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 facilities at low cost and requiring no special equipment to be fitted in aircraft, apart from the basic VHF communi­

cation 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 control desk mounting

Simplified aerial system

QDM or QTE-50 kc/s channel spacing-frequency range : 100-156 Mc/s

Bearings and triangulation can be superimposed on Marconi radar displays

Marconi air traffic control systems The M arconi Company Limited, Radar Division, Chelmsford, Essex, England LTD SSO

Sat co

Efficient transport means prosperity

Satco comprises the ground equipment to predict, coordi­nate, check and display the movements of air traffic en route and in terminal areas. It provides an extremely rapid method of calculating flight paths, for assessing potential conflicts and for coordination between Area Control Centres. Special features are included for military/ civil coordination.

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

N.V. HOLLANDSE SIGNAALAPP.ARATEN - HENGELO - NETHERLANDS

TYPE 1500 MILITARY /CIVIL TRANSPONDER The simultaneous use of common airspace by civil and military aircraft intensifies the critical necessity 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 the ground control stations. Military aircraft can now fi~ tr~nsistorised transponders embracing the entire range of performance features for operation m any A.T.C. Secondary Radar area in the world. The Cossor SSR.1500 transponder is designed to meet the divers requirements inherent in civil and military operations. The equipment reliability is extraordinarily high; yet the 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, B, C and 0), and functions in 2 .and 3 pulse side-lob.e suppression environments. The small size is achieved by unusually high component density i whilst retaining sufficient flexibility and accessibility for rapid maintenance. The SSR.1500 complies with the requirements of Annex CCB. to 29/69 CANU KUS (military), l .C.A .O. Annex 10, and relevant sections of Arinc characteristic 5320.

IFATCA JOURNAL OF AIR TRAFFIC CONTROL

THE CONTROLLER Frankfurt am Main, January 1965 Volume 4 · No. l

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

Officers of IFATCA: L. N. Tekstra, President; G. W. Monk, Executive Secretary; Maurice Cerf, First Vice President; Roger Sade!, Second Vice President; Hans W. Thau, Hon. Secretary; Henning Throne, Treasurer; Walter Endlich, Editor.

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

Production and Advertising Sales Office: W.Kramer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr 57a, Phone 44325, Postscheckkonto Frankfurt am Main 11727. Rate Card Nr. 2.

Printed by: W.Kramer&Co., 6 Frankfurt am Main NO 14, Bornheimer Landwehr 57a.

Subscription Rate: DM 8,- per annum (in Germany).

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

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

Contributions are welcome as are comments and criti­cism. No payment can be made for manuscripts submitted for publication in •The Controllern. 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. (4); The Decca Navigator Company, Ltd. (Inside Cover); The Marconi Company, Ltd. (1, 2); N. V. Hollandse Signaal· apparaten (3); SELENIA lndustrie Elettroniche Associate, S.p.A. (Back Cover)

Picture Credit: U.S. Air Traffic Control Association (16, 31); Federal Aviation Agency (28, 29, 32); Lockheed Geor· gia (10), Sud Aviation (9) U.S. Forest Service (6), Vickers (7, 9, 10, 11).

CONTENTS

Living with Vortices Tirey K. Vickers

Cumuli Cloud Formation and its Effects on Air Traffic Con-trol ................................................... .

Fatigue and the Controller John G. Wilson

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

ATIS, A recorded Assist for Controllers by Lt.Col. Joseph A. Gascoigne

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

ICAO, Twentieth Anniversary of Chicago Convention

1964 Technical Symposium of the British Air Line Pilot's Asso­ciation .................................................

Air Navigation and Air Traffic Control E.W. Anderson

Yugoslavian Air Traffic Controllers' Association founded

Air Traffic Control, Navigation, and Communication - the next ten Years ......................... · · · · · · · · · · · · · · · · ·

Group Capt. E. A. Johnston O.B.E., R.A.F.

Secondary Surveillance Radar - the next ten Years ..... .

FAA revised NOT AM Procedures ...................... · ·

University of Birmingham Aviation Courses

ATCA's Ninth Annual Meeting ......................... ··· Maurice Cerf

Address of IFATCA President L. N. Tekstra at ATCA Meeting

1964 Annual Conference of the Verband Deutscher Flug-leiter e.V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . · · · · · · · · · · ·

Problems of Civil/Military Integration in the German Air Traffic Services . . . . . . . . . . . . . . · · · · · · · · · · ·

Capt. K. Stieglitz

6

13

14

16

17

18

18

20

21

25

27

29

30

32

34

34

Living with Vortices

Figure 1

6

On this a rticle from o letter of the author to the editor

" ... The vortex article is o case in point -as this p roblem is worse in the USA today (than in other countr ies) because of our high traff ic density. But it wi l l show up in other countries soon wi th the constant increase in traffic density there. And I suppose my motive was portly humonitorion, as I felt that if my article could prevent o single accident some­where, it would be worth the effort . .. "

Insecticide discha rged from underwi ng nozz les ro lls up into vort ices generated by this converted BT-13 _(left) _ and Ford tri motor (rig ht). du ring fores t spray operations 1n western

Un ited States . U.S. FOREST SERVICE PHOTOS

Introduction

by Tirey K. Vickers Hazeltine Co rporation

Streaming across o clear blue sky in sharply-outlined pristine w hiteness, o jet contrail is o lovely sight. Yet it is also o reminder of o growing hazard in aviation - the menace of trailing vortices.

Every winged aircraft which ever flew hos generated vortices in its woke. The growing danger of this inherent characteristic is due mostly to the increased weight of some modern a ircraft. The long jump from the 24,000-pound DC-3 to the 300,000 pound intercontinenta l jet hos brought a large increase in the amount of energy which can be wrapped up in the resulting wakes. Usually in­v isible, these wakes con be encountered by other aircraft without warning. Because of the growing number of acci­dents which hove been attributed to such encounters dur­ing the post few yea rs, on increasing amount of research is being focussed on this problem.

The purpose of this art ic le is to summarize the most important facts w hi ch hove been learned about the gene­ra t ion and behovior of trail ing vortices. It is hoped that th is knowledge wil l give airport traffic controllers and pilots o better understanding of vortex phenomena, and thereby enable them to ovoid the most serious effects, in their do ily operations.

A little Theory

In the expanding jargon of space technology, the term "spin-off" is now used as a synonym for the more prosaic term "by-product". Trailing vortices are the inevitable by­product or spin-off of the lift generation process. The new word is particularly apt in this case, as the vortices literally spin off the wingtips continuously in flight, as shown in Fig. 1. What causes this spin-off? To gain a better feel for the factors involved, it may be desirable to review some of the fundamentals of the lift generation process.

Every winged aircraft must deflect a continuous stream of air downwards, in order to generate the lift necessary to sustain itself in flight. This process is diagrammed in Fig. 2, where we see a wing of span b generating a lift L by imparting to the air a downward velocity v.

The amount of air which the wing can deflect is equi­valent to the amount which can pass through an imaginary circle with the span b as the diameter. The area of this circle is n b2/4. The volume of air which the wing can de­flect in one second is equivalent to a cylinder of diameter b and length V, where V is the airspeed of the aircraft, expressed in distance per second. The volume of air in this cylinder is (:r b 2/4) V. The mass of air in this volume is (:r b 2/4) V p, where p is the air density.

FI ight Path

Figure 2 Lift Generation.

Factors affecting Vortex Intensity

Going back to Equation 2, we find that the average downwash velocity v, which determines the rotational velocities encountered in the vortices, is directly propor­tional to the aircraft weight and the load factor, but is inversely proportional to the airspeed, the air density, and the square of the wing span. These factors are discussed in the following paragraphs.

Weight. The higher the gross weight, the more lift is required, and the stronger are the vortices. If other factors stay the same, a long-range jet will generate a more vio­lent wake on departure, than it will on approach a few hours later, due to the difference in fuel load (and conse­quently, gross weight).

As the strength of the vortices depends on the amount of weight being lifted by the wings, a tricycle-geared air­craft will not generate significant wingtip vortices on the takeoff run, until the aircraft is rotated for th.= lift-off. On landing, the generation of vortices will stop as soon as the full weight of the aircraft is being carried by the land­ing gear.

The lift L is equal to the mass times the downwash velo­city, so L = (.:-r b 2/4) V p v. Let's call this Equation 1.

The amount of lift being generated at any given moment can also be expressed as the gross weight of the aircraft W, times the load factor g, or L = W g. In straight and level flight, g = 1, so the lift is equal to the weight of the aircraft. In a sharp pullup or a steep bank, the load factor (and consequently the lift) is increased appreciably. For example, in a 60-degree banked turn, g = 2 and the lift is doubled.

Substituting W g in place of Lin Equation 1, we obtain: W g = (:7 b2/4) V p V.

Transposing this equation, we get:

Wg v

(:7 b2/4) v p

Let's call this Equation 2.

It is a very useful little package, as it can show us how a change in any of the basic factors will affect the down­wash velocity, and ultimately the rotational velocity of the vortices.

v

I I

v

/

Load Factor. The higher the load factor, the higher .the lift, and the stronger are the vortices. Certain local no1se­abatement procedures which force all departures to make a sharp turn immediately after takeoff can create a dan­gerous situation if an aircraft gets banked up for the turn and flies into the extra strong outside vortex of a preced­ing aircraft which had made a turn at the same place.

Wing Span. As vortex velocity is inversely propor~io­nal to the square of the span, a small reduction in wing span can cause a large increase in the intensity of the wake. For years, the tendency in aircraft design has .been toward higher span loadings, which means either higher weight for the same span, or shorter spans for the same

weight class of aircraft. This factor becomes very important with the advent ~f

slender (very low aspect ratio) delta wings. for ~upers~nic aircraft. The Concorde is a case in point. With high weight and very low span, such aircraft are expected to generate much higher vortex velocities than those produced by pre­

sent jet transports.

7

Airspeed. It may come as a surprise to many people that the lower the airspeed, the stronger are the vortices. The reason is apparent in Equation 2. The slower the air­craft is flying, the less air it e ncounte rs each second. In order to generate the necessary lift, it must give this air a greater downwash ve locity.

The kinetic energy per second required to generate the lift is equal to half the product of the lift and the d efl ec­tion velocity (L v/2). Low airspeeds require high deflection velocities which in turn requ ire increased power.

In simple terms, we could say that the trailing vortices result from slippage of the air during the lift generation process. The lower the a irspeed, the more slippage occurs, and the more power is required to maintain altitude. For this reason, helicopters require maximum power to hover a t ze ro airspeed. Some idea of the high downwosh velo­cities which ore required for hovering fl ight, may be gain­ed from Fig. 3.

Around airports, aircraft a re more likely to be fl ying ot lower airspeeds, and thus churning up stronger vortices.

Vortex Rotation

W hen the cylinder of air shown in Fig. 2 is deflected downward by the wing, the static pressure of the air immediate ly under the wing is increased, while the stat ic p ressure of the air above the wing is reduced. Because of the natura l tendency for these pressures to equalize again, t he air in th e high-pressure area unde r the wing tends to

This factor undoubtedly contributes to the increased rate of vortex-induced accidents in this area. However, th ere ore other contributing factors. Traffic density is highest around airpo rt traffic patterns; this raises the probability of vortex encounters. In addition, aircraft are more likely to be at low altitudes around airports; if a vortex upsets on aircraft, less altitude may be available for recovery.

Air Density. The lower the air densi ty, the higher the vortex velocity. If other factors were unchanged, vortex ve locity would be highest at high altitude. Fortunate ly, air­speeds are usually much higher up there, whi le tra ffic den­sity is relative ly low.

Summary. If Equation 2 leaves you cold, an easy way to remembe r the effects of the va rious governing factors, is that any change which would force the aircraft to fly at a higher angle of attack would increase the downwash velocity, and thereby increase the strength of the trai ling vortices.

spi ll outwards around the wingt ips, and the n converge in­to the low-pressure area above. This late ral spillage of the air sets up two oppositely-rotating horizontal whirl­winds, or vortices (one spinning off each wingtip), wh ich quickly involve th e e nti re moss of ai r deflected by the w ing.

Figure 3 Radial wind-streaks, concentric wh itecaps, ano a temporary d imple an the face of the ocean, indicate the intensity o f the downwash wh ich supports th is 31,000-pound Sikarsky HR-25, as i t hovers long enough ta sna tch an astronaut from 0 Aoat ing Mercury space capsu le.

N ASA PHO TO

8

In the case of a conventional wing, the vortices roll up be hind the wing, as shown in Fig. 1. In the case of a slen­de r delta wing (which aerodynamically is s imply a couple of giant wingtips), the high-pressure air under the wing spi lls out around the outer edges, which in this case ore also the leading edges. The air then converges in to the low-pressure a rea above, forming the vortices at the some time. As shown in Fig. 4, the vortices ore already rolled up before they pass the trailing edge of the wing.

In e ither case, the cylinder of deflected air (a s shown in Fig. 2) is shoved downwards through the surrounding air moss. On the underside of this cylinder, the su rround­ing air is pushed sideways, around the periphery of the cylinder. This fact is strikingly evident, if you ever get a direct head-on view of the smoke tra il from a toil-engined je t, a s shown in Fig. 5. Looking down the tube, as it were, you con visualize its cylindrical surface as the smo ke spira ls out behind the aircraft. Caught in the initial down­wosh, the smoke sweeps down to the bottom of the tube, where it splits into two stra nds which follow semicircular paths outwards, upwards, and inwards to the top of the tube. Here the strands merge and start downwards again, perhaps a thousand fee t o r more behind the aircraft.

So much for the outer periphery, but what goes on in­side the cylinder? Each of the two vortice s hos a core, or a circle of maximum rotational ve locity. These cores ore quite visible in Fig. 1. The air with in each core rotates around the core axis; thus the tan ge nt i a I ve locity decreases to zero at the center of the core, as shown by the velocity graph of Fig. 6. This ro tating air inside the core is also moving forward at high speed, toward the retreating aircraft. Outside the core of the vortex, the tan­ge ntia l veloci ty of the ai r decreases with distance from the core surface, as shown in Fig. 6.

The loterol distance between the centers of the twin vortices depends on the lift distribution of the wing, but in most coses is approximately n/4 (about .78) times the wi ng span.

Up 40

~ u.. 20 .. >.. -u 0 0

~ 0 20 u -... 40 ~

Figure 4

Figure 5

.~.,~~~~·ltdv.;;.~ Cross-section o f vortex flow post tra iling edge of Co ncorde wing , in mode l tests in Onero Water Tu nnel.

SUD-AVIATION PHOTO

Head-on view of smoke tra il from Boeing 727.

60 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Down Figure 6 Typica l distributio n of vertical ve locities shortly after roll up of vortices .

9

When partial-span wing flops ore extended, on addi­tional set of vortices forms at the ends of the flops. Al­though these vortices finally get rolled up into the wing­tip vortices, the flops hove several effects worth noting. By shifting more of the lift inboard (away from the wingtips) they tend to move the main cores closer together, and to weaken the tip vortices. The flap vortices tend to diffuse the resulting main cores. Observations indicate that when partial-span flops are used, the vortices tend to rotate slower and die out foster than when no flops ore used.

Wake Movement As shown in Fig. 1, the size of the cores gradually in­

creases with time. Their rotational speed gradually de­creases, due to the internal friction of the air. Unless torn apart by shear, turbulence, convection, or interference by some externo l object, the vortices will continue to spin for several minutes. Meanwhile, they will drift with the wind. However, they are also subject to another very important

motion - a downward th rust which is proport ional to their rotational velocity. Both the downward thrust and the rotation ore caused by the initial downward deflection of the air by the wing. Consequently, the wake will be p ro­pelled steadily downward either until the vortices dis­sipate or until they reach the surface of the earth. The sinking speed of the woke from a typical four engine jet transport is initially around 350 fee t per minute (31/, knots).

If the wake reaches the surface, the cores level off at on altitude of ha lf the wing span, and immediate ly spread apart laterally, as shown in Fig. 7. Their horizontal velo­city in still a ir is approximately equal to the ir previous sinking speed. As the p rogress of each vortex is subject to the wind, a moderate crosswind will blow both vortices away. However, as shown in Fig. 8, a light crosswind com­ponent con hold the windward vortex in o steady position.

If the aircraft is near the surface of the ground when the woke is generated, as shown in Fig. 9, the wakes will spread apart at a foster rote than when generated at a higher altitude.

Wind Calm

111 11 1111111 11 11111111111 1

' '

figure 7 Sinking vortices spreod loterally as soon os they reach the surfoce .

Wi nd Di rection

\

Figure e A light crosswind con counteract horizontal movement of windward vortex and create a ha zardous situation for other airc raft.

Figure 9 Cu rling clouds o f d us t s ho w the lateral spread of the wing tip vo rtices, as thi s Lockheed C-130 "Hercules" nea rs touchd own on a n un· paved airstrip. LOCKHE ED-GEORG IA PHOTO

10

Helicopter Vortices

Many years ago, when midget automobiles were first introduced in the United States, a favorite bit of parking advice was "Don't park under a horse!" As downwash problems have changed considerably since then, the re­mark should now be paraphrased to read: "Don't fly under a helicopter!"

Each rotor blade tip of a helicopter sheds a separate vortex. The resulting vortex trail is a highly complex, inter­twined wake. However, in forward flight, these vortices soon rearrange themselves to form the cores of twin vor­tices which trail the rotor path like wing-tip vortices trail an airplane wing.

