Fatigue is a general
term which is difficult to define medically. Usually thought of simply
as "tiredness," fatigue may be more aptly described as a depletion of
body energy reserves, leading to below-par performance. Because fatigue
lowers your efficiency as a pilot, you should understand its causes and
Fatigue falls into two
broad categories: (1) acute fatigue (short-term), and (2) chronic
Chronic fatigue, extending over a long period of time, usually has
psychological roots. (An underlying disease is sometimes responsible,
however). Continuous stain on your job, for example, can produce chronic
fatigue. You may experience this condition in the form of weakness,
tiredness, palpitations of the heart, breathlessness, headaches, or
irritability. Sometimes chronic fatigue even creates stomach or
intestinal problems and generalized aches and pains throughout the body.
When the condition becomes serious enough, it can lead to emotional
illness. If you suspect that you are suffering from chronic fatigue,
consult your doctor. Self-help cures are rare. Above all, don't fly!
Acute fatigue, on the
other hand, is short-lived and is a normal occurrence in everyday
living. It is the kind of tiredness you feel after a period of strenuous
effort, excitement, or lack of sleep. Rest after exertion and 8 hours of
sound sleep ordinarily cures this condition.
A special type of acute
fatigue, called "skill fatigue," is worth mention here because pilots
are especially susceptible to it. Skill fatigue has two main effects
upon your performance:
disruption - You appear to perform a task as usual, but the timing of
each component is slightly off. This makes the pattern of the operation
less smooth, because you perform each component as though it were
separate, instead of part of an integrated activity.
Disruption of the perceptual field - You concentrate your
attention upon movements or objects in the centre of your vision and
neglect those in the periphery. This may be accompanied by loss of
accuracy and smoothness in control movements.
Acute fatigue has may
causes, but the following are among the most important for the pilot:
Mild hypoxia (oxygen deficiency).
Physical stresses produced by the aircraft, such as fighting
severe turbulence, icing conditions, malfunctioning of the equipment.
Psychological stress, some of it emotional and some resulting
from the demanding intellectual activity required for successful flight
Depletion of physical energy resulting from psychological
stress. Sustained psychological stress accelerates the glandular
secretions and prepare the body for quick reactions during an emergency.
These secretions make the circulatory and respiratory systems work
harder, and the liver releases energy to provide the extra fuel needed
for brain and muscle work. When this reserve energy supply is depleted,
the body lapses into generalized and severe fatigue.
Acute fatigue can be
prevented by a proper diet and by adequate rest and sleep. A well
balanced diet prevents the body from having to consume its own tissues
as an energy source. Adequate rest maintains the body's store of vital
energy. You can sleep best in quiet, comfortable surroundings.
Excitement and worry will diminish the benefits of sleep. As a pilot,
you should get approximately 8 hours of sleep a night. If you are
especially tired, tense, or ill, you will need more.
Keeping your body in top
physical condition makes you less susceptible to fatigue. In addition to
getting regular exercise, you should avoid overweight. Obesity lowers
your flight performance, taxes your body, and shortens your life,
If you find yourself
suffering from either chronic fatigue or acute fatigue, stay on the
ground until your alertness and energy are restored!