A MEDICAL SURVEY OF. CLIMATIC EFFECTS ON

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1 213 A MEDICAL SURVEY OF. CLIMATIC EFFECTS ON ARMY AVIATORS OPERATING IN SOUTH ARABIA * Captain I. C. PERRY, M.B., B.S., L.R.C.P., M.R.C.S., R.A.M.C. Department of Aviation Medicine, Army Aviation Centre. Introduction CLIMATE has varied effects on personnel. Little has been written of the effects of the South Arabian climate on Army pilots. A year's survey was carried out, by means of. personal interview, review of medical documents, and by questionnaire. The aim of this paper is to review briefly the climatic conditions of South Arabia, and to illustrate their effects upon pilots, with some recommendations as to improvements which could be made. The South Arabian Climate Figure 1 compares the Aden and South Arabian climates, in terms of monthly average effective temperatures, with those of Hong Kong and Singapore, based on figures over five years. Table 1 shows average daily maximum and minimum temperatures recorded in various places in South Arabia. Locations are shown on the sketch map (Figure 2) with a rough indication of altitude in feet. COMPARISON 0': ADEN, SOUTH ARABIA AND OTHER C/./MATES MEAN MONTHl.Y TEMPERArtlRES. J R Army Med Corps: first published as /jramc on 1 January Downloaded from 60.JAN. FEIJ. MAR. APR.. HAY JUN. JIJL. AvG. SEP. Fig. 1 * Abridgedfrom the successful entry for the Parkes Prize, HONG KONt1 OCT. NW. Die. on 7 June 2018 by guest. Protected

2 214 A Medical Survey. of Climatic Effects on Army Aviators Operating in South Arabia MONTH JAN FEB MAR APR MAY,JUN JUL AUG SEP OCT NOY DEe Table 1 Average Daily Maximum (a) and Minimum (b) Temperatures in South Arabia (In Fahrenheit) Height above sea level infeet ADEN MUKERIAS DHALA BEIHAN MUKALLA SALALAH MASIRAH (RIYAN) a b a b a b a b a b a b 64 a 78 b esana YEMEN I / / /" C/.eNUQUB 3100 I ~S IHAII J300 i I /"1..,/" i... / /,.- /...: ~1.8 /)HA _ (-MUKEIRAS LObAR 3200,,".,..." """.,.-Qi~ABA I e/)haja 'IEZ./ HAIl'JAY'",fA <: ~p.~,...). 1tt /" SOU ;.-... _/ l.ahej Fg.2, ~ I i. '. '. enisab32001 fj4taq'1. MAFIDHe2~O AHWAR.2()00 MILES [ J 0 40 so ',,!!rll"!'! I! [ ( I I

3 1. C. Perry 215 In the mountainous' up country' areas during the hot season the temperature range is wide with high day temperatures and much lower night temperatures. At midday, at an altitude of 3,800 feet, the cockpit temperature of a Beaver aircraft with both doors open, was recorded as 160 F, whereas the night temperature fell to around 75 F. In another region at an altitude of 6,500 feet, the midday temperature reached loo F, falling at night to 50 F. It will be seen from these examples, that a man based in Aden itself, where an average hot season daily temperature of around loo F is recorded, may, if he flies up-country and stays the night, experience changes of temperature of anything up to 60 F.. Variations in humidity with only small changes in temperature greatly increase discomfort. In Aden itself, during the hot season, the difference between maximum and minimum daily temperatures may be as little as loop to 15 P, whereas the relative humidity may vary from 30 per cent to 80 per cent The greatest discomfort is felt at night when the humidity rises and the temperature falls. In stations at higher altitudes, this increase is naturally not felt so much. The result of this, among other things, is that there is no shortage of' up-country' volunteers. Wind speeds vary greatly during the hot season, as does air turbulence. Hot air rising up over the mountain regions causes such turbulence that flying is prohibited, except in emergency, over the plateau regions where the escarpment rises from just above sea level to 6,500 feet. Variable wind speeds with severe turbulence cause light fixed wing and rotary wing aircraft to be thrown about dangerously. Ground wind speeds recorded at the main air base in Aden vary from 5 to 50 knots. The higher the wind speed, the greater the association with sandstorms, which can develop quite suddenly and can vary in altitude, from 50 to 2000 feet. The sand haze can range up to 10,000 feet with visibility down to less than some 300 yards. To summarise, the South Arabian climate is very variable at different altitudes. Generally, it is very hot during the day with a low humidity, and a higher night humidity, with a wide range in temperature, ranging from a fall of only loop to 15 F at sea level, to SOop to 60 0 P at 5,600 feet. The cool season is very pleasant and stable, whereas in the hot season, variable wind speeds, turbulence, sand and dust storms make flying light aircraft a very strenuous, and at times a hazardous occupation. Effects of Climate and Machine on the Man General The facts and figures which follow are based on a questionnaire given to Army pilots serving in Middle East Command and from observations carried out on pilots over a period of one year. The total number of pilots covered in the survey was about fifty. The number is not specific as.some were engaged on non-flying duties, some were interviewed and did not answer the questionnaire, and a number left the Command before the questionnaire was circulated: The length of stay in the theatre ranged from a few weeks to 20 months. The types of aircraft flown by Army pilots in Middle East Command were Beaver fixed wfug monoplane, Westland Scout and Bell Sioux rotary wing aircraft. The average monthly number of flying hours completed per pilot was 30. The range was from 15 to 45 hours. The Regimental Sioux troops had a higher average,

