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Aviation History
1953
1953 - 0609.PDF
• FLIGHT, 15 May 1953 603 MEDICAL ASPECTS OF AVIATION . . . Bends are pains in the joints or muscles, which may be mild or excruciating. They are increased by movement, and unaffected by morphia. Chokes is the term applied to a condition of respira tory pain and proneness to coughing which can lead to air hunger and collapse. It is a serious condition. Collapse can also take place by itself, accompanied by pallor, sweating, nausea and giddi ness. Other symptoms include dimness of vision associated with migraine, skin irritations, abdominal distensions, and a general sense of unease with inability to concentrate. In the vast number of cases, recompression will effect an immediate and permanent cure, but—inevitably—there are a few who suffer from after-effects. These may be mild, but "post- decompression shock" can be severe or even fatal unless treated properly, i.e., as for normal shock. The cause of the trouble is, at any rate largely, the develop ment of bubbles of nitrogen within the body as a result of low external pressure Nitrogen is normally in solution in the tissues and fluids of the body at a partial pressure corresponding to that of the atmosphere; when this external pressure drops, nitrogen bubbles form, notably in those regions where blood supply is least and nitrogen content greatest. Onset of symptoms are affected by a number of factors. Below 25,000ft the condition is rare, above that the chances of it increase rapidly. Time spent at height is of more significance than actual altitude, within reason. Age has a pronounced effect, subjects in me 35-47 age-group having proved to be about five times more susceptible than those under 25. Fatness is another unfavourable characteristic, because nitrogen dissolves readily in fat at atmos pheric pressure, whdst the blood supply in such deposits is very poor. Temperature and rate-of-ascent appear to have negligible effect, whilst residence at high altitudes naturally implies low free-nitrogen content of the body, and hence is conducive to reduced effects at altitude whilst flying. Prevention of decompression sickness can be effected by pres- surization, by selection of suitable aircrew, and by denitrogena- tion. The last-named can be achieved by breathing pure oxygen for two or three hours at ground level before take-off, thus forc ing the nitrogen normally dissolved in the body to leak away via the lungs. The method has value for experimental pilots, but is impracticable for operational aircrew. PSYCHOLOGY OF OPERATIONAL FLYING (Summarized from an article by WjCdr. J. S. Howitt, A.F.C., M.R.C.S., L.R.C.P. T HE total psychological load on a modern pilot is considerable, and is made up of the mental work done in the performance of the job in hand, together with the mental tension attendant on the results of that work. The subject—considered largely in the light of fighter operation—can conveniently be examined by dividing it into five sections. Weather Conditions and Instrument Flying.—Bad weather has always imposed considerable fatigue on a pilot, who has to co-relate die readings from his six blind-flying instruments, apply radio or radar information and keep an eye on the rest of his dials. Now. with a nearly all-weather Air Force and modern aircraft that occasion both high speed and rapid rate-of-change of altitude, the problem has become accentuated. The standard blind-flying panel can no longer be considered entirely satisfactory, and there seems to be a case for the introduction of a Zero Reader type of system. Formation flying in cloud is another factor which adds considerably to the total strain on a pilot under bad weather conditions. Range, Fuel and Navigation.—The jet fighter has a fan- range but little endurance, which means that the pilot cannot afford to get lost, nor can he hang about for long in a landing ''stack." Yet he operates at great altitudes from where map- reading is usually impracticable, and is frequently solely at*rhe mercy of his radio equipment. Duplication of radio alleviates the problem, but clearly the need has arisen for specially designed aids for sincle-seater aircraft, and these are, in fact, being developed. High Altitude.—Flying an aircraft to its operational limit at great altitude, where the gap between critical Mach number and stalling speed is at its narrowest, is a tricky business. It is a simple matter to lose one's companions in a turn, and once this has hap pened it may be very difficult to regain formation. Another risk is that of pressurization failure, with all its attendant dangers, not the least of which is the fact that it will entail a substantial reduction in height with a corresponding reduction in remaining endurance. [Special flying suits which inflate in the event of cabin pressure failure have been developed in America and in this country to offset the effect of rapid decompression at extreme altitudes, which would otherwise be fatal.