The intensity of helicopter vortices varies (like airplane vortices) directly with the amount of lift being developed, and inversely with the forward airspeed, the air density, and the square of the wing span (which in this case is the rotor diameter). In hovering flight, the airspeed approaches zero, and the wake intensity reaches very high values, as illustrated in Fig. 3.

In hovering flight, the wing-tips describe a closed loop. Consequently, the downwash immediately below the heli­copter is squeezed into a circular area one-half the area of the rotor disc. Within the lower area, the downwash velocity is twice the velocity at the rotor plane. A typical downwash velocity under an S-58 helicopter in hovering flight is about 60 feet per second (35 knots).

Helicopter vortices settle toward the ground, and ex­pand rapidly when they get there. Vortices shed in cruis­ing flight tend to sink more slowly than those shed in hovering flight.

Vortex Dissipation

Airplane vortices come in symmetrical pairs. When one core is broken, the other core usually breaks at the same place. At low altitude, any wind of more than five knots usually has enough velocity gradient and turbulence to shear the cores apart in a minute or two. In sunny days, thermal (convection) currents play havoc with the cores, tearing them apart vertically.

When a temperature inversion exists, however, convec­tion currents are suppressed in the area below the inver­sion level. When the inversion is accompanied by a calm or extremely light wind, as is often the case between sun­set and sunrise, the vortices can roll along undisturbed for many minutes, subject only to a very gradual decay due to internal friction, until they reach a particular stage where they break up rather abruptly and becomes diffused in the surrounding air mass.

How do vortices break up, in smooth air? Perhaps jet contrails can give us a clue. We have recently ~ad the opportunity to observe a number of high-altitude 1et vor­tices (in contrail form), at close range, flying parallel to the trails in a direction opposite to the generating ai~craft. From these observations, it would appear that the life of any part of the trail depends on maintaining unbroken vortex cores, all the way from the generating aircraft; ~nd that once a break occurs, that portion of the trail behind the break soon loses its identity as a unified rotating mass. Th is is how it looks:

In smooth air, continuity of the cores can be mainta.in­ed for many miles, and the twin contrails stream out like fluffy white cylinders. Gradually, however, perhaps clue to precession or instability as the cores slow down, they take

on a slight helical (corkscrew) motion. The amplitude of the wiggles gradually increases until suddenly, if you are watching very closely, you will see thin radial spikes of vapor protruding from each core. Within seconds, both cores shear apart vertically at this point. Almost instantly, the spikes blossom out into twin puffs, and the cores be­hind break into a series of short segments, with puffs at each break. Soon the segments are absorbed into the puffs, and the puffs evaporate in a wispy mass of turbu­lence. There may still be a considerable amount of energy left in the wake, but it is now greatly diffused and dis­organized.

Penetration

When one considers the millions of takeoffs and land­ings which are made each year, and compares this with the number of accidents and near-accidents which have been due to vortex encounters, it may appear that the actual hazard is insignificant. The relatively low number of encounters is due to the fact that any encounter re­quires that an aircraft be in a certain limited volume of airspace at a certain time and under certain atmospheric conditions. Yet, when these contingencies occur, the results can be sudden, violent, and sometimes disastrous.

The actual effects of a vortex encounter will vary wide­ly, depending on a vast range of possible factors. These factors include all those which have been discussed so far on the generation and behavior of the vortices. They also include such factors as the relative size of the generating aircraft and the penetrating aircraft, the elapsed time bet­ween generation and penetration, the angle and speed at which the vortex is encountered, as well as the control characteristics and the structural design limits of the pene­trating aircraft.

Aircraft Size. The chances of a small aircraft becom­ing completely immersed in the rotating wake of a large aircraft are obviously greater than the opposite case. Con­sequently, in a mixed aircraft environment, small aircra_ft are more likely than large aircraft to become involved rn a dangerous vortex encounter.

Aircraft Separation Time. The time between vortex generation and penetration has a significant effect on the forces involved in the encounter. Tests indicate that the original intensity decays very little during the first thirty seconds, but then drops off at a faster rate, depending on atmospheric conditions. Pilots have reported vortex en­counters with separation times of as much as 5 minutes; however, few if any measurements of vortex intensity have been made at separation times of more than 160 seconds, largely because of the difficulty of locating the actual wake after that time.

The wake of a large jet aircraft can be dangerous to any other aircraft during the first minute. In any case, the greater the aircraft separation time, the lower the intensi­ty which is likely to be encountered.

Penetration Angle and Speed. If the penetrating air­craft is flying essentially parallel to the wake and enters the downwash area between the cores, as shown in Fig. l 0 .. the result will be either a rapid settling or a significant reduction in the rate of climb. This type of situcition is most likely to occur if the penetrating aircraft descends or climbs into the wake or is overtaken by another aircraft passing overhead. B~cetuse of the strong downdraft. the

11

Figure 10 Porollel Pene tration betwee n cores.

settl ing con be dangerous at low al ti tude. There is also the possibility that the pilot may stal l the aircraft in try­in g to compensate for the dow nwosh. In any case, a lower airspeed w ill worsen the situation.

If the penetrating a i rcra ft is flying essentially parallel to the woke and flies into o ne of the cores, as shown in Fig. 11, it will be subjected to a roll ing motion induced by a downward airflow on one w ing and on upw ard a irflow on the other. If the rolling forces ore greater than the maximum control force which can be opplied by the aile­rons, the aircraft w ill rol l o ver in spite of anything the pilot can do. The slower the airspeed, the less control force w i ll be available to counteract the induced roll.What usually happens is that the aircraft is flipped to on invert­ed posit ion and thrown out of the bottom of the woke.

If the penetrating aircraft runs into the woke crosswise, as shown in Fig. 12, it wi ll fl y first into the outer upwosh; then the airflow is reversed instantly as it posses the cen­ter of the core and the aircraft hits the downw osh area ; passing the center of the other core the flow is again re­versed as the a ircraft hits the upwo sh area on the for side. The effect, w hich is si mila r to a rap id series of sharp-edged vertical gusts, con produce v iolent pitching and verti cal motions, as well as severe strai ns o n the a ircraft structure. The higher the speed, the higher the structural loads. We know of at least one in stance w here a light aircraft broke up in fligh t, os o res ult of this type of encounter.

Figure 12 T ro nsvcrse Penetrotoon.

12

Figu re 11 Parallel Penetration into core.

How to avoid upsetting your Clients

The two known ways of avoiding encounters with vor­tices may be stated briefly in six words :

1. Give them time.

2. Give them room.

Giving the vortices time to dissipate is not alw ays prac­tical. The almost unlimited number of poss ible combina­tion s of variables which con affect vortex intensity and decoy rates will make it very difficult for any regu latory agency to tai lor a set of time separation standards which would :

1. Guarantee that every woke would be harmless at the end of the prescribed separation period;

2. Be simple enough for easy application in doily opera­tions;

3. N ever unduly restrict ai rport uti l ization or air t raffic flow.

Giving the vortices plenty of room implies that one be able to v isualize the location of these normally-invisib le disturbances at any moment of their active lives, and then control any subsequent flight path so as to remain clear of the active area. Here is where a wo rking knowledge of vortex behovior con pay off, in lowering the possibility of exposing aircraft to the most dangerous effects.

Any of the points brought out in the preceding sections of this article may have application at one time or an­other. However, in our opinion, the one most important characteristic to remember at all times is the basic "down­and-out" motion of the vortices - downwards until they reach the surface, then spreading laterally outwards as shown in Fig. 7. Some important applications of this cha­racteristic are listed below:

1. In crossing the flight path of a preceding aircraft, it is better to cross at a slightly higher, rather than a slight­ly lower, altitude.

2. In following a larger aircraft on approach it is desir­able to fly the same, or a slightly higher, path; but never a lower path, unless a strong cross-wind is pre­sent to blow the preceding wake offside. The use of a common ILS or VASI glide slope by all aircraft is a desirable practice, for this reason.

3. Flight directly under, and parallel to, the wake of an­other aircraft should be avoided, because of the in­herent sinking characteristic of the wake.

4. Takeoff or landing by a light aircraft should be avoid­ed, immediately after a heavy aircraft has made a low pass (or missed approach) down the runway in use.

5. When a light crosswind exists, controllers and pilots should anticipate possible vortex encounters on a run­way behind a larger aircraft taking off or landing; this situation is illustrated in Fig. 8.

6. It should also be anticipated that the ultra-high-velocity vortices shed by slender-delta-wing interceptors and SST's will sink quickly out of the way of following air­craft on the same flight path, but that such vortices probably will travel faster and farther laterally (against stronger crosswinds) when they reach the surface.

7. Whenever possible, operations of light and heavy air­craft should be segregated on different runways. To avoid problems with vortices from one runway inter­fering with operations on a parallel runway during crosswind or calm conditions, it has been recommend­ed that parallel runways be spaced at least 2 500 feet (800 meters) apart, if both are used for takeoffs and landings. However, if one runway is used exclusively for takeoffs and the other for landings, a lateral spac­ing of only l OOO feet (320 meters) will still keep the hazard at a very low level.

8. Except for the condition described in Item 5 above, it is usually safe for a light aircraft to follow the takeoff of a heavy aircraft on the same runway, if the light aircraft lifts off after a shorter ground run and remains above the climbout path of the heavy aircraft as long as it is on a common course. If this is not possible, a takeoff interval of at least two minutes would be desir­able.

We would not close this article without a last reminder '.hat vortices ore likely to be most dangerous when the air is most peaceful, during calm or very light wind conditions, between late afternoon and early morning. Wind direction is more unpredictable then. Vortices will stay stronger longer, and may occasionally show up in some unexpected places.

Bibliography

We hope that the foregoing information will be of practical use to controllers and pilots. Meanwhile, if any readers are interested in digging deeper into the details of this fascinating subject, we would recommend the re­ports listed below.

1. "Big Plane Turbulence Can Cause a Flight Hazard", Safety Suggestion No. 8, Beech Aircraft Corp., 1952.

2. D. R. Andrews, " A Flight Investigation of the Wake Behind a Meteor Aircraft, With Some Theoretical Ana­lysis", RAE Technical Note Aero 2283, ARC CP 282, 1954.

3. C. C. Kraft, "Flight Measurements of the Velocity Dis­tribution and Persistence of the Trailing Vortices of an Airplane", NACA Technical Note 3377, 1955.

4. Report of Project NR AVN 2656 "Effect of Wing-Tip Vortices and Sonic Shock on Army Aircraft in Flight", U.S. Army Aviation Board, 1957.

5. T. H. Kerr and F. Dee, "A Flight Investigation into the Persistence of Trailing Vortices Behind Large Aircraft", RAE Technical Note Aero 2649, 1959.

6. J. W. Wetmore and J.P. Reeder, "Aircraft Vortex Wakes in Relation to Terminal Operations", NASA Technical Note D-1777, 1963.

7. Leighton W. Collins, "Caution Advised", Air Facts Magazine, May, 1964.

8. "Evaluation of the Wake of an S-58 Helicopter", final report, Project 348 011 01 V, Federal Aviation Agency, July, 1963.

9. R. Rose & F. W. Dee, "Aircraft Vortex Wakes and Their Effects on Aircraft", RAE Technical Note No. Aero 2934, December, 1963.

10. A. B. Connor & T. C. O'Bryan, "A Brief Evaluation of Helicopter Wake as a Potential Hazard to Aircraft", NASA Technical Note D-1227, March, 1962.

Cumuli Cloud Formation and its Effects on Air Traffic Control

The Technical University of Berlin, Institute for Pilotage and Air Traffic, intends to do some research work on the problems arising for aviation, and in particular for air traffic control, from cumuli cloud formations. The study will deal with frequency of occurrence and intensity of cumuli clouds in Germany, resulting turbulence, and usability of flight levels immediately below such cloud formations.

Comments on this topic would be greatly appreciated and are invited to be addressed to

Dr.-lng. R. Bernotat Lehrstuhl flir FlugfUhrung und Luftverkehr

Technische Universitot Berlin

l Berlin 10

Marchstraf3e 12 15

13

!FATIGUE and the CONTROLLER

The author is Air Traffic Controller at Toronto Air Traffic Control Centre, Canada, on Associate of the Royal Aero­nautical Society, and a Technical Member of the Canadian Aeronautics & Space Institute.

"The controller, in applying the standards contained herein, should remember that he is completely responsible for the safety of human life and of valuable aircraft and cargo. Human error is completely intolerable."

How many ATC Manuals contain similar statements of ideal and human standards? To be read with an inner glow, and shown to the other agencies and users with pride ...

Which is all very commendable, but despite such high­flown ideals, which no professional controller deliberately compromises, human error does occur. There can hardly be a controller, engaged in IFR control, who has not some time or another seen an error committed. An error which maybe, was caught in time and did not cause an incident

1

or which did not cause an incident just because there wa~ no other aircraft there, or which did, in fact, cause a "paper" incident, solved by a hurried transition to other separation standards - typically, radar saves the day. Very occasionally small percentage statistics work out and a genuine hazard to navigation is caused, leading to in­vestigation, publicity, mudslinging, and a general lower­ing, for a time, of the mutual confidence so necessary bet­ween pilot and controller.

Where and why do such errors creep in? Noticeably, they do not seem to occur in the final phases of approach and landing, where all possible conflict has previously been resolved, nor do they occur in VFR circuit conditions, except where a pilot has failed to carry out his instructions - quite another consideration and outside the scope of this article.

We are then left with the major problem area, which is so susceptible to human error and where the implications are so serious; that is the transfer of control data followed by the transfer of control, either between Centres, or sec­tors, or between units within a Centre's jurisdiction.

Now, if we accept that no controller is normally and deliberately going to create a lack of separation, then we have to seek some factor which could affect his complete physiological state, and thus make him, in effect, a tempo­rarily different person in his mental and motor reactions

to the situation of the moment. When we set it out this way and then eliminate the

more obvious external influences, such as personal illness, drug effects, etc., we find we are left with one culprit only

- fatigue. This is, of course, an easy conclusion to arrive at, espe­

cially in view of its intangible nature. Possible this has something to do with the fact that very little published work exists dealing with fatigue in the ATC environment. Professor Dr. van Diringshofen's article on "The Human Factors in Collision Prevention" gives an excellent and outhoritative viewpoint from the medical side of the fence, whilst Arnold Field's address to the Royal Aeronautical Society's symposium on Air Traffic Control, published in April 1961, gives the viewpoint of the senior and wise con­troller studying his colleagues in their environment.

by John G. Wilson

In the fleld of aviation medicine, however, far more study has been given to the effect of this insidious factor on aircrew, and it seems to be important that this material is not wasted, and is, in fact, analysed and related to our ATC environment. The general effects of fatigue are un­likely to be different, since we are all human beings but it is the functional results of the general effects that

1

will be different for a controller and need to be considered, known and understood by all of us so that we can operate most safely and efficiently, even whilst under its effects, and so that we can train ourselves and others to recognise its onset and stave off its effects. This is essential for with the general and gro~ing shortage of personn~I, the in­escapable fact remains that the job must still be done '.11aking it mandatory that we are always consciously look~ ing for the symptoms and results of fatigue in ourselves and others and that our personal procedures and self­indoctrination are of the fail-safe variety insofar as the effe~ts of fatigue .are c?ncerned. Many of the genera I con­clus.1ons upo~ which ~his article is based originally appear­ed in an article entitled "Fatigue", by Col. w. R. Turner, MD, USAF, published in "Interceptor" and subsequently in the RCAF "Flight Comment".

So what is this fatigue that is so insidious - that so many managements try to laugh out of existence? What are its effects and results?

. Whe~ we are fatigued, we experience drowsiness, las­situde, tiredness etc., however these factors are incidental,

and the importa~t f~ct, w.hich should always be present in ev:r~ controllers. mind, 1s that fatigue results in loss of ~ff1c1e~~y and skill. T.he medical symptoms of circulatory instabd1t~, l~ss of weight, hypoglycemia, and disturbance of coordination are only overt symptoms. Because fatigue

is an i~t~ngibl~, and we cannot measure or define it, we have d1ff1culty_ 1n contro~ling it, but we can study the factors that produce 1t and their relationship to each other.

First then the causes, which can be categorised into environmental and personal causes. In the environmental category we have:

Long and continuous periods of duty.

Operationally_ unsatisfactory equipment, which is probably serviceable and technically adequate.

Equipment irregularities or outages, with resultant "make do" situations.

Traffic density.

Actual position being filled.

To these more operational factors we must add ex­ternal physical factors such as: '

Uncomfortable seating.

Ambient temperature conditions too hot, cold or humid.

High general noise level.

Badly laid out position from the point of view of time and motion study.

Now these fatigue-inducing circumstances are all ex­ternal factors, but we are human beings and are subject to internal stresses as well. Let us consider some of these internal or personal factors:

Boredom Responsibility Concentration Anxiety Frustration Apprehension Attention Panic Uncertainty Fear

Quite a list, is it not? Now let us add some more:

Hunger and thirst Lack of experience Family illness Financial problems Known personal inadequacies Suspected teamwork inadequacies Unsatisfactory personnel management from front office

So now we have compiled this formidable list and loaded it onto the controller's back, what is the result? An error is made in something which is relatively simple and easy on face value, an error of the type which always seems so inexplicable and incomprehensible to subsequent investigation.

