. Whereas it may be th engthy and costly business to create e software, once it exists it can be ~~ed. over and over again - just by d" pying the instructions - at no ad.1tional cost. On the other hand each s~~ulator needs to have the whole vi ~omap generation hardware. hus if a standard software pack~~~ c~m be created to execute many . simulator functions and included 1 nman · devel Y simulator systems, the cost of s t 0 Pment can be spread over all u~~ ers. If this is combined with the dispf mass-produced computers and ma· ay syste.ms, there can be very ~or. reductions in simulator costs.

Dir cicon have such a solution - our notec~or ITS product. No doubt we are meaa one. Our hope is that this may and n less ~ressure on simulator time, eachrnor~ simulator time available for trainee controller.

The Future tif

Pr~bably

two trends can be iden-

th~d ~n ATC simulators today. Firstly,

lar re is the tendency to include simuatiion and training facilities on operca~nal .co~soles so that controllers ondl tram 1~ slack conditions. Secc Y• there is the tendency to use low si~t, less.realistic training systems like £le microcomputer skills trainers. uppose as seems likely that softVv · · t are c ontmues to expand in import~nce. Then it is possible to imagine at extremely powerful software ~~~k~ges will arise, with all possible fecti eatur~~ and a large variety of efve training features Such soft Ware pa k · . f igured t c0 ages could then be con displa run on all computers and corn Y systems from cheap personal sirnJ~t~;s through medium realistic soles Ths to full operational concond~cte en ATC t~aining could be different d on a variety of displays at · · extremal 1stages of training at effective~e~:.' cost and high training Should this when con .d . come about then. s1 enng rad . I instead ofth· k" . ar s1mu ators. of dis 1 in. mg first about the type of the~ ay refquired, one may think first ype 0 software package. Also it THE CONTROLLER/DECEMBER 1985

may be that hardware companies will New Selenia Radar for no longer dominate the ATC simulator world but that companies whose Oslo Airport prime area of expertise is software, like The new ATCR 33 radar produced Scicon. may come to the fore. by the Selenia company, installed at Note: This paper is not intended as Oslo international airport. successfully an academic dissertation and I have passed recent flight tests.

The Italian radar was chosen by the not referenced the original sources for Norwegian administration (NTA) at the ideas therein. Many ideas derive from David Carratt. Peter Maltbaek the end of an international compeand others of Scicon. Many others are tition with the participation of all the manufacturers of radar of this type, clearly not original to Scicon at all. both European and American.

The offer from Selenia. the leading company of the Raggruppamento Selenia Elsag (IRl/STET Group), was Ed Pinto Joins AOPA adjudged the best both from the techAircraft Owners and Pilots Associ- nical standpoint and price and speed ation has announced that Edmund of delivery. The new ATCR 33 was in Pinto will join AOPA as Senior Vice- fact delivered in only six months, an president, Communications. Pinto is exceptionally rapid time for this type of currently Assistant Administrat~r .tor supply. and set in operation with the Public Affairs at the Federal Av1at1on full collaboration of the Norwegian Administration. technicians.

'We are both delighted and fortuThe apparatus is similar to the type nate to have Ed join us'. said AOPA being installed at Fiumicino Airport; President John L. Baker in making the besides at various Italian airports, the announcement. 'Ed brings to AOPA ATCR 33 radar is also installed at an impressive background and formi- many foreign ones. among which Budable communications expertise that dapest Mexico City, Lagos and Lima. will enhance and guide every aspect of The heavy schedule of flight tests drawn up by the Norwegian civil avithe association.'

At the FAA since 1982, Pinto has ation authorities was completed in a been in charge of all FAA's internal short time thanks to the use of a new and external communications, as well piece of apparatus developed by as the agency's aviation education Selenia's technicians: the CDS-80 and consumer programs. Pinto was Scan Converter. which transforms the recently honored with a Superior traditional radar presentation into a Achievement award. the agency's television type presenta~ion. T~is enables one to obtain the image, vishighest.

Prior to joining the FAA. Pinto was ible also in daylight. of a great nu.m~er Director of Public and Consumer Af- of revolutions of the antenna; this imfairs at the National Highway Traffic age can be recorded with normal Safety Administration. Both the FAA commercial-type recorders and be and NHTSA positions were Adminis- viewed on any television. tration appointments.

The flight tests of. th~. new radar Pinto has also served on Capitol took on a particular s1grn.f1c~nce. ~e­ Hill. where he was press secretary for cause they practically co1nc1ded "":'1~h Senator Bob Packwood (A-Oregon) the twentieth anniversary of Sel_erna s and Senator Jacob Javits (R-New activities on foreign markets in the York). A veteran newsman. Pinto was radar sector. In February 1965. prea supervising editor at the Associated cisely near Oslo. the first ra~ar to be Press in Washington during the completed designed and built by the Watergate crisis. Prior to that assign- Italian company in fact beca~~c°G~~ ment, he was AP' s state editor for ative· it was a long-range which is still in service. ~o the full satNew York. based in Albany. .. In ad.dition to his demanding pos- isfactior.i of the Norwegs1ars .. ·s ATC 1t1ons. Pinto is a commander in the US Twenty years later ~ eni~ e in mor Naval Reserves. and has recently re- systems are now .operating Among fecent ceived command of a major, award- than thirty countries. h" h fast .

New Zealand w 1c · winning public affairs unit operated I 1ents h d three Selenia air out of Willow Grove Naval Air Station cFebruary. pure ase traffic control systems o~ ~he new in Pennsylvania.

Pinto is a private pilot and is cur- CDS-BO type. with telev1s1on type rently working on an instrument rat- radar presentation. ing. He set the first world record for a STOL aircraft time to climb to 3000 meters, and holds the national speed record for a STOL aircraft over a 1525 km course.

15

Covering a landscaped area of 240 km2, the new King Khaled airport at Riyadh is the largest international airport in the world.

Four triangular-shaped marble and glass terminals can handle an estimated traffic volume of up to 15 million passengers per year, while a vast fully-automated cargo centre can serve three B747's simultaneously.

Then there's a beautiful mosque for 9000 worshippers and a superb housing estate for airport personnel and their families.

In fact, King Khaled International airport exemplifies Saudi Arabia's well-deserved reputation as the 'Kingdom of magnificent airports'.

Technical facilities are equally impressive. Many of them supplied by Philips: long-range radarand fully-automated flight plan processing for ATC; 'Dynavision' X-ray baggage inspection; and an optical transmission link between the airport and Saudi's public telephone network.

You will also find Philips contributing to efficiency, safety and security at other major airports the world over.

With AEROPP switching systems for AFIN and CIDIN, securely handling vital information such as: flight plans, Notams, OP11ET data, departure/ arrival messages, and ATC data. And voice logging systems for recording air-ground conversations.

Terminal, apron and airport lighting, including mobile and portable airfield and heliport lighting systems. And high-definition ground movement radar, ASDE, to monitor, control and co-ordinate all airfield movements.

Write for our new Aviation brochure to Philips, CPMS, Eindhoven, The Netherlands.

Philips. lhe sure sign of expertise worldwide.

PHILIPS

Evolution of the Air Traffic Control Beacon System

By C.F. Philips A TC Advanced Program Manager Westinghouse Defense and Electronics Center

Foreword During and following World War II. civil ATC was a manual control system. The ATC controller used communications. flight strips. a map. and various 'fixes' to form an image of the aircraft position under his control. As the number of civil aircraft rapidly increased. primary radar was added which gave the controller accurate aircraft positions and increased safety. The establishment of aircraft identity with primary radar only was difficult and often required aircraft maneuvers. such as a 360° turn. When their ground beacons were added to the primary radar. controllers quickly observed that the beacon system made aircraft identification much simpler. Still. the ATC beacon system is a cooperative system which requires transponders in the aircraft.

