How does Fatigue Affect Pilot Decision Making

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Introduction Fatigue plagues all of us at some point in our lives. In aviation, fatigue may cause a pilot to fall asleep during cruise flight or it may impact alertness during take-off or landing. Pilots have a huge responsibility due to the fact they have a lot lives in their hands. This paper will discuss what fatigue is, how it affects the pilot decision making process, and what the government is doing to help combat fatigue and protect the flying public. What is Fatigue?

According to the Federal Aviation Administration (FAA) fatigue is a physiological state in which there is a decreased capacity to perform cognitive tasks and an increased variability in performance as a function of time on task. Fatigue is also associated with tiredness, weakness, lack of energy, lethargy, depression, lack of motivation, and sleepiness (Federal Aviation Administration, 2010). Some signs that a pilot may be fatigued are: Lack of alertness, impaired physical and mental performance, poor decision-making skills, slow reaction time, forgetfulness, lack of interest, moodiness, diminished creativity.

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There are two types of fatigue: acute, and chronic. Acute fatigue 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 steep ordinarily cures this condition. Acute fatigue degrades attention, coordination, concentration and just the overall decision-making process. Simple tasks become overwhelmingly difficult and all of the remaining energy is channeled into apparently menial tasks.

A special type of acute fatigue, called “skill fatigue,” is a form of fatigue that pilots are more susceptible to. Skill fatigue has two main effects upon the pilot’s performance: The first one is timing disruption . This is where the pilot appears 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. The second effect is the disruption of the perceptual field.

The pilot concentrates their attention upon movements or objects in the center of their vision and neglects those in the periphery. This may be accompanied by loss of accuracy and smoothness in control movements. Acute fatigue is brought on by many causes, but the following are among the most important for the pilot: 1) Mild hypoxia (oxygen deficiency). 2) Physical stresses produced by the aircraft, such as fighting severe turbulence, icing conditions, malfunctioning of the equipment. 3) Psychological stress, some of it emotional and some resulting from the emanding intellectual activity required for successful flight operations. 4) Depletion of physical energy resulting from psychological stress. Sustained psychological stress accelerates the glandular secretions which 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 (Pilot Fatigue).

Chronic fatigue accumulates over time and is caused by lack of sleep, stress and jetlag. Chronic fatigue usually has psychological roots. Continuous strain on the pilot’s job, for example, can produce chronic fatigue. The pilot 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 (Novacek, 2003).

How does fatigue affect pilot decision making Maintaining optimal alertness and neurobehavioral functioning in operational environments is critical for achieving high levels of safety, efficiency, and success. High levels of alertness and performance are necessary to operate complex technology and machinery as well as to make critical task decisions on a sustained basis. Individuals working erratic schedules experience conflicts between the biological circadian rhythm and environmental time cues and work demands.

This physiological conflict can cause a sense of drowsiness (subjective fatigue), mood changes, performance degradation, and physiological upset. Two adverse effects of the circadian conflict between the sleep/wake pattern and the biological rhythm worsen performance levels and sleepiness: Trying to sleep when a person’s biology is highly energized, and Attempting to maintain alertness and high cognitive functioning at a time when a person’s biological clock is programming the body to sleep (Federal Aviation Administration, 2010).

In 1994 Neville, Bisson, French, Boll, and Storm performed a study of pilot fatigue by the military. They studied airline crews that were exposed to extended work periods, reduced sleep, night work, and circadian dysrhythmia caused by shift work and time zone crossings during Desert Storm. Their research showed that recent sleep and f light histories are correlated with high subjective fatigue levels. They also found a tendency for fatigue to correspond with pilot error. Pilot fatigue can also be studied in aircraft simulators.

A recent study at the Walter Reed Army Institute of Research tested flight performance of eight pilots on a flight simulator based on time awake. The study examined pilot air refueling flight performance across 27 hours of continuous wakefulness. Preliminary analysis suggests that severe performance deficits occurred after one night of continuous wakefulness (Goode, 2003). Another study performed by Caldwell, Hall, Erickson in 2002 determined whether the electroencephalographic (EEG) changes associated with sleep deprivation could be reliably recorded from aviators flying standardized maneuvers in an aircraft.

In-flight EEG data were recorded from 10UH-60 helicopter pilots who were kept awake for approximately 26 hr. In addition, resting EEGs and mood data were collected in the laboratory between flights. Results indicate that EEG theta activity, and to some extent delta activity, increases as a function of sleep deprivation in both settings. In addition, mood decrements were associated with the fatigue from sleep loss. These results indicate it is possible to monitor a pilot’s general fatigue levels via the EEG without interfering with the primary duty of flying the aircraft (Caldwell, Hall, & Erickson, 2002).

There is a complication in understanding past accidents and in preventing future ones is that airline accidents rarely have a single cause. Rather, accidents are usually the culmination of a sequence of events that involve multiple causes and contributing factors. Assessing the role that pilot fatigue may have played in an accident is a challenge because of other potential contributing factors. In some cases, the cockpit voice recorder may reveal that pilots talked about being fatigued during the flight or there may have been other signs of fatigue from the cockpit voice recorder.

In other cases, the record may be clear that a pilot received very little sleep prior to the flight. There is strong evidence that fatigue can result in deteriorated pilot performance even in such cases, the fact that a pilot is likely to have been fatigued does not necessarily mean that the pilot’s fatigue resulted in errors made during the accident sequence or contributed to the cause of the accident. Well-rested pilots have been involved in airplane crashes and fatigued pilots have completed flights without accidents.