Now we are told that the Cambridge cockpit studies on fatigue, conducted on a Spitfire simulator, came up with several conclusions.These are set out with the original wording modified to flt our ATC environment:

1. Motor responses suffer as fatigue develops. (Have you ever caught yourself, for example, clearing an aircraft to a completely different destination from that on the strip, or passing an estimate to the wrong Centre, apparently without cause?)

2. Fatigue produces a willingness to accept lower stan­dards of accuracy and performance. (The "couldn't care less" attitude.)

3. Fatigue tends to induce a shift from control based upon the situation, as it appears on the board, to rule-of­thumb control.

~T~~ "habit" of always giving that particular flight its in1t1al descent at that particular fix.)

4. Fatigue induces a failure to check all the control fac­tors before implementing a control decision. (The same situation as 3.)

So much for the facts - what, then, are some of the more obvious dangerous results or reactions of this fatigue effect?

Failure to remain alert Carelessness Drowsiness Day-dreaming Lack of stability Loss of self-control

Becoming aware of an error but being apathetic about correcting it

Irritability Irrationality

Once again a formidable list, however the one which is perhaps most worthy of more detailed consideration is the last - irrationality - doing something quite inexplic­able with dangerous implications; in addition, and this ~eems to be characteristic of this fatigue symptom, the individual often cannot remember or explain the action.

One typical effect is some times referred to as "hearing cross-eyed" or "transposition error". It seems to be caused by a breakdown in the communication path within the individual where, for example, one hears information, understands, reacts, and instigates a motor response to write or speak - somehow, what was heard does not get written or spoken as originally heard, as for example, the taking of an estimate or progress report. Possibly in the fatigued state, the unconscious is able to slip in a pre­vious and unrelated memory out of the filing system, how­ever this is purely uneducated speculation. Nevertheless the individual will be quite convinced that what he wrote was what he heard, because he has no other memory of the train of events, but somebody else, monitoring the exchange, may well be horrified to see a responsible and competent colleague write down an altitude quite different to that being dictated by the adjacent Centre, or a time quite different from the aircraft's actual report. Of all fati­gue symptoms, it is perhaps the most dangerous in the ATC environment, because of the vast amount of control data which is passed verbally between Centres, and will be for some years to come. The potentiality for incidents due to this sort of error is considerable.

How, then, can we reduce the effects of fatigue? In one word - training. The development in the individual, through his own, or formal, indoctrination, of routine safe habits, habits which may be somewhat restrictive, or phra­s~~logies which may use extra words, in light traffic con­ditions, but which, in conditions of heavier traffic and fati­gue inducing circumstances are a safe rock upon which a controller may stand, whilst he assembles his deteriorating concentration and completes the solution to the problem. Develop the habit of always reading back time and alti­tude on an estimate or progress, which gives someone else the. opportunity of picking up your error before it gets serious. Develop the excellent American practice of using ever Y communication concerning a flight as an oppor­t~nity of double-checking the altitude. Stick rigidly to rou­tine and procedure and indoctrinate yourself to do this normally, and you will do it automatically when you are fatigued. "Be flexible and expedite" is fine, if you are in top form mentally, but if you let your normal operation become a non-routine flexible affair, then you are over­taxing and relying heavily on your concentration, which is one of the first factors to deteriorate under the effects of f~tigue. The more proceduralised and routine the opera­tion, the less the concentration needed to run it, which results in more of the controller's mind being available for the non-standard problem, or in a bigger cushion against fatigue effects.

Finally, the supervisory responsibility - and here it should be stated that although the controller himself has a duty to report when he feels he is suffering the effects of fatigue, the onus is upon the supervisor to be looking for it and to ring the changes before it gets dangerous. Detecting fatigue is, in itself, fatiguing, but it can be done and should be done, even though the results may only seem to be negative - incidents that do not happen -however awareness of and alertness to the symptoms it­self aids in preventing the typical errors. Every level of management has a responsibility in eliminating the fatigue factor. When long hours of shift cannot be avoided, fati­gue must be recognised as a potential hazard and sensible precautions taken at the on-the-floor supervisory level.

15

ATIS A recorded Assist for Controllers*

Seventy-five miles from Kennedy Airport, a jetliner cap­tain tuned in the Kennedy VOR and received weather, air­port and approach information. Before taxiing at Van Nuys, California, the pilot of a Cessna 170 heard depar­ture information on the VOR. At Chicago O'Hare, a pilot on the ramp leisurely dialed a discrete frequency to pick up a similar broadcast before starting engines.

What's going on? They are all taking advantage of the new recorded Automatic Terminal Information Service (ATIS), soon to be available around the country. FAA's Air Traffic Service is moving ahead on an expedited schedule to implement ATIS nationwide at high density locations to ease the communications burden for pilots and ground and approach controllers.

The thrust of the ATIS effort has resulted in a double payoff - a positive assist to the controller, better avail­ability for the pilot; and a mutual benefit for both - more time to devote directly to control.

Looking back over more than twenty years, we see a decidely different picture of recorder use in air traffic con­trol. Beginning with the days of the frequently changed grease-pencilled belts (believe it or not - some of the museum pieces are still on active duty), recorders were just that - electronic documenters of clearances issued. The wide loops were stored one upon the other in neat chrono­logical order to authenticate "the situation".

During those early years, a sprinkling of complaints could be heard now and then that the recorder represented a backhand swipe at the integrity of the controller - that his word had to be electronically verified. The majority, however, realized its worth in a broader sense, and used the record to sample technique, to peg training curricula, and to use the device for the positive purpose of constant

e---1 4 I 1

REMOTE CONTROL PANEL

by Lt. Colonel Joseph A. Gascoigne Executive Director, ATCA

improvement. As in any scientific endeavor, the search for new air traffic control methods leads to ever-widening applications and the recorder has been an unsung, simple machine that has figured so often in a number of these advances in our profession.

Recent years have seen advanced sophistication of re­cording gear to numerous channel capability with capacity to record air to ground as well as facility position activity. Recorded voice identification on navigational aids is an­other application.Training use has also expanded appreci­ably and certainly, the record review has contributed to improved service by offering a means of checking control technique and methodology that might be revised bene­fically.

Then there have been the other uses - piecing the incident together - or the rare tragedy. Unfortunately, in those instances, blame fixing by vested interests was some­times prominent whereas "cause" must be the true ob­jective - learning by reconstruction.

Now Automatic Terminal Information Service comes on the scene with a new wrinkle in recorder application to lend a third hand and a second voice to the controller. During the early months of last year, in a joint effort of the Air Traffic and Systems Research and Development Services, field evaluations were conducted at Chicago, San Francisco/Oakland, Van Nuys and New York to determine operational feasibility.

The gist of the effort was to learn how and what repe­titious elements could be lifted out of control messages and broadcast repeatedly, thereby reducing clearance length and reaping the obvious side benefits. The clear­ance elements we refer to are the routine but necessary noncontrol items such as altimeter, wind, ceiling under cer-

AUTOMATIC RECORDING

" ... ALTIMETER TWO NINER NINER TWO, CEILING ... "

R1~pr1nted from the Journcil of Air T1·off1c Control by kind permission of the Editor

16

tain circumstances, departure and arrival runways in use, approaches in use, facility outages and so forth.

Here is one sample that illustrates message content:

"This is San Francisco Airport Information. Measur­ed Ceiling four hundred Overcast, visibility one, Fog, Wind two two five Degrees at eight. Altimeter two niner niner two, ceiling lower northwest: lls Runway two eight right Approach in use. Landing Runway two eight. Compass Locator outer ma r k er not operative. Inform San Francisco Approach Con­trol or Ground Control on Initial Contact that you have received bravo Information."

At Chicago O'Hare, for example, the controller origi­nated and updated messages using a small remote con­~rol device recessed in the console. The three-inch by flve-1~ch remote panel included an On,VOR Light, a Dictate Light, Repeat Dictate Light, Dictate Level Switch and two monitor jacks. One jock was used as an oral m~nitor for the VOR and the other jack was used as an oral monitor for the transcribing machine. Beginning at midnight the "Alpha" message was recorded and transmitted con

1

tinu­ously over the VOR. As conditions changed, new messages ~ere .recorded, each with a succeeding phonetic alphabet 1dent1fler.

During conditions when certain message elements such as weather changed rapidly, those items were dropped from the broadcast and issued live until the circumstances again stabilized. Similarly, when there was a sudden or brief change to any part of the broadcast the controller had the obvious advantage of giving the ~ost recent in­formation on initial contact.

.It is readily apparent why we label ATIS a "recorded assist for controllers". In a "hot" operation when time is measured in split-seconds, eliminating information that normally. takes anywhere from fifteen to thirty and more seconds is a boon to the controller. Multiply these critical seconds by the number of initial departure and arrival contacts you have on a heavy watch, and the time ad­vantage score adds up to a bundle. The "spiel" is taken out ~f the clearance, and you gain time to concentrate on precise vectoring to frnal approach.

On the pilot side of the ledger we can also tote up a number of advent At h . b

. ages. t e ramp, while passengers are eing ushered abo d th ·1 .

b d ar , e p1 ot can casually tune in the

roa cast for the d t · . h

epar ure s1tuat1on. Inbound, he can pick up t e message lo b f h b h kl" ng e ore e ecomes occupied with c ec. ists and the like. Furthermore, the message can be monitored for as m

d any repeats as desired. In either case

- eparture or arrival I I . ta t h d . - w 1en t 1e pilot makes intial con-

t. c :, eF a vises the controller that he has "Bravo informa-1on o th 'T I · ~ e 1tt e fellow" who wants to fly through a

metropolitan area th b d . ' e roa cast can be sampled for a ~1cture of how best to avoid the pattern swarm. Big or little, fast or slow ATIS spells ·1m d . ' prove service.

Currently, ATIS is being earmarked f h 1 . or eavy vo ume locations. We can also see a need at th · e many mrports not counted among the top ten twenty or th. t Th ' , ir y. ese are the towers where a comparatively light traffic load means that a controller has to double on posit1"ons H t d . . . e, oo, nee s an assist which ATIS can provide.

When these several dividends are counted Automat· T

. I IC

erminal Information Service means valuable time for the controller and continuous availability for the pilot _ and

these translate to increased safety, a common and constant effort with which we are all concerned.

ICAO

Twentieth Anniversary of Chicago Convention

Twenty years ago representatives of more than frfty countries meeting in Chicago, USA, signed the Convention on International Civil Aviation. On Monday, 7 December, at the Headquarters of the International Civil Aviation Organization in Montreal, and during the same week at ICAO regional offices in Bangkok, Cairo, Dakar, Lima, Mexico City and Paris, special ceremonies were held to commemorate the Convention which has helped, during these twenty years, to make the aeroplane into a major instrument of world transport.

The Chicago Conference, which was held from 1 No­vember to 7 December 1944, was convened by the Govern­ment of the United States of America, after discussions with other states, to consider the development of inter­national civil aviation in the post-war world. When the Conference opened it heard a message from United States President Franklin D. Roosevelt, which said in part: "Air transport will be the first available means by which we can start to heal the wounds of war, and put the world once more on a peacetime basis ... You are fortunate in having before you one of the great lessons of history. Some cen­turies ago, an attempt was made to built great empires based on domination of great sea areas. The lords of these areas tried to close these seas to some, and to offer access to others, and thereby to enrich themselves and extend their power. This led directly to a number of wars both in the Eastern and Western Hemispheres. We do not need to make that mistake again. I hope you will not dally with the thought of creating great blocs of closed air, thereby tracing in the sky the conditions of future wars. I know you will see to it that the air which God gave to everyone shall not become the means of domination over anyone.

"As we begin to write a new chapter in the funda­

mental law of the air, let us all remember that we are engaged in a great attempt to built enduring institutions of peace. These peace settlements cannot be endangered by petty considerations, or weakened by groundless fears. Rather, with full recognition of the sovereignty and juri­dical equality of all nations, let us work together so that the air may be used by humanity, to serve humanity."

The most important achievement of the Chicago Con­ference was the drafting of the Convention on lnterna­tiona I Civil Aviation. The ninety-six articles of the Chicago Convention establish the principles of international air navigation. They provide for the adoption of international standards and recommended practices regulating air navi­gation, recommending the provision of airports and the installation of navigation facilities by member states and the facilitation of air transport by the reduction of customs and immigration formalities at national frontiers. The Con-

Continued on nncic 3,,

II

1964 Technical Symposium of the British Air Line Pilot's Association

Executive Secretary G. W. Monk represented IFATCA at the 1964 Technical Symposium of the British Air Line Pilot's Association (BALPA), which was held at the Mount Royal Hotel, London, on 10/12th November 1964.

This was a remarkable meeting: BAL PA thinks that a crossroad has been reached - the lessons of the past should be a signpost to the future.

The Chairman of the Meeting was Captain J. R. Jeffrey. On the platform were, in addition, the Vice Chairmen of BALPA, Captain R. T. Merrifield, and Captain L. Taylor, Chairman of the BALPA Technical Committee.

Seventeen papers were read, and an extract of these is included in the Executive Secretary's report on the Symposium, which hos already been distributed to Member Associations.

Following, we are now reprinting some of the papers in full, which ore thought to be of particular interest to Air Traffic Control.

Air Navigation and Air Traffic Control by Wg.Cdr. E. W. Anderson

Introduction

Great minds discuss ideas, mediocre minds discuss topics and women discuss people. For the purpose of this paper, let us try to consider the developing patt"ern of ideas without defining too exactly the devices of the equip­ment that we shall need to transform those ideas into action. Above all, let us try to disassociate ourselves with people, and look at the problems impersonally.

The basic proposition on which the paper has been founded is that British Air Line Pilots, Air Traffic Control­lers, and industrialists are interested in arriving at the truth, at least in the long run. Let us therefore ask a num­ber of basic questions and see where the answers lead us.

Do we need the Pilot?

Automatics are becoming increasingly able to perform routine actions more quickly, more precisely and more consistently than the human. As Majendie pointed out in his classic paper on automation [1] by automatics it is pos­sible to compress into a few seconds of automatic control the output of hundreds of men working over long periods of time in conditions free from the stress of physical dan­ger. Few human pilots can be so presumptuous as to be­lieve that they can compete with this concentration of

human effort.

Unfortunately, the very remoteness of the engineer from the situation in the aircraft introduces fundamental limita­tions. The automatic system can only undertake those tasks which the engineer has designed it to undertake, and it can only undertake them in the environment that the engi­neer has predicted. If the environment has not been fore­seen the automatics can lead the aircraft into disaster. For ~xample, an automatic landing system cannot take cognizance of civil disturbances or blocked runways. There is thus an engineering requirement for a human operator within the aircraft able to appreciate when the equipment

is operating in an unforeseen environment.

There is also a passenger demand for a captain. The human being is unwilling to trust his whole future to a black box that has no fear of destruction. He has a psycho­logical need to know that the rnan ultimately responsible

for his safety is shoring his environment.

Before finally accepting the requirement for a human captain of an aircraft, it is necessary to examine the limi­lc1tions of the human being. He is, compared with auto-

18

matics, slow, inaccurate and inconsistent, but adaptable. Unfortunately, he occasionally makes mistakes. It is a cha­racteristic of these mistakes that they are nearly always recognised by a second human being and indeed generally recognised by the originator of the mistake when pointed out. It follows that the real requirement is for two human beings rather than one except where the flight is relatively short and simple.

The requirement for two human beings is only valid if the two can communicate freely. In practice, a captain may be emotionally unwilling to be corrected by his junior just as a junior may be emotionally unwilling to correct his captain. However, there are airlines operating to-day which organise the cockpit work load so that the captain is able to adopt a mainly monitoring role and therefore can devote his attention to commanding the flight.

With a captain and a co-pilot in an aircraft, it ought to be possible so to automate the rest of the equipment that no other crew members are required to navigate. It may take a considerable period of time before this can be accomplished. Nevertheless, there would seem to be no fundamental reason why progress should not eventually reach this goal.

Can Aircraft be navigated by Air Traffic Control?

Radar only covers a relatively small fraction of the sur­face of the earth and, outside radar cover, navigation must be entirely under the control of the captain. Radar cover­age is naturally provided in high air traffic density areas and, in these areas, the problem of collision has become more pressing than the original navigational problem of finding the way. Since no single aircraft can be equipped so that it can have information of the intentions of all other aircraft in its vicinity, collisions have to be avoided by separation exercised by Air Traffic Control authorities. Furthermore, even if an aircraft were equipped to avoid an imminent collision, unilateral action could lead to even greater dangers subsequently.

Unfortunately, although Air Traffic Control has to direct aircraft in high traffic density areas, it can only par­tially navigate them. This is for two reasons. Firstly, the aircraft has an intention which is positive whereas the aim of Air Traffic Control, so far as collision is concerned, is negative. This is appreciated by Air Traffic Controllers who

see their task as assisting in the safe and orderly fllow of air traffic. In this very definition, there is an admission that the intention or aim of a flight must be defined by the captain. All that Air Traffic Control can do is to seek a modification to that intention so as to avoid a dangerous situation.

The second problem is practical. It has been pointed out [2] that there are three navigational loops:

a) The positional loop by which deviations from the in­tended path of the aircraft can be recorded.

b) The course and speed loop by which the velocity need­ed by the aircraft to achieve its intentions is generated.

c) The control loop by which the aircraft is accelerated or its heading altered in order to achieve the velocity needed to achieve its intentions.