Soon. aircraft owners and operators recognized the advantages of the beacon system and began to install transponders in their aircraft. especially in commercial aircraft. The safety and efficiency of the ATC system in the United States and in many other countries was greatly enhanced as the ATC beacon system became widely implemented. both on the ground and in the air. Without it. today's modern ATC alphanumeric displays would not be possible. Primary radar is still required. especially in the terminal areas. but mainly functions in the enroute environment to detect aircraft with no or inoperative transponders. It also provides hazardous weather information.

The ATC beacon system has developed a number of problems as its implementation has increased. Ground sensors. an outgrowth of the World War II IFF system. interrogate at 1030 MHz. Transponders reply at 1090 MHz which creates a major potential interference problem. This paper summarizes the problems encountered in the ATC beacon system as it grew in numbers and the various improvements implemented to cope with these problems. including the latest Mode S (Select) and its associated monopulse operation.

The Air Traffic Control Beacon system has evolved over the years to become the primary ATC Surveillance System. It has had numerous problems; however. many improvements have been made. This paper summarizes the evolution of the ATC beacon system and describes the latest improvement to Mode S. which will extend the life of the system well into the next century. characteristics of the system. both the ground and airborne equipment. meet the standards set forth by the International Civil Aviation Organisation (ICAO}. The purpose of the ATCRBS (or SSA} is to have worldwide compatibility independent of the country of origin and the equipment manufacture. ICAO standards also apply to the new Mode S (Mode-Select} improvement to the ATC beacon system.

Figure 1 illustrates the operation of the beacon system. The beacon antenna as shown is typically located on the top of the primary radar antenna. The civil ATC ground interrogations at 1030 MHz are

RESPONSE INTERROGATION

18

IDENTIFICATION CODE

~ 3J~63J

npr;nqq

MODE A

MOOE C ATC:-

... nan

1 - - - 20.3µs - - - t

Operation of the ATC Beacon System The A TC beacon system is known as the Air Traffic Control Radar Beacon System (ATCRBS} in the United States and the Secondary Surveillance Radar (SSA} throughout the rest of the world. The

shown for two modes- Mode A for aircraft identification and Mode C for aircraft altitude. Other military modes may be used also. and these interrogation modes are interlaced with t~e civil interrogations. The P2 p~lse shown 1s for sidelobe suppression as discussed later. !he airborne transponder resp_onds to the m~errogations at 1 090 MHz: with a pulse_ tram with up to 15 pulse~ in a. 20.3~m1cro~econd_ pulse reply tram. ~his ~rov1des aircraft identification and altitude m response to Modes A and c respectively. The aircraft's identification i~ ente~ed m_anually by the pilot with the aircraft s altitude entered automatically by th_~ altimeter for those aircraft equipped with Mode C. Before automation was added to the ATC system. the beacon transponder replies were displayed as double slashes on the controll~r· s display adjacent to the blip from the primary radar. Passive decoders were supplied and each ATC controller ~ould e~ter manuall_y the code of the part1~ular aircraft he wished to identify. The pilot ~ould_ enter mannually the particular co~e m ~1s transponder via communications with ~he controller. Then the controll~r would ~nstr~ct th7 particular aircraft he wished to 1dent1fy to squawk ident' and the area ~etw~en the beacon slashes wo~ld be f1ll~d-m. thus providing identification. Special codes were provided fo other p~rpo~es such as an aircraft emer~ g~ncy s1tuat1on. Many countries still use this form of beacon operation T~e final step_ before auto~ation was t~e 1mpler:ne~tat1~n of horizontal bright displays w!th shnrr:ip boats'. These were cle~r plastic ta~s with the aircraft identification and altitude marked on them b crayon. The controllers moved the shrim~ b<?ats so that _they stayed over the radar bhps on the display.

The fi_rst step in the implementation of automat~o~. for the ATC system was the use of d1g1t1zers for both the primary and bea?on radar systems. Digitizers automatically converted the radar and beacon

a..1·--21µ.s ---i·I

I I"-'

Figure 1. Air traffic control radar beacon system (ATCRBS) THE CONTROLLER/DECEMBER 1985

returns received within the beam of the antenna into digital messages. each having the range. azimuth. identity. and altitude. Then these digital messages were transmitted from the radars to the ATC display and control centers via narrowband (telephone) circuits. The digitizing process eliminated the need for broadband microwave links or coaxial cable. although the broadband links were retained on some systems as a backup in case of computer failure . Today. systems ~ave a digital backup and the broadbank links are being eliminated.

Large computers such as the IBM 9020 in the United States and UK enroute systems were introduced to provide a fully automated ATC system . Tracking of the r~dar returns and other features were provided . . allo~i.ng the alphanumeric display of the 1dent1f1cation and altitude of aircraft on a vertical brihgt display with keyboard e~try . Figure 2 is an example of such a d1sply as seen in ATC control centers throug~out the world today. lmprovemen!s 1 ~ automation of the ATC system are continuing; however. the performance of these systems is still very dependent upon the performance of the ATC beacon system. In the automated ATC system . the perfo~manc~ of the beacon for tracking and display is much more critica l than with broadband or ana log presentations.

ATC Beacon Problems and Improvements The extensive implementation of ground. b.eacon i~terrogators along with the !ap1d increase in the number of aircraft having transponders created a situation "':'here in aircraft could be interrogated simultaneously. or nearly so. by a number ~f ground systems. This crea ted a severe ~te7eren ce problem on the controller's isp ay. This interference was termed

C. F. Phillips addressing the Conference in Athens

'fruit' which is the display of unwanted transponder replies received by any parti cular ground beacon interrogator I receiver resu lting from interrogations by other ground systems. To eliminate this problem. 'defruiters¡ were added to the ground systems. The defruiter eliminated all replies except those in synchronism with the interrogation rate of the ground interrogator. A lso. the interrogation rate of all interrogators in a region were staggered to enhance the defruiting process.

Defruiting is done muc h more effectively in today¡ s digital radars and in the computers associated with th e ATC system.

Figure 3 shows a 200-mile ARSR display before and after defruiting 1 â&#x20AC;˘ These sidelobe int errogations can create a severe interference problem as was determined in the early implementat ion of the ATC beacon system. Figure 4 1 illustrates t he beacon returns from a single transponder.

W it h multiple transponders it is obvious that the interference problem is much more severe. At one time. the beacon syst em was virtually useless because of sidelobe interference. Oftentimes. controllers requested pilots to turn off their transponders at short ranges to reduce the interference .

(b)

Figure 2. Typical modern alphanumeric digital A TC display

TH E CONTROLLER/ DECEMBER 1985

..

Figure 3 . Defruiter performance at Elwood ARSR Display (200-nmi range. 70-nmi range marks); (a) before defruiting. (b) after defruiting 19

TIA•SPOMOEl REPLIES -

-

-

-

-

-

-

-

-

-

-

-

9 db

- - - - - - - 0 ~b

TIAllSPOMOER SUPPRESSES

DIRECT IOUL

ONll I 0 I RECT IOUL

Figure 4 . PP/ tim e exp osure for a radial flight. showing ringaround effects

To eliminate the sid elobe interference prob lem . a sid elobe suppression system (SLS) was implemented in the ATC beacon system . An omnidirectional antenna was mou nted on the top of t he ground b eacon anten na and a p ulse P2 was added to the int errogation pulses as illustrated in figure 5 1 . The operation of t he SLS is quite simple. The amplitude of the P2 pulse in the transponder is com pared w it h t he amplitude of the P1 p ulse. The transponder only replies when the amplitude of the P, pulse is greater than the amplitud e of the P2 pulse. within preset limits. so t hat the transponder only replies to mainlob e interrogations.

