IFATCA JOURNAL

OF AIR TRAFFIC CONTROL

Landekursantenne KO ln/Bonn

Erfahrung seit mehr als einem Vierteljahrhundert auf dem Gebiet der Funknavigation

Das moderne, auf die automatische Allwetterlan­dung nach ICAO Kategorie 3 weisende lnstrumen­ten-Lande-System auf dem Flughafen Koln/Bonn mit Landekursanlag e LK 2 war die Voraussetzung fUr di e dart durchgefUhrten automatischen Landu ngen.

Do p p ler VOR-Drehfunkfeuer

SEL-Beitrage zur Ortung und Navigation: VOR-VHF-Drehfunkfeuer nach FAA-Richtlinien

_1> 1u 1u

ILS - Landefunkfeuertypen LK 1 und LK 2 fUr alle Flughafenkategorien FBll - Facherfunkfeuer und Z-Marker ZFB- Mittelwellenfunkfeuer-NDB D-VOR - Doppler-VHF-Drehfunkfeuer TACAN - Rho-Theta-System fUr Mittelstrecken Standard Elektrik Lorenz AG Stuttgart

Besuche n Sie uns auf d er Hannover-Messe 1965, Halle 13, Stand 94

..

Sat co

Efficient transport means prosperity

Satco comprises the ground equipment to predict, coordi­nate, check and disp lay the movements of air traffic en route and in termi nal areas. It provides an extremely rapid method of calculating flight paths, for assessi ng potential conflicts and for coordination between Area Control Centres. Special f eatures are included for military / civil coord ination.

The system has been ordered by The Netherlands and Ger­man Governments. The f irst phase has been in operatio­nal use at Amsterdam since 1961 and the second phase has now been installed.

N.V. HOLLANDSE S IGN AALAPPARAT E N - HENG ELO - NETHERLANDS

.e B B

Marconi Complete Air Traffic Control Data handling and Display Systems

o Direct view storage displays

o Transistorized PPI displays

o Transistorized height displays

o Transistorized tabular displays

0 Projection displays o Synthetic displays

o Composite display consoles

o Computers o Radar links

o Video map generation

Marconi air traffic control systems The Marconi Company Limited, Radar Division, Chelmsford, Essex, England S9

Marconi AD210C automatic VHF direction finder

IN HIGH DENSITY TRAFFIC AREAS

IN LOW DENSITY TRAFFIC AREAS

VHF DF is an invaluable adjunct to radar for positive identification of aircraft in high density air space and on busy airways.

The most useful single, all-weather, ground navi­gational aid providing air traffic control facili ties at low cost and requiring no special equipment to be fitted in aircraft, apart from the basic VHF communi­cation equipment . Easy to operate and maintain .

Push-button selection of five frequencies

Automatic presentation of bearings on 8-inch indication meter

Facilities for repeater display units up to 500 ft from main display and control units

Remote control up to eight miles from aerial site

Small display units, suitable for desk or main cont rol desk mounting

Simplified aerial system

ODM or QTE-50 kc/s channel spacing-frequency range: 100-1 56 Mc/s

Bearings and triangulation can be superimposed on Marconi radar d isplays

Marconi air traffic contro l systems The Marconi Company Limited, Radar Division. Chelmsford, Essex, England LTD 550

Solartron high resolution VIDEO MAPS

Solartron ATC SIMULATORS atairtieldsin:

SOLARTRON For- Data Systems · T ransducers · Computers

Simulators. Electronic Instrumentations

M & PS201

PROGRESS REPORT ... Solartron equipment has been chosen by a number of Civil and Military Air Traffic Control authorities throughout the world . Installation and construction currently in hand include:

in Belgium, Denmark and at ATC centres and several airfields in the U.K.

Norway Poland Hong Kong Ireland Canada Finland South Africa

- Oslo- Fornebu - Warsaw - Kai Tak - Shannon - Carp. Ontario - J yvaskyla - Langebaanweg

THE SOLARTRON ELECTRONIC GROUP LIMITED Military Systems & Simulation Division Victoria Road ·Farnborough · Hants. Telephone Farnborough ( Hants) 3000 Telex : 85245 Solartron Fnbro. Cables : Solartron · Farnborough

A MEMBER OF THE SCHLUMBERGER GROUP

IFATCA JOURNAL OF AIR TRAFFIC CONTROL

THE CONTROLLER Frankfurt am Main, April 1965 Volume 4 · No. 2

Publisher: International Federation of Air Traffic Con­trollers' Associations, Cologne-Wahn Airport, Germany.

Officers of IFATCA: L. N. Tekstro, President; G. W. Monk, Executive Secretary; Maurice Cerf, First Vice President; Roger Sodet, Second Vice President; Hons W. Thou, Hon. Secretary; Henning Throne, Treasurer; Wolter Endlich, Editor.

Editor: Wolter H. Endlich, 3, rue Roosendael, Bruxelles-Forest, Belgique Telephone: 456248

Production and Advertising Sales Office: W.Kromer&Co., 6 Frankfurt am Main NO 14, Bornheimer Londwehr57o, Phone 44325, Postscheckkonto Frankfurt am Main 11727. Rote Cord Nr. 2.

Printed by: W.Kromer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr 570.

Subscription Rote: OM 8,- per annum (in Germany).

Contributors are expressing their personal points of view and opinions, which must not necessarily coincide with those of the International Federation of Air Traffic Controllers' Associations (IFATCA).

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

Contributions are welcome as ore comments and criti­cism. No payment con be mode for manuscripts submitted for publication in •The Controller·. The Editor reserves the right to make any editorial changes in manuscripts, which he believes will improve the material without altering the intended meaning.

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

Advertisers in this Issue: Cossor Electronics, Ltd. (Inside Back Cover); The Marconi Company, Ltd. (2, 3); N. V. Hollandsc Signaalapparaten (1); The Solartron Electronic Group, Ltd. (4); Standard Elektrik Lorenz (Inside Cover); Telefunken A.G. (Back Cover)

Picture Credit: Cossor Electronics, Ltd. (32, 33, 34); Hazeltine Corporation (26, 27, 28, 29, 30); Heinrich Hertz I nstitut fur Schwingungsforschung (35, 36); Simonis, Vienna (8); The Solartron Electronic Group (16, 17); Trumler, Vienna (6, 7); Whittaker Corporation (26, 27, 28, 29, 30)

CONTENTS

Welcome to Vienna Conference Programme ............................... · · ·

Highlights of Addresses to the Conference ............... ·

Making Use of Radar ............................... · · · · · Caplain 0. Abarbanell

The Evolution of a practical Secondary Radar System for Air Traffic Control ........................................ · ·

B. R. Newman and W. E. Webb

High Resolution and other Improvements in Video Mapping R. N. Harrison

Secondary Radar Implementation Dates in Europe ....... .

Data Processing applied to Air Traffic Control ........... .

Zambia becomes Member of ICAO ..................... .

The Turkish Air Traffic Control Association ............... .

Yugoslav Air Traffic Controllers Association applies for affiliation with IFATCA ................................. .

lOth Annual Convention of the AirTraffic Control Association

Venezuela and New Zealand Members of IFATCA, The Solartron Electronics Group and ITT Europe Corporation Members

1 Bth Annual FSF International Air Safety Seminar

Progress with HARCO and the Digital Data Link W. E. J. Groves

Speed Control .......................... . R. Solinger

Operation and Applications of the Hazeltine Alpha-Numeric Generator ............................................. .

Tirey K. Vickers

Controllers Gossip

Factors involved in the Choice of SSR Ground Radar R. Shipley

Long Range Detection of Thunderstorms G. Heydt and H. Volland

IFATCA Addresses and Officers

Books .......................... .

IFATCA Corporation Members

6

8

9

11

16

18

20

21

21

21

21

21

21

22

24

27

31

32

35

37

39

40

6

II 11

PROGRAMME

Monday, 12. April

Arrival of Delegates and Observers

Conducted tours of the Technical Exhibi tion in the pas­senger hall of Vienna Airport

Visit to the a irport facilities

Film "Supersonic Transport and ATC"

Lecture with colour slides on video mapping by Mr. R. N. Harrison (The Solart ron Electronic Group, Ltd.)

Tran sport to the Intercont inental Hotel at 18.00

Eve n ing:

Reception and Opening Address by the Austrian Minister o f Transport, Mr. Otto Probst; Cocktai ls

Address by the Pres ident of the Austr ian Air Traffic Con­trollers Association, Mr. Herbert Brandstetter

Tuesday, 13. April

Mo rn ing:

Open ing Ceremony a t the Intercontinen tal Hote l

Address by the President of the Federal Aviation Depart­men t, Dipl.- ln g. W. Watzek

Address by the Lord Mayor of Vienna, Mr. Franz Jonas

Address by the Governor of N iederosterreich, Dipl.-lng. DDDr. h. c. Leopold Figl

4th ANNUAL IFATCA CONFERENCE, APRIL 12th-15th, 1965

Address by the Chairman of Austrian Airlines and Presi ­dent of IATA, Dr. Lambert Konschegg

IFATCA business session

Noon:

Reception by the Director of Vienna Schwechot Airport, Dipl.-lng. Heribert Kreis; Cocktails, cold meal

Afternoon:

IFATCA business session

Evening:

Reception and Dinne r by the Lord Mayor of Vienna, Mr. Franz Jonas, ot the Vienna C ity Holl

Wednesday, 14. April

Morning :

IFATCA bus iness session

Noon :

Luncheon sponsored by the Cossor and Selenio Companies

Afternoon:

IFATCA business session

Evening:

Heurigenabend sponsored by the Marconi and Thomson Houston Companies

Thursday, 15. April

Morning:

Technical Symposium with papers, submitted by IFATCA's Corporation Membe rs, on the following subjects:

Factors involved in the choice of SSR

Progress wi th HARCO and the Digita l Dato Link

Doto processing applied to air traffic control

Operation and appl ication of the Hazelti ne Alphanumeric

Generator

Experience with Dig itrack

Bright tube displays

Lessons learnt in 9 years SATCO

Improvements in p rimary rodo r

High resolution ond other improvements in video mopping

General purpose computers in air t raffic control

The evolution of o practical SSR system fo r air traffic con­tro l

N oon:

Luncheon sponsored by Austrian Airlines

Afternoon:

Plenary Meeting

Evening:

Heurigenobend arranged by the AA TCA under the protec­tion of the Governor of N ieder6sterreich

7

HI G HLIGHTS OF ADDRESSES TO THE CONFERENCE

8

The Lord Mayor of Vienna, Mr. F. Jonas On be~olf of the ~ustrion Federal Capitol I extend a hearty welcome to you, at the some time expressing my thanks that you hove chosen Vienna as the venue for yo ur fourth _Annual Conference. But I t_honk you a lso for making it possible by perform ing your highly complex and responsible_ task th~t so many passengers a l l over the w o rld may ~ofely ~oke c:>ff on~ lond, notwithstanding all the pro blems which occur in the ever increasing air traffic. You o!e gotheri_ng in Vienna to stud>:' !e:chnic~I and operational problems and to establish the p_o li~y for yourf~rther o~t 1v1t1es. B~ing the. mayor of a c~ty which attaches the greatest s1gn1ficonce t? internot1~no l tourist traffic, I take a sincere interest in your endeavours. Moy I w ish you, ladies and gentlemen, a very pleasant and en joy ­able stay in our hospital Vienna which b ids you a friendly greet ing.

The District Governor of N iederosterreich, DDDr. h. c. Dipl.-lng. L. Figl The tremendous technica l progress of our time hos caused a great number of new professions to become necessary for the purpose of taking core that man remains the master of all that human wit hos inven ted and human industry hos developed. Among these p rofessions is that of the air traffic controllers, the men who at a irports all over the world arrange for air traffic to be conducted with the highest degree of safety and who thus take core that technical progress will be a blessing for man. The aircraft hos closely li nked countries and cont inents, unfortunately the liaison of thought hos not always been established with equal rapidity. Air traffic across conti­nents req uires a wor ld w ide air traffic control _system. Only in very few professions is the need for international cooperation as obvious as in those connected w i th modern air traffic. As the Governor of the Austria n Bundeslond in which the biggest Austr ian airport is situated, and wh ich hos contributed internat ionally recogn ized pioneer work to avia­tion some six decodes ago, I extend a hearty welcome to Delegates and Observers to the fourth Annual IFATCA Conference on? wish their deliberations every success. Every resolution passed by this Conference indicates the necessity for international cooperation in order to solve the problems brought about by rapid technical deve­lopments. We citizens of Niederosterreich or~ very glad. tha t yo~ wil l ~ave, in addition to the work which is devoted to the exacting profession ?fair. traffi c con tro_ller,_ on oppor­tunity to v isi t our Bundeslond. Klosterneuburg, which wd! be the des!inot1on of your little excursion, is historically and culturally of greatest importance in the evolution of Austria. You ore heartily welcome in a country who se pe~ple hove;, already on o~count of the geographical location of their homeland, recognize? the 1mport.once c;if international cooperation. Moy I also wish you much success in your del1berollons which ore intended to serve al l peoples.

The Federal M inister for Transport and Power, Mr. Otto Probst ... It is quite clear that your common ~o.ol s c~m only be rea lized w ith the coopera­tion of your appropriate notional odmin1stro t1ons. It falls to you, the_ref~re, to con­vince these administrations that the p roposals and pla ns for the reo lizot1on of your tasks ore correct and suitable. All of us w ho ore concerned with a ir traffic ~n?. its ! equirements know that the p roc­ticing controller bears a very great respo~si b i lity in l ~e perform.o~ce ~f his duties. Mutual cooperation between A T<;: oss?c1ot 1ons and notiona l odm1n.1strot1ons, a s well as international organizations w il l, without any doubt, be very fruitful for the fu lfil -ment o f your p lans a nd tasks. . . . I assure you_ of course I con only spe:ok for Austria. in this respect - that the Fede-ral Ministry of Transport and Power 1s deep ly sensib le of your. problen:is and w ill always consider them w ith sympathy. In any even_!, I am quite certain that my Austrian co lleagues will take great benefit from this IFATCA Conference and the

technical discussions. . · I · Moy I repeat w hat I expressed eo~lier: It !s a grec;it p eosure to me that this <;:on-ference which is so significant . for 1nternot1onol ov1allon takes place on the sod of our metropol is so rich in tradition.

The Chairman of Austrian Airlines and President of IAT A, Dr. L. Konschegg On behalf of Aus trian Air lines I wish you a hearty welcome to Vienna. Moy I empha­size that th is invitation is not a i;iure f?r.mol ~ne. It was extended I~ you because the Austrian national carrier, Austrian (1-1 rl1nes, 1s fully o""'.o~e o f the 1mpo_rtonce. of on even better co-operation between fli ght personnel o f airl ines and the 01r traffic con-

tro llers. II f . I b h f . . . h ... The main factor, howe_v~r, in ~ pro ess1ono ro.nc ~so . ov10 t1on 1s ! e attitude towards the work. A pos1t1ve attitude connected w ith 1deo l1sm o.nd satisfaction in work will always lead to the best resu lts. Please remember that 11 makes no d iffe­rence that some of us ferfo~m our tasks on the ground and others in the a ir. We all work in that branch o traffic we ore so much attached to, and the fin~ I aim of our work is th e further development and the absolute sa fety of commercial air traffic.

Making Use of Radar

Oded Aborbonell, was born in Tel-Aviv Israel on August 16, 1926. Graduated from the Hebrew "Herzlio..' Junior Col­lege (Literary Side), studied Social Sciences at the Hebrew University, Jerusalem, and received his B. A. (Political Science) from Columbia University, New York City, N. Y. Joined the Aviolion Circle at the Hebrew "Herzlio" Junior College on 1. 9. 1939 and the Aero Club of Palestine on 1. 9. 1940. Slarled gliding on 8. 4. 1942, obtained gliding and soaring licences A, B and C and broke the Palestinian single­seat sailplone altitude record on 3. 8. 1947, obtaining his Gliding-Instructor's rating 22 days later. Started flying light aircraft at the • Aviron" Co. flying-school in Ramlah on 1. 9. 1943. Joined the Israeli Air Force on 1. 3. 1948, went through military flying-school and obtained his mililary pilot's wings. Served as pilot and later went through Flying-Instructor's School and served as Flight-Instructor. Was released after 41'2 years of service holding the rank of Captain, the De­fence, Guard, Independence and lhe Sinai Campaign Me­dals, and having been twice mentioned in Despolches. Join­ed "El-Al" Israel Airlines on 1. 10. 1952. Flew as Domestic­Captain on the Curtiss-Wright C-46 and as International Captain on the Lockheed 049-149 "Constellation" lhe Brislol "Britannia" 313LR and since the beginning of l961 on the Boeing 707-458. Was Training-Captain in 1962/63, Deputy Superintendent of Training and Chairman of the Flight Safe­ty Group in 1963/64. Completed an Aircraft Accident lnves­tigolor's Course at the University of Southern California, Los-Angeles, on 28. 6. 1963. Is now flying the line on all "El-Al" routes. Is Aviation Consultant to the Public Council for the Prevention of Noise and Air Pollulion in Israel. Member of the Israel Society of Aeronautical Sciences. Cap· loin Abarbanell is married and has three daugthers.