It is now evident that an Air Traffic Control system can­not navigate an aircraft. It is able by radar to measure the position of the aircraft. However, it cannot measure speed instantaneously but only over a period of time suf­ficient for an appreciable distance to have been covered. Still less can it record acceleration.

It would be possible in theory for an aircraft to signal back to the ground information regarding velocity and acceleration. However, this information would have to be related by the ground controller or ground computer to the type of aircraft and possibly to its loading. Further­more, it is difficult to see how the system could allow for unexpected circumstances such as the loss of power of an engine. The requirements for communications and the de­mands on the ground organisation and computer would be excessive if each aircraft were to receive the individual attention that its captain can give it.

It is now evident that Air Traffic Control can only play a limited part in the navigation of aircraft. In high traffic density areas, where the radar coverage is good, it can monito: the position of the aircraft and advise the captain acco:dmgly. However, it cannot measure the velocity of a~ aircraft e~cept over an appreciable period of time and stil~ less can rt control the aircraft by measuring its accele­rations. Therefore, the captain must operate the course and speed and the control loops.

Must Work Load increase?

Sinc~.Air Traffi.c C?ntrol can generally only assist with t~e pos.itronal n~v1gat1on loop, it has to transmit this posi­tional mformatr~n to. the aircraft and the captain must consequently ad1ust his velocity by control of his aircraft. As traffic densities increase and the relative positions of aircraft ha.ve to be more exactly controlled, so the volume of instructions must increase. As a result, the work load demanded by Air Traffic Control must tend to increase with time. This is an inevitable feature which is the com­mon experience of all pilots and it implies no criticism of Air Traffic Controllers. The denser road traffic becomes in our city streets, the more signs spring up, the more fre­quent the incidence of traffic lights, and the number of one way diversions is increased.

However, as Captain Masland has pointed out in his concept of aerial motorways [3], flow control can be achieved without a multiplicity of regulations. But there seems to be no way in which this navigational work load

can be permanently lightened in terminal areas of increas­ingly heavy density although the burden of passing in­structions may be reduced by various means. In particular, the passing of positional information from the aircraft to the ground may be made automatic although the captain will, if he is conscientious, feel the necessity to monitor this information. However, the work load can be lightened if we can simplify the operation of the course and speed or velocity loop and the control or acceleration loop.

The control loop has already been largely automated by autopilot and autothrottle. There are still gaps in the control, the two most noticeable being the climb away and the let down, particularly the end of the let down when the aircraft is descending close to high ground, into denser traffic layers and often into a converging traffic pattern. The first requirement is therefore to improve the automatics of aircraft and to extend their use to all regi­mes of flight. Perhaps it is not inappropriate in the con­text of Air Traffic Control to mention not only the value that can be gained by extensions such as auto-landing, auto-overshoot and auto-take-off but also the possibilities of speed control for aeroplanes to produce a measure of collective automation to assist the controller.

The second major requirement is to improve the auto­matic coupling to radio and other inputs. This can evident­ly make a major saving in the work load. The saving must be extended not only to the horizontal plane but also to the vertical plane. Height holding is as valuable as a means of lightening the load as coupling to a VOR radial.

Finally, there are the areas outside which Air Traffic Control cannot exercise any positional control. For these areas of lower traffic density, the crew must navigate the aircraft. Fortunately, the need for Air Traffic communica­tions is reduced and therefore, provided there is automatic coupling and good automatic control systems, the work

load will be appropriately lightened.

In all these elements the inclusion of the pilot in the control or monitoring l;ops emphasises the need for im­provements in presentation. Rolfe and Huddlestone [4] have pointed out that methods of displaying flight control information are not improving whereas the work load in

the cockpit has reached saturation.

There are two difficulties that tend to inhibit the deve­lopment of improved displays. Firstly, the pilot will be unwilling to accept a new type of display until it is proven in operations and it cannot be proven in operations until he has accepted it. Secondly, the building brick philosophy admirably developed by ARINC for many excellent rea­sons tends to discourage a departure from the established pattern and, in particular, militates against the develop­ment of a unified system.

It may also be interesting to examine that fashionable device the moving map display. The map element portrays the ground below and this could have some value when not over the sea and not above cloud were it not for the great additional work load involved in the pastime of map reading. Nor will the airline pilot live to an old age if his avoidance of high ground depends on the reading of heights and contours on a moving map display.

A display that shows the position of an oircraft com­pared to th~ position that the captain intends can provide a most useful check provided that it does not demand a large additional work load and that it is operoted by a

19

system independent of the main navigational system. At least one airline uses a pictorial display in this way. This particular display is orthogonal but it could well be that a different form of display could be more effective even if it were completely symbolic.

How will Navigation develop?

In the past, control systems and velocity systems such as compasses and speed indicators have been duplicated in aircraft for increased safety just as the pilots are dupli­cated. This is possible because the information on which these systems depend comes mainly from sensors within the aircraft or from stable phenomena such as the force of gravity or the earth's magnetism. Positional navigation on the other hand has traditionally relied on electro ma­gnetic waves, either short and precise light waves in the instance of visual or astro systems, or longer and less pre­cise radio waves in the instance of radio navigational equipment. These waves are subject to interference by weather. It is therefore essential to navigate by systems with characteristics differing according to the weather and to support visual by radio and perhaps radio by astro. This use of complementary aids is sometimes known as the

belt and braces policy.

It is worth noting that this policy is now in the process of being undermined. In inertial navigation, we have a system that is basically self-contained within the aircraft and dependent only on the earth retaining its circular shape and in the continuation of gravity. Should either break down, it is unlikely that man will have further inte­rests on this planet. Therefore, it can be said that inertial navigation is practically immune from interference. The belt and braces policy therefore fails. If the inertial braces break, then the answer can be a second pair of inertial

braces.

The introduction of inertial navigation is of importance for another reason. Since it depends on measurements of acceleration, it is able to contribute not only to the posi­tional loop by double integration but also to the velocity loop by integration and to the acceleration or control loop directly. Hence, it is the ultimate in navigation. Never­theless, from the point of view of reducing work load, it has no obvious advantages over a radio track guide. The captain of the aircraft must still define his intention and ensure that his aircraft velocity is being controlled so as to fulfil that intention within the limits imposed by Air

Traffic Control.

Unfortunately, inertial navigation is a dead reckoning syslem whose accuracy decreases as the journey progres­ses. It is therefore necessary to replace it at the end of the flight by an aid whose accuracy increases as the jour­ney reaches its conclusion. Visual and radio. system ori­ginating in the airfield must therefore be retained for the

final stages of approach and landing.

As aviation has developed, so the division between the short range or pilotage aids and the classic long range position finding aids has changed. Thirty years ago, a flight to Rome was a long range operation. To-day it is undertaken with the use of terminal aids. The extension of radio aids has therefore changed the balance between en route and terminal navigation. Furthermore, short range radio aids have been extended into the long range field.

20

Loran, Dectra and Consol stretch out over the North Atlantic.

The development of long range radio aids is hindered by difficulties that arise in forming international agree­ments. In 1899, all the countries in the world agreed that longitude measured from 0° to 360° either way was better than longitude measured from 0° to 180° both ways. How­ever, since they could not agree which way to measure it, they had to leave it as it was.

If nations can learn to work together, radio aids may develop to the point where there is little requirement for inertial systems. However, if international agreement re­mains a fragile plant liable to be replaced at any instant by the weeds of enmity, then inertial navigation, which operates on laws of nature rather than by the rules of man, must become more attractive.

Summary

A broad review of the problem of Air Traffic Control and navigation suggests that:

a) The captain, assisted by a co-pilot, will continue to be responsible for operating his craft.

b) Air Traffic Control will increasingly assist the captain to avoid dangerous situations but will not exercise direct control over the aircraft.

c) Navigation will tend towards increased use of radio rather than inertial navigation only if the laws of man can become as universal as the laws of nature.

d) It is essential to reduce the work load in the cockpit. Automatic data transmission is a first step. Improved displays could help but maps tend to increase work load.

Acknowledgments

This paper could not have been written without the kind help and advice of Mr. Peter Cane, Operational Ad­viser to Smiths Aviation Division. Thanks are also due to Mr. K. Fearnside, Technical Director, for permission to publish this paper. Nevertheless, the views expressed are not intended to represent the views of the Company.

References

[l) A. M.A. Majendie, Automatic landing - the role of the human pilot, !AS man machine competition meeting, Seattle, 1962.

[2) E. W. Anderson, A philosophy of navigation, Journal of the Institute of Navigation, Vol. XIV, page l, 1961.

(3] W. M. Masland, North Atlantic air operations and SST, Fifth ATC Convention, Bournemouth, October 7th, 1964.

[4] Rolfe & Huddlestone, The display of information to aircraft: pro­blems and methods, Meeting of the British Association for the Ad­

vancement of Science, August 26th - September 2nd, 1964.

Yugoslavian Air Traffic Controllers' Association founded

On 20th October, 1964 the Air Traffic Controllers' Asso­ciation of Yugoslavia was founded. I FAT CA President L. N. Tekstra already discussed the possibilities of joining IFATCA with the Vice-President of the Association, Mr. Veres and with Mr. Mrakovic, a member of the board of Directors.

Air Traffic Control, Navigation, by Group Capt. E. A. Johnston, o.B.E., R.A.F.*

and Communications - the next ten Years

A Forward Planner's View of Problems and Solutions

Introduction

I propose to outline very briefly the implications of the changes in the nature of air operations that we foresee over the next 10 years; to utter some personal thoughts on the basic relationship between navigation, air traffic con­trol and communications; to indicate how we planners see solutions developing for our U.K. Domestic and our North Atlantic problems; and finally to outline how far our plans encompass the problems of the SST.

The Changing Nature of Air Operations

Over the next ten years there will be a 40% increase in civil air transport activity in U.K. domestic airspace. Unless there is a radical change in travel habits and a relaxation of noise abatement requirements, it will all be crowded into the same busy periods of the day. It will lead to more flying on routes outside present CAS, either because exist­ing CAS will be too small or because new traffic generat­ing centres will be developed outside CAS. The envelope of flight profiles used by civil transport aircraft will nar­row as a result of growing use of turbojets on all stage lengths - in particular, climb profiles will become increas­ingly homogeneous. The growth of other civil activity, mainly in the lower levels of the airspace, is difficult to predict: it could be substantial.

We suggest present indications are that, the overall proportion of military traffic peaks will decrease and may reach parity with the peaks of all civil flying early in the 1970's. I include in the military the considerable fleet ope­rated by the Ministry of Aviation and the Industry on multi­farious tasks of Research Development. The vertical distri­bution of military traffic will veer proportionately towards the lower levels but it will still predominate both the UAS and the LAS. Performance will tend to increase; there will be a continuing requirement for dispersion: and therefore, of course, no reduction of demand for airspace in the middle and lower levels.

Over the North Atlantic the "busy hour" rate is expect­ed to climb from 19 per hour experienced this year to 35 per hour in 1971, but in spite of the increased flexibility of the second generation of subsonic jets they will still want to fly near the optimum minimum time tracks in the narrow height band between FL's 310 and 370.

Towards 1975 the SST could dominate the North Atlan­tic situation with something like 250 movements in 24 hours and a peak flow rate of 23 per hour. Domestically, both sociological and technical considerations will dictate the evolution of novel ATC procedures for the SST.

But new ATC procedures will be needed anyway. With­in CAS, we shall have to pack more aircraft into the same limited time period on existing routes. Whatever improve­ments we make in control efficiency, it boils down in the end to putting aircraft closer together. This means a bet-

Deputy Director of Control (Plans) 2. National Air Traffic Control Service.

ter navigation capability in those areas where navigation is the limiting factor, and it means better communications, not only between pilot and the ground organization but also between elements of the ground organization.

There are genuine and formidable problems in extend­ing the volume of the U.K. airways system as currently conceived; it can be done only at the expense of airspace freely available to other categories of user unless we can evolve a category of controlled airspace which enables non-route traffic to share the same airspace as air-route traffic without unacceptable penalty. After all, the basic problem is not to enlarge the areas in which a specialised concept of control is exercised, but to protect transport operations without placing prohibitions on the movement of other traffic.

In the lower airspace (i. e. below 5 OOO feet outside CAS), problems vastly outnumber solutions; we have the widest divergence in speed, manoeuvrability, equipment, crew competence and mission requirements; we have a growing general aviation and an increase of high per­formance military traffic; we have an ever growing popu­lation of low-density civil airfields which are bound to have increasingly complicated interfaces with the swarm of military airfields; and we have the immutable laws of propagation which militate against centralized, systematic solutions. We are far from an overall solution - and it looks as if we shall be making ad-hoe answers to indivi­dual questions for some time yet.

In short, the story is one of a growth in total flying coupled with inevitably a greater degree of intermingling of civil and military traffic. In general interest, all users must accept increased constraints or commitments simply because the U.K. consists of a small amount of airspace, a large number of traffic generating points, and every­thing from supersonic aircraft to gliders. In the long run there is not (except in isolated instances) enough airspace to reserve parts of it permanently for particular users. Inevitably we shall have to evolve what will amount to a system of priorities - applied not to a particular group, but to individual aircraft and even then varying with the phase of flight.

The Inter-relationship between Navigation, ATC and Communications

Regardless of ATC requirements, operators have re­quirements for a navigation capability in all three dimen­sions. These requirements are very diverse indeed in terms of both nature and accuracy, and are determined solely by the operator's assessment of the factors conditioning the job he has to do. These jobs are very diverse - they include basic flying training, advanced weapons system trials at supersonic speeds and scheduled transport opera­tions, to name only three. The principle task of en route ATC is to enable all sorts of operators to go about their business without endangering each other. A TC ought not, therefore, make requirements for en route navigation more

21

stringent than those which the operator needs for his pur­poses.

Now this is a very contentious statement and opens up the whole question of ATC methods and systems. The pri­mary function of ATC is to keep aircraft a safe distance apart from each other. In order to do this, the controller needs first of all to know where the aircraft are. It is here that the function of navigation and the function of ATC begin to cross wires. Without radar at his service, the con­troller can only derive his knowledge of aircraft positions from a pilot's report of where his particular navigation system says he is. Hence the dependence of civil control systems to-day on navigation capability.

In order to fulfil! his safety task, the second thing the controller needs to know is the intention of aircraft. In a control system based on a route navigation system - as the airway system is - the known accuracy of the naviga­tion system, coupled with the flight plan, provides that in­formation. The air/ground communications link provides him with x, y, z, and amendments to flight plan times. The reverse link provides, essentially, the pilots with instruc­tions necessary for keeping the aircraft a safe distance apart.

If the navigation capability is so crude that the separa­tion standards are enormous the control system becomes saturated by a low traffic level. If the operators cannot accept the penalty they cry for a better navigation capa­bility to reduce separation standards. So long as the only problem is that of fixed route traffic flying o~ commercial schedules, this general line of development 1s capable of considerable exploitation for ATC purpose, because these aircraft, given the navigation capability, can follow plan­ned profiles and routes with great accuracy, al.though .t~ey are not very good at keeping to planned t1me/pos1~1on relationships. So we can envisage close lateral separations on air routes as a major contribution to expedition - pro­vided we can solve the problems of intersecting routes and of non-airways traffic requiring to penetrate the air­

ways.

But this is to look at one category of traffic - route­flying scheduled traffic - in isolation, and I think this is wrong for two reasons. First - although we must pr~te~t this traffic the amount of private airspace we can give 1t may not b~ enough. Second - not all missions ~tall times want, or even are able, to conduct themselves in accord­ance with a fixed navigation capability. So we have to look towards a control system that will protect transport traffic not only from its own kind, but also ~rom other cat.e­gories of traffic both inside and outside airways type air­

space.

Let me therefore revert to my original thesis: that in general en route ATC should not demand a greater navi­gational capability than an operator requires for ~is ~~n purposes, and let me this time postulate the availabil1ty

of radar as a tool.

Few radar systems can give directly to the controller without any further communication x, y, and z accurately and at a high data rate, as well as identity.

The air-ground communication lin~ is nec.essary, as be­fore, to provide collision avoidance instructions. Th~ con­troller can derive from the radar quite a lot about inten-

t . _so long as the aircraft remains in a steady state of ion d h . .

motion. The rapid data rate, moreover re. uces t ~ s1gn1-f1conce (from the collision avoidance point of view) of

22

long term intention as expressed in a flight plan. The first effect of radar used as the main control tool, therefore, should be to reduce the voice communication load; the second is the ability to separate traffic without knowledge of long-term intention at small separation standards which are independent of navigation capability but depend ulti­mately on maneouvre envelopes.

As the density of traffic and complexity of traffic pat­terns rise, one is faced with the problem of breaking the task down within the control organization; when complete­ly random traffic is intolerable, then we can start channel­ling such of it as is amenable to channelling. The capabili­ty of those categories of aircraft which have a high navi­gation accuracy and which wish to fly fixed routes can and should be exploited within an area radar control system. On the other hand, we should not have to channel people who don't want it.