The defruiter and SLS beacon ' fixes· eliminated interference of unwanted transponder replies from t he controller' s display. However. w hen a want ed transponder reply arrives in th e ground beacon receiver at the sam e time as an unw anted reply. a situation known as a 'garble ' occurs. Garble is the mo st serious problem of the ATC beacon syst em . Garble can cause the loss of beacon replies. w hich in turn can cause azim uth errors in the beacon replies or a complete loss of a bea con reply. When the u nwanted and wanted replies are not overlapping. i.e .. t hey are interleaved. modern digitizers ca n separate the two p ulse trains. Still. the garble p roblem can be very serious. especially in high density termina l areas. It is also one of the reasons for the development of the Mode S system .

In 1969. the interference probl em in the ATC beacon system at some locations in the United States became so serious that its useful life was in question . As a part 1Kadar Handbook & McGraw-Hill Book Company Skolnik. Ed11or-1n Chief - Chap 38 by R. Ashley and J Perry A IL D1v of Culler Hammer 2 See Repon of Depanmen1 of Transponatoon Aor Traffic Control Advisory Committee. December 1969

20

Figure 5. Sidelobe suppression system {SLS) amplitude relationships and antenna patterns

of a special comm ittee to the United States Department of Transportation2. recommendations were made for improvements to the ATC beacon system to extend its useful life. One recommendation was to improve the performance of the beacon ground antenna.

As seen in figu re 1. the ATC beacon antenna on the top of the primary radar antenna has a small vertical aperture . As a result. the vertical antenna pattern is very wide. This wide pattern heavily illuminates the ground in the vicinity of the radar. causing the actual vertical pattern to break up into peaks and nulls. This well-known phenomenon is termed ' lobing'. To obtain beacon .coverage in ~he nulls of the pattern . a higher beacon interrogator power is needed as compared to that if lobing was not present. This higher power produced exc essive pow er in the peaks of the pattern . thus contributing to the beacon interference problem . To combat this problem . the Federal Aviation Administrat ion launched an antenna improvement aimed at increasing the vertical dimension of t he an tenna . This effort resulted in the development and production of a 5 -foot high 'open array· shown in figure 6. The array uses resonant reflectors between the dipole elements. giving a weight and wind loading approxi mately the same as for the old ' hog trough' beacon antenna . In addition. it is a direct replacement for the old antenna . The new beacon antenna also incorporated an integral SLS pattern with a null in the mai n beam direction for improved SLS operation. A sum and difference monopulse pattern was al so built into the an tenna in an ticipation of the new M ode S. The performance of the open array became an immediate and important step in improving the beacon ATC system. The narrower verti ca l pattern . w ith a sharp c utoff to the underside of its vertica l pattern . greatly reduced the lobing . It was

determined that the beacon interrogator transmitter power cou ld be reduced greatly wit hout sacrificing system coverage. .

Some vertical lobing is still present w ith the open array . Its ext ent vari~s w ith the nature of the surrounding terrain . 1. e .. flat ground. water. hills. etc . Rather than have the same interrogator power for each location . fl ight tests at each loc~tion were conducted to establish the required power so that excessive power w as not radiated.

The A TC beacon system also had a false target g enerati on probl~n:' because of reflections from large buildings. hangars. etc. This problem is illustrated in figure 7 . and is particularly severe in terminal areas.

The problem grew as t he number of. stru ~­ tures at large airports increased w ith airport expansion . False beacon targets are a serious problem to system safety.

An example of th is problem was at th e Washington DC Nation al Airport w here reflections from the bridges over the Potomac River generated severa l false targets at times. With the ability of the controll ers to recognize false reflections. serious accidents were prevented. When the.open array was installed. the sharp underside to its vertical pattern eliminated many of these false target reflections. This provid ed an unexpected benefit. Al so. fixes w ere incorporated into the software of the ATC processor to remove the fal se returns. using the fact that the false returns are always at a greater range than the true return beca use of th e greater path length .

False target reports generated from reflection. sidelobe interrogations. second-time-a round . and interference cannot be tolerated in the aut omation system as compared to a nonautomated system .

Everything possible was done by the FAA in the United States as w ell as Civil Aviation Agencies in other countries to red uce the beacon interference problem .

Restrict ions w ere placed on the use of THE CONTROLLER / DECEM BER 1985

interrogators unless absolutely necessary.

The use of military interrogators was restricted. such as the use of shipborne systems when in harbor. Radar I beacon systems were relocated on airports and placed on higher towers to reduce the reflection problem. as well as to reduce shadowing of the coverage by buildings (this also included reflections from the vertical stabilizer structu re of the large jumbo jets). This program is cont inuing.

False tracks. double data blocks. track deviation (stitching). pop-up targets. and false identification result in serious problems for the controller in an all-digital automated system.

The useful life of the ATC beacon system w as once again extended because of the great effort of many individuals in Government. special technical organizations associated with air traffic control. controller organizations both in the US and internationally. as well as in industry.

However. everyone recognized that additional effort was needed to extend the life of the ATC beacon system into the next century. while a new ATC surveillance system. possibly using satellites. was being developed. This additional effort was the development of a new mode of operation for the ATC beacon system termed 'Mode s· (Select) by ICAO.

Apparent Aircraft Location

Actual Aircraft Location

I / I

I I

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Reflecting Surf ace

Beacon Antenna Figure 7. False target generation in the A TC beacon system

M ode S System Description From the preceding discussion. it is obvious that the objective of any future improvement to the ATC beacon system is the reduction in the number of ground interrogations. This is the major purpose of the Mode S improvement to the beacon system.

Three main features of Mode S are monopulse processing. selective interrogation. and a digital data link. Mode Sis a major improvement to the exist ing beacon system and not a new or replacement

system. Mode Sis completely compatible with existing beacon transponders. however. to make full use of the selective interrogation and data link features of Mode S. a new transponder is required.

The monopulse feature. w hile required for M ode S. is not inherent to Mode S but also offers an improvement to the existing beacon system in terms of reducing potential interference by reduced interrogations.

Mode S also incorporates all of the improvements made to the existing bea-

. ed and in. . co n system previously d 1scuss in it s pror corporates improved degarb ing cessor.

Monopulse

the In today's beacon system. ~s raft · articular a1rc antenna scans past any P · the airit interrogates the t_ransp~ndf~a1ln terminal craft a num ber of t imes. YP f 1oto systems with an antenn_a scan rate ~r more 1 5 15 rpm receive approximately . ft To individual replies. from ea?~ air~r~h~ airdetermine the azimuth pos1t1on ? t d with craft. the beacon digitize~ ass?c1a e rates the ground beaco:i ~e.ceive~ incorp~etec­ what is t ermed a sliding w i_n?owwindow tor In simple terms. the sliding 1 determines the cent er o f each group ~1 · resents the az replies. which in turn ~ep ft If II of t he muth position of the a1rcra · a rding tra nsponder replies are present. the s ~ window process is quite accurate -. ~~~ 1ies ever · in many cases all of the rep the accunot present which dec~eas~s Id be racy . A typical problem s1tuat1on wou (not two aircraft at the sam~ rang~d not necessarily at the same alt itude) a · separated .in angle b Y Iess th a n the full az1h. muth beam width of the antenna. In is situation . rep lies from one aircraft ( tra~~~ edge replies) may overlap or garble h the leading edge replies from the ot er aircraft. Th e sliding window ~etec~~~ actually may produce azimuth pos1t1ons . the two aircraft that indicate a greater ~zi­ muth separation than actually exists. Likewise. the garble. of individua l pulses. in ~ single reply t rain resulting from 1nte ference may produce azimuth 1~accu­ racies wh ich make the tracks appearing on the controller" s display vary in azimuth position.

-r

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-.~ ,.,......

Figure 6. Air traffic control radar beacon system {ATCRBS)

22

'' '

' ..

..

THE CONTROLLER / DECEMBER 1985

Boresight

Often this is referred to as off-boresight monopulse. The particular method of using phase rather than amplitude and the sum and difference ratio makes the measurement independent (a ratio of unity is on boresight). and provides information as to whether the return is to the right or left of boresight.

