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Aviation History
1962
1962 - 2116.PDF
FLIGHT International, 20 September 1962 479 WHITHER ATC? By E. W. PIKE, AFRAeS, FIN* SO much has been written in recent years about air traffic control that one may feel with some reason that there is little new to say. The ICAO approved system, like Topsy, has "just growed"; and you now find in the large population centres of the world (and also in some other, stranger, places) the familiar half-lit complex of tabular dis plays, communications equipment, radar consoles and so forth, in which that comparative newcomer to the world's professions, the air traffic controller, practises his skill. In essence ATC is a voluntary and co-operative activity be tween pilots and controllers whereby the former is given by the latter on request a clearance to proceed in a specified manner based on current available data and a rather com plicated set of rules. Sometimes clearances are based entirely on pilots' position reports, when what is termed "procedural" ATC is applied. Where primary radar cover is available, how ever, the position of aircraft in plan can be determined from the ground and therefore closer horizontal spacing can be tolerated. Identifying radar targets sometimes represents a difficulty, so secondary radar is being developed both for this purpose and to transmit automatically additional information, particularly aircraft altitude, to the ground controller. Traffic growth in recent years has increased the pressure on both pilots and controllers, especially in the sphere of voice com munications, so that means have had to be found to reduce their workload. Various alleviating possibilities have been tested, such as "sectorization," but they in turn usually intro duce new difficulties. Increases m ATC staff and the mainten ance of a larger crew complement in aircraft than would otherwise be needed have been inevitable. The latest move is to enlist help from automation (that much-abused and misunderstood term) to help controllers deal with the massive amount of data they need to do their present job. Much thought and effort have also gone into developing ATC data displays, because some people hope (a trifle optimis tically) that, if you can only present controllers with a well conceived three-dimensional picture of the airspace and its occupants, most problems will disappear. Experiments with large electronic computers are also proceeding to determine 'Manager, Air Traffic Management Division, General Precision Systems Ltd. Now nearing completion is the first EAC One-Eleven fuselage being assembled at Hum from components built in other RAC factories at Weybridge, Filton and Luton. The One-Eleven is scheduled to make its first flight from Hum in the second quarter of 1963 how they can help—and even whether they can replace—the human controller at some undefined but distant date. Another obvious step, that of supplementing the voice communications channel by an automatic air /ground data link, appears to be making somewhat slow progress at the present time. In ATC planning the popular trend is towards so-called "area control," meaning that service is provided not only along a few narrow airways, but to all traffic on any route in the area. A laudable objective, but if not impossible certainly far from easy to achieve. A further target is civil/military co ordination, whereby all air traffic becomes subject to the same control—another by no means easy task So far so good. One may conclude correctly that much effort and expense is being directed towards ensuring that to day's ATC system is capable of handling the inevitable increase in air traffic. If one assumes that the present basis of the ATC system is correct or inviolable there is in fact little else that could be done. I deliberately refrain from any reference to private flying, which for a variety of reasons finds it almost impossible to participate in the present ATC service, or from argument as to whether visual collision-avoidance could be tolerated in certain circumstances. However, I do venture to suggest that there is a good case for taking a fresh look at ATC, not with the object of ques tioning current efforts to improve today's system, but to enquire whether in the longer term the very basis on which collision avoidance is being attempted is technically and economically sound. In particular, one must query whether, when air traffic really expands, we shall be able to tolerate a situation in which an individual service has to be given by ATC to each individual aircraft as the main means of pre venting catastrophe. Even today the number of controllers required to protect aircraft against collision risk in busy areas is disproportionately high; if the full cost of the ATC service were passed on to aircraft operators it would invoke loud pro tests. It seems to me to be wrong to expect to deal with the crowded skies of tomorrow in the manner in which we try to handle the relatively uncrowded skies of today. Men And Discipline Human beings are generally very receptive to the necessity for discipline when it can be shown to be desirable. We accept, for example, speed limits, queueing and "keep out" notices quite happily in our terrestrial life. We prefer freedom within the law to having to check each step with the legal authority. Although the death rate on the roads (for instance) is appallingly high, we generally rely on corrective measures by education and persuasion rather than restriction. We dislike in principle unnecessary controls, but accept them whenever they can be shown for social reasons to be necessary. The technical difficulties of an airborne collision-avoidance system at present unfortunately appear insuperable. Further more, in busy areas there is an obvious and very real risk that to take avoiding action will generate other collision hazards. The chances of free-for-all flight with no ground control, using a do-it-yourself collision predictor, seem at present to be as remote as having a radar/computer complex examining every aircraft movement, deciding when conflict is imminent and transmitting instructions to pilots at a far higher rate than could be obeyed. Some military operations are by their very nature not susceptible to close ground control. Whether or not they are permitted, and to what extent, is a decision outside the tech nical field. Looking ahead, however, it seems that eventually all flights should be amenable to some form of control, and planning must anticipate that happy day. As a first approximation, the cost of a ground ATC com plex may be assumed to be inversely proportional to the extent to which aircraft movements are predictable. Putting it another way, if you can predict that aircraft will be navigated with an accuracy commensurate with the separation criteria ATC employs in each dimension, there is a decreased requirement
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