Fatigue is a normal response to many conditions common to flight operations because characteristics of the flight deck environment,  such as low barometric pressure, humidity, noise, and vibration, make pilots susceptible to fatigue. The only effective treatment for  fatigue is adequate sleep. As fatigue progresses, it is responsible for increased errors of omission, followed by errors of commission,  and microsleeps, or involuntary sleep lapses lasting from a few seconds to a few minutes. For obvious reasons, errors caused by these  short absences can have significant hazardous consequences in the aviation environment.  Sleep-deprived pilots may not notice sleepiness or other fatigue symptoms during preflight and departure flight operations. Once  underway and established on altitude and heading, sleepiness and other fatigue symptoms tend to manifest themselves. Extreme  fatigue can cause uncontrolled and involuntary shutdown of the brain. Regardless of motivation, professionalism, or training, an  individual who is extremely sleepy can lapse into sleep at any time, despite the potential consequences of inattention. There are a  number of countermeasures for coping with fatigue, as shown in  Figure 1-7.  Complacency presents another obstacle to maintaining situational awareness. Defined as overconfidence from repeated experience on  a specific activity, complacency has been implicated as a contributing factor in numerous aviation accidents and incidents. Like  fatigue, complacency reduces the pilot’s effectiveness in the flight deck. However, complacency is harder to recognize than fatigue,  since everything is perceived to be progressing smoothly. Highly reliable automation has been shown to induce overconfidence and  complacency. This can result in a pilot following the instructions of the automation even when common sense suggests otherwise. If  the pilot assumes the autopilot is doing its job, he or she does not crosscheck the instruments or the aircraft’s position frequently. If  the autopilot fails, the pilot may not be mentally prepared to fly the aircraft manually. Instructors should be especially alert to  complacency in learners with significant flight experience. For example, a pilot receiving a flight review in a familiar aircraft may be  prone to complacency.  Advanced avionics have created a high degree of redundancy and dependability in modern aircraft systems, which can  promote complacency and inattention. During flight training, the  flight instructor  should emphasize that routine flight operations may lead to a sense of complacency, which can threaten flight safety by reducing situational awareness.  By asking about positions of other aircraft in the traffic pattern, engine instrument indications, and the aircraft’s location in relation to  references on a chart, the  flight  instructor can determine if the learner is maintaining situational awareness. The  flight  instructor can also attempt to focus the learner’s attention on an imaginary problem with the communication or navigation equipment. The  flight  instructor should point out that situational awareness is not being maintained if the learner diverts too much attention away from other tasks, such as controlling the aircraft or scanning for traffic. These are simple exercises that can be done throughout  flight training, which help emphasize the importance of maintaining situational awareness.  There are numerous classic behavioral traps that can ensnare the unwary pilot. Pilots, particularly those with considerable experience,  try to complete a flight as planned, please passengers, and meet schedules. This basic drive to demonstrate achievements can have an  adverse effect on safety and can impose an unrealistic assessment of piloting skills under stressful conditions. These tendencies  ultimately may bring about practices that are dangerous and sometimes illegal and may lead to a mishap. Learners develop awareness  and learn to avoid many of these operational pitfalls through effective ADM training. The scenarios and examples provided by  instructors during ADM instruction should involve these pitfalls.  [Figure 1-8]  1-14 Operational Pitfalls  Figure 1-7.  Countermeasures for coping with fatigue. 