Fatigue is a major human factor that has contributed to many maintenance errors resulting in accidents. Fatigue can be mental or physical in nature. Emotional fatigue also exists and effects mental and physical performance. A person is said to be fatigued when a reduction or impairment in any of the following occurs: cognitive ability, decision-making, reaction time, coordination, speed, strength, and balance. Fatigue reduces alertness and often reduces a person’s ability to focus and hold attention on the task being performed. [Figure 13-4]
Symptoms of fatigue may also include short-term memory problems, channeled concentration on unimportant issues while neglecting other factors that may be more important, and failure to maintain a situational overview. A fatigued person may be easily distracted or may be nearly impossible to distract. He or she may experience abnormal mood swings. Fatigue results in an increase in mistakes, poor judgment, and poor decisions or perhaps no decisions at all. A fatigued person may also lower his or her standards.
Tiredness is a symptom of fatigue. However, sometimes a fatigued person may feel wide awake and engaged in a task. The primary cause of fatigue is a lack of sleep. Good restful sleep free from drugs or alcohol is a human necessity to prevent fatigue. Fatigue can also be caused by stress and by overworking. A person’s mental and physical state also naturally cycles through various levels of performance each day. Variables such as body temperature, blood pressure, heart rate, blood chemistry, alertness, and attention rise and fall in a pattern daily. This is known as one’s circadian rhythm. [Figure 13-5] A person’s ability to work (and rest) rises and falls during this cycle. Performance counter to circadian rhythm can be difficult. Until it becomes extreme, a person may be unaware that he or she is fatigued. It is easier recognized by another person or in the results of tasks being performed. Flying alone when fatigued is particularly dangerous.
The best remedy for fatigue is to get enough sleep on a regular basis. Pilots must be aware of the amount and quality of sleep obtained. Countermeasures to fatigue are often used. Effectiveness can be short lived and many countermeasures may make fatigue worse. Caffeine is a common fatigue countermeasure. Pseudoephedrine found in sinus medicine and amphetamines are also used. While effective for short periods, a fatigued person remains fatigued and may have trouble getting the rest needed once they try to sleep.
If you find yourself suffering from acute fatigue, stay on the ground. Glider pilots often become fatigued while flying due to soaring in close proximity to other gliders in areas of lift or because of the constant requirement to see and avoid other traffic. Getting adequate rest is the only way to prevent fatigue from occurring. You should avoid flying when you have not had a full night’s rest, when you have been working excessive hours, or have had an especially exhausting or stressful day. If you suspect you are suffering from chronic fatigue, consult your doctor.
Hyperventilation occurs when you are experiencing emotional stress, fright, or pain, and your breathing rate and depth increase, although the carbon dioxide is already at a reduced level in the blood. This can happen to both the experienced and novice pilot. Hyperventilation causes an excessive loss of carbon dioxide from your body, which can lead to unconsciousness due to the respiratory system’s overriding mechanism to regain control of breathing.
Glider pilots who encounter extreme or unexpected turbulence or strong areas of sink over rough terrain or water may unconsciously increase their breathing rate. When flying at higher altitudes, either with or without oxygen, a tendency to breathe more rapidly than normal may occur, which can lead to hyperventilation.
It is important to know the symptoms of hyperventilation and correctly treat for it. [Figure 13-6] Treatment for hyperventilation involves restoring the proper carbon dioxide level back in the body. Breathing normally is both the best prevention and the best cure for hyperventilation. In addition to slowing the breathing rate, you also can breathe into a paper bag or talk aloud to over-come hyperventilation. Recovery is usually rapid once the breathing rate is returned to normal.
Inner Ear Discomfort
Gliders are not pressurized, therefore, pressure changes can affect glider pilots that are flying at high altitudes. Inner ear pain and a temporary reduction in ability to hear are caused by the ascents and descents of the glider. The physiological explanation for this discomfort is a difference between the pressure of the air outside the body and the air inside the middle ear. The middle ear cavity is small and located in the bone of the skull. While the external ear canal is always at the same pressure as the outside air, the pressure in the middle ear often changes more slowly. Even a slight difference between external pressure and middle ear pressure can cause discomfort.
