Fatigue in Aviation (Physiology of Flight No. 16) ~ 1990 FAA Pilot Training (Patreon)

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Originally a public domain film from the Library of Congress Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/Pilot_fatigue

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

The International Civil Aviation Organization (ICAO) defines fatigue as "A physiological state of reduced mental or physical performance capability resulting from sleep loss or extended wakefulness, circadian phase, or workload." The phenomenon places great risk on the crew and passengers of an airplane because it significantly increases the chance of pilot error. Fatigue is particularly prevalent among pilots because of "unpredictable work hours, long duty periods, circadian disruption, and insufficient sleep". These factors can occur together to produce a combination of sleep deprivation, circadian rhythm effects, and 'time-on task' fatigue. Regulators attempt to mitigate fatigue by limiting the number of hours pilots are allowed to fly over varying periods of time...

Effect on flight safety

It has been estimated that 4-7% of civil aviation incidents and accidents can be attributed to fatigued pilots. "In the last 16 years, fatigue has been associated with 250 fatalities in air carrier accidents." Robert Sumwalt, NTSB vice chairman, said at an FAA symposium in July.

Symptoms associated with fatigue include slower reaction times, difficulty concentrating on tasks resulting in procedural mistakes, lapses in attention, inability to anticipate events, higher toleration for risk, forgetfulness, and reduced decision-making ability. The magnitude of these effects are correlated to the circadian rhythm and length of time awake. Performance is affected the most, when there is a combination of extended wakefulness and circadian influences.

Studies on the effects of fatigue

A Federal Aviation Administration (FAA) study of 55 human-factor aviation accidents from 1978 to 1999, concluded accidents increased proportionally to the amount of time the captain had been on duty. The accident proportion relative to exposure proportion rose from 0.79 (1–3 hours on duty) to 5.62 ( more than 13 hours on duty). This means that "5.62% of human factors accidents occurred to pilots who had been on duty for 13 or more hours, where only 1% of pilot duty hours occur during that time."

In another study by Wilson,Caldwell and Russell, participants were given three different tasks that simulated the pilot's environment. The tasks included reacting to warning lights, managing simulated cockpit scenarios, and conducting a simulated UAV mission. The subjects' performance was tested in a well-rested state and again after being sleep deprived. In the tasks that were not as complex, such as reacting to warning lights and responding to automated alerts, it was found that there was a significant decrease in performance during the sleep deprived stage. The reaction times to warning lights increased from 1.5 to 2.5 seconds, and the number of errors doubled in the cockpit. However, tasks that were engaging and required more concentration were found to not be significantly affected by sleep deprivation. The study concluded that "...fatigue effects can produce impaired performance. The degree of performance impairment seems to be a function of the numbers of hours awake and the 'engagement' value of the task."

One United States Air Forces study found significant discrepancies regarding how fatigue affects different individuals. It tracked the performance of ten F-117 pilots on a high-fidelity flight simulator. The subjects were sleep deprived for 38 hours and their performance was monitored over the final 24 hours. After baseline correction, the systematic individual differences varied by 50% and concluded that fatigue's effect on performance varied drastically among individuals...