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Aviation History
1939
1939 - 0766.PDF
/ FLIGHT. MARCH 16, 1939 by other machines ot whose position he is not at all certain. Purists will at once point out that in QBI only a single aircraft is in the Zone at a time—the one whose turn it is to land—and so there is no danger ; but the less pure know that, while this ideal is the aim of all, it would be an unsafe assumption on many occasions. After flights of over two hundred miles without any view of the ground, a wait of possibly 45 minutes, still flying blind, changes of altitude as advised by the Control into strata where the wind is very likely considerably different from the one accounted for during the route flight, and remembering the speed of modern aircraft, it is only natural that the machines which are numbers 2, 3, 4, 5, etc., for landing may be trespassing occasionally in the sacred territory ot the controlled Zone. Apart from the chance of colliding with No. 1, who is the legitimate occupier, trespassers may cause a mistake to be made regarding '' motor noises signals," especially if they are flying similar types. With the above risks in mind, and having before him the flight plan of departing aircraft commanders, the care ful Control Officer is more likely to adopt the much more positive method of advising each aircraft, as it enters his area, to fly at a stated height determined, so far as possible, by the expected order of landing. This work is made much easier for him when each commander radios his E.T.A. (estimated time of arrival) as soon as he enters the station communication area (some forty-five minutes away, on a rough average), and it also prevents his slide rule over heating. By this means No. 1 would be lowest. No. 2 next lowest and so on, and descent by QGP 1 (to use the Q-code designatibn of the first in landing order) is safe irrespective of the wanderings of the others (see diagram) The Moving Staircase It is a matter requiring a good deal of concentration to devise this stratified structure of swiftly moving aero planes, some coming, some going, and others passing ; some entering the area high who would be better low, some off course to starboard who would be very much better off course to port, some silent who should be communicative, others chatty who should be quiet. The Control Officer would be very puzzled indeed to know what advice to give to any machine which did not adhere to the advised height, because, with all adjacent strata allocated to aircraft also flying blind and their positions only approximately known, any move made by the errant one might well prove dangerous. Fortunately, airline commanders are clearly aware of this possibility and mostly adhere very closely to the advice given, even when tempted to change height by- the sight of an unexpected break in the clouds. The snag about descent through such a " hole " is, of course, either that it may close up or that the pilot will find him self unable to continue flying below or between cloud and be suddenly compelled to fly blind at a height other than the safe one advised. This would be a most unpleasant contingency and it would obviously be redundant to ask, '' Are there any aircraft flying in my vicinity ? So the wise commanders stick to their original heights and scrupulously avoid any unadvised variations. Compared with the channels used by shipping traffic the 'illimitable" quality of the airliners' ocean seems to reduce to infinitesimal insignificance the risk of collision A few dots smaller than pin points moving over a four- mile-to-the-inch map do more than represent an aeroplane to scale, and the number of strata over a given area are almost beyond measure. At first glance it would seem that aircraft are as remote from each other as the molecules in gas, but, unfortunately, a number of circumstances exist which make this assumption quite wrong. While the molecules are free to wander anywhere, aircraft are con centrating on the same objective and emanating from the same source. They tend to seek approximately the same altitudes because of engine requirements, weather condi tions, and habit, and they tend to fly on the same tracks between their terminal points. There is a similarity between their angles of climb and their angles of descent. In fact, there are too many influences at work tending to crowd aircraft into quite close proximity. Any senior air line commander can recount at least one instance when he saw a shadowy form pass in thin cloud, in spite of the vastness of the sky. This crowding tendency has been acknowledged in the United States, where for some years flight planning '' has been the order of the day in airline work. Conditions are becoming similar in Europe and Notice to Airmen No. 279 of 1938 applies a similar pro cedure to flights in the United Kingdom and Northern Ireland. The routine is simple: Prior to departure the pilots of aircraft with radio advise Control of their times of departure, routes to be followed, heights to be flown, destinations, next stopping places, and estimated times of arrival at the next stopping places. With this information before him the Control Officer can more quickly and with confidence advise other aircraft heights to fly and route to follow. The successful working of Control is dependent upon pilots adhering strictly to the flight plans submitted, and reducing to a minimum the number of times they change height. The altitude graphs of some flights look more like a preliminary sketch for a proposed switchback railway than a record of orderly civil air transportation. Pilots are often criticised, sometimes by other pilots, sometimes by knowing onlookers, for some irregularity in their use of the air; but it should be kept in mind that their skill in flying is almost certainly exceeded by the mass of assorted information, legal and otherwise, which they are expected to know. For instance, all pilots must be familiar with current Notices to Airmen, which flutter from the Air Ministry like autumn leaves (over 300 were issued last year). They should have digested the impor tant items from "Temporary Conditions Affecting Fly ing " (out of the front of The Air Pilot), because a number of these are bound to affect them. At the time of writing there are 20 miscellaneous warnings and a similar number of "Conditions at Civil Air Stations" current. Then there are air navigation regulations with which persons engaged in aviation " should acquaint themselves.' According to The Air Pilot there are over two score ol these. They include "The Air Navigation Act, 1920," and ditto 1936, just to mention two of the smaller items! To fly without transgressing any regulation or involving himself in any possible danger, each pilot must, further, be familiar with much of the contents of the remainder of this excellent volume, including a big list of danger areas whence there is popping-off of various cannon, mortars, and diverse ordnance, not to mention bombing and towing of aerial targets, cloud-flying areas, places with lofty obstructions to safe aerial navigation, and so on. These are but a few of the items, chosen at random, and merely indicate in outline the enormous mass of informa tion which the perfect pilot may be expected to have at his finger-tips. In the case of pilots who fly abroad there is a corresponding list for each country which they traverse, so they may well be excused occasional varia tions from perfection of procedure here and there. International Complications The I.C.A.N, is an excellent effort to minimise the num ber of legal difficulties in international flying, but, unfor tunately, signatory authorities take advantage of the permission to make such local regulations as they may think necessary, with the result that the average pilot flies on in what he considers a normal manner until he comes headlong against some unsuspected regulation. He notes it for future avoidance, tells his colleagues about it and proceeds as before to the next occasion. This method works out not too badly in practice, but it makes the authorities a bit irritable to find that their nice new regu lation is regarded as a queer local practice by international airline commanders, whose daily flights take them to many capitals. Shipping companies minimise transgressions of local regulations, either by employing captains with local pilotage tickets or else by engaging pilots for the naviga tion of complicated waterways. It may be that a similar procedure will, in time, be forced upon airline companies, because it is difficult to see how any one pilot can really be thoroughly familiar with the necessary regulations at many busy airports in as many different countries, and, as traffic continues to increase, misunderstandings will involve something more serious than an interview with local commandants or air traffic control officials.
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