HUMAN ERROR SAFETY Unrefreshing sleep  Headaches Fatigue Pain Poor concentration Irritable mood Loss of motivation Loss of pleasure Panic attacks Avoidant behaviour Diarrhea/ constipation Abdominal pain Bloating Myalgia arthralgia Tender points C h $_{r}$o n $_{i}$c f a t ig u e  $_{s}$ y n d r o m e F i b r o m y a l g i a D e p r e s s $_{i}$o n A n x i e t y I r it a b l e b o w e l s y n d r o m e Prolonged fatigue states Figure 13-4.  Fatigue can be mental or physical and effects both  mental and physical performance.  Figure 13-3.  Safety awareness will help foresee and mitigate the  risk of human error. the Pilot’s Operating Handbook (POH) and unintentionally  transposed the number 62 to 26. He or she did not mean to  make that error but unknowingly and unintentionally did.  In aviation, an intentional error  should really be considered  a flight violation. If someone knowingly or intentionally  chooses to do something  wrong, it is a violation, which  means that one has deviated from safe practices, procedures,  standards, or regulations. 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:  cognitiv e ability, decision-making,  reaction time, coordination,  spee d, 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 concentra tion 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. Intentional  Human and Physiological Factors that  Affect Flight Fatigue  13-4