Now what about terminal problems? The main problem of TMA organization arises from the mutual interference of arriving, departing and overflying streams at a number of airports. In low densities aircraft can be cleared on an ad-hoe basis, and, if the operator so requires, radar vec­toring can overcome the deficiencies of a crude airborne navigation capability. Dense streams, however, require for­mal vertical separations at intersections. In the larger and more populous TMAs, traffic patterns must be highly for­malized, knowledge of intention is essential to the con­troller, tracks must be fixed, not free; and separation stan­dards must be low enough not to inhibit the maximum run­way capacity of the TMA. The organization of flow must be such as to cater for the highest levels of traffic that are expected, and the flow must be based on an adequate air­bor~e navigation capability - although in less busy periods some of the restrictions of rigid routing can be removed by the intelligent use of radar vectoring on an ad-hoe basis.

T~e size of a TMA depends on how compactly the over­passing and underpassing network of streams can be orga­nised as well as on the size and number of holding areas ~eeded to serve the main direction of approach. Separa­~1on standards and navigational flexibility are therefore important fa~tors. The ability to fly predetermined curvili­near paths in th~ TMA is a navigational requirement placed upon the flight deck directly by ATC. The accuracy m~st be compatible with the accuracy of the radar which will be used to monitor the separation. In the vertical plane, our in~bility to predict accurately climb and descent path~ leads direc~ly to large vertical separations and wast­ed .airspace a~d indirectly to increased longitudinal sepa­rations. In ma1or terminal areas there is 0 need for instru­mentation in aircraft to enable them to follow determin­able gradients: so that either a pilot can nominate 0 gra­dient h~ intends to follow, or ATC can stipulate 0 range ?f ~rad_ients for particular routes; in both cases the ob-1ect1ve is the ready freeing of altitudes for traffic which might otherwise conflict.

The Development of ATC in U.K.

On Mar~h _ l_st of 1964, the Eurocontrol Agency assum­ed respons1bil1ty for Air Traffic Services to General air traffic in the U.K. upper airspace (i. e. above FL 250). Under an agreement between U.K. Government and Euro­control, this responsibility is being discharged through

NATCS who provide upper airspace services on behalf of Eurocontrol. Eurocontrol has set up a Regional Service in U.K. which provides liaison between NATCS and the Agen­cy HQ to ensure that from day to day Eurocontrol's re­sponsibilities are carried out in accordance with agreed policies and directives. Planning is carried out under the wing of a Joint Planning Policy Committee. Because of Eurocontrol's limited responsibility within U.K., it has to be recognized that the need for compatibility with ATC ser­vices to other traffic is of major importance.

In domestic U.K. airspace, our short term plans include the extension of basic radar cover and the provision of back-up radars with the object of progressively introduc­ing a mandatory positive area control system in the UAS.

Our medium term plans include an extension of radar cover throughout the airways system, its remoting into the air traffic control centres, and stepping up the efficiency of those centres by providing up to date displays and new layouts to reduce the problems of inter-controller liaison. At this stage there will still be three centres, and the air­spaces controlled by them will be little changed, but by 1967/68 they will be operating with new equipment in new buildings at West Drayton, Barton Hall (near Preston, Lanes.) and Prestwick.

Our long term plans - will start about 1968/70 to re­volutionize the control organization in U.K. Here at last we fuse the civil and military ATC development plans, and co-ordinate them with plans for new defence radars and advanced computery. We shall provide over most of the U.K. FIR south of 57N not only solid primary and secon­dary radar cover above 5 OOO feet, but also duplicated electronics and in many cases duplicated installations so that for the first time we will be able to rely on radar data as the basis of separation standards. Within the Airways System this should lead to a radical revision of the rela­tionship of procedural and radar controllers. We will pipe these radars in to the three centres. At West Drayton in particular, in addition to sophisticated display media we shall use a digital computer system for data handling and transfer. At this Southern ATCC we shall handle the major, and most complicated, part of U.1<. control - namely :

1. All UAS south of 57N.

2. All English CAS apart from Manchester TMA and the airways radiating north and west from it.

3. Civil and military middle airspace services up to the Scottish Lowlands, apart from the small area belonging to Barton Hall.

The role of Northern ATCC will be to handle the Man­chester TMA and the airways and middle airspace in the northwest of England and Irish Sea on raw radar with simple flight plan processing until some undetermined, future time.

The Scottish ATCC at Prestwick will operate on modern radar displays but without data processing. It will control Scottish CAS, and offer advisory services on the Highland and Island routes, and will be responsible for service in the whole of the UAS north of 57N. A special UAS control area may be created for the control of traffic in transition between domestic airspace and the Atlantic.

We expect certain benefits: reduced separation stan­dards from the continuous and reliable availablility of

radar data; and increase in the complexity of traffic situa­tions that can be handled; and increased mixing of various categories of airspace users without detriment to the pro­tection that commercial carriers require - because the controller will be able to concentrate on the elimination of conflict.

Of course, there will continue to be some missions, par­ticularly in experimental flying and military training, which at certain phases of flight may not be able to operate within the normal rules of ATC. For these we see no alter­native to temporary airspace reservations.

So much for the control picture. It is all based, on the assumption that in general a navigation capability exists on the flight deck. From the purely civil point of view, ICAO reached its decision in February, 1959 that VOR/ DME should be the standard short range navigation aid until 1975, so we are pressing ahead with the implementa­tion of the current EUM plan. It is to be expected that the VOR/DME, despite any shortcomings, will be in use over the next l 0-15 years or even longer particularly if some­thing can be done to improve the bearing accuracy signi­ficantly. If we could learn to exploit the coupling of im­proved bearing accuracy with the use of DME I am sure, we could make a major breakthrough in our critical ter­minal area problem.

Meanwhile, both nationally and through Eurocontrol we are also supporting evaluation of an alternative, Harco, as a possible contender for the more accurate and flexible navigation system which in our view will be necessary in the future, and we are exercising our minds on the problem of how l"o evolve from one ICAO standard towards its­ultimote successor.

With the growing interest among long range operators in the exploitation of self-contained navigation equip­ments - Doppler and/or Inertial - there is a poiential case for doing some trials on the effectiveness of such equipments used as the primary short-range en-route navi­gation aid with a view perhaps to relegating (in some circumstances) the standard VOR to the status of inde­pendent check on gross errors.

The North Atlantic

Over the North Atlantic, airborne navigation based on a variety of methods is the only source of position infor­mation to ATC, and separation standards are based not only on the accuracy of position fixing but also on the probable errors of estimating future positions. These stan­dards effectively surround each aircraft with 6 OOO cubic miles of empty airspace. It is argued by operators that the maintenance of these separation standards involves signi­ficant economic penalties, although we have our doubts. But certainly they greatly increase the workload on the flight deck and in the centres - in the form of protracted negotiations about onward clearance.

Formal track systems designated by ATC have a greater capacity than o random free-for-all, where aircraft com­pete in an undisciplined way for what they individually estimate to be optimum tracks and levels. The designoted track system based on daily minimum time tracks, and used in a flexible way and only when traffic demands its initiation, is, I suggest, here to stay unless something very

23

dramatic happens to separation standards; we need to find a more scientific approach to estimating and promul­gating the ATC track structure for the day, - this must involve some sort of rationalization of the basic data from which minimum time tracks are derived.

During the last four years there have been extensive studies on both sides of the navigational accuracy over the Atlantic, with and without Doppler, and we on our part intend to extend them into the inertial navigation field. The results so far obtained indicate that present day separation standards are not far wide of the mark for cur­rent navigation practice because of the statistical distri­bution of what we call blunders. But we do see some pro­mise of reduced lateral separation through the use of Doppler (suitably updated by adequate navaids) or com­parable, e. g. inertial, equipment, because the evidence suggests that it reduces the blunder rate.

Studies in vertical separation, although encouraging, have not yet provided enough data to make a case for safe reduction of the separation standard. We feel that it is too early to say whether longitudinal separation can be reduced on the basis of cruise Mach No. procedures.

Better communications do not pay a real dividend until we achieve a major increase in navigational accuracy. A big jump in communications capability, of course, would throw up the possiblility of using the Atlantic area in the same sort of way as we use domestic controlled airspace. The ATC authority would have greater opportunity to re­clear in flight. To satisfy the major need which is to reduce conges~ion by cutting separation standards, would only be satisfied, however, if better navigational data was avail­able for passage along these communication links. This is merely to say that for the Atlantic, good navigational and cornrnunication facilities need to be developed hand in

hand.

Our short-term approach to a reduction in lateral sepa­ration to 90 miles - is largely dependent upon the moni­toring of navigation performance to see that improve­ments are made, upon large across-track errors being reported promptly to ATC, on Doppler or similar capabi­lity, and a continued high standard of navigation discipline on the flight deck. In the longer term we believe we could contain the peaks of subsonic traffic forecast for the early l 970's in a track structure having similar dimensions to to-day's if lateral separation was reduced to 60 nm and longitudinal to 15 minutes. There is no single, dramatic roacl to this goal. In collaboration with the other fiv~ North Atlantic Provider states (so called because they provide the A TC and related services for the main traffic areas) we are preparing a systematic approach along all the lines I have mentioned, which will be aired at ICAO's Special NAT

meeting in Montreal next February.

T awards the end of the next 10 years the SST could dominate the North Atlantic. I will therefore conclude this talk with a few words about the way we planners see the

whole SST problem.

The Problems of the SST

We have, of course, hod supersonic aircraft under mili­tary control for a number of years, and in the UAS radar odvisory area in the Irish Seo hove some joint civil-military

24

experience of the interface between supersonic and UAR subsonic traffic.

In the terminal areas we propose to handle the SST much the same as other jet aircraft. Outside these areas the SST's requirement for rapid climb at high subsonic speeds (which it shares with many military aircraft) coupled with its need for flexible routing indicates to me at least that a formal airways type of system will be unaccept­able, and that one must look towards an area radar con­trol system in the middle airspace as well as in the upper.

Inbound aircraft, apart from what they can do en route, should be able to modify their ETA over a wide range by exercising choice over their transition to subsonic and by varying their descent profiles. ATC can only exploit this potential freedom in the vertical plane with an area con­trol system. The domestic data acquisition, processing and display system which we are planning should, by evolution, be able to cater for this.

Because the SST will be very sensitive to temperature, but much less to wind at operational heights, we expect the desired oceanic tracks to be consistently close together and generally south of the great circle. Unlike subsonic Atlantic traffic, the flow will be mixed east and west­bound - maybe something like 3 tracks each way will eventually be wanted. Within this route structure, of course, the traffic will be remarkably homogenous and we shall hope to exploit its potential for speed control en route. Essential problems we must solve through simulation are the vertical separation of aircraft which require a drift-up supersonic cruise and the maintenance of longitudinal separation between accelerating and decelerating traffic. The problem _of pr_iority during transonic flight is relatively easy of solution given radar cover, although sophisticated computer techniques will probably be needed to solve all three of these ATC problems. This suggests that in the long term, Oceanic control will have to be co-located with a highly sophisticated domestic control centre in order to make use of advanced data processing.

A new emergency problem which we have not yet ex­plored is that of solar flares, which with perhaps as little as half an hour's notice might cause all aircraft flying in the supersonic height bands to request immediate reclear­ance down to heights below 45 OOO feet.

Conclusion

The nub of the problem facing the U.K. ATC planner over the. n.ext. ten ye~rs is t~at wi.thin very small geogra­phical l1m1ts in a climate in which the maintenance of VMC can rarely be guaranteed, we have a large number of traffic generating sources generating an increasing amount of diverse traffic. We can no longer get by with independent planning and rule-making. At some level of management, one must take the decisions for all. It is to this end that the National Air Traffic Control Service has been set up with an integrated civil-military planning staff; and it is because the Deputy Director responsible for long term plans for civil as well as military airspace utilization and ground facilities happens to be me, that to-day you have an active military Officer talking to a symposium of Air Line Pilots.

Secondary Surveillance Radar - the next ten Years by R. Shipley Cossor Electronics, Ltd.

Evolution of SSR

Following the Second World War, there occured a rapid build-up in international air travel. At the larger air terminals the density of air movements reached such pro­portions that it was no longer possible to ensure the safe­ty of aircraft adequately by procedural means. Surplus military primary radars were used with some measure of success to supplement the procedural methods of control.

As the electronic industry swung over to the production of peacetime equipments, technical advances in the design of radars were made, particularly in the elimination of precipitation echoes and ground clutter. However, with the increasing density of air traffic, the higher speeds of trans­port aircraft and, finally, the advent of the jet aircraft, it was realised that a rapid means of identification was needed.

During the war a secondary radar system known as "IFF" had been devised for the identification of aircraft. It was natural that the civil air traffic organisation should turn to this system to ease their identification problems. After international discussions an extension to the military identification system was agreed within ICAO for use by civil aviation. This system is referred to as "Secondary Surveillance Radar" or more briefly "SSR''.

The ground equipment of the SSR system consists of a transmitter/receiver (known as the Interrogator/Receiver, using a common aerial system). Transmissions are made at a frequency of 1,030 Meis and the ground receiver ope­rates at a frequency of 1,090 Meis. The airborne equipment consists of a receiver/transmitter (known as a Transponder). This equipment receives on 1,030 Meis and transmits re­plies on 1,090 Meis. Replies received by the Interrogator/ Receiver are fed into a video processing equipment which decodes the signals and passes them on to the controller's operating position where they are presented to him in an easily intelligible form.

The ground transmissions (interrogations), are com­posed of pairs of pulse signals. In order to differentiate between ground interrogations for different purposes, the spacing or time interval between these pulse pairs is varied. The pairs of pulses are known as Modes.

The aircraft reply consists of a pair of pulses spaced 20.3 microseconds apart, these are known as the bracket. In order to differentiate between aircraft, a number of pulse positions are spaced between the bracket markers. Initially, six pulse positions were located between the brackets. By using permutations of these six pulse positions a total of sixtyfour codes could be achieved. Later, in order to increase the number of possible aircraft reply codes, a further six pulse positions were added between the bracket markers. Permutations of these twelve pulse posi­tions allows the use of 4,096 different codes.

The SSR aerial array has a wide horizontal aperture which produces a narrow azimuth beam width. However, sidelobes from the main beam can also trigger off an air­borne transponder causing large arcs or even complete rings at short ranges on the PPL

In order to overcome sidelobe effects in the SSR system, an omni-directional aerial is introduced, this is known as the control aerial. In the airborne transponder a compa­rator circuit measures the relative signal strengths of the two patterns. The signal strength from the control aerial is adjusted so that it is greater than the strongest sidelobe but not as great as the signal strength in the narrow inter­rogator beam. Thus, when a transponder is swept by the interrogator beam, the signal strength from the inter­rogator will exceed that of the omni-directional aerial and !he transponder will reply to this interrogation. When, how­ever, an aircraft carrying a transponder is swept by a side­lobe the control pattern will have a greater signal strength than that of the sidelobe. The transponder will therefore not reply to this signal.

In 1952 Cossor manufactured a ground interrogator/ responsor and an airborne transponder which employed the 3-pulse sidelobe suppression method. This equipment was demonstrated to the British and United States air traf­fic authorities. As a result of these demonstrations, a fur­ther interrogator/responsor was manufactured, using the 2-pulse sidelobe suppression technique.

The first recommendation of ICAO was for 2-pulse sidelobe suppression, employing Modes A and B, but inter­national argument continued as to the relative merits of the 2-pulse and 3-pulse systems.

At the 7th COM. session of ICAO, held in Montreal, January 1962, several decisions were taken which virtue lly crystallized the ICAO recommendations on SSR. The re­commendations arising from this meeting were:

Where sidelobe suppression is used in ground equip­ment, the 3-pulse method must be used on Mode A. The type of sidelobe suppression used for other Modes is left to the discretion of the national autho­rity. Provision should be made for two additional Modes (C and D). Mode C will be used for altitude read­out. The use of Mode D is not yet designated, but should be allowed for in future SSR equipment. Future decoding equipment should be capable of dealing with 4,096 codes on each mode.

These recommendations at last gave firm guidance to the designers of secondary surveillance radar ground and air equipments. Two main variants of ground equipment were now inferred:

3-pulse sidelobe suppression on Modes A, B, C and D: 3-pulse SLS on Mode A and 2-pulse SLS on Modes B, C and D.

For the airborne transponders the new requirements were:

For international use, the transpu11dei" must be cop­able of operating with 2 and 3-pulse sidelobe sup· pression systems.

25

The transponder must provide for Modes A, 8, C and D.

The transponder must offer 4,096 codes on each Mode.

The additional facilities now required in the airborne transponder virtually inferred a new design. At this time the manufacture of transistors had reached a state where reliablility was at least as high as that obtained from the thermionic valves. Since transistors have the attraction of being lighter than valves, and requiring less power to operate, most transponder manufacturers decided to pro­duce transistorised models. Another desirable feature has been included by most manufacturers. This is a self-test facility which enables the pilot to reassure himself that his transponder is operating satisfactorily.

Implementation of SSR

Having traced the development of SSR to its present status, we can now consider what steps are being taken towards the realization of a working system.

In the USA, SSR has been used for some time. The ope­rational equipment uses only Mode A with 64 codes and has no sidelobe suppression at present, yet in the dense traffic conditions (for example, Chicago), it has already proved its worth and has vindicated the bold decision to "use Mark I and let Mark II come later".

The more conservative (and financially, less well-end­owed) European Administrations have waited for "Mark II" as it were, with the additional facilities. However, things are now beginning to move. The first of the SSR ground equipments in the Southern FIR are installed at London Airport and from July 1 st 1965, it will be a requirement for aircraft using Upper Air Space to carry transponders.