In 1887, Heinrich Hertz, pioneering electromagnetic wa­ves, found that radio waves were reflected from solid obstacles. In 1904, a German engineer named Christian Hulsmeyer was granted patents in several countries on a radio-echo collision-prevention device. On June 20, 1922, Marchese Guglieme Marconi, then in New York, said: "It seems to me that it should be possible to design apparatus by means of which a ship could radiate or project a diver­gent beam of these rays in any desired direction, which rays, if coming across a metallic object, such as another steamer or ship, would be reflected back to a receiver screened from the local transmitter on the sending ship, and thereby immediately reveal the presence and bearing of the other ship in fog or thick weather." In 1925, Breit and T uve employed the pulse principle, in the form in which it came to be used in radar, in order to measure the height of the Ionosphere. There follows a long and com­plicated history of early experiment, total failure, and qua­lified success in the field of radio detection carried out in many parts of the world during the next decade. Finally, successful pulse radar systems were developed indepen­dently and nearly at the same time in the United States, England, France and Germany during the years 1935-1940. Then came the Second World War and Radar, proving to be a tremendously efficient device for early detection, both on the sea and in the air, as a controlling device in com­plicated air operations such as mass bombing raids when a 1 OOO or more aircraft had to be maneuvered within a comparatively small airspace, as an aid to the defending

by Captain 0. Abarbanell

fighter-pilot in finding his foe, as an aid to the weary bomber-crew in finding their base and the landing runway in the midst of a fog as thick as pea soup and as an aid in telling the difference between friend and foe, especially in the dark hours of the night, was intensively developed by the belligerent nations and especially by the British and the Americans during the years 1940-1945.

The Second World War has left civil aviation an im­portant, fruitful legacy, yet civil aviation was not too quick to grasp it. There existed, at first, the obstacles of military secrecy, classified information and restricted war materiel. Then another deterrent - the prohibitive cost of radar installations within air traffic control systems kept the de­vice from developing largely for some years. Lastly, the cost of airborne radar equipment and its excessive weight constituting a prohibitive drain on the small payloads then carried, prevented most operators from installing radar in almost any type of propeller-driven airplane for many more years. This period of "hesitation", lasting approxi­mately from 1945 to 1955 came to an end with the advent of the faster, higher-flying, more efficient and economical turbo-prop or jet-prop aircraft, the steadily increasing air traffic and the realization that the electronic industry did not stand still since the end of the war and made available a large variety of comparatively inexpensive and light radar equipment for both the controller on the ground and the pilot in the air.

Today the pilot flying almost any type of aircraft is guided by controllers working in vast air traffic control complexes covering almost all countries around the globe and who, making use of different radar devices, tell the pilot his exact location, any deviations from track or air­way, significant weather which might interfere with the smooth and safe conduct of his flight, significant traffic in his surrounding which might affect any aspect of his ope­ration such as altitude or track. The pilot helps the con­troller in his complicated task by "squaking" his trans­ponder, an improvement on the wartime I FF, thus helping the man on the ground identify him amidst many others, all flying in close proximity. Approach radar controllers talk pilots down and onto runways covered by an over­cast at 200 feet or with a runway visual range of 1/2 a mile and sometimes just 500 yards. The pilot and navigator, or NAV/RO uses another radar device, the Doppler, to assess his ground-speed and drift and sometimes feeds that infor­mation through a computer and into the aircraft's auto­pilot system thus navigating a large, fast and heavy jet airliner along nonstop for two or three thousand nautical miles with a navigational error of only 1/2 of 1 % or 15 miles in 3000. And yet the pilot is not satisfied, neither, I dare say, is the air traffic ~ontroller.

It is not the imperfections of radar that worry us. These were solved and overcome in the past and will certainly improve to a growing extent in future. It is the state of the art, which, in the opinion of many a pilot is far from the full extent of its possible scope. The pilot of today's sub­sonic jet is appalled when flying through an extensive con-

9

trolled airspace governed by an intricate radar coverage and finding out that as to altitude or level the controller has to rely solely on information supplied to him by the pilot. More aggravating is the airspace which is thorough­ly covered by radar up to level 250 but completely uncon­trolled above that, offering the pilot a poor choice bet­ween flying low through thick and thin, shaking up his passengers and consuming enormous quantities of fuel, or taking a risk and flying within an airspace filled with both military and civil traffic quite ignorant of each other.

A classical case of "wasted radar" is the one, which has occured to many a pilot more than once where the radar controller directs the flight for an interception of the ILS localizer at an airport, and whilst still 20 miles or so from downwind leg directs him straight into a cumulu­nimbus cloud laden with turbulence, heavy icing, hailstones and possibly a lightning strike to boot. The excuse given by the controller to the raging pilot was, of course, that his radar set is built to eliminate weather and that he had no inkling of the presence of that CB in the area, which is quite so. Another ridiculous example happened at one of the major international American airports when several aircraft were kept in a stack for congestion reasons: It so happened that the holding pattern in which these aircraft were held was covered by a severe thunderstorm, the hold­ing craft were tossed hither and yon amongst 7/s of large CB clouds, fighting severe turbulence, icing and hail. Needless to say none of the patterns these aircraft per­formed resembled, even remotely, the prescribed holding pattern, for it is indeed difficult, if not totally impossible to do so with a jet airliner, presenting all its geometric­aerodynamical problems and flying at a holding speed of between 200 and 250 knots, with gear and flaps retracted in order to give him the best endurance (lowest fuel con­sumption).This happened to be a comparatively condensed thunderstorm covering the small area of this particular holding pattern. Only 20 miles or so away it was clear and the sun was shining over another holding point, yet the controller did not know all this for his radar set eliminated all weather and brought out airplane blips only, and so he kept his heavy traffic bobbing up and down and swerving about in a crazy manner in the only uncomfortable and UNSAFE holding pattern in this area at the time. Had there been a weather detection radar set within the con­trol compound, and a set procedure whereby the weather­radar controller could advise his colleague of the weather picture in his area such occurrences would be eliminated. Similar examples of harassing situations for both pilot and controller abound.

The present day, subsonic jet airliner pilot would like to see, and believes that this can be accomplished at no great effort or cost with present day equipment: Radar coverage on all routes and airways around the world, which will allow him to omit position reports (sometimes required, especially within Europe, every 5 minutes or less), tell him when he errs from track or airway, tell him his dis­tance from major check-points so that he may ha':'e ~ double-check on his ground speed, advise him of signi­ficant traffic in his vicinity and of diversionary measur~s if required and advise him of significant weather on his route and fly him around such weather if required. A radar system that will cover the airspace from the ground up to level 500. Radar which will have information on both loca­tion and altitude of both aircraft and weather on all routes (excepting oceans) and especially in the approach area.

10

Last but not least: PAR on every major runway at every major airport, enabling approaches for jet airliners down to a minima of 200 and a half.

The time is not far off, and indeed experts predict that it will happen very shortly after we enter into the next decade, when the supersonic jet transport will enter upon the scene. A heavier aircraft, flying at twice or thrice the speed of sound and cruising at levels of between 500 and 700, bringing with it a multitude of new problems, not the least of which will be air traffic control problems. It is almost certain that radar will have to play a major part here'. There ':"ill have to be full global radar coverage, provided mainly, and for the control of air traffic on the various routes, by special satellites, belonging and operat­ed by some sort of world organization, and providing the controller ~n the ground with an accurate picture, possibly of a televised nature, of what flies on within his sector ~rom the ground or sea level and up to level 1 OOO, includ­ing such remote areas as mid atlantic or pacific ocean. The present, though improved, terrestrial radar installa­tions will .provide information within approach areas and comparatively low levels only. The SST whose long t flight over the longest stretch will only las; for two or th es hours, and which will navigate across oceans and /e~ . . on t1~ents using some sort of omni beacon or range, trans-mitted by these ve.ry same satellites providing the radar coverage, and which will be fed, together with ground­speed, drift: fuel ~onsumed and other data through a com­puter and into his auto-pilot system to provide hi 'th . . . f m WI constant pos1t1on in ormation and keep him on track will have to be closely monitored by Radar on th "D 't II

'II 11 " e on ea us, we ea you system and it will have to be efficient for catastrophe ma.y result if 20 such SST's will not be brought down hurriedly from high levels to lower ones when sun-flares occur or a high concentration of ·

d d . .

11 h ozone 1s

detecte . An 1t w1 ave to be accurate or ve · . . ry grim results may ensue 1f such a .. flying machine will not be guided smoothly and exped1t1ously through its opp h . f1I . . roac penetration pro. 1 e,. trans1t1ng from super to subsonic speeds and coming in for .a landing with enough fuel for another 10 or maybe 15 minutes of flying.

Will Radar be able to do all this? I believe it will. Avia-tion has surmounted greater obstacles than this in the t

d . 'f fl pas . It will have to o 1t, 1 we want to y faster and increase air traffic for th~ purpose ~f world travel. For if we reach the supersonic flight age with Radar not up to what it .11 have to be we really will hav~ a problem, and the ni;t­mare will be shared by both pilot and controller alike.

NATO Air Defence Ground Environment (NADGE)

Decca Radar Limited and Compagnie IBM France and IBM Italia S.p.A. have joined with Westinghouse Electric International of New York to form "Westinghouse NADGE Associates". This organisation, with offices in London, will present joint equipment proposals for the NATO Air De­fence Ground Environment system.

The 11 O m NADGE programme will be the largest elec­tronics project ever to be undertaken in Europe and will involve radars, data processing, and communications equipment forming an integrated NATO electronic air defence system. This project has resulted in the formation of a number of consortia comprising all the leading elec­tronics companies of North America and Europe.

The Evolution of a practical Secondary Radar System for Air Traffic Control

Introduction

A little over three years have passed since the seventh communications session of the International Civil Aviation Organization was held in Montreal in 1962. During this meeting, several significant international agreements were reached on the principals and details of secondary sur­veillance radar, which was recognized as a basic naviga­tional tool. A plan for SSR was enacted and in the inter­vening years, several member nations hav~ proceeded with SSR implementation. These include the United States of America, United Kingdom, Netherlands, Switzerland, a~d Canada. Other nations have initiated programs which will shortly lead to system implementation for their natio­nal authori~ies. In this category are Germany, France, and Sweden. Still others are approaching final decisions re­garding the specific characteristics required to meet the local and common problems of air traffic control in their airspace. Italy, and the Eurocontrol Organization are re­presentative of this group.

. In short, our IFATCA meeting occurs during a period of intense SSR activity, and at a time when twenty years of developmental work and ten years of international con­ferences are beginning to produce tangible results.

The way is not smooth for this program by any means. The ICAO meetings did not provide universal solutions or agreements between nations on several of the important detailed characteristics of secondary radar. Among the areas of dispute were the use of two-pulse versus three­pulse side lobe suppression, altitude reporting in 100-foot increments versus SOO-foot increments, utilization of modes 3/A, B, and D, etc. Meetings continue on these and other matters. In prior years, arguments were presented largely on theoretical grounds, and very little user experience was available. We now see some slow resolutions of these problems as users gather experience in the application of SSR.

The arguments are largely technical in nature and are not the primary subject of this paper. It should be noted, however, that the most far-reaching effect of the continued existence of the areas of dispute is that a burden is placed on the manufacturers of SSR equipment, who must be prepared to comply with one or another or a combination of the competing positions. This results in design costs higher than necessary and equipment capability greater than required. Since SSR equipment must be designed con­siderably in advance of its use, we, as manufacturers, and you, as users, cannot wait for these arguments to be re­solved before we proceed with our design implementation.

In studying the problems of SSR use, it is apparent that no one implementation and no one philosophy of SSR exists which is ideally suited to the needs of al I users. Such factors as geographical locations, height and density of air traffic, proximity of interrogator location to display site, existing primary radar display equipment, future growth forecasts, etc., often do and should dictate variant solutions to the problem.

by B. R. Newman and W. E. Webb Whittaker Corporation

The projected increase in air traffic activity, in most areas, and the advent of higher airspeed aircraft do de­mand equipment which materially reduces the controller's workload per flight by means of automation techniques, sophisticated display devices, and computerization of the collision avoidance function. On the other hand economic factors and the realities of the present-day air traffic situation usually point to an initial implementation which is relatively simple, and which represents a logical pro­gression from an existing air traffic control facility. A pro­gressive approach is invariably sought which, as needs and problem complexities increase, in no way obsoletes exist­ing equipment.

These last two points - the variety of SSR solutions and the progressive implementation of SSR capability -are the primary concern of this paper. The question is really how to approach secondary surveillance radar in a way which adapts to the specific requirements of an exist­ing air traffic control site, be it terminal or en route, while maintaining the capability for progressive expansion to meet future needs. The solution we present here is that which the Whittaker Corporation has adopted through seven years of experience in secondary surveillance radar, as suppliers to the Federal Aviation Agency in the United States, and as providers of SSR equipment to the Govern­ments of Netherlands, Switzerland, and now Germany.

Current Capabilities

As background information, an approach to an evolu­tionary secondary surveillance radar system must start with a description of current capabilities. This is doubly true because the starting point for signal data processing is the basic interrogation and decoding scheme common to all systems. Moreover, the basic system represents equip­ment now operational in the United States, Netherlands, and Switzerland, and has many similarities to military IFF/ SIF equipments in use throughout Europe and the Near East.

A series of secondary radar equipments, developed for use in the United States by Whittaker Corporation, have been designed, developed, manufactured, and delivered to the Federal Aviation Agency during the period from 1957 until the present. These equipments, known collectively as Air Traffic Control Beacon Interrogators, comprise three models, designated ATCBl-1, ATCBl-2, and ATCBl-3.

In the aggregate, these equipments now total nearly 200 and are installed at all U.S. terminals and en-route air traffic control centers, as well as at Schipol Airport in the Netherlands, at Cointrin near Geneva, and at Kloten near Zurich. The system is composed of two sites called, respectively, the Transmitter (interrogator) and Indicator (decoder) sites. Figure 1 shows a simplified diagram of the interrogator. It has a range of 200 nautical miles, a power capability of 70 to 3 500 watts, and provides for interroga­tion in modes l, 2, 3/A, B, C, and D with two modes inter­laced on a l-to-1 basis. Defruiting is available at the inter­rogator site, provided by a delay line Defruiter capable of either single or double defruiting.

11

Figure 2 shows a simplified dia­gram of the decoder. All systems currently in use are 64-code systems, but are expandable to 4096-code use when needed. The system is capable of a number of different kinds of

TO FROM INDICATOR SITE

TRIGGERS AND RAW VIDEO

CHANNEL I

LAND LINE

TO ANTENNA

t...=_ -~ PRE TRIGGER 0 FROM RADAR

MICROWAVE LINK

TRIGGERS AND RAW VIDEO

decoding. The primary means for display of decoded replies are the plan position indicator (ppi) units of the associated radar set. Each con­trol !er is provided with a control box that permits him to select the type of decoding he requires, with­out interfering with the decoding operations chosen by the other con­trollers. Figure 3 shows the operator control box for this system, and the ppi display is shown in Figure 4. Fig. l Interrogator Site, Simplified Block Diagram

The decoder presents all trans­ponding targets in real time through either a bracket or an all-aircraft decoding system. Each controller has provisions for further identifying cer­tain of these aircraft. This selectable identity capability provides a spe­cial presentation that permits the controller to identify and track up to 10 aircraft at a time. In addition, each selectively decoded presenta-tion can be provided with ident blooming. This wide-pulse presenta-tion appears when the controller enables the ident blooming function in one select-decode channel, and the pilot of the corresponding air-

TO FROM TRANSMITHR

SIH

I I

I I

I

COMMON

PHOTO [L(CTRIC R[AOOUT

TO PPI

TO PPI

PHOTO ELECTRIC READOUT

craft adds the SPI pulse to his trans­ponder reply.

II COMMON I

0[COD£R I ._ ____ _...~ <:1RC:lJITRV

L----:J COMMON RACK CHANN[L 2 An alternative real-time presen­

lation passes the demodulated air­craft reply, called "raw video",

Fig. 2 Decoder Site, Simplified Block Diagram

directly to the ppi display. This type of presentation per­mits the controller to identify an aircraft by observing the actual code configuration of its reply.

A more rapid means is also available for identifying a target aircraft. Referred to as active-readout decoding, this system provides instant decoding and readout of a target selected from the face of the ppi by a pistol­shaped device called a "light gun".

An additional type of decoding is provided for target information within the controller's sector. Called emergen­cy alarm decoding, this system generates audible and visible alarms in response to a code configuration de­signated as the emergency code. The aircraft transmitting the emergency code is identified on the ppi by an enlarged double-pulse presentation.

