Fatigue is frequently associated with pilot error. Some of  the effects of fatigue include degradation of attention and  concentration, impaired coordination, and decreased ability  to communicate. These factors seriously influence the  ability to make effective decisions. Physical fatigue results  from sleep loss, exercise, or physical work. Factors such as  stress and prolonged performance of cognitive work result  in mental fatigue.  Like stress, fatigue falls into two broad categories: acute  and chronic. Acute fatigue is short term and is a normal  occurrence in everyday living. It is the kind of tiredness  people 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.  Chronic fatigue, extending over a long period of time, usually  has psychological roots, although an underlying disease is  sometimes responsible. Continuous high-stress levels produce  chronic fatigue. Chronic fatigue is not relieved by proper diet  and adequate rest and sleep and usually requires treatment  by a physician. An individual 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 leads to emotional illness.  If suffering from acute fatigue, stay on the ground. If fatigue  occurs in the flight deck, no amount of training or experience  can overcome the detrimental effects. Getting adequate rest  is the only way to prevent fatigue from occurring. Avoid  flying without a full night’s rest, after working excessive  hours, or after an especially exhausting or stressful day. Pilots  who suspect they are suffering from chronic fatigue should  consult a physician.  A special type of acute fatigue is skill fatigue. This type of  fatigue has two main effects on performance:  When conducting preflight and post-flight inspections, pilots  must verify that the fluid levels in their aircraft meet the  levels specified for safe operations as stated in the Pilot's  Operating Handbook. These fluids include, but are not limited  to hydraulic fluid, engine oil, and fuel.  It is important that every pilot recognize the potential hazards  of working with these fluids as well as the recommended first  aid measures to follow should any of these fluids come in  contact with their eyes, skin, and/or respiratory system. As  the specific first aid measures for dealing with exposure to  these chemicals can vary by chemical type, it is important that  every pilot be familiar with the location and use of the Material  Safety Data Sheet (MSDS) for each chemical they encounter.  The procedures described in the following sections are  minimum guideline for first aid for each of the indicated  scenarios. Ultimately, the pilot should consult the MSDS  for first aid procedures specific to the type of chemical and  exposure scenario.  Sustained psychological stress accelerates the glandular  secretions that 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 proper diet and adequate  rest and sleep. A well-balanced diet prevents the body from  needing to consume its own tissues as an energy source.  Adequate rest maintains the body’s store of vital energy.  Acute fatigue has many causes, but the following are among  the most important for the pilot:  • Timing disruption—appearing 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 the pilot performs each component as though it  were separate, instead of part of an integrated activity.  • Disruption of the perceptual field—concentrating  attention upon movements or objects in the center of  vision and neglecting those in the periphery. This is  accompanied by loss of accuracy and smoothness in  control movements.  • Eye Contact—immediately flush the eyes with clean  water and seek medical attention if irritation occurs.  • Skin Contact—remove all contaminated clothing and  thoroughly cleanse the affected areas with mild soap  and water or a waterless hand cleaner. If irritation or  redness develops and persists, seek medical attention.  Should the hydraulic fluid get into or under the skin,  or into any other part of the body, regardless of the  • Mild hypoxia (oxygen deficiency)  • Physical stress  • Psychological stress  • Depletion of physical energy resulting from  psychological stress  • Sustained psychological stress  Fatigue  Exposure to Chemicals  Hydraulic Fluid  17-13 