Other European countries, including Switzerland, France, Germany and Holland are now providing ground stations and most others are planning their systems. The introduction of SSR in Europe will be an evolutionary pro­cess, starting from 1965, with perhaps virtually complete coverage over Western Europe by 1968, including altitude

telemetry.

It may be expected that all four modes will be intro­

duced in Europe:

Mode A Mode B Mode C Mode D

Common Civil/Military identification

Civil identification Automatic altitude Future system expansion

with 4,096 codes on all modes.

In other areas of the world, the introduction of SSR will be somewhat slower, since the density of Air Traffic has not yet reached the proportions of that in the West.

The Value of SSR in Air Traffic Control

We have now very briefly followed the history of SSR, had a short description of its operation and considered when it will be available. You will no doubt be asking,

"What has SSR to offer?".

To begin answering this question it may be useful to compare SSR with primary radar. The latter equipment depends on the reflection of signals from solid objects and

suffers from several disadvantages:

26

The strength of the aircraft return varies with the size and configuration of the aircraft and with its distance from the radar.

Weather clutter on the PPI (or, if rain cancellation is used, attenuation of range).

Ground clutter on the PPI (even when MTI is used, sub­clutter visibility may cause attenuation of signals).

Identification is slow, requires manoeuvres by the air­craft and numerous R/T transmissions.

Depending on the radar type, there is either no indica­tion of aircraft altitude, or at best, only an approximate altitude.

Secondary surveillance radar requires active co-opera­tion from the aircraft. The airborne equipment (transpon­der) receives the ground transmission and transmits a re­ply on a different frequency. The SSR system has several advantages over primary radar:

Increased range for less transmitted power. No weather clutter. No ground clutter. Positive identification without aircraft manoeuvres. Indication of Flight Level or Altitude. Reduction of R/T messages for initial identification and tracking.

It must be stressed that SSR is not intended to replace primary radar but must be used in a complementary role unless a 100% airborne fit of transponders is achieved.

Nevertheless, the facilities offered by SSR will give the Air Traffic Controller a more detailed and clearer picture of the air situation, which will be reflected in a better service to the pilot.

In the cockpit, SSR will reduce the workload, since posi­tive identification by SSR code will obviate the need for identification turns and the R/T messages necessary to achieve these manoeuvres.

SSR will also provide some solace to pilots in times of trouble, since the selection of codes 77 or 76 ("emergency" or "communications failure" respectively) will draw im­mediate attention to the state of emergency by automatic alarm and a special display and allow priority treatment by Air Traffic Control.

The application of SSR to Air Traffic procedures are many, but a few which spring to mind are:

a) In airways, the use of codes will allow the Controller to pick out his own aircraft from other traffic.

b) In the Terminal Area, identity can be retained right to touch-down, if necessary, whilst on climb-out identifica­tion will be positive as soon as the aircraft becomes airborne.

c) Handover from one control authority to another is achieved quickly and positively using SSR codes.

d) The greater ranges afforded by SSR will be most ad­vantageous for the early identification of the SST espe­cially in the sphere of Oceanic Control.

The foregoing list may give some indication of the pos­sibilities of secondary surveillance radar. It has been stat­ed earlier, that the application of SSR will be an evolution process. As more experience is gained in its operational use, we can expect a gradual cleaning up to ATC proce­dures, perhaps a greater degree of flexibility and above all, a greater degree of safety in the air.

f AA revised NOT AM Procedures

Introduction

In the United States the NOTAM volume has imposed a considerable burden on the Service A teletype network and has resulted in frequent delays in the transmission of vital NOTAM information. It also increased the amount of material which pilots must review with the result that critical items did not always receive proper attention.

Therefore, early last year, the US Federal Aviation Agency has revised its procedures for handling NOTAMS in an effort to improve dissemination of essential flight information to pilots and other aviation interests.

Strict Criteria for NOTAMs

Under the new procedures FAA issues NOTAMs only on items which have direct operational significance, i. e. only material meeting the following criteria will be trans­mitted on telecommunications circuits as NOTAMs:

1. A landing area condition exists which precludes safe operation of aircraft. This concerns only situations which normally would result in a pilot's or operator's decision to divert aircraft.

2. There is an unscheduled change in, or irregular opera­tion of, any components of the National airspace system which precludes the use of a facility for normal aircraft operations. An unscheduled change is defined as one not planned or foreseen sufficiently in advance to allow for dissemination by other means.

3. Any scheduled and published change to components of the National Airspace System affecting operations which is rescheduled or modified with insufficient time for publication of the new information.

4. New or modified instrument procedures or changes in operating minima are established without sufficient time for publication in advance of the effective date.

Airmen Advisories

Material which does not meet these criteria will be classified as an Airmen Advisory and given local distribu­tion only. Examples of advisory items include fuel jettison­ing, ramps and taxiway defects, birds/animals on landing field, and man/equipment on landing field.

Excessive Wordage avoided

Other changes will include elimination of excess word­age from NOTAMs and distribution of a daily NOTAM summary.

The new procedures are expected to reduce by 50% the amount of NOTAM (weather) information transmitted on the vital Service A teletype circuits.

The NOTAMs are normally issued by FAA Flight Ser­vice acting on information provided by Agency personnel or members of the aviation public. The station puts the information on its local circuits and may also broadcast it to pilots in the immediate area. In addition, the NOTAM goes on the Service A network appended to the station's weather report and is repeated each hour until the con­dition is corrected.

New Techniques

To further reduce the Service "A" load and help assure time for transmission of time-critical data, new procedures were developed. These changes include adding a serial number, eliminating the word NOTAM, eliminating (in most cases) the date (time group) creating a NOTAM sum­mary, and processing NOTAM data at a central point in the system through use of automatic data processing (ADP) equipment.

NOTAM Components

Under the new regulations a NOTAM shall contain the following:

1. The Automatic Data Processing (ADP) Code.

2. Three letter identifier of the transmitting station.

3. A serial number.

4. The location or facility identifier, call sign, or name of the affected aid, airport or location, if different from that appearing as item 2.

5. Information to be distributed, using the NOTAM Code, supplemented as necessary by authorised abbreviations and contractions, or plain language when the NOTAM code does not accurately and fully describe the con­dition reported. Reference to the AIRGI* is included only when directly applicable to the specific item re­ported.

6. Date/time group in GMT only when the condition will occur subsequent to the time the NOTAM was sent; absence of date/time means that the reported condi­tion is current.

7. Two or more NOTAMs, each assigned a separate serial number, may be included in one transmission, preceed­ed by one ADP Code. The "NOTAM to follow" (NTF) Code must be inserted between each NOTAM. The NTF Code is not used when the "End of Message" (EOM) Code terminates a NOTAM.

Note: The word "NOT AM" has been deleted; the ADP Code will identify the transmission, on Service A, as a NOTAM.

NOTAM Serial Numbers

Each NOTAM i.s assigned a serial number. The serial num­ber provides a method:

1. For accountability of NOTAMs transmitted by a faci­lity.

2. Of reference foi" servicing NOTAMs in the ADP equip­ment.

3. To indicate hourly (in the Al scan) those NOT A Ms that are still current.

AIRGI - Airmen's guide. A bi-weekly publication contc11n111g tabu·

lotions of air traffic control and air· navigation facilities. rnrports

and airspace; and special notices and other inform lion of on ope

rational nature concerning flight safety.

27

NOTAM serial numbers consist of one or two numerals to indicate the month of issuance; a slant mark, and one or more numerals to identify the chronological sequence of each NOTAM. Numbers are assigned consecutively and start with the number 1 for the first NOTAM issued at or after 0001 Z on the first day of each month. A serial num­ber for the sixth NOT AM from a facility for the month of March would simply be 3/6.

Normally, separate serial numbers are kept for each Flight Service Station (FSS) and each major location assign­ed to an FSS as tie-in facility, e. g., Washington would maintain a set of numbers for DCA, a separate set would be kept for Baltimore (BAL) and a third set for Dulles (DIA) NOTAMs. Smaller assigned locations would be incorpo­rated in the DCA serial number sequence.

The assigned serial number of all current NOTAMs (CNI - current NOTAM indicator) is appended to the hourly weather reports in the A 1 scan, until cancelled.

To cancel a NOTAM, the same serial number as assign­ed to the original NOT AM is used, preceded by the letter "C", e. g., C 515. When data appearing in a NOTAM is transferred to a printed publication and it is desired to cancel the NOTAM but not the data, the cancellation will carry a notation such as: "TSFRD to AIRGl",or other publi­cation as appropriate. For example: ABC CS/5 TSFRD to AIRGI.

To cancel a skipped serial number, a cancellation notice is transmitted, followed by the words S/N Blank, e. g., "C6/7 S/N BLANK".

In case two NOTAMs are sent with the same serial number, that number will be cancelled and the NOTAMs will be retransmitted, each with a new serial number.

When a NOT AM has been drafted but the condition is corrected before the original NOTAM is transmitted, the number is reserved for assignment to the next NOTAM issued.

NOTAM Transmission

In order for NOTAMs to conform to their intended dis­tribution pattern, and be processed by Automatic Data Processing Equipment, the data on the paper tape is pre­ceded and followed by specific preselected coding func­tions.

The first function on the paper tape is the ADP Code. The ADP code conditions the equipment to receive the data that follows. The National Flight Data Centre (NFDC) ADP equipment is arranged to begin receiving upon re­ceipt of the ADP Code, and to stop receiving upon receipt of the EOM Code. The automatic features associated with Model 28 teletypewriters (used by FAA) may be arranged in the same manner so as to print out only NOTAM data and suppress print of weather data. Conversely, it may also be arranged to print out weather data and suppres­sing NOTAM data by a reversal of the automatic action associated with the code.

To permit correct processing of the data, NOT AM in­formation must be transmitted in the following sequence:

1. New NOTAMs.

2. Cancellation notices.

3. Current NOTAMs (CNI).

Entries for which information is not available are omitted.

PATE 11 18-64 FILE MAINTENANCE PAGE

Tl"E 15CO

FSS NOTAH NUMBER

•••AAA AAAAAA •••AAA AAAAAA •••AAA AAAAAA oooAAA AAAAAA oooAAA AAA AAA

oooAAA AA AA AA •••AAA AAAAAA

oooAAA AAA AAA •••AAA AAAAAA oooAAA AA AA AA

oooSS/ cc cc cc oooSS/ cccccc

oooS/ cccccc •••SI cccccc

STATUS

FSS UNKNOWN FSS UNKNOWN FSS UNKNOWN FSS UNKNOWN FSS UNKNOWN

FSS UNKNOWN FSS UNKNOWN

FSS UNKNOWN FSS UNKNOWN FSS UNKNOWN

MISSING REPEAT CNltS MI SS I NG REPEA_T__<:!il! S

MISSING REPEAT CNl,S HISSING REPEAT CNl,S HISSING REPEAT CNI,S

NOTAM CONTENTS

FHU•l0/2AP 11/100 FHU 5040 113/39/21/0603/994 115 1100 24625 / PAM WlOXlF 180/69/65/33021005/RVl/4- VSBY SW21/2 WNO VRBL / TCM WlX3/8FK 261/37/35/0000/028/RVl& WNO LIVI 302 RZERO f / OOO 15// RZERO WR18 IGVW 8E5010 l97/35/28/0410Gl6/008/HAG03 I PAM COR 1500Z WlOXlF 180/69/65/3302/005/RVl/4- VSSY SW21/2 WNO VRBL/ 207

~6 ~~MR~~~5Z -XE5103/4FK 69/65/3505/005/RVl/45 FK7 VSBY NW-NEl/2 93.08•150E8025 278/25/21/2005/H/SC2AC8 603 EG E402FK 260/2312113102/018/SCl0-36 77 22t 1904/995

ZFJ •llj_~)(X Bi>_!F:__!I _________________________ _

91 MSP 11131 STP QAPOH 181600- 181800•11/20AI ll/22AN ll/29XX

603 162/ RZERO

oo•S/ cccccc oaoS/ cccccc -=-=-~---=-=-=~-~MISSING~~AT~C~N~l,GS.__ __________________________________ ~

oeo-/ cccccc •••-/ cccccc ---:,----=:-=-::-=---:M-:--:1;-;:S-;;-S.:I N"'G==---;;R-r:E-nP~E A..-TT CN I, S- ______ 5 _____ -

HISSING REPEAT CNltS 66 °6• 66

--------------------------

ooo/ cccccc •••/ cccccc

MISSING REPEAT CNl,S MISSING REPEAT CNl,S _19_£_ ----- ----- ----------

_.:....:...::.:.__ ___ .=_:::-==-_o.___.

ABE 11

oooABO cccccc ABO 11 8 ABO 11 9

llBR 11

----~-----

•••ACK cccccc

MISSING REPEAT CNI,S FAILED TO REPEAT--2

DELETED -

FAILED TO REPEAT

AP

--------- -----------------------------------MISSING REPEAT CN!,S AV-AK

Sample of weather and NOTAM distribution.

28

NOT AM Summary (NOSUM)

Once each day all current NOTAMs are compiled and transmitted on the Service A system. Its two-fold purpose is to provide:

1. A single reference document within a facility for NOTAMs.

2. A daily compilation, in plain language, of currently advertised conditions.

The summary is kept current by each facility through recording of individual NOTAMs and cancellation trans­missions to the NOSUM and through checking the serial numbers of current NOT A Ms as appended to the hourly weather report.

A separate NOSUM is prepared for each of the Series A area circuits. The contents include NOTAM information received from the same locations whose surface weather report appear on the circuit involved.

The NOSUM heading contains:

1. Abbreviation of the origination facility - FDC.

2. The word "NOSUM".

3. Abbreviation of the month.

4. Six-figure date-time group (Greenwich).

5. NOSUM.

Example FDC NOSUM JUN 010530.

The "New Look" of NOTAMs

Examples of a VORTAC outage NOTAM, appending the data to subsequent weather reports, the innage NOT AM and an example of how it would appear in the NOTAM Summary are given below. Comparison is made between the old and new systems.

Old

Outage DCA NOT AM QAPES 061422

Weather DCA ... 992 QAPES

lnnage DCA NOTAM QAPOK 061547

Summary None

References

FAA Notice ATP 7300.1, CHB, 16. l. 1964.

FAA Order OA 7930.l, 8. 2. 1964.

New

DCA 416 QAPES

DCA ... 992 DCA 4/6

DCA C4/6

FDC NOSUM 061530 DCA 4/6 VOR OUT

FAA Advisory Circular AC 210-1, 8. 2. 1964.

The New Look in NOTAMs, by Ernest G. Rice.

(Internal publication of the FAA Operations Branch.)

FAA press release 22-64.

Ut UtlOO SiiiiUFOC NOSUH DEC l 70659SiiUI# ABI 12/12 BWD RWY 17/35 CLSO ABQ l-27l5A/C-F-REQlZ4.3 NOW 124~---· ACK 12/17 FHH UHF-OF COHSND ACK1271a··FHHDF-305-~4 COHSND --­ACK 12/19 TUK CON STN HAINT 194KC 171500 ACT 10/6 TPL RWY 11/29 CLSO AGS 12/6 SBH FAC OCHSND HW CHSND 385KC AKR l-2/1z·A-TC_T _ii1-.7-NOW 121~9 - ----ALB 11/4 RBCNO ALB 11/5 LOU0'°"0'7N~AR=P=T~N~E=N=D~NSR~.iWY EXTOi)6-0FT. NS CLSD HANGER T·o---s­

ENO. RNWY 2 B CLSD INTIHL Y NOV & DEC. W ENO EW CLSD FH INT NS ALB 12/24 RWY 15/33 CLSD AHG 12/1 ARPT CLSO Ai.fof2/6-.Ao"3ARPT-CLS_D ___ - -- - -·-·--

AND 12/9 TDC VOR/VOICE HAINT TIL 172200 Aoo-i-219 4G9 RWV CLSO-- --- ------ ------------ -----

ART 10/2 DUFLO ARPT NY NE/SW RWY CLSD ART 12/1 RWY 1/19 CLSD ATL 10/45 LCZR RWY 9 UNUSBL EXCP FRONT CRS & 45DEGS EITHER SIDE ATL 12/19 PAR ELEY HAINT··· -- - . - ---------- ----------

ATY 12/1 TACAN AZI UNUSBL 218/238 BTN 19/25 HI AUW 11/4 LNL ARPTCLSD-- ICi:--S-NW-WINTER-HO-NTH·s:-·rnoG-AND RNLY-LCt"S

ON REQ WITH ADVANCE NOTICE FDNE 547-3777 LNL. AUW 11/5 HANITOWISH WATERS ARPT CLSU AVP 12/19 TACAN SHTDN EXTOO TO 12/17 AVP-12/20 TOH -TAC-AN NO T IL 12/ l 7 AXN 12/1 BRAINERD CTL ZONE EFCTV 12/10-12/31 0700/1930 LCL BAC 12/-9-BALLOON-RLS BGNG 161400-Tl(--2400 DAILY UFN. -F .. ToWSON--RD-­

LCTD BAL ASNDG 1000 FT PER HIN BALLOON DIA lOFT SUSPENSION DEVICE lOOFT 3LB PAY LOAD NO TRACK EXP-CO To REACH lOOOOOF I IP.PACI AREA UNKN.