Theoretically. the azimuth measurement of an aircraft position can be made on the basis of a single transponder reply.

Thus. the number of interrogations could be reduced from 15 to one. In practice. however. the measurement is averaged for more than one reply with the returns near boresight weighted in terms of greater accuracy. Plans call for the use of four in-

terrogations (two Mode A and two Mode C) to improve the probability of determining aircraft identity and altitude. However. a decrease from 15 or more to four interrogations is a major improvement in terms of reducing potential interference. Not only does the implementation of monopulse allow for the reduction of the number of interrogations. but it provides a far superior accuracy as compared to the sliding window detector. Figure 9 compares tracks for the monopulse scheme and the sliding window digitizer as obtained during tests at the FAA Technical Center for a prototype Mode S system known as the Discrete Address Beacon System (DABS).

Discrete Address (Selective Interrogation)

E/A Ratio

Consider a typical enroute ATC ground beacon interrogator with a 200-nmi range. All transponder equipped aircraft within line-of-sight coverage are interrogated by the ground system for every antenna scan. typically each 10 to 1 2 seconds.

The ground surveillance system under consideration may be interrogating and receiving replies from a number of aircraft

of no interest to its associated ATC display and processing system. Likewise. any one particular aircraft may be within the coverage of a number of ground interrogator I receiver systems. and its replies received by these systems are unwanted and represent potential interference. Also. the transponder replies may be received within the sidelobes of these other systems since the SLS previously described functions

Figure 8. Monopulse antenna azimuth patterns Surveillance Processing

Transmitter

Monopulse. a well known radar tech~ique employed for many years in tracking and three-dimensional radars. employs what are termed 'sum(~) and difference (a) patterns' as illustrated in figure 8. In simple terms. the monopulse system measures the difference in amplit~de between the beams. If the aircraft is directly in the center or at the boresight angle: it is equal in both beams. Off bores1ght. the difference provides the azimuth position of the aircraft so that the aircraft need not be at the boresight angle.

Channel Management

ntenna System Sum Difference Omni Multichannel Receiver

Network Management

I I I

Video Quantizer onopulse Digitizer

'------

Surveillance Data Distribution Interface

}Adjacent Sensors } TRACONs ARTCCs and NADIN

}TAACONa and ARTCCs

Radar Target Reports

Figure 10. Mode S equipment block diagram

l

,,_,---"'

::_ .

-~~~-~¡ ...

Beacon Track Improvement Using Monopulse Technique

Figure 9. Comparison of tracks for a sliding window and monopulse detector (courtesy of FAA) THE CONTROLLER/DECEMBER 1985

Performance Monitoring Surveillance Fiie Coverage Mod

,-~-

Beacon Tracks (Time Exposure) Using Sliding Window Detector

Data¡Unk Processing

Ground mmunlcatlon Interface

~

only on interrogation_ The Mode S discrete address or selective interrogation feature is designed to combat this particular problem. Each aircraft equipped with a Mode S transponder is assigned an individual aircraft identity code. More than 16 million individual aircraft identity codes are provided in the Mode S system which is enough to give every aircraft in the world its own exclusive identity code. Each Mode S ground system interrogat~s only those aircraft for which it has surveillance responsibility_ The ground system stores the predicted position of each Mode S equipped aircraft and interrogates when the azimuth beam of the beacon antenna is pointing at the ~ircraft' s . predicted position. The uplink interrogation codes are much like the downlink codes for the existing system as s~own in fi~ure 1. This selective interrogation technique keeps the number of interrogations and replies to a minimum with a consequent reduction in the overall interference level.

Another advantage of the selective interrogation is that the individual

23

20 µsec

I I Int errogation P 1

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Sync Phase Possible Reversal Phase Reversal Positions 0.4 µsec-I :-1st CHIP ·

~S~L~S~C=-=-o~nt_ r~o_l_ __ ____~ ___J~L----------Transmission I+- o.a µsec aS-0680-v-1 Figure 7 7. Mode S interrogation pulse sequence

Preamble

Data Block

14--- - - - 8.0 µ sec ------~----- 35 or 112 µsec

B"t

Bit

IBit1IBit 21Bit3IBit41 IN~1I N I r-r- r -1- r-r -,-, - r-,/h - r r -,-.- , 1110:1 : o:no:1 : 0: : : :1:0 : 110:

I

0.0

I

0.5

I 1.0

I 3.5

a;o 9~0

I 4.5

Time (µsec)

I I I I I I

~JUL_ 101011101

Example: Reply Data Block Waveform

010111

Corresponding to Bit Sequency 0010...001 85-0680-V·l

Figure 72 . Mode S reply waveform

interrogations are t imed by the ground system . so that replies from aircraft at the same range and azimuth. b ut at different altitudes. do not overlap and garble each other.

It is noted that monopulse is an inherent requirement for the Mode S system. since the single or limited number of Mode S replies do not allow the use of a sliding window detector.

Mode S transpond ers are fully compatible with the existing ATC ground beacon systems. Mode S equipped aircraft are entered initially into the ground syst em by the stand ard b eacon interrog ations shown in figure 1 .

Implementation of Mode·S Ground Equipment The Federal Aviation Administrat ion awarded the Westinghouse Electric Corporation. Defense an d Electronics Center Baltimore. Maryland. a contract in Octob~ er 1984 for the production of 13 7 Mode S ground systems. Westinghouse and the Systems Development Corporation. a Burroughs Company. are supplying the

equipment as a J01nt venture. Figure 13 illustrates th e hardw are configuration of M ode S as install ed w ith the AS R-9. also being supplied to the FAA by Westingh ouse . The Mode S equipment is comp letely solid state. dual channel. using the lat est in electronic technology for high reliabi lity and ease o f ma intenance . The ASR-9 radar. Mode S syst em shown in figure 13. is designed for unattended operation. The b eacon open array antenna is show n on the top of the ASR-9 antenna in t h e background .

Th e question has been asked regarding th e advantage to t he airc raft owner and operator which would just ify the cost of t he installation of a Mode S transponder.

The sam e question was asked w hen insta llation of the existing beacon transponders was first conside red. The answer is stil t he same in that installation of Mode S transponders wi ll increase t he efficiency. safety. and t he life of the ATC beacon system.

Another question whic h often arises is whet her th e addition of M ode S to an existing faci lity or the replacement .of existi ng beacon ground eq u 1pmen~ w1~h Mode S is wo rt hw hi le in a low density airc raft environm ent . This occurs in many coun tries in the world . Westinghouse believes t hat it wou ld be wort hwhile in ma ny cases. sin ce even in the low density enviro nment. Mode S increases overall ATC system sa fety w h ich cannot be measured in t erms of m oney. Also. t~e digital data link is of va lue under any circumst ances . Perhaps in such instances. th e im plementation o f t he Mode S ha_rdware should be in two ph ases. The first wo uld be the front-end monopulse antenna. interrogator. receiver. a_nd digitizer w ith t he full computer processing added at a lat er dat e. However. the original insta llation shou ld be in terms of the full Mod.~ S system to ensure ha rdware compa t1b1hty w hen t he com put er processing is added.

Digital Data Link The M ode S improvement to the ATC beacon syst em also incorporat es a digital data link. Differential phase shift keying ( DPSK) is used on t he uplink and pulse position modu lation is used on the d ownli nk. This feature is only available for airc raft with M ode S transponders. It is expected t hat this fea ture will reduce the burden on the voice communication cha nnels for both the controllers and pilots for transm ission of routine information. such as weat her advisories.

Figure 1 0 is a basic block diagram of the Mode S ground equipment. Figures 1 1 and 1 2 show the Mode S interrogation and reply waveforms .

The preceding information on Mode S is very brief. Additional detailed information may be obtained by contacting the Federal Aviation Administration or the Westinghouse Electric Corporation .