4 216 A Medical Survey of Climatic Effeots on Army Aviators Operating in South Arabia but when broken down, flying time was not spread evenly over the month, but concentrated into periods corresponding to operations and exercises. Most pilots experienced discomfort while flying during the hot season except at high altitudes. This was most noticeable in helicopter pilots, especially on low level runs and during start-up and run-down periods when the machines were stationary. Very high cockpit temperatures were recorded, and an average of readings taken is given in Table 2. These ranged between 60 and 160 F. The Sioux Helicopter had the highest Scout Helicopter Cabin doors off Sioux Helicopter Cabin doors off Beaver Aircraft Table 2 Cabin Temperatures of Aircraft Taken between May, 1965 to July, 1966 All are average figures In flight Ground running, tie down etc. In flight Run down and starting Taken for the study over a period of 2 days in July Demonstrating the temperature r~nge 9000 feet at 0930 hours flying 3600 feet at 1115 hours on ground 3800 feet at 1200 hours on ground 6000 feet at 1200 hours on ground 1700 feet at 1330 hours on ground Khormaksar, Aden, 1800 hours on ground Habilayn, 2000 feet at 1030 hours on ground 6500 feet at 0700 hours flying over desert 6000 feet at 0930 hours flying over hills 2500 feet at 1730 hours flying. Outside 65 P 97"P 97 P 77 P 97 P 90 0 P 95 P 75 P 70 0 P 84 P Cabin 86 P 125 P 123 P 95 P P 98 P 112 P 92 P 94 P 94 P All temperatures were taken in Beaver with Bimetallic Coil Thermometer 8~ 86 P p l00-f04 P oP Full Sun 108 P 155 P P P P readings, mainly due to its all-perspex bubble cockpit, which has no colouring and gives no shade from the sun. In-flight temperatures are lower and all aircrew preferred to fly with the doors off to increase airflow through the cabin.. Sweating All pilots experienced discomfort from sweating. One of the main problems was sweat running down into the eyes. This often required hands to be taken off the controls, which could be hazardous during a manoeuvre when full concentration was necessary. It is difficult to see how this problem can be overcome. 'Fans and streams of cool air have been suggested; absorbent head bands and fully closed air conditioned cockpits have been proposed. The last is obviously not feasible in' operational helicopters, and the answer seems to be some form of cool air flow directed around the pilot's head and shoulders, as in some RAF transport aircra(t. Air conditioned suits would involve an unacceptably complex system. Sweating made helmets uncomfortable and produced rashes. Common sites were around the forehead and the throat microphone areas, the

5 I..C. Perry 217 latter causing more concern, since talking aggravated the rash. Some pilots had to give up throat microphones, which most prefer, to allow rashes to recover. Another common site was on the buttocks, where the sweat which runs down is concentrated. A remedy would be to make the seats more absorbent, or by ventilating them. Closely associated with this condition is chafing by. the seat straps, mainly on the shoulders; this can be minimised by personal hygiene and clean and adequate clothing between skin and straps. A common fault is that flying suits are not cleaned often enough, with consequent hardening of the material.. Glare Discomfort from glare, whilst being a universal complaint, was a particular problem in the Sio.ux helicopters. Without exception all Sioux pilots and passengers experienced trouble unless sun glasses or visors were worn. It is considered that whilst flying in the Middle East, some form of anti-glare substance should be attached to the upper surface of the Sioux canopy. Many pilots reported that after 1 or 2 hours flying, actual visual distortion occurred, which presented as a flying hazard. Some form of tinting, whilst cutting down the glare, would also reduce the cockpit temperature. Postural effects Sitting for long periods in the same position in flying seats is uncomfortable. In. the Sioux helicopter this problem has been found to be considerable. Over the year some 10 to 12 Siouxpilots reported sick with severe low back pain. A number of cases were admitted to hospital, others were bedded down and the rest grounded. In this. theatre ' Sioux backache' has presented as a major problem. One Regimental air troop was grounded as both its pilots had severe backache. A pilot who had flown Scout helicopters for about 4 years converted to Sioux whilst in the Command, and within three weeks began to experience severe low back pain which resulted ~n his being grounded. After extensive investigation of seats, pilots and aircraft, and their relative positions in flight, the cause seems to be postural. The Sioux helicopter never flies straight, always appearing to have a slight nose-down attitude. The result is that the pilot corrects his position by straightening up in his seat and leaning forward. He has to crane his head up and his back forward to get level vision, and, to compensate, he arches his back. The result is an unnatural position, the pilot leaning heavily on the straps, with much back strain. A further complication is the low position of the controls. The pain is always in the same area of the back where corrective flexion occurs to maintain flying position. More recently, it has been suggested that vibration may be a contributory factor. This is now being investigated. Remedies may be a redesigned seat, or the re-positioning of the seat-in both cases with corresponding adjustment of the control positions. Peisonal efficiency Pilots were asked to comment as to whether they thought their efficiency had altered during their stay in Sout!). Arabia. The majority considered that it had, the main complaints being a loss of stamina and of powers of prolonged concentration. This applied to pilots of all types of aircraft. It is recognised that many Europeans are less efficient after some time in a hot climate, despite acclimatisation. Pilots undergo theatre conversion on arrival, and for the first few months, although becoming tired after