—ED.1 Another hazard is that of oxygen failure. With existing British equipment it is possible for a leak to exist undetected between oxygen regulator and mask, and in any event failure of the system may occur elsewhere. As is well known, the onset of anoxia is a very insidious thing, and needs to be continuously watched. [Although cabins are pressurized, the internal altitude when an aircraft is at, say 40,000ft will still only be of the order of 20- 25,000ft, and oxygen will therefore be required continuously.—En.] High Speed.—Speed as such has no adverse effect on the human body, nor does it directly create any very great psychological problem. Speeds are becoming so high, however, that for certain tasks man's speed of thought is becoming inadequate. Intercep tion of bombers at, say, 50,000ft by a fighter with a very high rate of climb is an obvious example, as is the brief time available for firing at the bomber when once it has been found. Escape in Emergency.—The ejector seat has noticeably lightened the psychological load on the pilot in this field; but, even so, getting away from the seat and operating the parachute have not always proved easy, and cases have occurred of pilots ejecting and then making no obvious attempt to leave the seat, thus losing their lives. The introduction of th? new fully-automatic seat, and the modification of existing ones, will therefore be a valuable contribution. PSYCHOLOGICAL ASPECTS OF COMBAT FLYING (Summarized from a paper by Denis Williams, M.D., D.Sc.t F.^.C.P., Civil Consultant in Neurology to the R.A.F.) F ROM the physical point of view it is a relatively easy matter to pick a suitable aircrew member, but it is extremely difficult to estimate psychological make-up in the course of one or two short interviews. Sorting out those capable of accepting the risks of ordinary flying—who thus have a good chance to fly or otherwise perform well—is not too difficult, and the psychological tests that are so much in vogue do exhibit some success in rejecting potentially hopeless cases. When, however, it comes to selecting personnel who are so constituted psychologically that they can fly well and fight well at the same time, the difficulties really begin. Statistics show that in World War II the omnipotent cause of neurosis caused by flying duties was fear; the task before the selectors, then, is to find personnel who have a high capacity to continue their task efficiently in spite of fear. No reliable method of selection has yet been found, and the best that has been devised is the rejection of the grossly unsuitable at intake, following by others on the advice of the flying instructor in the early stages of train-'n?. Psychiatric interview is useful only if the psychiatrist is first-class and if the men rejected can be as usefully employed in other less hazardous work. Turning now to prevention of neurosis in those who are selected, it is found that the incidence varies greatly according to the duties invoh'ed. Percentage incidence during the last war was: night-bomber, 12; day-bomber, 11; day-fighter, 6; night- fighter, 4: coastal reconnaissance, 3\\ and Training Command, 1. The individual's response to the risks he meets can be modified bv two means, and both these were employed in the last war. Firstly, systems such as that of being asked to carry out two tours onlv, with a rest between them, were successfully estab lished, giving the man some chance of survival, some plan for the future. Secondly, every effort was made to strengthen morale. In this the part of the squadron and flight commanders was hard to over-estimate; wives, on the other hand, had an adverse effect. Morale is bolstered by success, by giving credit for success, and bv making the credit known to the whole squadron. The imme diate decoration, the impromptu party, and high-level praise— all have their nan. It is lowered by blameworthy failure, by emnhasis on difficulty, hazard and futility. A regular rhythm of living, whether of sleep, off-duty, leave, or games, needs close attention. The man must know of his obligations and his relaxa tions beforehand; he must not be kept in the dark, and, above all, he must not be frustrated by frequent change of plan or policy. Lastly, if fear must be endured, anticipation of that fear must be reduced to a minimum. By these means, neuroses can be kept to a minimum. This is vita', because once a man has been removed from combat flying for neurotic reasons, experience has shown that the chances of returning him to it are negligible. Prevention is the best treatment. HEALTH OF AIRLINE CREWS (Summarizedfrom a paper by K. G. Bergin, M.A., M.D., D.P.H., A.F.R.Ae.S., Area Medical Superintendent, B.O.A.C.) T HE medical supervision and care, in all its aspects, of the fly ing personnel of a civil airline presents many problems, which might not be apparent at first sight to those not fully acquainted with airline operations. The reason for this is that there is prob ably no class of person whose work is more closely bound up with, and influenced by, their physical, mental and psychological con dition, and any impairment of function in these spheres is reflected in their flying efficiency, and consequently the safe and effective control of aircraft for which they are responsible. After potential candidates have been tentatively accepted by
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