Obiects of the advanced Digital Decoder Program

Several shortcomings in the system described above became obvious when this equipment was matched against the ICAO specifications and the current trends in SSR user requirements. We saw the need for additional capabilities in both the decoder and interrogator, and undertook the development of a system capable of meeting these known objectives.

12

First among these was the need to add f ·i·t· d

. . ac1 1 1es for presenting an using aircraft altitude data Mode C. reported in

Secondly, an increase in the flexibility of m d h

. . 0 e use was needed to treat t e s1tuat1on where military and · .

1 •

. d h . CIVI air-craft occup1e t e same airspace, or where identit . f

· · d I lt"t d · f y in or-mation in two mo es p us a 1 u e 1n ormation or d e nee ed simultaneously. In other words the transmitter m t

d . I d . us pro-

duce three-me e inter ace interrogation It is d · bi · es1ra e for the master controller and operating controllers to h discretionary use of the mode selection functions. ave

Next, the multiplicity of modes in use make it advis­able for the controllers to restrict the mode or modes in use on each selected target.

Fourth, sectorization in the third dimension of altitude for each controller operating in a dense ATC environment is needed. Establishment of upper and lower altitude limits and consequent filtering of targets to the display is a viable solution.

In addition, expansion of the emergency decoding cap­ability to provide Communications Failure decoding and automatic altitude readout for any emergency target is mandatory.

The controllers and maintenance personnel need · _ d fid

. . In crease con 1 ence 1n continuous equipment operation.

• • ~

C9 11' (j)

(j)

·~ 'i-

<i

• Fig. 3 ATCBl-3 Operator Control Box

8MIC MARK X REPLIE~

( phos~d out in 19GI)

• G

OQ

• • ---ft.~ GO~

-~

~ ~ • "

COl.4MON ~'t'~TEM REPLIB

~

I /OENf. (8#/

EMERGENCY ,, if !?APAR

SLIP

Fig. 4 PPI Display of Basic SSR Information

•

•

Interna l monitoring of system performance hod to be ex­panded and the new function s supervised through quick­control switchover capabilities.

Another objective was to improve d isplay techniques for target information so that at least three addit ional useful types of target presentation could be made avail­able . These o re :

a) The direct correlation of the response appear ing on the display with the corresponding code recognition chan­nel selected on the control box. For this purpose, single­r.horocter nume ric symbols ore presented adjacent to the corresponding reoltime target "blips".

b) The readout of ident ity, mode, and altitude of an un­known target d irectly on the display adjacent to that target's response. This coincides with the use of the active decoder targe t-designating device.

c) Alphanumeric togging and tracking of all SSR targets whose identity codes hove been selected for recogni ­tion.

A further objective was to study the controller's rela ­tionship with the data processor to ease his physical use of the equipment and to establish o single-point e ntry of SSR codes. Automatic transfer of active ly identified un­known targets from the display to an available select channel in this process was also desirable.

Lastly, it is necessary to inte rface the passive and active decoders with the more automatic systems as air traff ic will require them in the future. Specially, reduct ion of the controller workload through automation of the flight pro­gress checking function and the conflict pred iction activity, coils for the insertion of computers into the ATC system. It is necessary to ensure that the real-time information derived from the radars and decoded by the system be formatted and provided as o digi tal output compatible with the tracking computer selected at o later dote. Flex­ibility in formatting and compatibility with o wide range o f possible computer choices must be built into the decod ing system.

These technical objectives were undertaken within o fram ework of economics d ictated by establ ished radar pr ices and appreciation o f the need for low-cost phased implementation . Mo dularity, therefore, is o decoder re­quirement and was incorporated in our planning.

The some objectives of reliability and long Mean Time Between Failures incorporated in our ATCBl-1 , -2, and -3 eq uipments were used a s the min imum standards for the new d ecode r. Two specific improvements here were con­templated :

a) The use of solid-state components and microcircui t units, which exhibit inherently higher reliability charac­teristics, provides the feasibility for a low-cost first step, in that we can now think in terms o f single-channel operating systems, rather tha n the dua l-channel stan­dards used before.

b) The use o f o minimum number o f ofte n-repeated basic bui lding b locks, provides for a reduction in down-time thro ugh quick-change modules tha t restore the system functioning capabil ities immediately and permit the repair o f the module at the bench.

Advanced SSR Equipment

Figure 5 sho ws the operator 's control box to be sup­pl ied wi th the first advanced SSR system to be installed in Ge rmany later this year. An analysis of its operating characterist ics demonstrates how the objectives out! ined a re being real ized in the new equipment.

The box may be composed of four modules. Three of these modules are identical, each with provis ions for five channels o f passive selective decoding, thus permitting 5, l 0, o r 15 selectable channels to be provided at each con­troll er position.

13

r-----------------------},;;!·;--------- _____________ _J

Fig. 5 Operators Control Box

Each channel of selectable decoding is provided with a 4096-code selection capability by means of four indicating thumbwheels. A fifth thumbwheel designates the mode in which each code is to be recognized. These thumbwheels are selected in advance by the controller for each aircraft expected within his control sector, and may represent either a functional code (e. g., aircraft descending from 20 OOO to 15 OOO feet) or a unique code associated with the

aircraft from the inception of its flight. Opposite each selected target a three-digit display of

altitude, measured in hundreds of feet, is provided. Any selected target which reports its altitude in Mode C will activate these digital indicators and will update them auto­matically each time the aircraft's altitude changes.

The section of the box to the controller's left contains an active readout panel, providing information needed for an unknown target selected from the display by means of the light gun, rolling ball, or joystick target designator. The active readout panel shows the mode, code, and altitude

of the target so selected. This section of the control box also presents emergency

and communication failure information. The identity field will read 7 700 in case of civil emergency, 7 600 in case of

communication failure, and the ac­tual aircraft identity code when a military aircraft emergency is en­countered. Altitude readout for the emergency target is also provided. Audible and visible alarms are sounded, and the bloomed slash marker appears on the display.

The height sectorization or filter­ing process is provided by the estab-1 ishment of upper and lower limits

for targets passed to the display. e Using these controls, the operator eliminates from his display all tar- I 1lol113161 gets reporting in Mode C which are above or below his zone of interest.

BAROMETRIC SETTING

Targets which fail to report altitude will not be filtered from the controller's display In a h" h d . . . . . . · 19 - ens1ty s1tuat1on effective sectorizat1on of the enfire · · "bi ' . air space 1s poss1 e.

Figure 6 shows the Master Control B .d d . h ox prov1 e wit each SSR system. The master control! h th .b. · b · h" er as e respons1 1-lity for esta l1s ing mode interlace p tt d 1 . . . . a erns an se ectrng the perm1ss1ble interrogation modes Th th . · us, e master con-troller may select a single mode interrog t" t d • •

1 a ion, a wo-mo e

1-to-1 ratio inter ace pattern a two- d 2 . . ' mo e -to-1 ratio interlace pattern, or a three-mode 1-to 1 t 1 · ·

0 - - o- ratio inter-

lace pattern. ne selected mode is prew· d · th . ire rn e system and the specific second or third modes ·t d . perm1 te to be interlaced are selectable by the master t II R . . h , con ro er. efer-ring again to t e controllers operating bo h

· · d f h x, eac control-ler 1s advise o t e modes possible for inte t. b . . . . rroga ion y means of illuminated indicators. The cont II

1 · d ro er se ects which mode or mo es of those possible he cho t . oses o em-ploy. The interrogator then acts in the modes h" h w 1c one or more controllers have selected. Only the modes 1 d

. I I I .11 b se ecte by a part1cu or contro er w1 e displayed on h" · d" .

• IS In IVl-

dual pp1. The other functions of the master controlle · 1 d . . r me u e

selection of which interrogator, defruiter or decode h

0 NO CONTROL

0 ® CHANNEL SELECT

NO CONTROL

~ 0 ® DEFRUITER SELECT

NO CONTROL

8 0 ® DECODER SELECT

' r c an-

IL/RI

IL/RI 5.25"

(133mml

'-------INTERLACE PROGRAM------"

~ lc:J....------------- 9.0" ____________ _,._] (229mml Fig. 6 Moster Contrnl Box

14

nel of a dual-channel system is to be used. He also resets emergency alarms when they have been sounded, and is made aware through failure indicators of any mainten­ance requirement in the interrogator or decoder. Another function provided to the master controller is the insertion of local atmospheric pressure by means of a barometric control on the master control box. Discretion remains with the individual controller to select either flight level (uncor­rected) or QNH (pressure corrected) reporting, depending upon which criterion his target aircraft uses for altitude assignments.

These, then, are the operating functions of the advanc­ed SSR site currently in manufacture for the German government and available now for use in international air traffic control. All of the features, such as altitude filtering, barometric setting, three-mode interlace, 1 through 15 channels of selectable decoding, active readout, 4096 (ver­sus 64) code decoding, 1 through 12 decoder positions, and single- or dualchannel operation with automatic switch­over, are available as incremental choices that can be added or subtracted from a particular installation initially or at any time in the future. Most of these functions are provided by means of plug-in cards and modules, and space for all of them is provided in the basic design.

Some of the features of the system not referred to spe­cifically above include standard side lobe suppression (three-pulse), defruiting operations (with either delay line or storage tube variations), variable power output up to 3500 watts, antennae of both the directional and beam varieties, double and triple rotating joints, antenna pedes­tals and turning mechanisms where on-mounted primary antenna synchronization is not possible, test equipment, spare parts, and installation and maintenance service.

Expansions for the Future

Though the system described above represents advanc­ed capabilities, it is still to be looked upon as an interim system capability. In some applications the interim phase may be as long as the service life of the equipment, e. g., 20 years or more. In other applications, forecasts show that additional automation will be required and justified within five years after initial installation. For the latter eventuali-

®4263 A126

~6127 A164

Fig. 7 Typical Alphanumeric Display of SSR Target Information

ty, the system incorporates inherent expansion capabilities. Again, these may be added initially or at any time in the future. These expansion capabilities are:

a) Alphanumeric target display and tracking. Figure 7 shows how the displays may present either synthetically written target circles and leaders pointing to data blocks, or single target designators which provide direct correlations with decoder channels on the operator's control box. These displays are possible with either ppi displays or scan-converted display systems using tele­vision raster techniques. The addition of an active readout, on-display data block is also possible. This system produces a triangle around the target with a leader attached to the data block. All data blocks track their related targets on the display. The position of the data block is optional, and the controller has the abili­ty to inhibit some or all of this information as desired.

b) Monopulse resolution improve­

I,· :,1 I ' I ~ · I ment. A monopulse resolution improvement receiver for increas­ing target definition by reduction of slash width display is avail-