24

Figure 73. ASR-9/Mode S installa tion THE CONTROLLER / DEC EMBER 1985

Radars in Air Traffic Control a Status Report

by P.A. Jorgensen (of Selenia)

The radar is such a basic and fundamental tool in air traffic con trol that it seems hardly necessary to discuss the subject. Neverth eless. a status report m ay be useful .

We can today claim to have solved all th e basic radar problems . The Adaptive Radar techniques pioneered

by Selenia some ten years ago. effectively solved the problems concerning visibi lity in ground clutter. and the recent introduction of MTD (Moving Targ et Detection) with adaptive notch filt ers has allowed us to obtain full detection even in the presence of heavy prec ipitation and angels.

The resea rc h has therefore been concentrated on obtaining effective methods for subsequent radar data processing .

Five years ago Selenia presented its new Primary Surveillance Radar (PSR) w it h integrated radar data extractor.

The experi ence since then shows that our claims for plot accuracy and discrimination were fully justifi ed. and that presentation of synthetic video. instead of raw video. even during approach con trol. is perfectly acceptable.

It was therefore logical to integrate the extractor in the newest Selenia SS R radar. the monopulse SI R-M .

The perfection of the extraction technique was necessa ry in order to reac h the next goal for radar systems designers. the pra cti ca l implementation of Multi-Rada r Tracking .

Selenia has now delivered two large system s w ith MRT. namely th e Italian ATCAS system. and the Mexican M azatlan ACC system (Fig. 1 and 2) .

Multi-Radar Tracking makes use of all avai lable radar informat ion from all radars in th e system to create one System Track for each airc rah .

The advantages of MRT are: Higher aircrah position acc uracy; Improved probability of detection ; Higher data renewal rate; Less vulnerabl e to radar fai lure.

The resea rc h in Selenia was directed at severa l fronts.

Fig. 7 Schematic radar coverages 1 . The theoretical research was followed by intensive computer simulations to develop suitable and practical algorithms which took all radar characteristics into account.

2. A whole set of diagnostic tools were developed to be able to implement and set the system. and to m easure th e system performance. inclusive of the resultant system accuracy.

3 . All the necessary hardware. inclusive of a special digital scan converter radar display for system monitoring. were designed.

Each radar head. in the Selenia system . is equipped with a radar head processor (RHP). in which the data

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MVllCO

P.A. Jorgensen

TH E CO NTROLLER / DECEMBER 1985

Fig. 2

25

1----;T~--,

II TRACKING L ___ - _ RADAR 1

I

MOHORADAR

r;;;;;--1 I II L ___ _J

TRACKS

RADAR 1

_J(POSITIOH)

,--------, I I

VD.OCl'N

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SITE 2

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1,

MONORADAR TRACKING

~,___

a: w

z

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iii

~

L-.----.--J ,__._ ___._--, I

I

u

...~

I

IL _____ _J RADAR H

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= 0. 2 °.

0-&

Position

Or =

= 250

km.

1 00 m monoradar 700 m

multi radar 500 m

5-10 kn

4-7 kn

20_30

1,5°-2°

Ov

Direction Oa

Experimental results with two radars.

I

I

i I1 I a a

I

I Ia

I i

I Fig. 4 Probability density function of errors in range 26

I

PLOT

MRT with centralized architecture

Op

Velocity

RADAR N

USER

----t!M

I L ___ _J

Fig. 3 MRTwith distributed architecture Table 1 Pd = 90%. range a = 6 m/sec 2

PLOT

L ___ .J ,-;;;:--1

:.:

u

I

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ia !=

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I

i ....·------------------· .... ,11 1111.. .......

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Fig. 5 Probability density function of errors in azimuth

from the PSR and the SSR are combined. and local tracking is performed (See Fig. 3). The tracking is based on the Kalman algorithm with adaptive parameters. In case of SSA or combined plots, the tracking is initiated automatically after two scans.

In case of PSR only, the tracking is initiated automatically after four good plots out of five. The RHP further performs all necessary filtering in order to protect the low-speed transmission lines against overload.

The Multi-Radar Tracking is performed by the radar data processor (RDP) at the center.

All the local tracks arrive to the center via low speed transmission lines (telephone lines). and the RDP creates a system track. using all the available radar information. Each local track contains information concerning position. time of detection. quality. and SSR codes when applicable.

The system track is made by weighing and merging the various monoradar tracks in overlapping areas.

In this way. the single controller selects on his display a system area. and not a single radar. Blind zones may be virtually eliminated. and the track has perfect continuity during the passage from one radar to another without boundary jumps.

In the ACC system. the updating of the system track is usually set to six seconds. and in terminal areas the updating may be still faster.

One of the most important parameters is the accuracy with which THE CONTROLLER/DECEMBER 1985

the system track is calculated and presented.

Figure 4 and 5 show the errors in range and azimuth at the output of the integrated radar extractor. The tracking algorithm in the RHP tends to further reduce the errors. In the overlapping areas. the MRT will finally minimize the position uncertainly to the mean geometrical value of the errors of the single sources.

Our experience has shown that a key element in obtaining a satisfactory result is the siting of the radars; especially the exact knowledge of their geographical position. as well as a precise alignment to the north. are essential.

Software programs to perform radar triangulation and automatic north alignments have been developed. and the north alignment package. for instance. is part of the on-line diagnostic.

In order to be able to perform. and record. a perfect testing of the radar. the CDS-80 Digital Scan Converter Display was designed. This display allows the technician to perform an accurate setting of the radar. and to test directly the performance of the extraction and local radar tracking. The displayed video is at the same time recorded on an ordinary TV cassette and these data are stored for subsequent analysis and comparison. The CDS-80 Digital Scan Converter Display has proven an indispensable tool for this purpose.

The experimental results from the Rome ATCAS system. and the Mazatlan SATCAS system show that MRT has now reached a state of operational maturity.

The MRT will now also be implemented in terminal areas where several radars are available. The first contracts for this have been undertaken by Selenia.

The MRT in Italy and in Mexico are implemented using two different approaches. For historical reasons. the ATCAS employs large mainframe computers. and the M RT process the radar plots. In the SATCAS system. the local tracking is performed at the radar site. thus the M RT is made by mini-computers.

The experimental results are equally satisfactory. In a new system. the SATCAS is. however. by far the most cost effective and promise a very acceptable low life cycle cost.

THE CONTROLLER/DECEMBER 1985

{Km)

TscAN•

65

••3m/s2 4

, 2

MUll'IRAOAR (MOST OVDURABLE CASE)

X2

0

Fig. 6 Influence of sensors relative position in the measurement accuracy

ioo

-

(1C111)

Fig. 7 Maximum error on the forecast position

New Terminal Airspace Expected to get FAA OK Expect a Notice of Proposed Rule Making (NPRM) within the next few months aimed at nationwide implementation of Airport Radar Service Areas (ARSAs).

Utilized on an experimental basis during the past year at Austin. Texas. and Columbus. Ohio. the cross between a Terminal Control Area (TCA) and a Terminal Radar Service Area (TRSA) has generally found favor with pilots and controllers.

The ARSA. as tested. is a two-tiered cylinder of airspace around an airport served by a radar facility. A 1. 200-foot high cylinder with a radius ?f fi~e miles is ~opped by another cylindrical layer with a radius of 1 O miles from 1 200 up to 4000 feet. Pilots must establish radio contact with ATC prior to entering the area - which constitutes permission to enter the airspace. Unlike a TCA. there are no additional equipment requirements.

The goal of the ARSA is to reduce the potential for midair collisions by improving communications between controllers and pilots within the airspace.

The ARSA that will be proposed will have a third. outer cylinder with a radius of 20 miles effective from the ground up.

Within the core area (out to 10 miles) it will be mandatory for pilots to establish radio communications and for controllers to provide traffic

advisories; between the core and the outer. 20-mile limit radio contact ·by pilots will be voluntary. but traffic advisories will be mandatory by controllers. Participation both by pilots and controllers is voluntary from the 20-mile limit outward to the limit of radar coverage.