BDL ll71Y ISCAND ARPT-CLSD-­l!DL _ _1_2/41 BAF RWY 9/27 CLSD BFD 12/5 POTATO- CITY-AR·P-CC-(SD-FOR-WINT BGH 12/12 LCZR-GS RTS LCZR UNUSBL LHH-5 NH BI L 12/3 RYEGAT E ARPICVJru~6;.;.;lN=s.;;N_W=.:..:.:.~.-:.:.c-----------B I L 12/10 LAVINA MONT ARPT :cvRD 4-6IN CRUSTED SNW BIL 12/20 PAVED SF~Jfol IN PACKED SNM BIS 11/7 D65 ARPT OPEN SKI ACFT ONLY BIS 12/1 67D ARPT CVRD BY SN:.::Wc:....:..2....:_:c.7:.::l~N-D-R-F~T-S-R~C~M~D-S~K~l~S~bN~(~y~---BIS 12/2 67D LNOG AREA FAC NO BIS 12/3 HAZEN NDKT OK SKl-EQPDAC°FTON[Y BIS 12/9 95D ARPT OK SKIS ONLY BIS 12/10 RWY 12/30 CVRD 4IN SNW DRIFTS CVR 50 PCT BKT 12/4 R6602 CLSD SFC-18500FT TIL 190000 llLF 12/ l PSK V-ORTAC MAINT-Sei . .;._~.c:..=.--=---'-'------------BLI 12/2 RNWY 2/20 PERHLY CLSD BOI 12/10 IDAHO CITY ARP.-CLSD BOI 12/11 GS NO ea·s 12/ lSA"PTH'~L"G=T-B~A~R~/-S-F[~4-R~N0-1-1-c-A-e-1~12~7-2s--··

:g~ g~~~ !}:I~!~E2 ~~~~.:..T,...;~~~~~:_:::D _______________ _

BOS 12/28 FIT RWY 2/20 CLSD BRL 12/1 C20 ARPT CLSD BRO 12/1 RWY LGTS NO 13R/31L CLSO XCPT LGT ACFT OALGT 1217-4/10 BTL 11/10 TACAN NO/DHE OK BTR 12/7 TACAN MAINT 1/4-1/25/65 BUF 11/5 BATAVIA NY GENESEE ARPT RNWY 10/21! OPENED Osf PAVED sFCS CAE 12/1 OM NO

Sample of NOTAM Summary.

University of Birmingham Aviation Courses

The Electronic and Electrical Engineering Department of the University of Birmingham (U.K.) is offering a series of twelve month Postgraduate Courses based on a combi­nation of lectures, tutorials and laboratory and project work. The Courses lead to the degree of M.Sc. for students already holding a Bachelor's degree or the equivalent, or to the Diploma in Graduate Studies for Non-Graduates. The following topics are available:

Information Engineering.

(Communications, computers, and control, together with either solid state devices or microwave engi­neering.)

Air Traffic Engineering.

(Radar and navigational aids, air traffic control, computers, communications and traffic studies.)

Solid State Electronic Engineering.

Control Engineering.

Machine Control Systems.

Application forms, further details and notes on financial assistance, may be obtained from The Registrar, University of Birmingham, Edgbaston, Birmingham, 15.

EH

29

The Air Traffic Control Association's Ninth Annual Meeting

by Maurice Cerf

Atlantic City - October 1964

"Air Traffic Tools for to-morrow" was the theme of the ninth annual meeting and exposition of the Air Traffic Control Association of the United States. Indeed, this theme was both timely and logical, because development in avia­tion is in the process of reaching quickly a dramatic point when equipments cannot be allowed to lag behind. SST is at the door step, bringing along a batch of new problems for Air Traffic Controllers who, too often, have to make do with whatever obsolete equipment they have plus a good deal of common sense and inventive spirit. Well, the Air Traffic Controllers who attended the ATCA meeting cer­tainly went back to their respective facilities convinced that the tools demanded by to-morrow have been design­ed, tested, evaluated and will, eventually, be put at their disposal.

While the ATC Council sat in Executive session, the par­ticipants had the possiblity of devoting their attention to a number of lectures, panels, symposiums and forums, they could also join conducted tours of the NAFEC facility near by, or visit the industrial exposition.

Advanced studies in every field concerning Air Traffic Control are currently conducted by scientists and re­searchers, some of them were induced to leave for a while their laboratories to give the meeting the benefit of their views at the present stage and their expectations for the future. It is of the greatest interest for Air Traffic Con­trollers to hear of the developments in ATC from the very ones who are responsible for them, rather than from hear­say, indeed their interest is more likely to be roused and thus, they will prove wholly cooperative when a new con­cept or a new system is put into operation.

I cannot report on all the interesting lectures I heard, I will confine myself to a mention of some of them:

- Advanced Radar ATC Systems. - Automatic Terminal Information Service. Lt. Colonel

Joseph A. Gascoigne (Systems Research and Develop­ment Service) described a device which will ease the communications burden for pilots and controllers by using a recorded transmission of the repetitious ele­ments which tend to jam the frequencies, i. e.: altimeter, wind, ceiling, departure and arrival runways in use, approaches in use, facility outages, etc .... The record­ing is updated whenever necessary. The usefulness of such a system is obvious especially for heavy volume locations. Joe Moraski, past President of ATCA, was moderator of this panel.

- ATC Control Load and Sector Analysis. Stored Program Alpha-Numeric System. Computer Updating with a panel discussion animated by representatives of IBM, UNIVAC, Air Traffic Service and Operational Controllers. Selective Weather Presentation on the Radar Scope.

- Mosaic Radar Displays. I saw more on this while visit­ing the NAFEC facility. It consists of a display on a single scope of portions of the pictures from different

radars.

30

- Report on the Supersonic Transport and the Affect on the ATC system. NAFEC currently conducts a simulated experiment on this problem.

- The Future of Automation in ATC, a discussion by government and industry representatives on the possi­bilities and limitations of electronic computers now cur­rently used in a number of facilities to assist controllers.

An Industrial Symposium gave manufacturers the oppor-tunity of delivering presentations on their material. Among other speakers, we heard our friends Tirey Vickers of the Hazeltine Corporation and Ted Bonner of the Decca Navi­gator Company.

On the last day, an open Forum took place with the active participation of Controllers. Various topics were dis­cussed: Common IFR Room - ADC Operations - Radar Hand-Off Procedures - Radar Non-Reporting Procedures - Oceanic Control.

An Industrial Exposition was open throughout the meet­ing, allowing one to wander away from the lecture room when the subject on hand was not of immediate interest to him. The Decca Navigator Company was represented by Ted Bonner and Jack Groves whom most of you know.They were so busy answering questions at their much visited stand, that I could hardly have a word with them.

Other organisations such as the American Telephone and Telegraph, the American Encyclopedia, USAF, NAFEC, displayed samples of their activities and production.

The Pacific Plantronics stand attracted many, if not all participants. Reason number one being their latest pro~ duct ion: an ultra light head-set (two and a half ounces in weight) which FAA has recommended to be incorporated into the common system. The other reason was that this head-set could be tried on with the assistance of t~o gor­geous young creatures clad in bathing-suits, not the bikini type, some ever frustrated character might complain; yet, as a controller confided to me, they were "quite an eye­ful", and I agreed. While you had this ultra light set on your head, one of these ultra pretty girls on each of your sides, a weak and strained smile on your face, a picture was taken.

Plantronics had the considerate forethought of deliver­ing the pictures on the spot instead of sending them to your home where the true spirit of advancement in science which inhabited each one of us who submitted to this valu~ able test, might have been misunderstood.

:American Controllers seem to enjoy this annual oppor­tunity to gather, exchange views on matters of common interest, get information on the techniques they will apply and have some fun. Some travel a pretty long way and take part of their annual vacation to be there. I value the Forum System our Latin ancestors liked so much, it allows any one to come up and give his op in ion on topics care­fully selected as being of immediate interest to every one. I do hope that the discussions are not just idle talk, but that a study of the recordings will permit to extract what­ever good stuff they contain.

President L. N. Tekstro and Hubert Brandstetter, Presi­dent of the Austrian Air Traffic Controllers Association joined me on the third day of the meeting, they encoun­tered some transport difficulties which delayed their arri­val. J. R. Compbell, President of the Canadian Association, was there too, his presence gave us a good chance for some sound discussion on the active participation of our Canadian friends to the work of the Federation. A group of Canadian Controllers come fo r one day and we were very pleased to meet them.

President Tekstra was on Honoured Guest at the Awards Banquet presided by the Honorable Jennings Randolph, United States Senator from West Virginia. Awards were presented to a number of highly deserving people who, by their skilled work and quick spirit of decision, have ren­dered important services to the users of the airspace.

The "Air Traffic Controller of the year", Mr. Richard W. Young, a professional Air Traffic Controller at Austin, Texas, RAPCON/Tower, assisted two flights whose pilots hod lost sight of the airport. On one particular instance, Mr. Young, by the calm and the assuring instructions he gave on inexperienced and somewhat panicky pilot, suc­ceeded in bringing safely to the ground on aircraft on a VFR flight, lost on top of the overcast low on fuel.

It is with a certain amount of pride that a Controller hears of such an achievement which shows one of the best aspects of the profession.

Mr. Oswald Ryon, Generol Counsel for ATC, and on unanimously respected personality of aviation, introduced Senator Randolph .

Ted Bonner, Toast Master for the banquet, didn't fail his many fans, he kept the audience in a merry mood throughout his witty declaration.

Ted Bonner hod them roll ing in the aisles again .

Richord Young being presented with the "Controller of the Year• award by Cliff Burton .

I was on Honored G uest at the Administrator's Banquet. The Honorable Najeeb Ha laby, the Federal Avia tion Agen­cy Administrator, in his remarkab le speech, a ssured the controllers that the 89th Congress of the United States, wi ll make strong efforts to enact a "proper, early and re­wording retirement pion ", he also allevia ted fears that automation would seriously cut into the ranks of contro l­lers. He pointed out that in the six years of the FAA opera­tion, there hod been a 300 per cent increase in the number of employees, and average salaries hod jumped from 5000 to 9000 do llars.

The Toast Moster for this banquet was Arthur Godfrey, the we ll -known te levision artist, a former a irman himself he kept the audience in an uproar with a speech where his own experiences with air t raffic control hod a la rge part.

President Tekstro and I met a great number of distin­guished aviation personal ities, we were particularly p leas­ed to be introduced by the newly elected ATCA President, Mr. Joe l Bostian, to th e Council, most of the members of which we already knew. L. N . Tekstra gave an explanation of the objects o f IFATCA followed by a general discussion showing, by the questions we hod to a nswe r, that the sub­ject had aroused some ge nuine interest.

Edward H. Cockerham the able Executive Director of ATCA has left his positio~. Joseph A. Gascoigne hos been appointed to ta ke the vacant position. To make himsel f avai lable, he will retire from the U.S. Air Force as Lieute­nant-Colonel, he hos been connected with the Air T roffic Control Research and Development Area of the Federal Aviation Agency.

The new President o f ATCA, Joel C. Bostian, is a Super­visor at the Atlanta (Georg ia ) Air Traffic Control Ce nter.

31

He previously served the ATCA as Vice-President, 1963- 1964 and as Nationa l Councilor at Large, 1960-1961.

During the convention, At­lantic City had the vis i t of Senator Goldwater who, al the time, was actively cam­paigning.

One morning, on coming down to the lobby of my hotel, I saw a crowd of peo­ple wearing plastic hats, but­tons, carrying banners, al l th is with declarations of faith for Barry Goldwater.That was the time an hotel employee wise­ly selected to hand me a huge cow-boy hat bearing in enor­mous letters: "Vote for L.B.J ." which I had been given the day before and forgotten some place. In order to avoid a diplomatic incident. I beg­ged the zealous hotel atten­da nt to keep the hat for me till a more propitious moment.

Ou r Vice President among the dignitaries, doesn't he look praud? l. to r. Arthu r Godfrey, Maurice Cerf, the Hon.Nojeeb Halaby.

Address of IFATCA President L. N. Tekstra at the Ninth Annual Meeting, ATCA

Mr. President, Members of A TC

It is a great privilege for me to address th is your 9th Annual Business Session. I rea l ize you have quite same business to attend to, but nevertheless I have asked for some of th is premium time and your president has been very kind to me by offering 10 minutes of your precious

time together. Now there should be a very good reason for me to ask

for this privilege and I had therefore better introduce my­self a nd the cause I would like to bring to your attention.

My name is Tekstra. I am one of your professional col­legues working as radar approach controller in Amster­dam's Schiphol Airport. Although I am proud of both be­ing Dutch and an Air Traffic Controller, it is in neither of these capacities that I am addressing you.

The reason for my being here is to bring to your atten­tion an enterprise in ATC of which you may have heard, but which is certainly not familiar to you: the International Federation o f Air Traff ic Controllers' Associations, I FATCA. Since its foundation 3 years ago in A msterda m I have been the President of this Federation and in that capacity I have today the honour to address this professional gathering. It is my intent ion to give you a short history of our Federa­tion, the thoughts behind it and its aims and hopes for the

future.

It is five years ago this fall that the first international meeting of controllers was held. Judging by the history of

32

our port of the world, international ism is a European hobby. The numerous national ities and national bounda­ries in a comporitively small reg ion of the world both necessitate and facil itate internationa l ism.

It is therefore logical that this meet ing took p lace in Europe, actually in Frankfu rt, Germany, November 1959. Its immediate ob jective was to explore the feasibility o f on Internat iona l Federation of Air Traffic Contro llers' Asso­ciations. It accepted the first draft Constitu tion, which was based on a federation of European associations as a first step towards the ultimate goal of a world wide federation.

It took us two yea rs to finalize the Constitution· the constitutiona l meeting took place 3 years ago th is m~nth, in Amsterdam October l 9th, 20th 1961.

It is worth noting that from the beginning it was agreed that such federa tion could only be based on the princ ip le of cooperation on technical p rofessional matters the fun­damental object being the furtherance of safe 'and effi­cient ai r nav igation by promoting the ATC profess ion.

The Constitut ional Meeting mode a very drastic lost minute amendment to the drafts by changing the intended name of Europea n Federation ... into International Fede­ration, the reason ing behind this being the consideration that European is in fact internationa l; further considera­tion were undue restric tions of a reg iona l organization both in membership and act ivity.The preamble to the Con-

vention of IFATCA very aptly states the reasoning for its existence and I would therefore like to read this out to you:

"WHEREAS, air traffic control promotes and maintains a safe, orderly and expeditious flow of air traffic through­out the world; and

WHEREAS, the objects, functions and problems of this essential service to aviation are of similar nature in all countries irrespective of national boundaries; and

WHEREAS, these objects, functions and problems can be mastered only by the common effort of all nations, which should be based on close international co-operation and on a continuous exchange of ideas and experience;

NOW THEREFORE, it is indispensable that Air Traffic Controllers of all nations be united in a world-wide pro­fessional Federation for the furtherance of safe and effi­cient air navigation and for the protection of their com­mon professional interests.

THEREFORE, the

INTERNATIONAL FEDERATION of Al R TRAFFIC CONTROLLERS' ASSOCIATIONS (IFATCA)

has been founded by the determ:nation and agreement of the professional Associations in Europe."

Well, that was the start-up period. What has grown out of this after 3 years you may ask. The first three annual conferences have been held in Paris, London and Brussels respectively. The original 12 member Associations with some l 400 members were succesively joined by 8 new member associations. Israel was the first member outside Europe to join us (although some maintain that the U.K. should be given this honour). They have been followed by Central Africa, Canada and Uruguay. T::>tal membership is now 20 associations with approximately 3 OOO individual members, whilst contacts with associations all over the world warrant the expectation that within a year or so this will be 25 national associations.

Co-operation from industry is also growing; we have 10 corporation members and this number surely leaves room for some multiplication.

The budget shows a very optimistic approach to finan­cial problems. Membership fee is only 10 shilling (S 1.40) per individual member which gives an income at the moment of only some £ 1500, adding corporation member­ship it adds up to some £ 2000, which is a mere S 5600. If you feel like asking how we manage to operate on that, I very much feel like throwing the question back to you! We manage to publish a quarterly international ATC publication called: "THE CONTROLLER", which serves a very useful purpose as goodwill ambassador for the Fede­ration and the profession. Practically all our work, includ­ing this Journal, is spare time activity.

What has been accomplished sofar with respect to the objectives of the Federation is another likely question. I can give you some answer to this one: we have strengthen­ed the ties between controllers of many countries; al­though at our conferences some 25 nationalities are re­presented, this does not show up conspiciously, it is much more a controllers' meeting than an international one.

In these three years we have found out that successful international activity in our profession is far a good deal identical to activity at ICAO level. No matter where we work on earth, our basic procedures are determined by States in the International Civil Aviation Organization and if we want to have a finger in the pie, it is at that level that we must start. Realizing this, our work-programme is closely linked to that of ICAO. Our first representation was made at the RAC/OPS Divisional Meeting, last summer in Montreal, Canada.

Although some member States of ICAO eye our activity with a certain amount of suspicion, we have accepted this fact and we hope to prove to these States that we are really trying to contribute to air safety, by supplying at the highest level the considerations of the front line executives in ATC: the professional controllers. As our views are not influenced by political or budgetary considerations they may not always coincide with the views of State repre­sentatives, but they stick out by being honest technical requirements. By airing these we hope to influence top level discussions to the benefit of air safety.