However, because the contribution of fatigue can be difficult to detect during an accident investigation, it is quite possible that fatigue may have contributed to accidents even when there is no clear evidence of pilot fatigue in the accident record (Council, 2011). Below are two charts that show fatigue related accidents from 1982 to 2010. Injury CategoryTotal AccidentsFatigue Accidents Part 121 Fatal952 Part 121 Serious4234 Part 121 Minor780 Part 121 None3373 Total8639 Total Accidents and Fatigue Accidents by Injury Category 1982-2010 (Council, 2011)


Fatigue Related Accidents 1982-2010 (Council, 2011) What is being done to combat fatigue? The best weapon to defeat fatigue is to get plenty of sleep. It is advised that the average person requires at least 8 hours of sleep (Federal Aviation Administration, 2010). Lifestyle is another way to help defeat fatigue. There are new technologies in the form of cockpit design to help eliminate mental workload fatigue of the pilot. The biggest tactic to combat fatigue would be the FAA. The FAA has regulations in place to help the pilot combat fatigue but accidents and mistakes still occur.

The FAA has proposed a stricter regulation and is now in the decision making process. The current regulation limits flight time and pilot rest and has been in place since the 1940s. The rules for domestic flights do not explicitly address the amount of time a pilot can be on duty. Rather, the rules address flight time limitations and required rest periods. Current FAA regulations for domestic flights generally limit pilots to eight hours of flight time during a 24-hour period. This limit may be extended provided the pilot receives additional rest at the end of the flight.

However, a pilot is not allowed to accept, nor is an airline allowed to assign, a flight if the pilot has not has at least eight continuous hours of rest during the 24-hour period. In other words, the pilot needs to be able to look back in any preceding 24-hour period and find that he/she has had an opportunity for at least eight hours of rest. If a pilot’s actual rest is less than nine hours in the 24-hour period, the next rest period must be lengthened to provide for the appropriate compensatory rest. Airline rules may be stricter than the FAA’s regulations if the issue is part of a collective bargaining agreement.

Flight time and rest rules for U. S. air carrier international flights are different from the rules for domestic flights. International flights can involve more than the standard two-pilot crew and are more complex due to the scope of the operations. For international flights that require more than 12 hours of flight time, air carriers must establish rest periods and provide adequate sleeping facilities outside of the cockpit for in-flight rest (Federal Aviation Administration, 2010). The new regulation proposal reflects the universal nature of fatigue.

The proposed rules would be the same for all types of Part 121 flights (passenger and cargo airlines): domestic, flag (international), or supplemental (unscheduled). There are currently different requirements for each of these categories of operations. The proposed rule does not apply to Part 135 operators, but FAA may address fatigue for Part 135 operators in the future. Unlike the current rules, the proposal provides a circadian component for reducing the flight time and duty time when the pilot is operating in his or her window of circadian low.

The proposal clearly states that fatigue mitigation is the joint responsibility of both the airline and the pilot. A pilot may not accept an assignment if that pilot is too fatigued to fly. The proposal would give airlines the flexibility to adopt individual Fatigue Risk Management Systems. Fatigue Risk Management Plans, recently mandated by Congress and now addressed by FAA policy, would set out a carrier’s own policies and procedures for reducing the risk of fatigue and improving alertness.

These plans are specific to an air carrier’s type of operations, are subject to the FAA’s review and acceptance, and include fatigue education and awareness training. The FAA proposes to set a nine-hour minimum for rest prior to flying-related duty, a one-hour increase over the minimum in current rules along with certain flight and duty time. Flight time will consist of the following: Weekly: The proposal provides pilots with at least 30 consecutive hours per week free from all duty, compared to the current 24 hours free from all duty on a weekly basis – a 25 percent increase.

Monthly: Under the proposal, there is a 100-hour maximum for flight time in any 28 days. Current rules set a limit of 100 hours for every 30 days. Yearly: There is a current limit of 1,000 hours in any calendar year for domestic flights. Under the proposal, all types of operations will now be limited to 1,000 hours per 365 days. For duty time there is currently a 16-hour duty period between rest periods. The proposal would limit the daily flight duty period to 13-hours, which could slide to nine hours at night (Federal Aviation Administration/September, 2010). Conclusion

Pilot fatigue is a problem that can evolve into bigger problems if it is not properly taken care of. This is a problem that has caused the loss of people’s lives. Hopefully with proposal of new regulations, technologies, and with some training pilots and passengers alike will be safer. This paper has answered the questions it set out to answer. “My mind clicks on and off. I try letting one eyelid close at a time while I prop the other with my will. But the effect is too much, sleep is winning, my whole body argues dully that nothing, nothing life can attain is quite so desirable as sleep.

My mind is losing resolution and control. ” Charles Lindbergh about his 1927 transatlantic flight Works Cited (n. d. ). Retrieved August 24, 2011, from studentpilot. com: http://www. studentpilot. com/articles/medical_articles/article. php? medical_id=27 Caldwell, J. A. , Hall, K. K. , & Erickson, B. S. (2002). EEG Data Collected From Helicopter Pilots in Flight Are Sufficiently Sensitive to Detect Increased Fatigue From Sleep Deprivation. THE INTERNATIONAL JOURNAL OF AVIATION PSYCHOLOGY 12:1 , 19-32. Council, N. R. (2011).

The Effects of Commuting on Pilot Fatigue. Washington,DC: National Academies Press. Federal Aviation Administration. (2010). AC 120-100 Basics of Aviation Fatigue. US Department of Transportation. Federal Aviation Administration. (2010). Fact Sheet- Pilot Fatigue/ January. FAA. Federal Aviation Administration/September. (2010). Fact Sheet- Pilot Fatigue. FAA. Goode, J. H. (2003). Are pilots at risk of accidents due to fatigue? Journal of Safety Research 34 , 309-313. Novacek, P. (2003, april). How can avionics help reduce pilot fatigue. Avionics news , pp. 50-54.

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How does Fatigue Affect Pilot Decision Making. (2019, May 02). Retrieved from

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