Proposals to convert TRSAs to ARSAs will be timed to coincide with aeronautical chart revisions.

While AOPA expects at the present time to respond favorably to conversion of TRSAs to ARSAs. the association has a number of concerns to be considered. such as: • •

•

e

Conversions should be considered during individual public hearings at each site; Only a limited number of the existing 140 TRSAs should be converted and only if justified by traffic density and experience. TRSAs not converted should be eliminated; Establishment of two-way communications should be the only mandatory requirement for pilots (those without radi~s .may telephone for prior per~1ss1on JUSt as with an Airport Traffic Area); and.

FAA should conduct a review of existing Terminal Control Area (TCA) rules that could be eased based upon results of the ARSA test.

27

Air Traffic Control System Engineering

by J. Paul Locher Ill Technical Director, Transportation Systems Engineering Division, The Mitre Corporation Mclean, Virginia USA.

A Desire for Success Success is what we have when things turn out the way we had hoped they would. Many people are concerned with the appearance of success, others a:e concerned with the measurement of success, far too few are concerned with the method of success.

difficulties by providing a struct~redl approach to ensure that thc;>se things are being done that experience has shown to be necessary for succes~ .. Experience has shown th?t. ~ maJ~r contributor to system acqu1s1t1on difficulties is the approach used to define requirements. Without a properly defined. and agreed upon. set '?f •equir& .. ents. there is no sound ~as1s for a system acquisiti?n. There is no basis for the preparation of a me~n­ ingful system design. f?~ pr~parat1fn of procurement spec1f1cat1ons. or testing the delivered system: and finally for assuring an operationally acceptable system. .

Requirements difficulties ~su~ 11y result from a number of ?o~tnbutmg factors. such as uncerta_1~t1~s about the future and the unfam1lranty of ?Perational personnel with the poten~'-~~ of new technology. Unless ~hese I 1early in the proculties are a dd resse d . . ·n cess. frequent chang~s in des1i~n d~ occur during prod.uctron. caus I~ of lays cost escalation. poor qua h the , delivered product and per aps unacceptable system perfo~~a~~:~ss It is often ne_ce~sary defined set alternatives for satisfying a . the apf irements to determine

The old saying. if at first you dent organizations concerned with plansucceed. try. try again. might be good ning. acquiring and operating sysadvice to a child learning to walk. But. tems. These organizational entities can you afford to follow such advice must properly plan what has to be when planning, acquiring and imple- done and control the process. Frementing a new or improved air traffic quently, the responsible organization control system? And yet. it seems does not have within its staff the exsome organizations tend to follow perience or knowledge about how to such advice with unfortunate results. proceed. In cases like this. these orKnowing that we want to succeed. ganizations frequently augment their that we must succeed. is not a suf- staff with experienced systems engificient condition for success. Desire neers from the outside.

A great portion of the effort involvwithout ability usually leads to failure.

Before considering a solution to the ed in properly planning and conductimplementation success puzzle. let us ing a system acquisition should take look at one question: What is the place before products and contractors leading cause of failure of most proj- are selected. Unfortunate experiences ects? Generally. the inability to man- in acquiring ·systems can often be age properly is a leading contributor to traced to insufficient planning and failure. In any major undertaking, attention to details before eliciting whether it be producing a new prod- proposals from industry. The effort reuct or implementing a new air traffic quired during production. installation. control system the key to success is and testing of a system is generally good management. much more straightforward if proper And good management of an air planning has been accomplished betraffic control acquisition effort often fore going our for procurement. depends upon system engineering Now let us review some of the which blends unique technical skills problems that are experienced and the with managerial skills. Systems eng- kinds of practices that avoid them. ineering is the ability factor which can make an air traffic control system acquisition turn out as we had hoped; Acquisition Problem Areas There are diverse factors that must to succeed. be considered to properly plan and conduct a successful acquisition. The What Is Systems larger the system that is being acquirEngineering? ed. the more complex this process Systems engineering is an organiz- becomes. Without some structured ed way of planning and acquiring sys- approach. there will be critical factors tems based on knowledge and experi- that are inadvertently overlooked or ence from the past. An important el- not recognized until late in the proement of this methodology is follow- cess. The difficulties result from the ing known. good practices for what interrelationships that these different must be done to minimize surprises factors have on each other. and a number of other factors that need to and difficulties.

Carrying out systems engineering be considered. Systems engineering efforts is the responsibility of the can help to minimize or preclude these

E=~~~h;~n~~~~n~;~~~e:h~~:es~;>:~

capability. There is a dy~a~~~~~e~ancd tion between softw~re. ar with techprocedures that c a_ngesl personnel nd operat1ona . noIogy a be that all of the defined needs. It may t be satisfied requirements cann<? b d et within the existing time and uel~cconstraints. If thi~ is t~e c~~~~~ents tive implementation ~ re . ·onsto needs to be planned wrth p~ov1s1 nts in be able to satisfy all requireme the future. . to acAnother majo~ c~ntnbutor lanuisition failure is incomplete p q_ of all the things that have to hap n~n9 to ensure a successful concluP. Areas frequently not adequately s1on . d d for are· how the newly acprov1 e · . d f ncan . ~ qu .1 red items will interface · 1· · rov1s1ons tion with existing facr 1t1es; P for spare parts. tools_ and docu~~~~ tation; support req~1red from_ tractors following delivery to train P.~r sonnel. maintain the system. prov1 ~ for enhancements to the system. an resolve any system problems no~ previously found: and. ho_w the new i~ems will be transitioned into operational useConsequently. you can see that to properly plan and organize a. system acquisition. one has to take into account not only the procurement of the individual components but also factors. such as: the operatio~al n~ed: the most appropriate conf1gurat1on, THE CONTROLLER/DECEMBER 1985

28

the alternatives; the size of the system that is needed now and in the future; the effects of costs over the total life of the system in which it will be operated; the operational features that are required; the expandability that is needed: the flexibility to adapt to different situations; and the maintainability and reliability aspects of the system. Systems engineering is the process of planning for everything that is required in a system and recognizing all of the interrelating factors in preparing for a proper design and subsequent procurement. This is best accomplished by drawing on the experience of others who have previously worked with planning and conducting similar procurements.

Method for Success The systems engineering theory may sound good. but is it really a method for success? The best way to appreciate the methodology is to review the acquisition process and see how it can be applied to the various phases. The first of these phases is Understanding the Problem. and here. there will be a number of studies and analyses conducted to determine what are the needs now and in the future. Alternative concepts are investigated and assessments made of the capabilities needed for air. traffic control now and in the future. Based on this work. a set of requirements is formulated and coordinated with all parties involved with the planning. use. and maintenance of the resulting final system. An important result of this phase in the process is to obtain agreement of all the parties. that if these requirements are satisfied. the resulting system will be acceptable.

In the next phase. the approved requirements resulting from the previous phase are now translated into a system design. a set of specifications for procurement. and a plan for accomplishment. The first step will be to structure an overall system design and to prepare a description of the intended system at different phases into the future. A second step will be to prepare a Master Plan which covers all of the activities and functions that must take place to result in a successful operational system. Finally. it is necessary to prepare the specifications for those things that are to be procured from worldwide industry or to be developed by in-house resources.

The third. or Procurement phase. is where all of the necessary procurement documentation is prepared.

Procurement specifications are available from the previous phase. However. additional information must be prepared for the prospective bidders.

THE CONTROLLER/DECEMBER 1985

These would include instructions to the bidders concerning proposal preparation. a statement of work. and other supporting documents.

The source selection process needs to be documented to define how the selection will be made between different contractors¡ offerings.