When a glider ascends, middle ear air pressure may exceed the pressure of the air in the external ear canal, causing the eardrum to bulge outward. This pressure change becomes apparent when you experience alternate sensations of “fullness” and “clearing.” During a descent, the reverse happens. While the pressure of the air in the external ear canal increases, the middle ear cavity, which equalized with the lower pressure at altitude, is at lower pressure than the external ear canal. The result is higher outside pressure, causing the eardrum to bulge inward.
This condition can be more difficult to relieve due to the fact that air must be introduced into the middle ear through the eustachian tube to equalize the pressure. The inner ear is a partial vacuum and tends to constrict the walls of the eustachian tube. To correct this often painful condition, which causes temporary reduction in hearing sensitivity, pinch your nostrils, close your mouth and lips, and blow slowly and gently in the mouth and nose. This procedure, called the valsalva maneuver, forces air up the eustachian tube into the middle ear.
For glider pilots, prevention is the best remedy for spatial disorientation. If the glider you are flying is not equipped for instrument flight, and you do not have many hours of training in controlling the glider by reference to instruments, it is best to avoid flight in reduced visibility or at night when the horizon is not visible. Susceptibility to disorienting illusions can be reduced through training, awareness, and learning to rely totally on your flight instruments. [Figure 13-7]
Dehydration is the term given to a critical loss of water from the body. The first noticeable effect of dehydration is fatigue, which in turn makes top physical and mental performance difficult, if not impossible. Glider pilots often fly for a long period of time in hot summer temperatures or at high altitudes. This makes dehydration very likely for two reasons: the gliders clear canopy offers no protection from the sun and, at high altitudes, there are fewer air pollutants to diffuse the sun’s rays. The result is continual exposure to heat that the body attempts to regulate by perspiration. If this fluid is not replaced, fatigue progresses to dizziness, weakness, nausea, tingling of hands and feet, abdominal cramps, and extreme thirst. [Figure 13-8]
Water should be taken on every flight to prevent dehydration. The effects of dehydration on a pilot’s performance are subtle, but can be dangerous and are especially a factor in warmer climates. Some glider pilots wear a hat to block the sun from distracting their ability to fly and see the instruments. Pilots should ensure that the brim of the hat is not too large, which can interfere with the ability to scan for other gliders and air traffic.
Heatstroke is a condition caused by any inability of the body to control its temperature. Onset of this condition may be recognized by the symptoms of dehydration, but also has been known to be recognized only by complete collapse. To prevent these symptoms, it is recommended that you carry an ample supply of water and use it at frequent intervals on any long flight, whether you are thirsty or not. Wearing light colored, porous clothing and a hat provides protection from the sun. It is also helpful to keep the cockpit well ventilated, which aids in dispelling excess heat.
When flying at higher altitudes, the inside of the glider can get cold. Proper clothing is a must since temperatures of –30° to –60 °C may be encountered at altitude. Proper preparation for the cold is especially difficult since temperatures on the ground are often pleasant on wave soaring days. Sunshine through the canopy keeps the upper body amazingly warm for a time, but shaded legs and feet quickly become cold. Frostbite is a very real threat. After an hour or two at such temperatures, even the upper body can become quite cold. Layered, loose-fitting clothing helps insulate body heat. Either wool gloves or light, fitted gloves with mittens over them work best for the hands. Mittens make tasks such as turning radio knobs difficult. For the feet, two or three pairs of socks (inner, silk; outer, wool) with an insulated boot are recommended.
In addition, the low temperatures can cause two other symptoms: it frosts your exhaled breath on the inside of the canopy and it causes the kidneys to excrete liquid at an accelerated rate.
A clean piece of cloth (that will not damage the canopy) can be used to wipe the condensation or frost from the canopy, if needed, but the best way to clear the canopy is a little fresh air through the side or front vent to help delay the buildup of frost. Unfortunately, this also quickly lowers the inside temperature, so it is best to wear clothing in layers so that you can easily take off or put on what is needed. There is little that can be done for the kidneys excreting liquid at an accelerated rate. The best course of action is to plan for it in advance by making a bathroom stop before you take off. Remember that the body is dehydrating more rapidly because of the cold and always be looking for signs of dehydration.