Co-operation with our professional counterpart the International Federation of Air Line Pilots' Associations has been very good from the early days of IFATCA's con­cep~ion, and is fostered from both sides in the interest of both profess:ons.

Now what do you buy for this, a practical member of the audience might ask me. Well, gentlemen, it has be­come clear that these three years have already dragged the controller from behind fhe paper curtain of State regu­lations that kept him apart from the international world of aviation. The term "air traffic controller" is increasingly heard at ICAO meetings and even put down in writing. The image of an Air Traffic Controller is being formed, his key position in aviation is being recognized. Our organization has only just started. We are faced with enormous pro­blems, but sofar enthusiasm and improvisation have brought us where we are now. There is no way back with­out deadly harm to the image of the profession. We must go forward to our ultimate goal: a really world-wide Federation of Air Traffic Controllers' Associations.

Knowing and admiring the exploits of your association which is dedicated to progress in the science of ATC, I wonder whether you have meant to keep this progress within the boundaries of this great country of yours. If we agree that this science is an international one, we must recognize the importance of spreading our knowledge over the world, to the benefit of our fellow controllers and to air safety in general. I am not asking this meeting to take immediate action in this respect, this will probably have to be taken by your council. I am however asking every individual member of ATCA who is present here, to consider what I've said. One of my fellow officers has described the present situation of IFATCA by a different pronunciation of these 6 letters: IF - ATCA. This pronun­ciation I would like to offer you as the basis for your con­sideration: I F-ATCA. I trust that ATCA 's dedication to this, our truly international profession will in good time overcome any difficulties which stand in the way of active affiliation with IFATCA sofar. We from our side will do our utmost to accomplish our ultimate goal of a world wide federation to further air safety by the promotion of the ATC profession. IF-ATCA.

Thank you

33

1964 Annual Conference of the Verband Deutscher Flugleiter e. V.

The 1964 Annual Conference of the German Air Traffic Controllers' Association (VDF) was held from 24th till 26th November in Munchen, Germany. Controller delegations from all German ATC units, as well as from Austria, Bel­gium, and Madagascar attended the Conference. A great number of guests, among them the Honorary Members of the Association, Dr.-lng. H. J. Zetzmann and ORBR G. Preuf3, representatives of the German Air Force, the Ger­man Aero Club, the Technical University of Berlin, the elec­tronics industry, and the German Luftpool participated in the proceedings.

Wulf Dieter Graf zu Castell, Director of MOnchen-Riem Airport and former Lufthansa Captain, was host to the Conference. In his address he emphasized that everyone engaged in aviation must closely collaborate if the future problems shall be mastered. He further pointed out that, despite of automation, the human element must remain the determining factor in air traffic control, and that the planners should take advantage of the practical experi­ences of the experts in the field.

Hans W. Thau, President of the German Air Traffic Con­trollers' Association, reviewed past year's activities. Acer­tain consolidation has taken place in the Association and all powers should now be devoted to the future tasks, in particular to those delegated to the VDF by IFATCA. High­light of the 1964 proceedings in IFATCA was the Annual Conference in Brussels, which a great number of German Controllers attended. It is important that Controllers have

an opportunity to attend such meetings, because the ex­periences gained there will stimulate work in the own association. This will already be obvious at the Munchen Meeting, as it has been organized on the same lines as the Brussels Conference. Mr. Thau also mentioned the recep­tion of delegates and observers by Mr. R. Bulin, the Direc­tor General of the Eurocontrol Agency. This had been noted by all participants as real evidence of the positive attitude and international spirit of this European Organi­zation for the Safety of Air Navigation.

The Mi.inchen Conference was organized as a strict working meeting, subdivided into four Sub-Committees.The main topics dealt with by the Sub-Committees were

Sub-Committee

Sub-Committee II

Sub-Committee 111

Sub-Committee IV

Civil/military integration in the Air Traffic Services

Air Traffic Services and Gene­ral Aviation-Extended Con­trol

Route experience flights and flight training for Controllers

Controller recruitment and training

Captain K. Stieglitz, representative of the German Air Force, presented the following paper on civil/military inte­gration:

IPirob~ems of Civi~ I Military Integration nll'll the Geirman Anr Traffic Services

by Capt. K. Stieglitz

Based on the development of air traffic in the Federal Republic of Germany during the past years, it has become an accepted principle that only by the joint use of the available airspace will it be possible to solve the problems of tomorrow.

This realisation has soon been followed by the first practical measures, of which you are all well aware, and it can be said that things are under way organisationally and administratively, but in my opinion, real integration requires more than a shifting of tasks from one agency to another, or a rationalisation of the airspace structure.

If we really want to integrate services here, i. e. to combine separate parts into a single entity, then this re­quires, in particular, the acceptance of the spirit in which the proposals are made. For it is surely inconceivable try­ing to join two parts of a service if the people who are charged with its planning, management and operation do not acknowledge each other to be equal partners.

Where in the past these principles have been violated, the resulting misunderstandings and frictions have been clearly apparent. Here an important task falls to the Ver-

34

band_ Deu_tsc~er Flugleiter. The Association can play its part 1n bringing home to people the real meaning of the term "integration", that is to say, the acknowledgement of the other as an equal partner without belittling his profes­sional qualifications. Yet, in order to acknowledge, it is necessary to know, not only the people but also the tasks.

Knowing the tasks is particularly significant when, in the course of integration one should, and be prepared to, take over more and more functions from the partner. Therefore, I should try to familiarise you with some of the problems which are daily confronting military ATC. You will realise that it is not always possible to avoid a conflict of interest.

In the past this conflict had to be resolved by civil and military units, but now all of you have to deal with this problem. Basically different in our task is the fact that the responsibility of military ATC is not confined to avoiding collisions between air~raft and to promoting an orderly and regular flow of air traffic. Military ATC must create the provisions which are required by military aviation in order to carry out their missions. Be that, for example, by the establishment of special airspaces, or the development of new control and monitoring procedures.

Frequently the question of separation is considered less significant than the above mentioned problems. In addi­tion, realistic service for military air traffic requires some knowledge about its operations directives and principles.

Those of you who for some time already provide air traffic services to one or more military air bases will con­firm how essential these matters are. To date, already, 1/3 of all our bases are provided with air traffic services by civil units, a;id I am glad to state tl~at the/ am quite con­tent with them. The future development, however, especial­ly as outlined by long-term planning until 1975, will de­mand considerably more from the civil services. But the situation in the Federal Republic cannot be considered in isolation. Similar problems have already occured in inter­national collaboration for some time. Unfortunately, there has been a different approach to their solution. In this con­text some remarks concerning Euro cont r o I : You are all aware that the Eurocontrol Agency has taken over juris­diction for control in the upper airspace; unfortunately only for part of the air traffic, viz the "General Air Traf­fic". To explain why this is so we must go back to the years

1959/60.

At that time, when the plans for a European ATS authority were discussed, control procedures for the traffic in the upper airspace were little developed. First trials at various units, for instance at Birkenfeld did not prove to be very encouraging. They certainly did not meet all re­quirements of military aviation. Because of other tasks or missions or because of different technical equipment mili­tary aircraft were forced to demand other requirements ihan could be met by a classic, ICAO-slyle, ATC-system.

There were two alternatives: Either to develop a con­trol system meeting the requirements of all airspace users, or to look after only those airspace users for which the

existing means were sufficient.

As you all know, the second solution has been chosen. The division of air traffic into two groups, viz. General and Operational Air Traffic, appeared to their creators to be a panacea at that time.

We know today that it has not been one, nor is it one

now.

If you only look at the problems which have resulted from this division, for instance the question of civil/military co-ordination which has been talked over in endless dis­cussions. Here I think of the co-ordination between civil units controlling GAT and military units controlling OAT. Today this question has not been solved any more than it

was some years ago.

In the event, one attempted to circumvent the earlier decision. But once again we found that it is extremely dif­ficult to modify an internationally agreed decision. If one of the contracting parties does not join in the game, every­

thing must remain as it has been.

The same applied to our case. So, the sub-division of the air traffic is a basic principle of the Eurocontrol Con­

vention. Then the alternate systems of MA TRAC and COLOCA-

TION came into being. But all of that could not hide the fact that one had

devised a control system with two separate authorities independently controlling air traffic in the same airspace. It is true, there is a certain amount of interdependence, but ultimately they are operating independently of each other. Furthermore, a boundary between upper and lower air-

space had been established during the last preparatory period and although it was expressly designated provi­sional, this limit is firmly fixed.

That designat:c:-i was more a matter of routine prac­tice and prestige, rather than being based on operational considerations. Later, when the Eurocontrol Services were planned on the basis of this airspace boundary and the horizontal dimensions of the airspace were allotted, this resulted in such a small sub-division that nothing remained of the original requirement to create over large areas a uniform control environment for the high speed traffic.

That is why in the German Administration the question has now come up whether, in the interest of an economic airspace organisation and a smooth flow of traffic, it would not be more suitable to put the boundary between upper and lower airspace where the majority of vertical air movements have been complei·ed.

In other words the portion utilised for holding-, ap­proach- and departure procedures should be added to the lower airspace.

The upper limit of the lower airspace would then be shifted to about flight level 250. This would not result in a considerable increase of workload for the lower airspace sectors, for at present all flights have to be co-ordinated and processed anyway.

In this respect the results of the Dusseldorf trials are quite obvious. Consequently, artificial division of air traf­fic and arbitrary airspace delineation are not necessarily stimulating the further development of air traffic services. The Federal Republic of Germany has therefore decided to aim for full integration of its own national services in order to create an air traffic service which meets the re­quirements of al I airspace users.

Of course, this also means that the civil air traffic ser­vices, in accepting additional tasks, must now consider even more military interests.

Your Secretary of State has expressed this in a letter as follows:

"I agree with you on the following: The Bundesanstalt fUr Flugsicherung is the appro­priate Federal Authority for Air Traffic Services. It must realise that in the interest of the State it is one of its tasks to render the greatest possible assis­tance to military aviation in order to enable it to fulfil its task as a sovereign instrument, i. e. to estab­lish and maintain the readiness and efficiency of its flying units, even if this entails occasional disad­vantages for civil aviation."

The new tasks brought about in the course of full inte­gration, can hardly be described more clearly.

All of us, wherever our post in the Air Traffic Services may be, must realise the responsibility to safeguard the interests of the country in our work.

It is desirable that we should succeed in performing our task in such a manner that the requirements of non-State and State air traffic will be reconciled without friction.

But should a conflict of interests yet arise, the decision is equally applicable to everyone of ~s, and it is complete­ly insignificant whether one wears uniform or not.

Therefore, if we see our task right, there connot be a division in principle of civil and military ai1· trnffic ser­vices. Indeed, there are civil and m:fitmy ATC tusks. Ai1 Traffic Control, however, is a public service which all of us alike must perform in the interest of our country.

35

The Sub-Committees prepared recommendations on the various subjects which, after discussion in Plenary Session, were later adopted as Resolutions by the Conference.

An extract of the resolutions of Sub-Committee I is given below, with a view to l·he fact that the Verband Deutscher Flugleiter has been charged by IFATCA to study the subject of civil/military integration.

Sub-Committee I Resolution

The members of the Sub-Committee realized that it would not be possible to reach definite proposals in the short time available during the Conference. Efforts there­fore concentrated on an assessment of the situation in an area most familiar, the Federal Republic of Germany.

The Sub-Committee noted that a number of authorities are already dealing with matters of civil/military integra­tion, viz.

The Federal Ministry of Transport The Federal Ministry of Defence The Eurocontrol Agency The Bundesanstalt fUr Flugsicherung {Federal Agency for Air Navigation Services) The Liaison Unit of the German Air Force at the Bundesanstalt fur Flugsicherung. (This unit also re­presents the interests of the Stationed Forces)

At some German ATS units a co-location of civil and military elements has already been established. Air De­fence Notification Centres (ADNCs) exist at all German Area Control Centres. Coordination of day to day opera­tional matters between civil and military units is effected in accordance with letters of agreement, directly between

Controllers.

The airspace above the Federal Republic is presently divided in individual areas alloted for civil or military purposes. The different requirements of the airspace users are reflected in a considerable dispersion of the airspace into civil and military Control Zones, civil and military Terminal Areas, Airways, Upper and Lower Control Areas. Airspace under the jurisdiction of civil units is utilized by

civil and military airspace users alike.

General and Operational Air Traffic, although operat­ing jointly in the same airspace, are following different rules and procedures. Various different civil and military units are providing control and information to civil and military traffic flying in the same airspace. Frequently, the procedures do not provide for optimum efficiency, and the equipment does not meet todays requirements, let alone those of the future. This applies in particular to radar coverage, lack of secondary radar, insufficient VHF/OF equipment, and unreliable or inadequate communication

facilities.

Joint planning of control systems, operating proce­dures, and airspace organization, as well as joint procure­ment of equipment and efficient personnel planning are therefore paramount for the Federal Authorities.

The Verband Deutscher Flugleiter e.V. appreciates the agreement between the Ministry of Transport and the Ministry of Defence to integrate civil and military Air Trciffic Services and to delegate the task of certain military units to the Bundesanstalt fOr Flugsicherung. This agree-

36

ment is a realization of the principle that in the high­density airspace of the FRG only one control unit should have jurisdiction over a 11 traffic in a given area.

It is a logical development that Aerodrome Control and Precision Approach Radar for military airbases will con­tinue to be provided by military units. The Forces will also continue to be involved in the control of upper airspace traffic. The reorganization of the airspace and a new dis­tribution of jurisdictions can only be realized successfully if the technical and personnel means for the introduction of long term planning are provided in a reasonable period of time. The Federal Diet should recognize that the Air Traffic Services will require considerable financial support in the years to come. In this context the German ATCA emphasizes the stringent requirement for full radar cover­age in the entire airspace of the FRG.

* * * The Dornier aircraft company had invited for a plea­

sant and interesting visit to their plant in Oberpfaffen­hofen; Deutsche Lufthansa AG had quite generously assist­ed in transport arrangements for the Conference, and the whole meeting was excellently prepared by the Munchen Branch of the Verband Deutscher Flugleiter e.V.

ICAO Continued from page 17

vention accepts the principle that every state has complete and exclusive sovereignty over the airspace above its ter­ritory. Nevertheless, each state party to the Convention allows transit through its airspace and the right of land­ing for technical purposes to an aircraft of any other state party to the Convention without the necessity of prior authorization if the aircraft is engaged in non-scheduled service. A complementary agreement available to parties to the convention accords the same privileges to aircraft engaged in scheduled services.

The Convention also established the International Civil Aviation Organization, which now has a membership of 107 sovereign states. The major aims and objectives of ICAO are "to develop the principles and techniques of international air navigation and to foster the planning and development of international air transport". By a sub­sequent agreement, ICAO became a specialized agency in relationship with the United Nations.

The first year following the Chicago Conference in which the world was at peace was 1946. In that year, natio­nal and international airlines carried 18 million passen­gers, performed 16,000 million passenger kilometres (10,000 million passenger-miles). An indication of the growth of civil aviation is given by the figures for last year (1963) of all the domestic and international airlines of the states which are now members of ICAO, 135 million passengers carried, 147,000 million passenger-kilometres (91,000 m il­l ion passenger-miles) performed. The aircraft of the mid­l 940's (unpressurized, with cruising speeds below 400 km (250 miles) per hour, have by now been mainly replaced by jet transports, carrying more than a hundred passen­gers, flying at heights of more than 13 kilometres (8 miles) above the surface of the earth, and cruising at speeds only slightly below that of sound.

Corporation Members

of the International Federation

of Air Traffic 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

Marcon i's Wireless Telegraph Company, Ltd.

Radar Division

Chelmsford, Essex, England

N.V. Hollandse Signaalapparaten

Hengelo, Netherlands

Selenia - Industrie Elettroniche Associate S. p. A. Rome, Italy

Telefunken AG, Ulm/Donau, Germany

Texas Instruments Inc., Dallas 22, Texas, USA

Whittaker Corporation,

North Hollywood, California, USA

The International Federation of Air Traffic Controllers' Associations would like to invite all corpora­tions, organizations, and institutions interested in and concerned with the maintenance and promo­tion of safety in air traffic to join their organization as Corporation Members.

Corporation Members support the aims of the ~e~eration by supplying the Federation with technical . f rmation and by means of an annual subscription. The Federation's international journal "The Con­~~o~er" is offere_d as a platform for the discussion of technical and procedural developments in the field of air traffic control.

For further information on Cor~oration Membership please contact Mr. H. W. Thau, Honorary Secre-

IFATCA Cologne-Wahn Airport, Germany. tary, '

JET AGE TRAFFIC CONTROL

Selenia Air Traffic Control L-band Radar for

terminal areas and air route control

Gap-free and clutter-free coverage o Virtual elimination of blind speed o Low and high data rate availability o Frequency diversity operation o Extra high-angle antenna coverage for in-close targets o MTI system with double delay line canceller and triple staggered repetition rate o High Transmitter power Low noise Parametric Amplifier

~1 --=---=J-bm ~ INDUSTRIE ELETTRONICHE ASSOCIATE S.p.A. P.O. BOX 7083 - ROME OTALY>

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