~ ..__....II II~

B[Tl-Tl I

4

--- .... =-! £_~.· ··---.....

~~~T-~

L_l_ -~-· A, ' J __ L_J

~ t-i::.. N

• [ L

~-~ r.

~I

.,,,~

_J L'Pl''.Rj lllMtf,

~~ ··~ 1

! M1 !

-i -~ T I

"'

I ~ I : I ~ I c r· -r : ~ J~ able. The unit presents constant dimension targets at any point on the display. It also presents a radial stem at the target center to locate the aircraft position precisely (see Figure 7). The sys­tems provided to Germany incor­porate this capability from the

outset.

c) Keyboard enlry. Figure 8 shows a keyboard entry device for iden­tity codes and modes and height

Cantrnued on pogc J.\

Fig. 8 Autoniatic Keyboard Entry ior SSR

lnfornwllon

15

High Resolution and other Improvements in Video Mapping by R. N. Harrison

The Solartron Electronic Group, Ltd.

During 1964 there became available a video map with a resolution better than one part in a thousand of its radius. Its introduction into operational use is a matter of considerable importance as far as controllers are con­cerned. For the first time they are being given a measuring tool comparable in performance with their radar. In fact in accuracy and resolution it is frequently superior to cur­rent PPI displays.

Resolution is partly the ability to see something small, but it presupposes the ability to see as separate entities small objects which are close together. Imagine a sum­mer's day on which you are standing with your back to the sun looking at a hill. If somebody on the hill has a mirror and adjusts its angle until the sun is reflected into your eyes, you see it quite clearly. Now someone close beside him produces another mirror, and adjusts its angle so that this too reflects the sun into your eyes. While it is still moving, you are conscious that there is a second mirror, but when it is stationary you are unable to discriminate between them. As far as your eye is concerned, the patch of darkness between the two mirrors is lost. You do not see the mirrors as separate entities, but as one intensely bright area against a lower level of background light. Under conditions of glare, the eye does not have the abili­ty to resolve objects close together.

Although video maps vary in design, they are based on the principle of illuminating a photographic plate by a moving spot of light derived from a cathode ray tube. If this spot is big we get glare conditions and detail is lost. The analogy of sunlight is not an exact parallel but pro­vides a useful mental image. For instance sunlight shining through a crack into a darkened room makes the crack seem so much wider than it is. The CRT spot crossing a line on the plate is made to seem wider because some light starts to get through as soon as the edge of the spot touches the line and the line continues to be illuminated until the trailin; edge reaches the other side.

Then there is afterglow. The phosphor of the tube face does not stop glowing as soon as the electron beam has moved on, so that even after the spot has passed some light is still emitted. This effectively adds to the width of the line unless it is suppressed electronically. You can see how this happens if you consider how the illumination of a PPI is always related to time. The PPI picture is painted by a spot which moves outwards in a series of radials. In terms of the scale chosen for the display, its speed is half that of an electromagnetic wave. The direction of each radial corresponds to the direction in which the radar pulse was transmitted, which is the same as saying the direction the aerial was pointing at the instant of time at which the pulse left it.

When reflected energy comes back to the radar recei­ver, it is applied to the spot to brighten it. In the same way the light passing through the video map plate is used to brighten the PPI spot offer interim conversion into a video signal. The rise and fall in that video signal (and the cor­responding variation in intensity of the PPI spot) is related to the amount of light passing through the video map plate. It is the time at which it passes through, and not the place which is important.

16

For this reason it is not possible to improve the quality of the picture seen on the PPI by drawing finer lines on the map plate. If the CRT spot in the video map is large in relation to the line thickness, it takes a significant time to cross the line and image on the PPI is thickened. CRT spot size and line thickness go hand in hand, and only with the introduction of microspot tubes has it become possible to take a significant step forward.

We can now have a spot size of .001" to .0015" over most of the working face area for 5" CRT. What is more, the size of the spot can be maintained within these limits despite the fact that the CRT face is flat. This flatness is important. If we look at Figure 1 we see that the spot on the map plate is produced as an image of the original spot in the CRT by interposing a lens. Maintenance of focus

PHOTOMULTIPLIER

OPTICAL CONDENSER

MAP PLATE

LENS

CATHODE RAY TUBE

fig. 1 Video Mop Optic

depends on the plate and the face of the CRT being paral­lel: the effect of any loss of focus is to increase the size of the spot with a consequent loss of definition.

Near the centre of the picture, the lines on the plate can be slightly thinner without loss of illumination, but nearer the circumference they may have to be drawn a little thicker, especially if they are radials or almost so. This is because the radial scan lines can be an appreci­able distance apart near the edge of the tube (i. e. if the PRF is low, and the rotation speed high in proportion). When this happens a radial line on the map may be illu­minated on average only on alternate sweeps, or where it is slightly divergent from a true radial it may be shown broken.

These effects are most noticeable when a display is expanded and off centred. However, with the shorter re­covery time now possible with PPl's, the tendency is to work at higher PRF's, and there is less risk that the map will be degraded towards its edge.

We have already touched on the question of afterglow and its suppression. This is done by clipping the video signal leaving the photomultiplier at the bottom of its amplitude curve. This clipping eliminates the first portion of the curve where the signal strength is increasing slowly, and also the last portion where due to afterglow the signal dies away even more slowly. It also serves to eliminate "noise". The signal is also clipped at its peak to ensure an even video level over this entire PPI. This avoids varia­tions in the brightness of the map as seen by the con­

troller. Looked at diagramatically (Fig. 2), we get a signal

which is almost straight sided between the upper and lower clippings, giving almost no variation in intensity from one side of a map line to another. Variations in in­tensity across a line produce an appearance of fuzziness and it is a natural reaction to turn up the gain to get a line which is apparently sharper. This is obviously a state to be avoided because if the map appears sharp at a low gain setting it is possible to include more information with­out a feeling of clutter. This is even more the case where lines on the video map are fine and much information can be accommodated in a small space.

- - --, TOP I 11PPINC1

I

P'Y.\ T tO"\J Of ·• ![Jt•~'I )l(,Nl~L

I

-----TIME

Fig. 2 Top and Bottom Clippinu

The fact that it is now possible to include more infor­mation and to display it with greater accuracy makes it necessary to take a look at the manner in which informa tion is laid out and the sources from which it is obtained. As regards layout, there is a prima facie case for stan-

dardisation of video map symbols, not only between coun­tries but between civil and military controllers*. As regards source, it is evident that to achieve a plate accuracy com­parable with the overall accuracy of video mapping equip­ment, six figures latitude and longitude positions must be used, and that the projection must be such as to produce minimal errors in range and bearing.

Fortunately the conical orthomorphic projection used in ICAO charts generates comparatively small range and bearing errors. On a typical 1 : 500,000 ICAO chart, the producing agency assessed the theoretical errors over a l 00 mile line as one and a half minutes in bearing and one part in 1,000 in range. Considered in relation to an accuracy of l O/o of the actual range or 0.1 O/o of the maxi­mum range (whichever is the greater) for the video map­ping equipment, these projection errors are acceptable.

It is therefore possible to use an ICAO chart as the basis for the preparation of a master drawing. To avoid the need to transfer lines of latitude and longitude, it is convenient that the master should be made as a tracing. As a high degree of stability is required, a Melinex or Mylar base such as "Permatrace" or "Stabilene" is used.

As video maps are centred on the position of the radar head, this position must be established with the same accuracy as any other. Indeed, it is more important than any other position, because the positioning of the plate in regard to the optical system and the accuracy of range and bearing are related to it. It is, of course, the centre of the tracing.

Working with a l : 500,000 chart, and preparing a plate of a one hundred and fifty miles radius, the master draw­ing will be about forty inchs wide. The scale of the chart is approximately ten times that of the plate, which has a working area 4" in diameter.

As the final line thickness will be for the most part .002", the tracing is done in lines approximately .020" wide. (The precise relationship is determined by the photo­graphic process: it is customary to over-expose the plates and this reduces the line thickness slightly.) The tracing is provided with aligning marks in the centre and at either end. These are used for setting the finished map plate accurately into its carrier, the work being done in a jig under a microscope, and to an accuracy of .001 ".

Scaling marks are included to serve as a check at the PPL These take the form of a letter "T" and are positioned 90c apart at the same radius from the centre, being in fact an arc of a circle designed to lie over a range mark. The alignment of North incidentally must be the same as that used for the radar. Where magnetic north, true north, or runway heading are used, it is important that the align­ment of the map and radar be the same.

The finished tracing must be photographed with great accuracy. This is the specialist field of the scientific photo­grapher. Points about which he must concern himself are the need to have his camera axis precisely at right angles to the tracing to eliminate scale distortion and to have his focus exact to avoid change in the line thickness. The plate emulsion must be one which will produce clear whites. A white which is even slightly grey can result in considerable light loss.

A paper describing a range of symbols currently under cons1de1ot1on

has been published in the April 1965 issue of Wo,-Jd Aerospocc Sys­

tems under the title 'Symbols for Video Mops Copies con be ob­

tained by writing to The Military Systems & Simulation Divisron

Solartron Electronic Group Ltd Victoria Rood. Fmnborough Hant·;

England

The finished plate is a negative of the tracing, the lines being white on a black ground. Where more than one iden­tical plate is required, they can be made from a master positive by contact printing, but specialised techniques are necessary to ensure that contact between the two emul­sions is fully maintained. Failure to achieve this means a variation in line thickness.

The completed plate is fitted in the carrier under the microscope in the alignment jig, and cemented into posi­tion. The carrier is then inserted into the optical system of the map and locked. Any slight adjustment necessary can be made by means of X, Y and 8 shifts on the optical system using the scaling marks on the plate as a guide,

usually in conjunction with a crystal-calibrated range mark generator.

Prior to insertion of the operational plate, two other plates have already been used for testing the system.These are the Resolution and linearity Test Plates. The first pro­vides an overall check of the efficiency of the system. The second ensures that the range measured along a radial is linear - that is to say that the scale remains constant. This in conjunction with the scaling marks on the operational plate, and the use of a precise range mark generator, ensures that the video map and radar picture are precisely related. In a plate having a radius of 100 n.m. this relation­ship will be within 200 yards at 10 n.m. and not more than ± 1 mile at 100 n.m.

Secondary Radar Implementation Dates in Europe

The Eurocontrol Agency has issued the following important Information Circular on the implementation of Secondary Radar:

European Organization for the Safety of Air Navigation Agency Aeronautical Information Service 72, Rue de la Loi · Tel. 138300 · Bruxell.,s 4

INFORMATION CIRCULAR

2/65 27 Feb

Implementation of Secondary Radar

1. Policy 1.1. The Eurocontrol Agency intends to make extensive use

of Secondary Radar in the provision of Air Traffic Services for which the Agency is responsible.

1.2. The upper airspace users and the ATS System will benefit fully from the advantages to be expected from the use of Secondary Radar only when all aircraft concerned are equipped with suitable transponders, and all ground units concerned are equipped with complementary interrogators, decoders and displays.

1.3. A coordinated time-table has therefore been estab­lished for the progressive implementation of Secon­dary Radar Service for the Upper Airspace of the Eurocontrol Area, and for the corresponding require­ment for aircraft to carry suitable functioning trans-

ponders. 1.4. In drawing up the attached time-table, account has

been taken of the intentions, already published by individual member states, regarding the compulsory carriage of Secondary Radar transponders and of the !CAO recommendations to give at least one year's notice of such requirements. (Recommendation 2/7 of the ICAO. Limited EUM/RAN SSR Meeting, November

1962.) 1.5. This time-table will be kept under review in the light

18

of progress achieved in the implementation of secon­

dary radar ground facilities.

2. Time-Table for Implementation of SSR

Notes:

1. The Secondary Radar Transponders required for carri­age in Civil Aircraft must initially conform to the Stan­dards laid down by ICAO in the 7th Edition (August 1963) of Annex 10, Part I, para. 2.5. (64 codes, Modes A and B). The extension of the system to the use of 4096 codes on Modes A and B will subsequently re­quire transponders modified in accordance with the Recommendations of the same Annex. To assist pro­gressive introduction of the use of 4096 codes, opera­tors are encouraged to have the corresponding air­borne capability available in advance of the manda­tory requirement.

2. The use of Mode C will be gradually implemented. Operators are therefore encouraged to have auto­m_atic altitude reporting capability available in their aircraft to assist the Air Traffic Services. Mandatory ~arriage of this facility throughout the area, however, is not foreseen before 1968. The dates for implementa­tion in some UIRs are stated in this circular. The re­mainder, with the minimum 12 months notice, will be promulgated later. The equipment required needs to transmit altitude information in 100 ft. increments in accordance with the recommendations of ICAO, An­nex 10 paragraph 3.8.

3. Military Aircraft flying as General Air Traffic should carry a functioning transponder giving coded replies to interrogation on Mode 3 (ICAO Mode A) with cha­racteristics conforming to those mentioned in Note 1 (above). At some time in the future this minimum pro­vision will become mandatory. It is desirable that as soon as possible military aircraft flying as General Air Traffic have Mode C altitude reporting capability also. This will become mandatory at a later date. Any additional requirements will be promulgated later.

4. The eventual use of Mode D is envisaged by ICAO, as a means of providing a system expansion capability. The future use of this mode is still under investigation.

Dates far Mandatory Region Flight Levels Carriage Modes

l. 7. 1965 Scottish UIR FL 250 and above A-8 London UIR Preston UIR

l. 3. 1966 Amsterdam UIR FL 200 and above A-B

l. 7. 1966 Paris Sectors of FL 250 and above A-8

French UIR

l. 4. 1967 Paris Sectors of FL 250 and above A-B

French UIR c

l. 7. 1967 Brussels UIR FL 200 and above A-B

l. 6. 1968 Amsterdam UIR FL 200 and above A-B

c

Brussels UIR FL 200 and above A-B c

Hannover UIR FL 200 and above A-8

c

Frankfurt UIR FL 200 and above A-B

c

Scottish UIR FL 250 and above A-B Preston UIR London UIR

c

Bordeaux Sector FL 250 and above A-B of French UIR

Marseille Sector FL 250 and above A-8

of French UIR

- Entire Eurocontrol Area D

The relevant Information Circular of the Netherlands Department of Civil Aviation (quoted above) reads as

follows:

INFORMATION CIRCULAR

1/65 15 Feb

Carriage of Secondary Surveillance Radar (SSR) Trans­

ponders in the Amsterdam FIR.

The experimental use during almost two years made of the SSR as an auxiliary to the Long Range Radar used by the Amsterdam Area Control Centre has confirmed that SSR should be considered as equipment which is essential to the provision of Air Traffic Services. The ground equip­ment has now been taken into operational use by Amster­dam Radar (AIP-NETHERLANDS, COM-1-14/15).

Transponders Remarks

I Codes

64 Notes l, 2 and 3 Intention already published by the U. K. Administration Ref. Civil Aviation Infer-

motion Circular 68/1964 of 27th Juli

64 Notes l, 2 and 3 Aircraft operating at FL 250 and above

will be required, to carry transponders with effect from lst Juli, 1965, but in

view of Recommendation 2!1 af the ICAO LIM/EU MIRAN/SS R Meeting 1962, the

Netherlands are willing to waive that date until lst March 1966 upon request of operators who experience consider-able difficulty to comply with the date of lst July 1965 (Netherlands Information Circular l/65 doted 15th February refers)

64 Notes l, 2 and 3

4096 Note 2 4096

64 Notes l, 2 and 3

4096 Note 2 4096

4096 4096 Note 2

4096 Notes l and 3 4096

4096 Notes l and 3 4096 Note 2

4096 Intention already published by the U. K.

Administration Ref. Civil Aviation Infer-motion Circular 68/1964 of 27th Juli

4096 Note 2

64 Notes l, 2 and 3

64 Notes 1, 2 and 3

4096 Note 4

Additional SSR ground-equipment will become avail­able in 1966 as an auxiliary to the primary radar equip­ment used for the control of aircraft operating in the Amsterdam Terminal Control Area.

For this equipment mode A will also be used, while the codehandling capacity of the decoding equipment will also be 64 codes (A and B pulses).

Policy

Taking into account the constantly increasing role which radar is playing in the provision of Air Traffic Control ser­vices, it is of the greatest importance that definite measu­res be taken with respect to the positive identification of aircraft. Taking also into account the weak radar reflec­tion characteristics of some types of aircraft, SSR is cap­

able of solving this problem.

Co11i1111n.:cl on DO(jf' .J1>

19

Data Processing applied to Air Traffic Control by F. J. Crewe Elliott Brothers, Ltd.

Introduction

Whilst the principles of Air Traffic Control are agreed internationally and remain the same throughout the world, the method of implementation varies from country to country and in many instances from ATCC to ATCC within a national boundary.

This being so, it follows therefore, when considering Data Processing for Air Traffic Control, that no one de­finite system can be exactly tailored to meet all ATCC requirements.

To overcome this basic problem, it is essential for a manufacturer to be able to offer a wide range of tech­niques and hardware in order that systems may be built up from standard and semi-standard modules to suit parti­cular ATCC or Air Traffic Control requirements. It must be borne in mind that such requirements may range from sim­ple first steps to sophisticated complex and complete ATC Data Processing Systems.

Principles and Aims

The aims and principles of the ATC Service are well known, so it is not proposed to examine or expound these aims and principles except where these influence the philo­sophy to be adopted by ATC Data Processing system de­signers.

Safety and Reliability

Naturally, the first and foremost aim which comes to mind is the safety of aircraft. Safety in the air and on the ground is enhanced by many factors, not least of which is the confidence engendered by reliable equipment and a reliable human operated service. It is true to say that the ATC Service and aircrew each have confidence in the

other's ability, largely brought about by knowledge and understanding of the difficulties of each other's task.

It is important then, that any proposed system which either overlays or modifies the ATC system being operated, must provide a high order of reliability at least as good as exists today, or improving upon this. Such reliability not only applies to the hardware but equally to the data being processed. This is the first consideration towards the con­tinuance of the confidence already built up.

The next consideration in this context is to introduce the Data Processing System in such a manner that the existing system is disturbed as little as possible. In other words, the transition is painless and smooth. This is im­portant both to the controller who is operating the system and to the service provided by the controller. A controller should never have to learn to use a complicated new system; it should be designed and then phased in so that it forms an "overlay". No break in the service therefore occurs, the controller quickly becomes familiar with the rnonagernent of the new system, and no degradation of the service is incurred.

20

This method permits the controller to evolve with the system development, his acclimatisation period creates confidence and he becomes aware of the potentiality of the system in a short time.

Additionally, the operational lessons learned from the introduction of a relatively simple ATC Data Processing System help to form a stable platform upon which the subseque~t phase~ may be based, and invariably provides valuable information towards the formulation of long term plans.

Step by step introduction permits the evolutionary deve­lopment. of ATC Data Processing Systems with the mini­~um of rnco.nv~nience an? down-time, and thereby ensur-1~g the ~ontrnu1ty of service essential during the installa­tion period.

Similarly, the introduction of further phases, when re­quired, should follow the same pattern.

Work Load

Wh.er~ !he computer has been introduced as a tool of trade, 1t rs important that t~is aspect is kept firmly in mind throughout the system design and installation. It is essen­tial that the ATC Data Processing System should make the task of the co~troller easier. It should not replace one onerous task wrth another equally onerous and time co _ suming. It is easy to fall into a trap here; great care mu~t be taken with the method of display, the amount of data and how long it should be displayed and the means f communicating with the ~omputer. The object of the syste~ must b~ to present the right amount. of data, at the right place, rn the cor~ect format, at t_he right time and for the right length of time, together with the simplest and t

f . . mos

rapid means o commun1cat1on between controller and computer.

The results of achieving such objectives are to red d d

. . k uce the liaison an co-or matron tas of the controller thereb leaving him with more time available to devote to thy control of aircraft. The main benefit which results from thi: will enable controllers to sustain peak period traffic hand­ling over a greater length of time without feeling the effect of pressures inherent today. In other words, his real efficiency is sustained over a longer period.

A word now about the effect of the introduction of ATC Data Processing systems on the Captain. Firstly, let us cover broadly the extent of ATC Data Processing sys­tems. This can embrace some or all of the following:

a) Flight Plan Data Processing, b) Primary Radar Data Processing, c) Secondary Radar Data Processing, d) Flight Plan Correlation, e) Conflict Prediction.

It can be said that any of the above, either in isolation or in toto, will reduce the work-load of the controller if properly implemented. It follows, then, if the work load on the controller is reduced, that the Captain will obtain an even better service than he is getting today. Communi-

cation delays which occur now will be reduced and the introduction of full SSR will render redundant many calls now made between Captain and Controller.

The effect, then, on the Captain is to reduce his cockpit work load and frustrating communication delays, and pro­vide him with a quicker and better service.

Decision

An often repeated argument in the decision making context is, "when computer systems are introduced into Air Traffic Control first the Controller and later the Cap­tain will become redundant". Take heart, all the present generation and probably the next and the one after of Controllers and Captains will be required to go on making decisions up to their normal retiring age.

The present state of technology does not as yet permit the Decision Making Function of the Controller or Captain to be replaced by the Computer or Data Processing Sys­tem. It will be many years before this function is removed

Zambia becomes Member of ICAO

Zambia became a Contracting State of the Internatio­nal Civil Aviation Organization on 29 November 1964, 30 days after its adherence to the Convention on Inter­national Civil Aviation was deposited. This brings the total membership of ICAO to 107 states.

The Turkish Air Traffic Controllers Association

The Turkish Air Traffic Controllers Association was founded in 1963 and is now contemplating to join the International Federation of Air Traffic Controllers Associa­tion. The President of the Turkish Association, Mr. Ibrahim Akkokler, will attend the 4th Annual IFATCA Conference, accompanied by the Association's Secretary, to discuss the

possibilities of affiliation.

Yugoslav Air Traffic Controllers Association applies for affiliation with IFATCA

The Jugoslovensko Udruzenje Kontrolora Letenja, Bel­grade, has applied for membership in the International Federation of Air Traffic Controllers Associations. This association has been founded on October 21, 1964; its President is Mr. Ivan Sirola, the Secretary is Mr. Aleks­andar Stefanovic. Delegates of the Yugoslav Air Traffic Controllers Association will attend the Vienna Conference.

1 Oth Annual Convention of the Air Traffic Control Association

The American Air Traffic Control Association, inc. will hold its lOth Annual Convention and Exposition from October 1 lth through 13th, 1965 in the International Hot~I, Los Angeles, California. The theme of the Conference :'ill be "A Decade of Progress". This will highlight accomplish­ments of the past decade, and emphasize the goals of the

coming ten years.

from the Controller or the Captain. This is not to say that either or both cannot be assisted by the Data Processing System provided the data is correctly presented and trial solutions are offered. In which case, the Controller or Cap­tain selects the solution offered and acts upon it. This is far removed, however, from the computer making the de­cisions. This is the right application of the computer sys­tem, a tool of the Controller's trade, albeit a very power­ful tool, but nevertheless the Controller will remain master for many years to come.

Conclusions No attempt has been made in this paper to specify any

particular type of equipment or to define the software requirements. The reasons stated at the beginning of the paper justify leaving out detail of this nature. However, it is apparent that a number of aims can be successfully met providing manufacturers adopt a realistic philosophy which keeps in mind the present operational requirements and evolutionary capabilities of the Air Traffic Control Service.

Venezuela and New Zealand Members of IFATCA, The Solartron Electronics Group and ITT Europe Corporation Members

A very hearty welcome to IFATCA's new Members and Corporation Members! Their affiliation with the Federa­tion is the final result of long and friendly contacts, and one aspect renders particular significance to the joining of New Zealand and Venezuela: with the ATC Associa­tions of Canada, New Zealand, and Venezuela IFATCA is now truly international. Dr. Carlos G. Osorio, the Presi­dent of the Venezuelan Association, wrote us about its 8th National Convention, held last January, and introduc­ed the Association's board of officers:

President:

Vice-President:

Secretaries:

Treasurer:

Vocals:

Dr. Carlos G. Osorio

Mr. Manuel A. Rivera

Dr. Alfredo Monque D. Mr. R. Salazar Mr. J. Blanco Villanueva

Miss Amelia Lara F.

Mr. Arturo R. Gil Prof. Vicente Smart D. Mr. Alfonso Parra

We are looking forward to meeting the representatives of our new Members and Corporation Members at the Vienna Conference.

18th Annual FSF International Air Safety Seminar

The American Flight Safety Foundation wil I hold its 18th Annual International Air Safety Seminar from Novem­ber 7th till 11 th in Williamsburg, Virginia, USA.

21

Progress with HAR CO and the Digital Data Link by W. E. J. Groves The Decca Navigator Co., Ltd.

At the 1962 IFATCA Conference in Paris, I presented a paper entitled "HARCO, A Hyperbolic Area Coverage Navigation System for Air Traffic Control". This paper was subsequently reprinted in "The Controller" Vol. l (3) July, 1962. Some of you will also have seen the airborne de­monstrations of HARCO which my Company arranged during the IFATCA Conferences in London and Brussels. The purpose of this paper is therefore not to describe again the features of HARCO, but to review the development of the system since 1962.

Similarly, it is appropriate to look at the lines along which our digital data link equipment has progressed since some of the IFATCA delegates saw a practical demonstra­tion during the London and Brussels Conferences.

Developments in the HARCO System

Over the past two years, progress with HARCO has fallen into two main categories:

a) technical developments in both airborne and ground

equipment,

b) the evaluation of the system against the Eurocontrol specification for a radio navigation aid.

Within the first category, one of the significant im­provements in ground equipment is the synchronisation of the lane and zone identification signals throughout a group of chains, to facilitate automatic chain changing in the airborne receiver. The English and French Chains have already been converted for synchronised operation and

more chains ore to follow.

The 1962 paper referred to work on the second version of the airborne digital computer, Omnitroc 2. This com­puter has now been in use for some two years, offers a much wider range of facilities to both pilots and ATC than Omnitrac 1 and will form the computer element of the air­borne navigation system. Apart from its coordinate con­version function to provide an undistorted pictorial dis­play, it can be used as a general purpose flight manage­ment computer, for fuel management, cockpit instrument monitoring and even for tailor made operational requir~­ments of a special nature, such as flight procedures, 1f

necessary.

The computer enables the pilot to select any desi_red point to which he requires range and bearing by a variety of means, including selection of any point direct from the pictorial display charts. It will also accept inputs from a variety of navigation sensors, e. g. Decca/HARCO, VOR/ DME, Doppler, Inertial, Dectra and air data. In this role the computer forms the heart of the compound navigation concept known as DIAN, Decca Integrated Air Navigation. "Compound" in this context implies the use of two or more navigation sources whose inputs are integrated by the compuier to prov:de a common display of noviga'.ional information for the pilot. Such an arrangement obv1ousl!' carries the advantages that there is a redundancy of novi­gaiional information and that it ovoids dependence upon o method of automatically transmiHing information from

22

a single navigation source. One example of the DIAN sys­tem is the navigation fitting specified by a British airline in their VC 10 aircraft. They ore installing Decca/HAR CO and Decca/Doppler, incorporating Omnitrac 2, with pro­vision for air data input and a self-setting Flight Log. In this case Decca can be used as the primary aid, with Dopp­ler and air data acting as back-ups. Alternatively Doppler may form the primary input with Decca automatically correcting the accumulated Doppler error.

. Further fac.ilities afforded by the Omnitrac computer include autopilot coupling on any desired track and to any desired poin~, calculation of elapsed time to any point and the calculation of the optimum slant track to make good a~y pre.determined point at any specified altitude. Corr~ct1ve action to ~aintain this slant track or profile will be displayed to the pilot and can also be fed into the auto­pilot.

Evaluation Progress

The second .category in the development of HARCO is that of evaluating the system to determine its capability to meet the Eurocontrol specification. Technical trials hove been carried. out by the Centre d' essais de Vol, Bretigny and by the Aircraft and Armament Experimental Establish­ment at Bascombe Down, both establishments acting as agents for Eurocontrol. Ground and airborne testing to deter~ine reliability, ~ccuracy, coverage, functioning and behaviour under varying weather, diurnal and seasonal conditions, were included in the tests. Considerable pro­gress has been made in this work, to the extent that the technical evaluation, by Bretigny and Boscombe Down has now been completed. '

At the time of writing (February, 1965), the Boscombe Down report has been submitted to Eurocontrol and the Bretigny report should be available within the next few weeks. Indications are that all components of the HARCO system have performe~ as forecast; however, no officio I announcement concerning t~e trials can, as yet, be made.

Technical ground and flight .testing is of course only one side of the complete evaluation. The next stage would be an operational. evaluation ~o examine the functioning of the equipment in on operational environment. For this purpose, the installation. ?f HA~CO in a number of repre­sentative airline and military aircraft would be required. The object of this aspect of the trials would be, not only to test and analyse operational performance, such as pre­cise track keeping ability, but also to extract information concerning the facilities afforded by the navigation system for ATC application. Such information would include the ability to define flexible route structures, reduced lateral separation and smaller holding areas. An evaluation of this nature must be comprehensive and therefore would be likely to take from one to two years to complete.

Developments of the HARCO Data Link

Although papers on the subject of air/ground data links have been presented to IFATCA it may be appropriate to consider the question "What is a data link?" Basically it is a method of automatically transmitting information from

one point to another. In our particular case, we are refer­ring to a small box in the aircraft which encodes the navi­gation information, position and flight level as seen by the pilot, for transmission, in digital form to Air Traffic Control. When each aircraft is addressed with its own call­sign by the ATC system, it replies automatically, on the specified UHF, VHF or HF communication frequency, with its latest position and Flight Level and repeats back its own identity. In the case of VHF, for example, this takes 1/sth of a second for each aircraft. This short digital transmis­sion is received on the ground in a form suitable for direct access to the ATC computer, where it can be correlated with other stored information. Alternatively, using simple automatic data processing equipment, it can be fed straight to the controllers' dynamic and tabular displays.

Data Link Functions

The first function of the data link has been described in the preceding paragraph, namely the automatic provision of air derived position and Flight Level, correlated with identity, to Air Traffic Control. The second function con­cerns the automatic exchange of A TC messages from con­trol I er to pilot and from pilot to controller. Recent progress with the HARCO data link may be described by reference

to these two functions. So far as the first function is concerned, we have been

working for the past two years on the display of basic ATC information. Originally the airborne position data was fed to a plotting table which displayed the precise track being flown by the aircraft. More recently this posi­tion data has been used to locate a symbol on a PPI tube, thus displaying the position of the aircraft dynamically in relation to a video map of controlled airspace, and also in relation to the displayed information from primary radar. Thus a direct comparison between raw radar and data link information can be made. At the same time the Flight Level, as received via the data link has been dis­played on a separate in-line indicator. Ultimately it will be possible to display Flight Level and identity using alpha numeric characters, alongside the position symbol on the controllers' displays.

Since the acquisition of this data is entirely automatic, no voice reporting is required. The information can be transmitted and received at a very high rate; with VHF using 600 bits per second, the equipment can interrogate and receive replies at a rate of 5 aircraft per second, 50 aircraft in ten seconds, etc.

The information derived from a data link can only be as good as the source of such data. It is therefore essen­tial to derive position and Flight Level from a highly accu­rate navigation system and digital altimeter in the aircraft. Furthermore the data link itself must have a high reliabili­ty and error detection capability. The HARCO data link, for instance, has been designed for fail-safe operation; on the principle that no information is better than wrong in­formation, the error detection process is designed to show up and eliminate any error or distortion in the transmitted message. During two years and over 2,000 hours of deve­lopment operation, 600 million bits of information have been exchanged and we have yet to display an incorrect message.

Work is now proceeding on the second function, i. e. the use of the data link for two-way communication. Using an entry keyboard and display, with a corresponding dis­play in the cockpit, the controller may incorporate instruc-

tions or reclearances to the aircraft in the routine call. As an example the controller may select the symbols --'-" 150, signifying a clearance to climb to FL 150. By pressing an action button this instruction is automatically transmitted to the aircraft concerned and appears on the cockpit indicator. When an "acknowledge" button is pressed by the pilot, confirmation that the message has been correct­ly received is sent to the controller. This also means that if the message is displayed erroneously in the cockpit, the controller is made aware of the error and can correct the message.

In like manner, we are working on the automatic trans­mission of control messages, such as request for reclear­ance from the pilot to the controller. The object in both cases is to permit the two-way exchange of routine control reporting and message so that the R/T workload can be considerably eased and voice communication reserved for non-routine and emergency messages.

Summary

The progress of HARCO and the data link may be sum­marised by referring to their application in Air Traffic Control. In the first place HARCO, by virtue of its highly accurate area coverage facilities, provides the pilot with a high degree of track keeping capability. Together with the navigation capability in the vertical plane, this signi­fies more accurate compliance with ATC clearances. This in turn means that clearances may be planned and issued on a longer term or "strategic control" basis, with less reliance upon "ad hoe" reclearances to avoid conflicts and hence reduced workload and R/T.

The data link provides the essential data on aircraft position, Flight Level and identity to corroborate the ad­herence to the ATC clearance specified. Used in conjunc­tion with data derived from ground radar, the data link forms an independent source of information for the con­troller, data moreover, upon which the pilot is conducting his flight. Furthermore the two sources, data link and radar, provide a degree of redundancy of information which, when added to the pilot's own capability of maint~ining his specified clearance, form the basis of a highly reliable and efficient Air Traffic Control System.

Congratulations

During the Working Session of the European Con­ference of the International Council of Aircraft Owner and Pilot's Associations (IAOPA) in January 1965, the dele­gates of Austria, Denmark, France, Federal Republic of Germany, Italy, Netherlands, Sweden, and Switzerland decided to create a yearly Meritorious Award for out­standing service to General Aviation by a European Air Traffic Controller.

A committee of three executive and private pilots evalu­ates reports submitted by General Aviation pilots.

The 1965 Award will be presented to Mrs. Yvonne Pope, former Air Traffic Controller at Gatwick Airport, during IAOPA's European Conference General Assembly in Mu­nich, 29th July - 1 st August 1965.

Mrs. Pope has recently left Air Traffic Control to be­come the first British woman pilot to fly for a commerc1ol

airline. We sincerely congratulate Mrs. Pope one! wish her the

best of luck.

23

Speed Control

Since the introduction of prop-jet and jet aircraft in civil aviation, aircraft enter terminal control areas with indicated airspeeds, varying from about 85 to 250 knots. Needless to say, traffic sequencing in these areas be­comes more and more difficult, especially in peak hours at airports frequently used by a great number of operators using different types of aircraft, which is the case at many civil airports in Western Europe.

This puts a heavy load on the approach controller's radar spacing technique and it is therefore no wonder that computers are being developed by the industry to assist approach controllers in proper sequencing, in order to effect a constant flow of traffic with the least possible delay for each aircraft.

It is, however, also possible to sequence efficiently with­out the use of special computers. As the variations in speed are causing the trouble, these should be attacked. This can be achieved by a technique called "speed con­trol".

Speed control simply means that pilots of aircraft ope­rating in a terminal area with the intention to land at an aerodrome within this area, are requested to fly at spec­f1ed speeds in order to enable ATC to plan the arrival sequence as efficiently as possible.

The first question arising from this restriction is by whom should these speeds be specified; by the State con­cerned or by the controller with authorization of the State?

One possibility is that governments lay down these speeds in Aeronautical Information Publications. In this case speeds could be specified e. g. for prop aircraft, prop­jet and jet aircraft flying in holding patterns, terminal areas etc. Some Governments have acted accordingly but merely with the intention of increasing safety in terminal areas with high traffic density.

However, speed reduction with no other reason than safety is no gain in respect to sequence planning, as at lower speeds less aircraft can be handled in a given

course of time.

This way of passive speed control is not flexible enough and therefore a way should be found to apply active speed control, by which is meant that the controllers have authority to decide whether or not the use of speed con­trol is useful in a given traffic situation.

This requires some knowledge of the performance of aircraft on the part of the controller using this "tool". A knowledge which is not always available. The object of this article is to introduce some facts and factors which controllers must know if active speed control is to be prac­ticed in a sensible way. It should be made clear that some explana: ions have been simplified without attacking their

truth. "Performance Requirements" and "Operating Rules" for

aircraft are laid down in various parts of the "U.S. A. Civil Air Regulations" (CAR) and in the various parts of the "British Civil Airworthiness Requirements" (BCAR) and "Air Navigation Regulations" of the U. K.

Most Governments of other countries accept these re­gulations and this is the reason why the airspeed no~en­clature found in the Aircraft Operations Manuals of d1ffe-

24

by R. Solinger

rent aircraft operators is the same for a special type of aircraft. If there are any differences they are neglible.

The following Viscount flight approaching its destina­tion, may serve as an illustration. When the Viscount 803 at "normal operating speed" is about to enter an area of severe turbulence, the speed will be reduced to "Rough Air Penetration Speed" (USA) or "Recommended Speed in Severe Turbulence" (UK).

This RAPS or RSST is defined as

RSST = Stalling Speed X Jl2,5

in which 2,5 is a limit for the loadfactor. The loadfactor which, in normal horizontal flight is equal to

I ift weight

finds a limit in 2,5, above which structural damage may occur.

At this RSST, which is the same speed as recommended for manoeuvres, stall will occur at 2.5 g (limited load­factor). This loadfactor of 2.5 may be caused by strong upward gusts (approx. 50 ft/sec.) or by hard manoeuvres (for instance when applying 66° angle of bank).

Under these conditions lower speeds should therefore be avoided because of the possibility of a stall, and higher speeds because of the possibility of a structural failure.

These speeds apply when flying level, climbing or descending through severe turbulence. Flaps should not be extended when flying in severe turbulence.

As speed control cannot be applied when turbulence exists, controllers should be aware of these conditions.

When clear of the turbulent area "normal operating speed" is resumed. While descending and upon entering the terminal area, the aircraft is reduced to the maximum speed below which flaps may be extended to 0 certain degree or in total, depending on the type of aircraft.

Should flaps b~ extended_ at a higher speed, they might be bl~wn off. :,his s_pee_d 1s called the "maximum flap extension speed , which 1s 200 knots for the Viscount 803 (see table).

When approaching the aerodrome the speed of the aircraft is further reduced to "circuit manoeuvring speed" with 0 flap (clean configuration). At this speed (recom­men~ed 150 knots for the Viscount 803) full manoeuvring is possible and allowed. Just before intercepting the glide­path, ~ops a~e par~ly extended ~nd "circuit manoeuvring speed forkth1s p)~rticular flapsetting (for Viscount 20~ flap, speed 140 nots 1s continued.

When established on final approach, flaps are further extended and speed is reduced to "recommended _

h d" (V. op proac sp~e . 1scount 125 knots). Flying at this speed, manoeuvring 1s no longer possible, so the aircraft should be well established. As soon as the decision to land has been taken, flaps are extended fully and speed is reduced to "threshold speed".

Analyzing the above mentioned example one should realize that flight technique varies with particular situations. It depends among other things on weather conditions cir­cuit to be made (short circuit, low circuit) etc. Beside~ all speeds given in manuals are recommended speeds, which

means that each pilot may hove his own technique to land on aircraft in a particular situation.

Returning to the subject of active speed control, on air­craft approaching to land will reduce speed according to the following sequence:

From "normal operating speed" to, successively, "maximum flop extension speed", "circuit manoeuvring speed", flop up (clean con-figuration),

"circuit manoeuvring speed" flap portly down, "recommended approach speed", "threshold speed".