6 218 A Medical Survey of Climatic Effects on Army Aviators Operating in South Arabia flying, seem quite fit. As time progresses, and although experience increases, efficiency falls off, tempers are shorter and risks tend to be taken. It may be considered that the length of tour should be limited, in hot climates, to a maximum of 1 year. -It has been observed that troubles appear mainly during the second year, when serious psychological and physical wear and tear on pilots becomes more,evident. Minor complaints become major events, and family disturbances affect the pilot far more.. Fluid intake Total fluid intake was found to be generally below what is considered adequate. It has been assessed that, during the hot season, pilots require 10 to 17 pints of fluid daily, and more If increased daily flying is carried out in extremes of heat and humidity. Personal observations were made, during a five day operation in mountain areas with altitudes averaging 4000 feet. The daytime temperatures reached 96 p with a low humidity. It was very dusty. Although most pilots drank 5 to 8 pints daily, ruter 2 to. 3 hours signs of depletion occurred. Headaches, irritability and thirst soon disappeared on raising the intake to 9 to 12 pints. Pilots move daily from trying altitudes and.fluid intake is forgotten on arrival at a pleasantly cool area. Education rapidly improved this situation, and the pilots felt much better for it. SeleCtion, Health Education and Personal Health All personnel are screened before proceeding abroad; as far as pilots are concerned,. this could be more thorough. The loss of even two men with skin disease or ear infections. can disrupt a small flying unit. A full briefing, by a medical officer, or by someone aware of the medical aspects of hot climate should be given before proceeding overseas. On arrival in the theatre, lectures and notes on the climate, its effects, and on heat illnesses should also be given. Ifpilots understand the problems, they can cope with them much better. Personal hygience, care of the feet and skin, cleanliness of clothing and regular' exercises are most important. The Australian flying suit seemed quite satisfactory to' all who wore it but unless regularly washed, its texture was found to harden from excessive sweating. A new British lightweight flying suit would seem, from preliminary study, to be better. The condition of' Aden Gut' is suffered by most newcomers to the area. Attacks of this can be minimised by eating properly cooked and prepared food. This applies even more to those pilots who have the occasional meal at ' up country' stations where the level of hygiene is not always as high as in the more permanent camps. The study showed that sensible amounts of alcohol were consumed and that there was little over-indulgence. The soundest sleep in Aden. State was gained in air conditioned quarters. Many pilots complained that if the air conditioning was not on, their sleep seemed ineffective, and next day they.would feel" washed out". 'Up country' after a few days, more sleep was needed, ten hours per night appearing to be the average requirement. Regular taking of paludrine has always been a problem. The survey 'brought to light that not all pilots were applying this simple preventive measure. Although Aden State itself is malaria-free, a pilot is liable to fly at very short.notice and to stop over in a malarious area. All pilots must therefore take. paludrine throughout their tour.

7 I. C. Perry 219 First Aid and Personal Survival Kits The majority of pilots were fully aware of the use of these, but many were critical of the contents, which they suggested should be reviewed. The first aid kit was studied and some minor changes were considered. A pilot is often loath to open the sealed package in order to dress a cut finger, or if up-country, to treat a headache or an attack of diarrhoea. It is suggested that each pilot should equip himself with a small personal first aid kit which he can use and refill to his own needs. Personal survival kits were not always taken on every flight,,as is mandatory.. Conclusion The survey has proved most interesting and raised a large number of points where improvements can be made, or where further investigation would be of value. Most pilots remained healthy during their tour, although fatigue was more evident the longer they remained in the theatre. It is suggested that similar surveys could be made in other climates and theatres, to compare with the findings described in this paper, to discover whether similar problems exist, and if so, to seek appropriate remedies. J R Army Med Corps: first published as /jramc on 1 January Downloaded from on 7 June 2018 by guest. Protected