Not a Tiring Matter

September 28, 2007
Written by Tarek M. Sardana, MD
Fatigue is a major contributor to accidents and lost productivity
On August 6, 1997, Korean Air flight 801, a Boeing 747-300, crashed at Nimitz Hill in Guam. Flight 801 departed Kimpo International Airport, Seoul, with two pilots, a flight engineer, 14 flight attendants and 237 passengers. The airplane had been cleared to land on runway 6 Left at A.B. Won Guam International Airport, but crashed into high terrain about three miles southwest of the airport. Of the 254 persons on board, 228 were killed; 23 passengers and three flight attendants survived with serious injuries.

The National Transportation Safety Board (NTSB) determined that the probable cause of the accident was the captain’s failure to adequately brief and execute the non-precision approach and the first officer’s and flight engineer’s failure to effectively monitor and crosscheck the captain’s execution of the approach. Contributing to these failures was the captain’s fatigue.

The NTSB examined several fatiguerelated factors, including time of day, recent sleeping patterns and the number of hours since awakening, to determine whether fatigue was a factor in the captain’s performance. On the basis of the time of day, statements recorded on the CVR, as well as sleep and fatigue research, it was concluded that the captain was fatigued, which degraded his performance and contributed to his failure to properly execute the approach.

Fatigue is the state of tiredness associated with prolonged work/activity, and/or prolonged wakefulness. Sleep deprivation and circadian factors are major components of the entire fatigue equation.

Recent studies within international aviation safety reporting systems indicate that over 7% of aviation accidents are identified as fatigue-related, and this is likely just the tip of the iceberg. The NHTSA (National Highway Traffic Safety Administration) attributes 100,000 accidents, 1,500 fatalities, 71,000 injuries, and US$12.5 billion a year in losses to fatigue in the US alone!

Since 1893, the electric light bulb changed night into day, extending work time, which has led to a 20% reduction in sleep time over the last century and as well, aviation improvements have enabled the crossing of one time zone per hour rather than one time zone per day. It is clear that society has become an increasingly 24/7 operation and it is anticipated that fatigue will become an increasingly concerning issue.

Pilots have indicated through various studies that fatigue is an issue of concern. Nearly 75% of military pilots say fatigue is a widespread problem, and 89% of regional airline pilots say fatigue is a moderate or serious concern. Between 50-89% of pilots have admitted to having fallen asleep in the cockpit depending on which type of study is reviewed. Pilots are not only susceptible to fatigue due to lack of sleep, they are also subject to the effects of circadian shift-adjustment problems (more commonly known as jet lag). This situation may be exacerbated with the advent of Ultra Long Range (ULR) aviation operations with flight times often exceeding 18 hours. Not only will aircrew have to function for long periods of time, but they will often be crossing 12 time zones twice a week. Fatigue is certainly not an issue specific only to pilots; schedulers and maintenance personnel, among others who do shift work, are also particularly susceptible to the effects of fatigue.

Fatigue-related decrements are similar to those caused by alcohol. A significantly fatigued individual will more commonly miss checklist items, not recognize emergency situations and not respond as crisply to an urgent scenario, etc. It is interesting that we would never allow a pilot/technician under the influence of alcohol to operate complex machinery, but we as an aviation system are much more accepting of allowing a fatigued individual to continue to function. A paradigm shift in the aviation culture of fatigue is required.

1. Light or melatonin to adjust to new schedules
2. Ensuring sufficient daily sleep (i.e., more than 8 hours)
3. Strategic Naps
4. Stimulants
5. Rest Breaks
6. Posture
7. Exercise
8. Environmental Stimulation
9. Positive General Health

Overall, the fatigue reducing strategies listed above can be useful in aviation operations. But remember, each operation is unique and in any gven situation an examination of particular circumstances will be necessary

Short naps of less than 30 minutes have proven effective in decreasing the effects of fatigue and improving task functioning. Regular exercise at least four hours prior to scheduled sleep improves quality and length of sleep. Being in good general health is also beneficial in countering the effects of fatigue. Small amounts of caffeine (less than three regular cups) have definite performance benefits.

Fatigue is a major contributor to accidents, lost productivity and poor quality of life in many facets of our modern society. It is important to recognize the impact that fatigue has; especially as demand for 24/7 aviation operations increases, the potential for fatigue-related problems will only become more significant. However, safety, performance, and general well-being can be preserved by adhering to well planned work-scheduling practices, implementing proven fatigue countermeasures, ensuring that off-duty workers have sufficient sleep opportunities and making adequate daily sleep a top priority. Remember, sleep is a physical necessity – not a luxury, and there is simply no substitute for sleep. I encourage you to review your personal and professional environment and assess if fatigue is a concern within your organization.

The author would like to thank Caldwell & Caldwell (2005) for allowing the use of some of their research data and charts.

Dr. Sardana is a pilot, a civil aviation medicine examiner (CAME) and president of Aviation Medicine International (AMI) Inc.; Comments on this article or future topic suggestions gladly appreciated at aviationmedintl@

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