The following table is included to give an idea of these

Recommended approach speed:

DC3 standard 100 kt minimum 95 kt

DC7 recommended 130 kt minimum 125 kt

Convair standard 125 kt minimum 118 kt

Viscount recommended 125 kt minimum 120 kt

Electro recommended 140 kt minimum 135 kt

DC8 126-156 kt depending on weight, at maximum landing weight 147 kt

speeds for the following types of aircraft: DC 3 (Dakota), Threshold speed (full flops): DC 7, Convoir 340, Viscount 803, Electro, DC 8.

Operational Speeds:

Rough Air Penetration Speed/Recommended Speed in Severe Turbulence:

DC3 DC7 Convair Viscount Electro DCB

120 kt 175-195 kt depending on weight 161 kt 165 kt 165-195 kt depending on weight 222-235 kt (all weight up till 15000 ft)

Maximum speed for flap extension:

DC3 DC7 Convair Viscount Electro DCB

135 kt 189 kt 174 kt 200 kt for flops from 0'='-20:i 190 kt for 7B% flaps (approach flops) 230 kt for flops from 0° -15°

Circuit manoeuvring speed in clean configuration (flops up):

DC3 DC7 Convoir Viscount Electro

DCB

110 kt 160 kt 140 kt 150 kt 170 kt

± 190 kt

(maximum 155 kt) (maximum 174 kt) (maximum 203 kt, minimum 160 kt)

(at maximum landing weight)

Circuit manoeuvring speed, flops partly extended:

DC3 flops 1 o·~ 105 kt DC7 flops 10 150 kt

flops 20 140 kt

Convair flaps 5-10 135 kt flaps 20 130 kt

Viscount flaps 20 140 kt flaps 30 130 kt

Electra flaps 7B% 150 kt minimum 140 kt

DCB flaps 25 136-169 kts depending on weight

DC3 DC7 Convair Viscount Electra DCB

80 kt 110 kt 95 kt

115 kt 125 kt 111 -141 kt depending on weight, at maximum landing weight 137 kt

Suppose a DC 8 is flying in a terminal control area 10 nautical miles behind a Viscount. There is insufficient space to allow manoeuvring in a lateral way (side by side) on account of the existence of in- and outbound routings or mountains etc. The DCB could be delayed by holding, but by applying speed control both aircraft con continue without excessive delay. Therefore we ascertain the Indi­cated Airspeed of the DCB and we assume that the ans­wer is 250 knots. From the table we see that the DC 8 con be delayed by reducing its airspeed to 190 knots, which is the "flap up manoeuvring speed" at maximum landing­weight. If this is still too high we ask the Indicated Air­speed of the Viscount and it appears to be 150 knots. It is obvious now that the Viscount is also flying at "flap up manoeuvring speed". To keep sufficient spacing, the DC 8 should be reduced to "circuit manoeuvring speed" (157 knots at maximum landing weight).

The DC 8 is now flying at a groundspeed which is ap­proximately 10 knots in excess of that of the Viscount, which results in a loss of only about 1 nautical mile in separation over a distance of 30 noutico I miles. (Notice that aircraft flying at some IAS, but at different levels, hove different T AS.)

The only calculation we now have to make is whether the remaining separation of 9 nautical miles is enough to guarantee 3 nautical miles separation at touch down. It is indeed sufficient and if you would like to check this, I kindly advise you to read again the article about "Radar spacing techniques for the final approach path" by Tirey K. Vickers, published in The Controller of October 1962. For those who are not in possession of this volume, Fig. 6 of this article, a spacing chart to obtain 3 nautical miles separation between landings with 1 nautical mile buffer added, is printed below.

The approach speeds of the aircraft in the above men­tioned example are 125 knots for the Viscount and 147 knots for the DC 8 (at maximum landingwerght)

In this example we only cons;dered reducing the DC 8. Another possibility would have been I.or os an extra) to request the Viscount to maintain at least "moximurn flop

25

extension speed" as long as possible (200 knots) and to advise the controller when further reduction of speed becomes necessary. It is obvious that pilots are in favour of this positive speed control as long as it prevents them from being delayed over holding points. Therefore this tool is not only useful for controllers but it will on the other hand save money on the part of airline operators. It prevents the pilot from "dead" flying at low altitudes and will thereby avoid excessive fuel consumption for jet

aircraft. It is not possible of course to give upper and lower

limitations for non reducing respectively reducing as these limitations depend on local circumstances (terrain etc.).

The extent to which controllers can use this technique should be laid down in local instructions after thorough consult with airline operators. Generally, pilots may be asked to fly at least at maximum flap extension speed until the aircraft is approximately 10 nautical miles from

the threshold. Reducing is possible to this "flap extension speed" and

also further down to "flap up manoeuvring speed" at all distances. As soon as the aircraft is about 15 nautical miles out, it may be further reduced to "circuit manoeuvring

speed". A request to reduce to "recommended approach speed"

is only acceptable, if the aircraft is well established on the

final approach path.

Secondary Radar Implementation Dates in Europe Continued from page 19

In view of the ground-equipment program and as ac­ceptable results can only be obtained with SSR if the necessary airborne equipment is installed, the Netherlands CAD plans to implement the following program on the mandatory carriage of SSR-transponders on board of air­craft. This problem is published below for the guidance

and information of operators.

Program

Phase I

The carriage of functioning SSR-transponders conform­ing to at least the Standards laid down in the 7th Edition (Aug. 1963) of Annex 1 Oto the Convention on International Civil Aviation, Part I, Chapter 2, para 2.5., will be required as from the 1 st July, 1965, for all civil aircraft operating in

the Amsterdam UIR at FL 250 or above.

N o t e : Taking into account Ree. 2/7 of the Limited EUM RAN Meeting (Oct. -Nov. 1962) the date of 1 July 1965 may be temporarily waived upon request of operators who might experience considerable difficulties in compli­

ance at that date.

Phase II

It is the intention to extend the requirement under phase I to include all civil aircraft operating in the Amster­dam UIR ot FL 200 or above w.e.f. 1 March 1966.

26

(I-MILE BUFFER ADDED) 180 I

-Cl) I-0 z :::.r::::

150 N

0 z 0 UJ UJ a..

120 Cl)

0 z :::> 0 a: (!)

90 90 120. 150 180

GROUND SPEED NO. I (KNOTS)

Spacing Chart to obtain 3 min. separations between landings. Numbers show separation required (in nautical miles) when No. l aircraft is po~s­ing reference point 6 miles from touchdown.

Phase Ill

It is intended that the requirement for the carriage of functioning SSR transponders be extended to the airways controlled by Amsterdam ACC by 1 January 1967.

If ground and airborne equipment becomes available in the period up to 1968 which will make the use of 4 096 codes (A, B, C and D pulses) on modes A, B, C and D possible, a further policy announcement will be made. It is anticipated that this type of equipment will become mandatory by 1970.

Policy to be followed by Eurocontrol

As Eurocontrol has assumed the responsibility for the provision of ATS for a large part of the Upper Airspace ·

E I. In

Western urope, a po icy announcement by Eurocontrol the subject of S~R-tr1ansponders will be published short~y~

The present c1rcu ar has been already coordinated with Eurocontrol.

ICAO Assembly to meet in Canada

The Assembly of the International Civil Aviation o _ . . ·11 . rga

ni~ation w1 convene in Montreal on 22nd June 1965 and will last for about four weeks This session the A bi • . · , ssem y s fifteenth since the Organization was founded w'll b , 1 e pre-ceded and followed by short meetings of the ICAO c _ cil. oun

Opeircitoon and Applications of the Hazeltine Alpha-Numeric Generator by Tirey K. Vickers

Hazeltine Corporation

An new alpha-numeric generator (ANG) equipment recently developed by the Hazeltine Corporation provides a long-awaited improvement in air traffic control - the positive association of aircraft identity and altitude infor­mation with the aircraft targets shown on radar displays.

Two of the Hazeltine ANG equipments have been de­livered to the Federal Aviation Agency. The first is a six­channel unit for the ARTS (Advanced Radar Terminal System) at the Atlanta terminal control facility. The second is a ten-channel unit for the SPAN (Stored Program Alpha­Numeric) system at the Indianapolis Air Route Traffic Con­trol Center. The number of channels refers to the number of independent radar displays which the ANG can feed simultaneously.

The present Hazeltine ANG equipments are designed to feed RBDE-5 scan-converted bright radar displays. This type of display is installed in many Federal Aviation Agency air traffic control facilities.

The heart of the ANG is the data converter, which con­verts digital data to television alpha-numeric video. The data converter is analogous to the scan converter which translates the radar picture into television raster form, for bright display. Converting digital computer data into tele­vision raster form, the ANG operates in parallel with the scan converter, as shown in Figure 1. The outputs of the scan converter and the data converter are combined in a video mixer, to provide a composite television display of radar and alphanumeric data.

,---------__ _......_ _ _....,

Display Concept

.A television picture is made up of a very large number of rn~remental picture elements. The RBDE-5 system uses a 945-lrne television raster which has 832 active lines. Each of these lines is made up of 512 separate picture elements. Thus the useable raster contains 832X512, or approxi­mately 426 OOO discrete picture elements.

E~~h tiny element occupies a discrete position on the tel:v1s1on raster, and is associated with a memory bit which may be discretely addressed by the computer or t~e data converter. By activating appropriate combina­tions of the memory elements, any alpha-numeric charac­ter or other visual symbol may be generated. All combina­ti~ns of visual patterns, from a single dot to a completely bright raster, may be generated, thus providing tremend­?us cap~city and flexibility in the amount and type of 1nformat1on which can be presented.

As .shown in Figure 2, the configuration of all alpha­numeric symbols used in the ARTS and SPAN system is based on a 5X7 dot matrix. This is the smallest matrix which will produce all numerals and all letters of the Roman alphabet, in easily-readible form. Larger matrices could be designed if necessary to accomodate larger or more complex symbology. In the ARTS and SPAN systems, aircraft target labels are generated in the formats shown in Figure 3 and 4.

PRIMARY RADAR

1218 COMPUTER

DECODER

RADAR VIDEO MAP

RADAR VIDEO MIXER

NOTE: ONLY 2 OF 10 IDENTICAL DISPLAY CHANNELS ARE SHOWN BELOW.

TO OTHER DISPLAYS

t------<l~-----.0-- - - - - ..

SCAN CONVERTER CONVERTER

I 2 ---- __ ALPHANUMERIC GENERATOR

r ---------------------------------------, I I

l DATA MAGNETIC VIDEO : I CONVERTER DRUM GENERATOR I I I I I L.--- - --------------------------- --------- ____ J

Fig. l Simplified Block Diagram of SPAN System

27

Fig. 2 Typical Letter Configuration based on 5X7 Dot Ma trix

Figure 5 shows the 10-channel ANG for the SPAN system. Figure 6 shows its main components. The operation of these components is described below.

28

Fig. 3 [obove)

Types of Doto d isplayed in Typica l Format

Fig. 4 (below)

Photograph of Targe t Formats on Display

Fig. 5 (left)

Ten-Channe l ANG Equipment; Magnetic Drum is visib le o t lower right

r--------c~E~MMY~~~~~~!~------ --- -- ---1

TO ANO FROM COMPUTER

EXTERNAL SYNC

RANGE

INPUT/ OUTPUT LOGIC

SYNC LOGIC

SCALE DISPLAY SEQ.

FCP MEMORY

INPUT/ OUTPUT MEMORY

VIDEO MEMORY

FCP LOGI C

VECTOR CODE GENERATOR TRANSLATOR

~OF~F~S~ET'------'~~:;~iis~;E'-'"~~--'-~~~~~~~~~~~

PROCESSING

TRACK BALL LOGIC

COORDINATE TRANSLATOR

L------------------------------------~

Controls

FROM SCAN CONVERTER

MAGNETIC ORUM

VIDEO GENERATOR

Fig. 6 Simplified Block Diogrom of Hazeltine ANG

Each display channel is equipped w ith o set of controls to enable the controller to select and position the data on his display, to enter new o r modified data into the com­puter, to coordinate target hondoff i nformation, and to transfer target jurisdiction to another channel. These con­tro l modules are shown in Figure 7 to l l . All modules ore mounted in convenient locations in the display console.

The tentative control instructions composed on the key­board or on the category/function selector, are disp layed temporarily on the controller's monitor display for veri­fication. Subsequently, the activation o f on entry button transfers the data to the core memory, as a service com­mand.

VIDEO MIXER

Fig . 7 Cotegory/ Function Selector

)

.)

Fig. 8 Alphanumeric Keypock Fig . 9 Slew Ball

CONTROLS

8

29

.• 'I> SELE~T ro) '~ .o· \ ,(\\ ,o·· ' 6 , ·d ,-i:\,. '.1.,_ ... _ ~~~~'J , , •.. ~ ·· · , •• ) :·" ... . ~ ... ~ ll"_.- ~!J

. . t - :i, ...

: INHIBIT

.·',:(~ .. •

Fig . 10 Inhibit/ Select Pa nel

An inherent characteristic of a ll pictorial ai r traffic control d isp la ys is that the d isplay surface con prese nt on ly o two -dimensional picture of o situation which is taking place in thre e dimens ions. Th is o ften causes the fo rgets to overlap. In such coses the re is a dec ided ten­dency for the a ssociated target labe ls to overlap too. This characterist ic con be corrected, by providing the contro ller with the ability to shift any target la bel to one o f eight d iffe rent direc tio ns from its a ssociated ta rget. In add ition, the controlle r con change the length of the leader lines, to change the d istance between the target labels a nd thei r a ssoc iated targets.

To ovo id the da nger of o verwhe lming the controlle r with too much informat ion, contro ls o re provided which enable h im to filte r the a lp ha-nume ric d a ta p resented o n his d isplay, to suppress the informatio n which is not of immed iate inte rest, and thus increase the visibility of the stra teg ic informa tion which is pertine nt to the si tua tion a t hand. The suppressed informat ion con be called up ins­tantly whe n need ed .

Input/ Output C ircuitry

Two-way data transfer, between the compute r a nd the ANG, is hand led in 18-bit d ig ital words. These bits ore transm itted in pa ra llel, one word a t a time. The ANG con ha ndle inputs and outputs a t the rote of 50000 words pe r second.

The co mputer-gene rated target da ta inc ludes a ircraft iden tification, altitude, bea con code, and posi tion coo rdi ­na tes, for e a ch ta rget. From 5 to 15 digital wo rds ore necessary to define a ll the da ta for a single ta rget. Whe n­ever a change in the display d a ta occurs, the computer furnishes the ANG with a compl e te new set of target d a ta . The ta rge t data is rece ived by a buffe r reg is te r and is transferred immedia te ly to the co re memo ry for storage.

Service commands g e ne ra ted by the ope rato r controls o re transmitted from the core memory through on output interface to the compute r.

Core Memory

O ne portion of the core memo ry sto res the target data received from the computer, a nd a lso accumulates the ser­vice comman ds received from the var ious o p e ra to r con­trols . This portion of the core me mo ry con store all the target a nd control data for as many a s 200 a ircraft ta r­gets. The core storage is shore d (used seque ntia lly) by a l I display channels. This design concept minimizes the system cost per chan nel. The magnetic core memory hos the ex­treme ly high d a ta rote capability wh ich is necessary for this ty pe of o peration.

All target data in the core storage is sca nned sequenti­a lly to select the data to be displayed by each channe l.

30

Fig. 11 Display Control Mo dule

Th is p ro cess provides each displa y channel with an up­dated d isplay every 11/ 2 seconds.

Coordinate Translator/ Vector Generator

The code trans la tor is the actua l symbol ge nerator of the Hazelt ine ANG. It receives the targe t do te bi ts from the core me mory. These bits define the channel a ddress leader, bar, a nd character codes. If a ve locity vector re~ quest is rece ived, the velocity log ic ci rcuits calcula te the incre mental posi tions wh ich comp rise the vector, in a dot­by dot mon~er. After the required vectors ore p roce ssed, the leader line and any required bars o re gene rated in a sim ila r manner. The a lphanumeric characters a re the n generated.

Each cha racter is translated from a six-bit cha ra cte r code word rece ived from the core memory, into the ind i­vidual sequence of video-coded bits which d efi ne the character. The characte r e ncoder works in conjunction with the ~emory address contro l to load each g ro up o f d ots farming the chara cter, into the proper locatio ns in the video core memory.

As each character is loaded, the memory contro l ad­vances to the sta rting address of the next character. A space of two dots laterally or three te levis ion lines ver­t ically, se parates adjacent characters in the target fo rmat.

Video Memory

A large section o f the core memory is used to a ccumu­late the video information from the code tra ns lator/vector g e ne rator. This memory un it p rovides 0 separate core fo r ea ch o f the more than 400 000 individua l dot positions of the tele vision ras te r. When the a lpha-numeric encod ing process ha s been comple ted for a parti cula r channe l a ll the selected dot posit io ns which will make up th fina l a lpho_-numeric p icture _hove been stored in d ig ital f~rm in the Video Memory. This ent ire memo ry store is the n trons­fe rre~ onto the tracks of a magnetic d rum during o ne re­volution _o f the drum. The core is the n ready to co llect the info rmation for the next d is p la y channe l.

Magnetic Drum

The magne tic drum of the 10-chonne l SPAN syste m con ­ta ins 10 groups of 32 tra cks each for the video informa tion 12 spore tracks, p lus 10 additional tra cks for system syn ~ chron izot io n p ulses.

The d rum rotates o t p recisely l 800 rpm, which corres­po nds to the 30 cycles-per-second fra me ra te of the tele­vision sys te m. :~us the magne tic drum con be synchro nized w ith the te lev1s1on scan converter to provide perfect re­gis tra tio n be tween the ra d a r picture a nd the alpha -numeric da ta.

The magnetic drum provides a very economical method of storing and reading out regeneratively the nearly 5 OOO OOO bits of information which are required to operate the SPAN system at full capacity. The drum has not only inherent compatibility with the scan rates used in television systems, but its memory is indestructable except by de­liberate erasure. This provides a safety factor in that the last data will continue to be available on the display even though a failure occurs in the computer or its associated

circuitry.

Video Generator The video generator accepts the drum information, and

provides amplification and pulse-shaping functions to prepare its output for the video mixer.

Video Mixer A separate video mixer is provided for each display

channel. Each video mixer accepts and integrates the out­puts of the scan converter and the video generator of the

"Communications"

Do you know that feeling in the early morning? You're just about to doze off at the board. Traffic-count is made; two more hours to go and the night shift will be over.

That silly buzzer rings and your equally tired counter­part 0~1 the other side of the line requests: "'ime 'heck, please.

So much for the state of affairs on the ground. Mean­while, about 10 kilometres above, on the flight deck of Speedliner 123, the crew are also looking forward to the end of a strenuous tour of duty.

Some 75 miles, then that (beloved) high-level let down, and they'll have made it.

"Mountain Control 1-2-3"; the controller's voice is calm and monotonous. The reply comes immediate and unexpected "Mountain Control from Speedliner 123, go ahead". (Undoubtedly they want to give us an en-route descent.)

But - "3-2-1, Mountain Control, test out".

* The "SAS Pilot" reports on a similar subject: Telephone Conversation.

- Are you there? - Who are you please? - Watt. - What's your name? - Whatt is my name. - Yes, what's your name? - My name is John Watt. - John what? - That's right. Are you Jones? - No I'm Knott.

ANG, to present the combined picture on the final tele­vision display.

The brightness or intensity of the alpha-numeric data, and the radar data, is separately controllable on the dis­play. An outstanding advantage of the Hazeltine display concept is that whenever the alpha-numeric information is updated or moved on the display, the old information dis­appears instantly without leaving a smear on the radar indicator.

Adaptability

The ARTS and SPAN systems are the first operational applications of the Hazeltine data-converter concept. The same principles can be used in other types of systems to translate computer-derived data.

The data converter concept used in the Hazeltine ANG is easily adaptable to color television displays. Using this concept, Hazeltine has successfully developed and de­monstrated various color TV displays of alpha-numeric and pictorial information, over the past two years.

- Will you tell me your name? - Will Knott. - Why not? - My name is Knott. - Not what?

Operator: "Time's up. Would you like another call?"

* ... and here is a nice story by Henry H. Talmade, which

I found in the ATCA Bulletin:

ATC EDUCATION: "The pilot of a small civilian air­craft called me one morning explaining that he was a new pilot and wanted to try one of these radar appro?ches he had heard other pilots talk about. He convinced me he had never made a radar approach before and that he knew nothing about the procedures used. After a brief explanation of what was to take place, I identified the target and the maiden approach got under way. As I remember it, it was about 0830 at this point. Being alert and on the ball, I gave traffic information, "Traffic, ten o'clock", etc. (just like the book says). I could tell this didn't go over too well. The pilot must have scratched his head, then asked, "Did you say there was some other traffic at ten o'clock?" I came back with a distinct, "Affirmative". There was another pause and, "Errr ...... that traffic at ten o'clock ...... do I land after he does?" Well, this LBF (little billy fellow) wasn't setting any speed records and the traffic was heading for the airport, so, another "Affirmative" seemed appropriate. With no hesitation the reply came back loud and clear, "You can just forget all about your silly radar approach; I can't wait until after ten o'clock to land!" "

Joe Chatterbox

31

Factors involved in the Choice of SSR Ground Radar

SSR AERIAL

VIDEO LINK

Fig. 1 Components of SSR System

System Requirements

The technical parameters and operational facilities re­quired for Secondary Surveillance Radars are laid down in Annex 10 to ICAO, as amended by 7th COM. session. The major components in an SSR system are shown in Fig. 1.

The main choice to be made by Administrations pur­chasing SSR ground equipment which will meet ICAO re­commendations lies between two types of equipment:

3 pulse sidelobe suppression (SLS) on modes A, B, C and D, or interlaced 3 pulse SLS on mode A with 2 pulse SLS on modes B, C and D.

Standards of Equipment

The physical and electrical form factors for the air­borne transponder are given in ARINC characteristic No. 5320. Thus, a degree of standardisation has been achieved for the airborne element of the SSR system. However, in planning ground SSR installations, it is not possible to have a "standard" system, since operational requirements, avail­ability of sites, technical and financial considerations can all effect the configuration of the equipment.

Operational Requirements

The golden rule to observe before choosing an SSR system is to decide on the exact operationo I facilities re­quired, both initially and for the future. The sort of ques­tions which must be answered are:

32

by R. Shipley Cessor Electronics, Ltd.

c::;=:-;-L?

\TRANSPONDER

SYSTEM _.r--i MONITOR__. -L_J

VIDEO PROCESSING

What density of Air Traffic is to be dealt with? What hours of operation?

