The National Transportation Safety Board’s (NTSB) Aviation Accident Database lists over six dozen reports in the past 20 years where flight crew fatigue was determined to be a contributing factor in the accident. This constitutes an average of over three accidents per year as a result of flight crew fatigue. The crash of American Airlines Flight 1420 in Little Rock, Arkansas, on 01 June 1999 cited impaired crew performance resulting from fatigue as being the most prevalent of three factors leading to the disaster. After touchdown, the MD-82 failed to stop before the end of the runway and struck part of the ILS localizer array, plowed through a chain link security fence, passed over a rock ...view middle of the document...
(as cited in Desmond, Matthews, & Hancock, 2012, p. 469)
From an aviation standpoint, the NTSB has determined that human error accounts for approximately 70% of fatal accidents. Of those accidents up to 20% can be directly related to flight crew fatigue (European Cockpit Association, 2014). Even for those accidents where fatigue is not specifically cited, it still may have been a contributing factor. While the consequences are apparent, the actual definition and parameters of fatigue are not.
Definition of Fatigue
Fatigue is a condition that is challenging to define and almost impossible to quantify, but we know of its existence. Sleepiness, lethargy, and tiredness are terms commonly associated with fatigue and are often used interchangeably. The Federal Aviation Administration (FAA) defines fatigue as “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” (2013). Salas and Maurino state that “fatigue is classically defined as a decrease in performance or performance capability as a function of tome on task” (p. 401). This is wherein the problem lies because as the definitions suggest, fatigue is experienced differently amongst individuals and there are no biological benchmarks for identifying levels of fatigue. In addition, research has highlighted a major disconnect between individual perception and objective physiological measurements of alertness. A NASA Ames Research Center study of pilots assigned to international flights discovered that the pilot’s perceived highest level of alertness actually coincided with the time when all physiological indicators pointed to the lowest level of alertness (Rossier, 2001). Recently revised FAA regulations better address the risk of flight crew fatigue, but still place the responsibility of fatigue determination upon the flight crew. This study would indicate that the flight crew would not be fully able to make a proper assessment of their fatigue level, especially if it is at a critical state.
The benefits of sleep are well known, including the positive effects it has on an individual’s health, longevity, safety, and overall physical and mental performance. Adequate amounts of quality sleep is a pilot’s first line of defense against fatigue. While it seems like a simple and straightforward solution, there are complexities involved with the mechanics of sleep that work against a human being. On average an individual progresses through four to six cycles of sleep during a normal night’s sleep. These cycles average 90 minutes and involve both REM (rapid eye movement) and non-REM states. Deep sleep is experienced within the early cycles, while lighter sleep and increased REM are encountered in the later cycles. Disruption of cycles or readjustment of sleeping patterns requires successive sleep periods to compensate for the loss of sleep.
The human body is controlled by an internal...