Also. the evaluation criteria and the weightings that will be given to different aspects of the proposals need to be defined. Finally. the tenders need to be evaluated to determine which is the most acceptable. considering both costs and technical factors. to ensure that the most appropriate bidder is selected providing the best capability. at the least risk within time and budget constraints. This is followed by a negotiation of the contract( s) to ensure that the terms and conditions are understood by both sides. Following the signing of the contract. it is necessary to closely monitor a contractor's performance.

There is a need to review the contractor's documentation to ensure that there is no misunderstanding of what is required. and to ensure that difficulties with the contractor's efforts are uncovered at the earliest date so that they can be promptly resolved.

During the fourth phase. Deployment and Test. the items delivered by contractors will be installed and checked out. followed by a very important step in the process. Namely. the integration of the people. the procedures. and the acquired system components. A complete system does

not exist until there are a trained set of operational and maintenance personnel with a set of procedures for using the acquired system to perform air traffic control. This is assured by a system test to demonstrate that an acceptable operational air traffic control capability will exist. The conclusion of the system test will be an agreement by all involved parties that the system is acceptable for operational use and can be transitioned into full time use.

And finally we have the Operational Use phase. During this phase in the process. it will be necessary to resolve any problems that may arise because of unforseen circumstances. and to plan for future enhancements to the system.

Final Thoughts This has been a brief summary of the systems' engineering process. structured to illustrate the need for proper planning and control. Studies of difficulties in procurements have shown that the most frequent cause of problems is the lack of a disciplined process following procedures which are known to be good practice. The second most important cause of difficulties is the lack of experience and knowledge of personnel involved in the overall process. What has been illustrated here is that experienced capability is available and has resulted in a methodology to minimize the problems most frequently encountered.

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Plessey Displays in Air Traffic Control

by Arnold Field, OBE (Consultant Plessey Displays Ltd.)

In 1984 the International Civil Aviation Organisation (/CAO) introduced for the first time an 'Air Traffic SeNices Planning M anual' (DOC 9426-AN/924).

The manual is a provisional issue but in its final form will undoubtedly contain many of its present obseNations. For example. in the introduction to chapter 2. ·use of Radar·. it states:

·As the ai r traffic control system has developed throughout the world. radar has become one of the more important tools used by air traffic controllers in providing for a safe. orderly and expeditious flow of air traffic .'

It is considered material to quote the ICAO statement in this article. on the 25th anniversary of the Federation's foundation. for. appropriately. it was in the early 1 960s that radar first began to be used as a tool of air traffic control away from the immediate vicinity of aerodromes. Before this time its role. certa inly in civil aviation. had largely been as an aid to landing and those w ho were present at the time of the birth of the Federation will recall the stalwart work done by the ground controlled approach controllers. more popularly known to the aviation press as 'talkdown controllers·.

The display units which they used to locate and direct aircrah into the azimuth and elevation funnel of the GCA. were usually 9 -inch hard blue cathode ray tubes which were only viewable in almost total darkness. Radar responses from aircrah were ohen hardly distinguishable from a variety of spurious echoes on the tube face and the only certain method of achieving identification was to turn the target aircrah 90 ° from its track. then back again on to its original course. Observations of both turns were necessary to confirm identification. Thereaher. with the aid of a chinagraph pencil to mark on the face of the display. it was possible to track and direct the target aircrah.

Today. 25 years later. this seems a very crude m ethod to provide a radar servi ce. What then has changed in thi s period of time? There have. in fact. been four m ajor developments which revolutionized the application of radar to air traffic contro l. So successful 30

have these advances been. t hat many authorities now employ ATC systems which are based primarily on the use of radar for separation purposes .

These major developments are:

The dramatic improvement in the performance of primary ~adar sensors and in the elimination of unwa n ted radar returns.

The advent of Secondary Surveillan ce Radar (SSR) which. has. ~ot only revolutionized a.nd s1mplif1ed the identification of a1rcrah targets but also increa sed t he ran(ile of detection of transponder-equipped aircraft. making the use of hea".'Y long-range rad ars superfluous in ma ny ATC systef!1S. T~~ future exploitation of th is faci lity as a communicat ion s channel (Mode S) also provides a basis for a number of important de'."~l opments.

The advent of d1g1tal data processing . The radar and f light data processing techniques developed by t he elect ronics industry ~nd the two-way intelligence provided by SSR promoted the arrival of har?war~ sohware and firmware. c;ir. in simple terms. computer-assisted air t raffic control systen:is. .

From the controller· s point of view.

I

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· · an mregral · whic hnired has Kin been_ The Plessey lnrelligenr Autonomous Display Console rs parr O•/ rh e w.a rchman . system . selec red by rhe M inistry of Defence as the replacement airfield surveillance radar for rrs arrf1elds m the U g dom and overseas. t a significanr This versatile. self-conramed display console wirh irs own dedicated mrcroprocessor represen s advance in the processing and presentation of radar dara.

THE CONTROLLER / DECEMBER 1985

possibly the most dramatic change of all has been in the display. Now viewable in near daylight conditions and. w here required . in total daylight. displays are avai lable in sizes up to 22 inc hes in working diameter. They show targets with remarkable c larity and carry intelligence on rada r targets undreamed of 2 5 yea rs ago.

The purpose of an ATC system is to provide the controller with the informati on he requires in an easily readable and unambiguou s fo rm . It is equally important tha t the controller's means of access to the computer data base should be ergonomically designed to faci litate its use. thereby reducing error-rate under stress . . Ple::;sey has not <:>nly been supplying displays for air traffic control throughout the last 2 5 years. but has also been deeply involved in the ~evelopment s which have led to major improvements in air traffic control throughout this pe riod . This required a detailed knowledge of the manner in Detail of Plessey Watchman display presentation. wh ich both primary radar and second a!Y r~da r are used. the processing and filtering of this data and the corre- the interfa ce between the controller ler was viewing them on a conlation and dissemination of flight data. and the rad ar data and flig ht data ventional cathode ray tube display.

Today. of course. this is known col- required for his task. The controller The facilities w hich this type of dislec.tively as ATC Systems Technology. has the capabil ity to interpret. alter or play console adds to the ~onventional Using its extensive knowledge and add to the information on his display. primary radar presentation can be experience in these fields. Plessey has and to coordinate automatically with summarized as follows: developed a ~es ign philosophy based other operationa l positions contained 1 . Secondary radar position symon the follow ing considerations. bols. w ithin the system . The illustrations What does the controller want to accompanying this article demon2 . Labels adjacent to the position see on his display? symbols of selected aircrah disstrate clearly the integrated nature of What interface does he require to the display and console. Watchman is playing the following data: access the systems data base? a) aircraft callsign or SSA code. equally suitable for air traffic control What interaction does he require applications requiring a single display b) flight level or height if the airbetween his disp lay and other dis- position or for those requiring many craft is below the transition level. plays with i!l the ATC system? c) supplementary flight plan data. displays. In a multi-display system the such as route information . airWhat detailed tasks is he requ ired consoles are connected in parallel to to p~rform within a particu lar ATC the data sources and inter-connected craft's destination. etc . service?

3. A 'leader' line. from each aircraft w ith each other by a simple highHow ca n the display and its con- speed data li nk. Si nce each console position symbol to its label. sole best. be designed to aid the holds a full copy of the system¡ s data4. Visual alarms for an aircraft operator in t he disc harge of these base. the fa ilure of any one console emergency. special hijack code. tasks? does not impact upon the continued or radio failu re. in the form of With these considerations in mind. o peration of the system as a whole. flashing symbols and labels.

Plessey has desig ned a new gener- thus providing extremely good fai l-soh 5. Trail dots. which appear behind at ion of autonomous intell igent dis- characteristics. Extra displays can be the aircrah' s symbol to indicate plays called ' Watc hman¡ . They are added readily when required. providthe track which it has been undoubtedly the most advanced ing flexi bility and system growth as following. equipment of their kind in use today. circumstances demand. As each dis6. A range and bearing line with Not on ly does the d isplay area provide play is self-contained. the system load reflective range and bearing. disthe controller with a viewing unit of is unaffected when extra displays are played at each end of the line. exceptional clarity but the console introduced.