~~~ (e~~ ~i~~ra:~ fun~tions to be provided with

C t I t ) ' C, Airways sectors, Approach

on ro e c ..

How many displa I . . Y conso es to be fitted with SSR?

Which ATC function will be the "M t " SSR trol? as er con-

What is the maximum . Wh. h th range required for control 2

i~ are . edmost vital areas in which SSR cover~ age 1s require ?

What forms of SSR read-out . ore required? What modes are required d f

' now on or future use?

When the engineer has 0 clea . t f h r pie ure o t f ·1· · required by the cont II h e ac1 1t1es ro er, e can then con "d th

needs in relation to the t h · 1

. si er ese . . ec n1ca environment. Some of the

dec1s1ons to be made ore given below.

Choice of Equipment

Sidelobe Suppression

Technically, there is little to choo b d 3 I SLS b se etween 2 pulse

~nl pu sel 'h ut.the use of 3 pulse SLS on all modes 1s ess comp ex t an interlaced 2 and 3 pulse SLS.

The SSR Aerial System

The SSR aerial array can be mou t d d. 1 · d n e 1rect y on the

primary ra or scanner (Fig. 2) or it b I . . can e mounted sepa-

rate y on its own turning gear the rotat' f h. h . ' ion o w 1c 1s syn-

chronised with that of the primary aerial by means of a servo system (Fig. 2b).

By mounting the SSR antenna directly on the primary array, Azimuth coincidence of both radars is assured, and separate turning gear is not required, but 1 or 2 additional channels in the rotating joint are necessary and may not be available in the primary. Again, certain primary radar scanners may not have sufficient mechanical strength to carry the additional weight and windage.

With an off-mounted SSR aerial, operational flexibility is enhanced, since the SSR can be used independently, or in conjunction with a second primary in the event of break­down of the main primary radar. The off-mounted SSR aerial should be sited as close to the primary head as pos­sible, since azimuth errors between primary and secondary returns become greater as the distance between the two radar heads increases.

The SSR aerial system can be composed of separate interrogation and control antennas (Fig. 3a). Alternatively, these two elements may be combined in one physical struc­ture, known as an integral aerial (Fig. 3b).

The integral aerial is preferable, since it ensures coin­cidence of the interrogation and control patterns in the vertical plane. However, such an aerial necessitates either a high speed switch on the aerial, or an additional chan­nel in the rotating joint.

A separate control aerial needs careful siting in order to prevent "shadowing" by the interrogator array and to ensure adequate matching of the vertical pattern. How­ever, when used in the on-mounted role it obviates the need for an additional SSR channel in th

1

e primary rotat­ing joint.

The Video Link

The choice of video link (see Fig. 1) is conditioned main­ly by site conditions. If the radar site is remotely situated, a microwave radio link will be required. Where the radar is relatively close to the operations building, a cable link (with repeaters as necessary) can be used.

Mode Interlace

The type of mode interlace programme required de­pends mainly on the traffic density, but it is wise to ensure that the lnterrogator/Responsor has a sufficiently flexible mode programme to cover the operational needs. A typi­cal interlace facility is for triple-mode interlace with re­version to a priority mode and a multiple choice of inter­lace programmes.

Video Processing

The coded SSR information received by the lnterroga­tor/Responsor must be translated into a form which can easily be assimilated by the controller. This process is known as "Video Processing" and consists of:

Rejection of asynchronous replies (defruiting). Rejection of garbled information (degarbling). Marshalling of Modes and Codes (decoding). Selection and presentation of the information actu­ally required by the controller (selection and read-

out).

~SSRARRAY

~ '"'MAOY ARRA>

Fig. 2a On·Mounted Aerial

Fig. 2b Off-Mounted Aerial

CONTROL ELEMENT

I I 1i I I I ~~

INTERROGATOR ELEMENTS

Fig. 3a Integral Aerial

INTERROGATOR ARRAY CONTROL AERIAL

Fig. 3b Separate Aerials

The choice of video processing equipment depends on the complexity of the traffic problems and can range from a simple manual system, up to full automatic data proces­sing. If future use of computers is envisaged, it should be ascertained that the manual video processing equipment chosen is capable of being built-up to flt into the auto­

matic system at a later stage.

System Monitor

Secondary Surveillance Radar is a communication sys­tem and such a system can be proved by the transmission of a signal and reception of the correct reply. This is done by means of a ground system monitor which monitors the major parameters of the transmissions and gives warning when the tolerances are exceeded.

Continuity of Service

In order that continuity of service can be retained in the event of breakdown, or during maintenance periods, it is normally accepted that dual radar channels are required. One channel is normally "Operational" and the other at "Standby". The amount of back-up equipment purchased is dictated by the intensity of the traffic, hours of operation and the financial backing available. As a guide to system configuration, some examples me given 1n Figure 4 (off~ mounted aerial) and Figure 5 (on-mounted).

33

PRIMARY = ~TURNING GEAR

~ ~~CONTROLRACK r1l11 Y/~INTERROGATOR

G G 88 c 8~ SERVO RACK

·-------. . .... _ --·- _,, ,---1 I r---' ,1, : I I I I

L-•• 11L--l

I __________ _!

~ ]f ![" 010 G~B I I

:r Cf T :r GG GG Fig. 4 Off-Mounted Aerial

Off-Mounted Aerial

With dual channel SSR and primary radars (Fig. 4a), four primary/SSR electronic combinations are possible. In the event of mechanical breakdown in the primary or secondary element, the other service can still be used

independently. Where two primary radars are available, the minimum

SSR to provide mechanical/electronic standby is as shown in Figure 4b, with two single channel SSR systems. Here, four mechanical combinations and eight electronic combi­

nations are possible. For a major high-density installation, where full round­

the-clock service must be assured, two dual channel SSR,

A practical Secondary Radar System for Air Traffic Control Continued from page 15

layering limits.This device, similar to an adding machine keyboard, automates the thumbwheels, eliminates the need for the controller to reach to his control box, and materia I ly increases the speed of data entry. Th is fea­ture also permits automatic transfer of an actively de­coded unknown target to the first available selected

channel for tracking purposes. d) Digital word formatting. The advanced decoder system

can provide a completely assembled digital message for transferring all SSR data to a computer input chan­nel. These data, including identity, altitude, mode, and target coordinates are available in a single digital word per target per antenna scan. The word is format­ted by field and flexible in voltage level, for wide us­ability with a variety of digital computers of varying

copobility.

34

Fig. 5 On-Mounted Aerial

used in conjunction with two dual channel primary radars gives four mechanical combinations and sixteen electronic combinations.

On-Mounted Aerial

The operational limitation with on-mounted aerial is that in the .event of. me.chanical failure, both primary and secondary information 1s lost. Figures Sa, b, and c give the same number of electronic channels and mechanical facili­ties as in Figs. 4a, b and c respectively, but it will be seen that me~hanical f~ilur~ or withdrawal seriously depletes the possible combin?tions. Thus, operational flexibility is halved, compared with the off-mounted aerial.

We have described an SSR system available toda d . . h h , . y an

built wit t e users economic requirements in mind. It can be i~~lemented very simply. and expanded to a very sophisticated level of automatic processing. Space is pro­vided in the equipment for any or all of the feature d _ scribed, including character generators for the a~ he_

. d. I f · P a numeric 1sp ay unct1ons. As such, the system can com-prise on integral part of any ATC system now and for the foreseeable future.

It .is important to. note that two paths of information to the display are provided - the direct real-time video th and the synthetic digital path. Video offers the ultima~ea in reliability and interpretability of ATC situations. The digi­tal path reduces the controller workload through p ·t· 'd •£'; • d . OSI 1ve 1 .ent111~ation an . ~n-d1splay presentation of the altitude ~1mens1on. Th_e d1g1tal wo.rd formatting offers the possibi­lity for remoting the SSR information to computers or dis­~lay systems .over long distances via narrowband data links where this may be required.

Long Range Detection of Thunderstorms by G. Heydt and H. Volland

The t itle of the originol poper, which has been published by the Heinrich-Hertz-lnstitut fur Schwingungsforschung, Be rlin, is · oie Ferno rtung von Gewillern·. The Eng li sh version has kindly been provided by H. Gunther and H. Schmid . Brussels.

One of the responsibilities of Air T roffic Serv ices is to provide early warning of heavy thunderstorms. This does not constitute a problem within western Europe where a dense network of meteorologica l observation stations is available. The task becomes more difficult over the Ocean or in less popu lated areas where there ore on ly few meteorologica l stations. Airport weather radars with their range of approximately 300 km ore inadequate for long range detection of thunderstorms. A device hos been deve­loped at the Heinrich-Hertz-Institute, Berlin-Chorlottenburg to meet this need, and hos been in operation at this loca­tion for more than one year (1 ]. The equipment makes use of the fact that l ightning is a broadband transmitter for very long waves w hich ore propagated in the zone bet­ween the surface of the earth and the ionosphere. Such impulses produced by lightning ore known as atmospheric disturbances or "atmospherics" .

The equipment consists of a DF receiver and a narrow­band amplifier. During the recording period, the spectral amplitude of each atmospheric disturbance appears as a dot on an oscillogroph, its displayed position d epending on th e azimuth . A example of a record is shown in figure 1.

The photograph was token during a 10 kc setting, us ing a poloroid camera wi th on exposure time of 5 minutes. The ordinate indicates az imuth of incidence; the abscissa shows the spectral amplitude of the atmospherics in units of rece iver output voltage U. In figure 1, severa l thunder­storms co n clearly be indentified, the ligh tning signals of wh ich ore distinct from the background noise caused by more distant thunderstorms. It con be d emonstrated that the number of atmospherics exceeding a receiver th re­sho ld voltage U equals

n (U, (!, f) = n0 exp (- U/g0 FB) (1)

where (! is the distance o f the thunderstorm f rom the ob­servation statio n, f represents the frequency, no the total number of l ightning flashes of the thunderstorm per re­cording period, gu (f) a character ist ic of lightning dis­charges, F (g, f) the transmission factor which is a function of :'o~e propo~ation and where B is an equipment factor w hich 1s a funct1.on of amp lification, bond-w idth and effec­tive antenna height [2].

By coun ting the number f th d " · d o o se 1schorges ossoc1ote with a thunderstorm which exceed · I U d . a given vo loge on by repeotin~ the count. at different va lues o f U, the shape of the function (equation 1) is obtained, from which the pora~eters no a nd go FB con be deduced. This has been done in the case of the thunderstorm located south-south-est in Fig. l ; the results ore shown on 0 s ·

1 "th · em1- ogarr m1c

scale in Fig. 2. Further recordings were made at 5 kcs and

10 kcs sett ing and the data obtained ore also 1 d · . . presen e in Fig. 2. Applying ~quallo~ [l J 0 straight l ine con be drawn through these points which must intersect U = 0 at no.

