CHAPTER 1. Introduction To Weight-Shift Control

Medical Factors

A number of physiological effects can be linked to fl ying. Some are minor, while others are important enough to require special attention to ensure safety of fl ight. In some cases, physiological factors can lead to infl ight emergencies. Some important medical factors that a WSC pilot should be aware of include hypoxia, hyperventilation, middle ear and sinus problems, spatial disorientation, motion sickness, carbon monoxide poisoning, stress and fatigue, dehydration, heatstroke, and hypothermia. Other factors include the effects of alcohol and drugs, and excess nitrogen in the blood after scuba diving.

A prerequisite to this chapter is the aeromedical factors portion of the Pilotís Handbook of Aeronautical Knowledge (FAA-H-8083-25) which provides detailed information a pilot must consider in all flight operations. All of the aeromedical factors described in that book are applicable to WSC. However, the following are additional topics applicable to WSC not specifi cally covered.


Because the WSC aircraft moves weight through pilot input, there is significant arm and upper body strength required to fl y a WSC aircraft, especially in turbulence. If flying a cross-country flight midday in moderate turbulence for more than an hour, a pilot would

require signifi cant strength and endurance. This signifi cantly adds to fatigue, as discussed in the Pilotís Handbook of Aeronautical Knowledge. This is accomplished all the time by experienced pilots, but it is a workout. If this type of workout is combined with dehydration in a desert environment, a greater than anticipated headwind, or fl ying an unfamiliar cross-country route, the added aeromedical risk factors could lead to a fatal error chain.


Hypothermia is an important factor and knowledge requirement in the WSC Practical Test Standards. Cold temperatures for long periods reduce the inner body core temperature when the heat produced by the body is less than the amount of heat being lost to the bodyís surroundings. This loss of heat is highly accelerated in WSC open fl ight decks with wind chill. The fi rst symptom of fl ying a WSC aircraft is cold hands because of exposure to wind chill. Symptoms continue with other parts of the body becoming cold until the entire body feels cold. Hypothermia results in weakness, shivering, lack of physical control, and slurred speech followed by unconsciousness and death. Dressing warm and/or aircraft heating systems to help the pilot remain warm during flight prevents hypothermia. Motorcycle gloves and socks that run off the aircraft electric system are commonly used and can keep a pilot from getting cold. [Figure 1-21] Also, carrying an appropriate survival kit prepares a pilot against hypothermia if forced down in cold temperatures.

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