7. Tabular areas - these are areas of within w hich it is housed is a self-conthe display which are not being The displays must be able to accept tained display and data processing inputs from primary and secondary used to control air traffic . and system . radar from sites where the primary upon which data of interest to the !~ E:3refc:ir~. in describing t hese radar and secondary radar are controller can be displayed. such faci11t1es. 1t 1s essentia l to include not co-located and I or w here the secondas advance details on aircraft only the display upon w hich is ary radar is remotely sited. Whichever which are due to enter his sector port rayed the air tra ffic. but also the situation obtains. the position symbols of responsibility. console in which the display is hous- to be displayed to the controll er must 8 . Synthetic map displays. such as ed. The console contains all the elec- be the positions at which the primary the outline of airways. air-routes. tronics w hich are essentia l to provide radar would show them if t he controlcoast line. danger areas. etc .

THE CONTRO LLER / DECEMBER 1985

31

These maps are usually programmed within the console' s computer memory but facilities also exist for the controller to draw synthetic maps on his display for specia l purposes. For example. a military exercise area or a temporary prohibited area for an air display can be shown.

9. A direction-finder vector with bearing displayed at one end. This feature is used in conjunction with a direction-finding equipment which g ives the bearing of an aircraft's R/ T tra nsmissions.

1 0. A rotatable electronic cursor. comprising seven parallel lines with bearings displayed at each end of the central line.

Additionally. the controller can select the amount of data he wishes to see on his display. related to his sector and area of responsibility. He does this by setting up messages known as data selection parameters. which he notifies to the processor within the console. by means of an input keyboard.

An exam ple of a typical selection program could. be as follows: 1 . Azimuth filter. The selection on the display of the sector for whic h he is responsible - say from 0 ° to 1 60 ° . Only this sector of the 360 ° sweep of the radar's antenna would be shown on his display

out to the required range in nautical miles.

2. Height filter. A number of ATC systems operate on a vertical split of responsibilities where one controller w ill look after traffic up to a certain level and another the traffic above that level. In these ci rcumstances a height band would be selected. say. from flight level 0 50 to flight level 240 .

3. M ode and code filter. Aircraft operating within an ATC system where the carriage of an SSR transponder is a requirement. are advised in adva nce of the SSR mode and code upon w hich they are required to operate. The processor is notified of the relevant modes and codes of the aircraft under the operators control. so that only information on these aircraft is displayed.

This filtering faci lity therefore allows each controller to have an uncluttered display which shows full information o nly on those aircraft which are of interest to him . However. in order that a controll er can check the information on aircraft which are not displaying full labels. there is an ·a ll data' switch on the display console. which. when activated. overrides the filters and gives full labels on all of the aircraft on the display. The de-acti-

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The manual input devices of the P!essey Watchman autonomous intelligent console.

32

vation of the switch automatically restores the display to ' filtered· targets only.

From time to time. a controller may w ish to query the information on a single rad ar target on his display. To do this he has a facility on his console known as a 'rolling ball'. The rolling ball produces an electro nic symbol which can be moved to any position on the di sp lay. By positi oning the symbol over t he ta rget. t he controller automatica lly ale rt s the computer processor to the fact that information is required o n t his ta rg et . The processor. having been alerted. wi ll then display to the contro ller t he radar data and flight data relating to t he selected target. An alternative method of initiating this action is to use a ' light pen' as the interface between the controller and the computer data base. Both these devices ca n be used for a variety of other 'fu nctions'. such as the movement of a tabu lar area from one part of the d isplay to another. or the movement of the origin of th e radar date source. known as · off-centering·. or the initiation of a ' hand-off ro utine. that is the transfer of control from one operator position to another. The rolli ng ball/light pen. therefo re. provides a li nk between the radar controller. the radar display and the software functions with which the computer has been program~ed.

Many of the fac ilities which have been descri bed will. of course. be fam iliar to the Federation' s Member Associations but it is hoped that the content of thi s artic le will rea ssure controllers that Plessey not only is conscious of the d iffi cult task which controllers have to perform. but is providing them also w ith ~he proper tool s w it h which to maintain the high sta ndards of th ei r profess io n.

It is indeed th is awareness of t hese requirements which has . e~abl ed Plessey. as menti oned ea rli er in t~e articl e. to develop the W atchman display . In summary therefore our long association w ith air traffi c control has enabled us to design t he display and its console to reflect this experience and in doing so provide th e co~troller wit h a piece of equipment. which not only enables him to see. with re:markable clarity. the a ir traffic for which he is responsible but also provide system interface facil it ies ergonomically designed for rapid and easy access by him. In support of this approach. to try to provide th e controller with equipm ent specifi ca lly designed for his use.

Plessey are proud to announ ce that within 2 years of the launch of th is product orders have been received for over 500 displays. We think w e have got it right - w e trust you w ill agree.

THE CO NTROLLER / DECEM BER 198 5

Corporate Members of IFATCA AEG Aktiengesellschaft, Ulm, FRG Cardi on Electronics, Woodbury, USA CAE Electronics Ltd., Saint-Laurent, Canada Cecsa Systemas Electronicos SA, Madrid, Spain Cossor Electronics Ltd., Harlow, UK Dictaphone Corporation, Rye, USA Eaton Corporation, Al L Division, Farmingdale, USA International Advisory Group Air Navigation Services, Westerngrund, FRG Ericsson Radio Systems AB, Stockholm, Sweden Ferranti Computer Systems Ltd., Cwmbran, UK Hollandse Signaalapparaten B.V., Hengelo, Netherlands EB TeleCom, Nesbru, Norway Jeppesen 8t Co. GmbH, Frankfurt, FRG Litton Communications Switching Systems, Frei burg i. Br., FRG Marconi Radar Systems Ltd., Chelmsford, UK Mitre Corporation, Mclean, USA Philips Telecommunicatie lndustrie B.V., Hilversum, Netherlands Plessey Displays Ltd., Weybridge, UK Racal Decca Systems Ltd., New Malden, UK Racal Recorders Ltd., Southampton, UK Raytheon Canada Ltd., Waterloo, Canada Rediffusion Simulation Inc., Arlington, USA Schmid Telecommunication, Zurich, Switzerland SCI CON Ltd., London, UK Selenia lndustrie Elettroniche, Rome, Italy SEL-Standard Elektrik Lorenz, Stuttgart, FRG Societe d'Etude et d'Entreprises electriques, lssy-les-Moulineaux, France Sofreavia, Paris, France Software Sciences Ltd., Farnborough, UK Thomson-CSF, Meudon, France Westinghouse Electric Corp., Baltimore, USA

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 Corporate Members.

Corporate 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.

Air Traffic Control SELENIA

SIR-M open array antenna mounted on G-14 antenna.

SIR, a new family of secondary surveillance radars.

The new Selenia Secondary Surveillance Radar family is a real modular system. A SIR is normally a dual-channel system with automatic change-over, housed in a single, modern designed cabinet.

By adding modules, the SIR is expandable from its minimum version through SIR-M to its maximum version SIR-S. The system is designed so the total cost of expansion is born by the units added, this to maintain minimum cost in each phase.

An SSR channel consist of a solid state programmable transmitter, a receiver, a processor/ controller and a power supply.

The very sophisticated processor/controller is a firmware programmed unit, which forms the extractor, and provides all control signals, timing, BITE, remote control functions and narrow band formatting. Furthermore, all the programmable functions of the transmitter and receiver are provided by the processor /controller.

SIR CABINET Dual channel configuration.

Selenia is experience in air traffic control.

INDUSTRIE ELETTRONICHE ASSOCIATE S.p.A.

CIVIL RADAR AND SYSTEMS DIVISION Via Tiburtina Km 12,400, 00131 ROME, ITALY Telex 613690 SELROM I. Phone 06-43601