The causes of fatigue are multiple; they may be physical, mental or a combination of both. The common causes are as follows: Physical Agents like: Cold, Vibration, Glare, Noise, Wind, Acceleration, Change of atmospheric pressure and Hypoxia. Others are Emotional Factors like: Boredom, Responsibility, Attention, Concentration, Alertness, Apprehension, Anxiety and Fear.
Captain Gulzar Ahmad Khan defines fatigue as a progressive decline of a man’s ability to perform his appointed tasks. It shows itself in deterioration of quality of work, lack of enthusiasm, inaccuracy, lassitude and disinterestedness. Captain Khan is a flight surgeon – assigned to Civil Defense Aviation Base, Makkah AL-Mukarramah.
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| Image via Wikimedia Commons: Crew Vehicle Systems Research Facility’s Boeing 747-400 Simulator at NASA Ames Research Center. Trials of Fatigue Countermeasures. In cockpit, pilots (L) Brian Spence and (R) Mike Holmboe – Uploaded by NASA Ames Research Center – Human Systems Integration Division |
Captain Khan said that fatigue manifests itself as various symptoms. He enumerated the common ones as follows:
- In-coordination: It is the lack of registration and interpretation of what is seen on the instrument panel, over or under correction. Forgetting or inadequate execution of essential activity among pilots.
- Positional Awareness: There is an unusual awareness of bodily position and sensation. Normally they are relatively unaware of the position in which they are sitting and minor discomforts are tolerated without much thought. Even in the early stages of fatigue. However, the minor sensations begin to obtrude themselves upon consciousness. The pilot may begin to fidget, to adjust a strap or move a buckle. Later there may be cramps and sundry aches and pains.
- Lack of Judgement: This may lead to lack of precision which is detrimental to safe flying.
- Irritability: The flier becomes unreasonable and irritable and starts blaming others for mistakes he has done.
- Reaction Time: It slows down due to fatigue.
To prevent fatigue in pilots, Captain Khan has pointed out some healthy tips that pilot should look at and adhere as follows:
- Sleep: Eight hours sleep per night is essential. It should be undisturbed and then only it would be relaxing and refreshing.
- Off-Duty Periods: Off-duty periods should be interposed at proper intervals.
- Leave: Leave and other aspects of welfare of the flier must be paid adequate attention.
- Food: Palatable food, well cooked and properly served and at the right temperature and at correct physiological time, on the ground and in the air, is an important factor.
- Cockpit Lighting: A well designed and properly laid out cockpit lighting are essential if fatigue is to be avoided; glare and reflected light or alternative inadequately lighted instruments can be a potent factor in inducing fatigue.
- Noise and Vibration: Every effort should be made to reduce this to a minimum with insulating material, ear plugs and other aids like ear muffs or helmets. This is very important in prevention of fatigue.
- Temperature, Ventilation, Humidity and Oxygen supply: The provision of an adequate circulation of fresh air and oxygen is important in preventing fatigue. The ideal temperature is from 60-75 degrees Fahrenheit with a relative humidity of 50-60 percent and with a circulation ensuring at least 1-2 lb. of air per aircrew member per minute. Oxygen should always be used in non-pressurized aircraft at heights greater than 10,000 feet by day and 5,000 feet by night.
- Seating Comfort: Aircraft seats should be designed on a basis of anatomical considerations with plenty of adjustment for individual variations in build and also variations which provide for different seating positions and muscular relaxation duringflights; accessories should include armrest, headrest and different angles of pitch for the back of the chair. Attention should also be paid to providing adequate support for the lumbar concavity.
- Grouping of Instruments: It should be proper and it is very important because if a pilot knows that the instruments are arranged in a certain way, he can review them more swiftly and with much less mental efforts. Their correct distance from the eyes, not less than 25 inches, is important if visual fatigue from constant accommodation is to be avoided.
Captain Khan also emphasized that provision of resting facilities on aircraft are a necessity when long periods of flying beyond the normal limit are inevitable due to operational requirements. And also when adverse psychological conditions exist, it is well worthwhile to release the person concerned for a short period to give him an opportunity of attempting to adjust matters. In serious cases, anxiety neurosis may supervene and this may be a further influential factor in the production of fatigue.
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