Thus the total .number of lightn ing discharges o ccuring during the recording period of a thunderstorm is obtained directly. Our examp le revea ls n,, = 125 l ightn ing discharges

per minute. The product g., (f) · F (g, f) B comes fro m th e gradient

of the straight lines. Si nce this product is basica lly known

and avai lable for various frequencies and var ious hours of the day, in the form of diagrams (see e. g. Fig. 3), the distance of a thunderstorm con readily be established. In our example the distance is g = 1 OOO km from the obser-

N

w

s

E

11n•••••• 111·'1111111111111 Ill ;~111111111111111111 Ill ~11111111111 11r .. ~m111111 llf ~~~~!!!111111111 m1 ·-~~11111111111111

-~,,,,,.I~ 0

_,_ Spectral Amplitude 2 3 4 5 6 7 8

Figure 1 5 minute exposure on the receiver oscillog raph loken on the 18th of September 1963 o t 14.00 CET al Be rl in-Wa idmannslust. Frequency = 10 kcs, the ordi nate shows azimuth on a linear sca le; the a bscissa s hows the spectral ampl itude of the dis· charge signal an a logarithm ic scale .

- Osz1llogr11phcin·Sk 111l11

1000

o~, I '-' ' '-I ' ', \ " '- to, I ", \ "' o, \ r--- , ',o l ~ ' ~ ·--1

\ ' '-I " 'o,

' I 0 '-'A " '- 10 kHz

100

I I', 1', \ " '-\ 40 kHz ' 'a.._,_

' \ o '-.

\ " ' \ ' t:kHI I

\ " ' ,a I ' I \ \ I I I x

\

0 125 02> OJ7~ o;

Au1J90.n9.,1p11nnunQ U 'VOlll

Figure 2 Nu mber of d ischa rges in a si ng le lhunderslorm o function of receiver o ulput vo llage U; the diagram 1s related lo the lhun· derstorrn centre siluated south-soulh-east in Fig 1 a nd recorded at freque ncies o f 5, 10 and 40 kcs The upper scale represen ts

the ascill ogroph scale .

35

- En1fet nung (k.m)

100 1000 10000

5 kHz

Figure 3 Colculoted value g .. FB as a function of distance at 5 and 10 kcs in daylight conditions.

0 Distance {km)

4000 8000 12000 16000

Figure 4 10 minute s exposure on the osc illogroph onb thel :6h4os~ ~Se~~u~e-ment equipme nt token an the 27th Septem er a · rs

at Berlin-Woidmonnslust. Mea suring frequency 8 kcs, f = 2 kcs.

36

vation station. Figure 1 shows a thunderstorm in an east­south-easterly direction at a distance of 1 500 km with a sequence of 60 discharges per minute.

The evaluation is very simple and quick to accomplish and can also be automated. The range of the equipment is approximately 3000 km during summer daytime, and about 4500 km during winter daytime. The lower range limit, close to 300 km, is equal to the range of weather radars. The directional accuracy is of the order of 5°, the distance accuracy about 10 to 150/o. Accuracy increases as more recordings ore made on frequencies below 20 kcs. If only the location of thunderstorms is of interest, a more convenient method may be appl ied. For propagation in the frequ ency range between 3 and 10 kcs and for dis­tances in excess of about 500 km, first reflection from the Ionosphere is the determining feature. Its group ve locity is frequency-dependent and the difference in group transit t ime of d ischarges with two adjacent frequencies is

cM M-

16 h2 f3 (!

(M = f2 -f,) (2)

where c is the velocity of light and h the height of the ionosphere. If the arrival times of d ischarge signals are measured on two adjacent frequencies and the difference determined, th is time d ifference, according to equation 2, is proportional to the d istance of the lightning flash . For a frequency f = 8 kcs, a n altitude h = 70 km (dayl ight condition} and f = 1 kc one obtains e. g.

M = -7,5 e µsec

if o is measured in un its of 1 OOO km. - A method of measurement developed at the Heinrich­

Hertz-Institute determines the difference of group transit time on the basis of the frequency dependent phase of the Fourier transform of each discharge signal [4]. Figure 4 s hows as an example the recording of the group transit time difference of discharge signals on two adjacent fre­quencies as a funct ion of az imuth. Again the ordinate indicates the azimuth. In this example the abscissa is d ivid­ed in proport ion to the group transit time difference and shows d irectly, as per equation 2, the d istance of the ligh t­ning discharges. Certa in groupings of dots con be observ­ed which allow the locatio n of the thunderstorm to be determined by direction and distance. The width of the dot groups is partly due to technical reasons, partly due to the fact that the phase references of the individual dis­charges, which ore statistically distributed, are added to the g roup transit time. The sizes of the dot groups consti ­tute at the same time a qualitative measure of the inte nsi­ties of the thunderstorms. This method allows separate observation of thunderstorms which are situated behind each other os viewed from the rece iver position.

References

[11 G. Heydt : Messung der Verteilung der spektro len Amplituden van Atmospherics unter Berucksichtigung des Einfollswinkels, Elektron. Rundsch. 18 (1964), 681

{21 H. Volland: Untersuchungen uber dos stotistische Ampli tudenspek­trum otmosphii rische r Storungen von einzelnen Gewitlerherden, Nochr. Techn. Zeitsch r. 17 {1964), 407

131 H. Volla nd : Bemerkungen zur Austin'schen Forme l, Nochr. Techn. Zeitschr. 17 (1964), 641

{41 G . Heydt : Ele ktron . Rundsch. 19 (1965)

1The ~nternational Federation

of Air Traffic Controllers Associations

Addresses and Officers

AUSTRIA

Austrian Air Traffic Controllers Association Vienna Airport Austria

Chairman Vice-Chairman Vice-Chairman Secretary Director

BELGIUM

H. Brandstetter L. Matzanetz 0. Kubes H. Kihr 0. Schubert

Belgian Guild of Air Traffic Controllers Airport Brussels National Zaventem 1 Brussels Belgium

President Vice-President Secretary Treasurer Director Director Director Director Editor

CANADA

A. Maziers R. Sadet R. Tamigniaux R. Maitre M. de Craecker M. Courtoy J. Lecourt Y. Viroux 0. Haesevoets

Canadian Air Traffic Control Association P. 0. Box 241 Malton, Ontario Canada

President Vice-President Managing Director Secretary-Treasurer

CENTRAL AFRICA

J. R. Campbell W. B. Clery L. R. Mattern C. D. Graham

Association of Air Traffic Control Officers

Private Bag 2 Salisbury Airport Southern Rhodesia

Secretary L. J. Cotsell

DENMARK

Danish Air Traffic Controllers Association Copenhagen Airport - Kastrup Denmark

Chairman Vice-Chairman Secretary Director Deputy

Henning Throne H. Dall H. C. Andersen H. Dall Jorgen Jensen

FINLAND

Association of Finnish Air Traffic Control Officers Suomen Lennonjohtajien Yhdistys r.y.

Air Traffic Control Helsinki Lento Finland

Chairman Vice-Chairman Secretary Member Member

FRANCE

Fred. Lehto Jussi Soini Vaino Pitkanen Heikki Riitaho E. Kurvinen

French Air Traffic Control Association Association Professionnelle de la Circulation Aerienne B. P. 21 Aeroport du Bourget Seine France

President Vice-President General Secretary Secretary Treasurer

GERMANY

Maurice Gregoire Francis Zammit Maurice Cerf Jean Flament Emile Mercier

German Air Traffic Controllers Association Verband Deutscher Flugleiter e.V. Cologne-Bonn Airport Porz-Wahn Germany

Chairman H.W.Thau Vice-Chairman E. Reddmann

Vice-Chairman M. Bahr Vice-Chairman H. W. Kremer Secretary F. Werthmann

Treasurer H. Prell

Editor J. Gertz Director G. Riediger

Deputy H. Krause

GREECE

Air Traffic Controllers Association of Greece Air Traffic Control Athens Airport Greece

President Vice-President General Secretary T reosurer Councillor Councillor Councillor

Chr. Tzomaloukos G. Elias C. Kioupis P. Vasilakopoulos B. Egglezos P. Math ioudakis H. Kopelias

37

ICE LAND

Air Traffic Control Association of Iceland Reykjavik Airport Iceland

Chairman Vice-Chairman Secretary Treasurer Member

IRELAND

Valdimar Olafson Jens A. Gudmundsson Kristinn Sigurdsson Olafur H. Jonsson Kristyan Simonarson

Irish Air Traffic Control Officers Association Air Traffic Control Service Department of Transport and Power Dublin Airport Ireland

President Vice-President Gen. Secretary (joint)

Treasurer

IS RAEL

D. J. Eglinton P. J. O'Herbihy J.E. Murphy T. O'Loughlin P. P. Linahan

Air Traffic Controllers Association of Israel P. 0. B. 33 Lod Airport Israel

Chairman Jacob Wachtel

ITALY

Associazione Nazionale Assistenti e Controllori

della Civil Navigazione Aerea Italia Via Cola di Rienzo 28 Rome Italy

Chairman Secretary

LUXEMBOURG

C. Tuzzi L. Belluci

Luxembourg Guild of Air Traffic Controllers

Luxembourg Airport Luxembourg

President Secretary Treasurer

38

Alfred Feltes Andre Klein J.P. Kimmes

NETHERLANDS

Netherlands Guild of Air Traffic Controllers Willem Molengraafstraat 22 Amsterdam-Slootermeer Netherlands

President Vice-President Secretary 2nd Secretary Treasurer Member Member

NEW ZEALAND

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

Air Traffic Control Association Air Traffic Control Centre Dept. of Civil Aviation, 8th Floor, Dept. Bldgs. Stout Street Wellington, New Zealand

Hon. Secretary

NORWAY

Lufttrafikkledelsens Forening Sola Airport Stavanger Norway

Chairman Vice-Chairman Secretary Treasurer Officer Director Deputy

SWEDEN

R. G. Roberts

Jon Stangeland Knut Christiansen Arne Gravdal Seren Norheim Arne Helvik Ottar Saebo Arne Gravdal

Swedish Air Traffic Controllers Association Air Traffic Control Bulltofta Airport Malmo 10 Sweden

Chairman Secretary

SWITZERLAND

Carl Ahlborn Lennart Jogby

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

Chairman Bernhard Ruthy

UNITED KINGDOM

Guild of Air Traffic Control Officers 14, South Street Park Lane London W 1

Master Clerk Executive Secretary Treasurer Director Deputy

URUGUAY

J. N. Toseland L. S. Vass G. Monk E. Bradshaw A. Field R. W. G. Mundy

Asociation de Controladores de Transito Aereo del Uruguay Potosi 1882 Montevideo Uruguay

BOOKS

Jahrbuch dcr Luft- und Raumfahrt

by K. F. Reuss, published in January 1965 by Sudwestdeutsche Verlogsonstolt GmbH, Mannheim; 443 pages with pictures, tables, and orgonigrommes, Plastic cover with silver letter

impression; DM 19,80

.. Appearing for almost one and a half decodes now, the • Johrbuch ~ur Luft- und Roumfohrt" today is on aeronautical standard publication in the Federal Republic of Germany. This hos come about because the

yearbook contains a wealth of information about every sector of Ger­mon aviation.

. T.he objectives o~ th.e editor are twofold: to publish annually on av1ot1on directory which 1s as complete and as accurate as possible and,

at. the ~.ame time, .to ~rovide 0 continuously growing "German Aviation History by reporting in each yearbook on the major aeronautical events of the post year.

The "Johrbuch hir Luft- und Roumfohrt" is subdivided into the follow. ing chapters:

Aviation Legislation;

Organisation of the aviation administration in the Federal Republic of Germany;

Germon aviation and space research, technical and scientific institutes;

Space aeronautics;

Air traffic;

Aviation and space economics;

The Germon Aviation Club (Club der Luftfahrt);

General Aviation;

Aviation press; publishing houses of aeronautical literature;

International aviation;

Chairman Secretary

VENEZUELA

A. R. Tard6guila J. E. Bianchi

Asociacion Nacional Tecnicos Transito Aereo Venezuela Avenida Andres Bello, Local 7 8129 Caracas, Venezuela

President Vice-President Secretaries

Treasurer Vocals

Statistics;

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

Who's who and where in Germon aviation;

Miscellaneous.

This, of course, is just o list of headings, but if one examines one of the chapters, say, the German aviation administration one will find a lot of detail on the Ministries of Tronspu1 I, Defence, Scientific

Research, Finances, Interior, Justice, Communications, and Economics. It also contains information on the Lander Governments as for as they are

concerned with aviation matters. Much space is, of course, devoted lo

the Bundesanstolt hir Flugsicherung (Federal Agency for Air Navigation) and the Luftfahrt-Bundesamt (Federal Office far Aviation), not forgc~;ing the Federal Meteorological Service.

This chapter also contains the latest amendments to the list of

German pilots, o table of newly registered aircraft in the Federal Repu­

blic and the types of aircraft which have received a German certificate of validation Some information is given on the "Deutscher Luftfohr·zeug Ausschul3" (Advisory Committee on Airworthiness and related matters).

Among the many helpful features of the yeor·book are cleverly arranged notes, registers, tables, etc. which enc1ble one to find the rc:­

quired information without wasting much time.

So far, the yearbook has been published in the German language

This does not matter much to the non-German-spcakrng reader as long

as he is only interested in names. addresses, organigrammcs and so on

The "report sections", however, are of little use in such a case In view

of the steadily increasing amount of information concerning European and i:iternalional aviation (The 196'.J issue contains, inter aiia. data on

ICAO, IATA, IFATCA, EUROCONTROL, FAI. OSTIV. EUROSPACE, ESRO ELDO), the publishers arc cons:der·ing a French and or English version This would, of course, greatly facilitate the use of the ycc,,baol: 1)y

international readers

Summarizing one can safely say that this book 1s on ·~·<tr·enir;ly

accurate and reliable aid to those interested i~1 0·11011011 par t1culn1 ly

regarding the Federal Republic of Germany EH

39

Corporation Members

of the International Federation

of Air T raffle Controllers' Associations

Cessor Radar and Electronics Limited,

Harlow, England

The Decca Navigator Company Limited,

London

ELLIOT Bros. Ltd., London

Hazeltine Corporation, Little Neck, N. Y., USA

IBM World Trade Europe Corporation,

Paris, France

ITT Europe Corporation, Brussels, Belgium

Marconi's Wireless Telegraph Company, Ltd.

Radar Division Chelmsford, Essex, England

N.V. Hollandse Signaalapparaten

Hengelo, Netherlands

Selenia - lndustrie Elettroniche Associate S. p. A.

Rome, Italy

The Solartron Electronic Group, Ltd. Farnborough, Honts., England

Telefunken AG, Ulm/Donau, Germany

Texas Instruments Inc., Dallas 22, Texas, USA

Whittaker Corporation,

North Hollywood, California, USA

The International Federation of Air Traffic Controllers' Associations would like to invite all co

d · · · · t t d · d d · h h rpora-

tions, organizations, an . inst1:u!1ons ~n eres e_ 1~ an concerne. wit t e maintenance and promo-tion of safety in air traffic to 1oin their organization as Corporation Members.

Corporation Members support the aims of the Federation by supplying the Federation with t h . 1 f

I b . . Th F d . ' . ec n1ca information and by means o an annua su script1on. e e eration s international journal "Th C troller" is offered as a platform for the discussion of technical and procedural developments ~n ~hn~ field of air traffic control.

For further information on Corporation Membership please contact Mr. H W Thau Ho S . · · , norary ecre-tary, IFATCA, Cologne-Wahn Airport, Germany.

-~--~- _____________________________ !

40

TYPE 1500 MILITARY /CIVIL TRANSPONDER The si~ultaneous use of common airspace by civil and military aircraft intensifies the critical !1ecess1ty for more efficient A.T.C. systems. Secondary Surveillance Radar provides this improvement. Civil Aircraft fitted with transponders already.benefit from the advantages of such a system, as do t~e ground control stations. Military aircraft can now fit transistorised transponders embracing the entire range of performance features for operation in any A.T.C. Secondary Radar area in the world. ~h~ Cosso~ ~SR.1500 transponder is designed to meet the divers requirements inherent in c1v1I and military operations. The. equipment reliability is extraordinarily hi~h; yet t_he transponder is designed for continuous operation at temperatures up to +140 C and altitudes up to 100,000 ft. It is extremely compact weighing only 27 lbs, yet incorporates all military and civil modes (1, 2, 3/A, 8, C and D) ~nd functions in 2 and 3 pulse side-lobe suppression envi ronments. The small size is achi~ved by unusually high component density; whilst retaining suffic ient flexibility and accessibility for rapid maintenance. The SSR.1500 complies with the requirements. of Annex C~B: to 29/69 CANUKUS (mi l itary), 1.C.A.O. Annex 10, and relevant sections of Arinc characteristic 5320.

Growing aircraft speeds Increasing air traffic

necessitate quicker and more accurate detection of

all movements in the airspace above extensive areas.

For air traffic control we supply

Data processing systems to automate ATC Services by employing digital computers to collate and process

flight data and to display the traffic situation at any

given time.

Radar for airway surveillance

Radar for terminal area control

Radar for precision approaches

Radar display transmission systems

Radar data links

z Ill

z

Ill

Ill