Crew Fatigue

Air Safety Week, Nov 7, 2005

The System for Aircrew Fatigue Evaluation (SAFE) model is a valuable tool for regulators to evaluate aircrew rosters, according to a new report sponsored by the UK's Civil Aviation Authority (CAA). Among the many flights studied, both long- and short-haul, the study recounted the assessment of pilot fatigue during Haj operations, when Britannia Airways crews flew Islamic pilgrims to Saudi Arabia.

"This operation, which was monitored over three consecutive years, was especially interesting since it was flown round the clock, with the same pattern of duty repeated at all times of day," the Oct. 31 study report notes. These particular flights were from Indonesia to Saudi Arabia, involving a three-hour sector from Indonesia to Batam, off the coast of Singapore, followed by a 10- hour flight from there to Saudi Arabia. Due to favorable winds and such, the return flight was flown direct.

Three findings from these flights are instructive:

"Results from the study indicated that crews were struggling to stay awake during some of the flights. The most difficult times were towards the end of duty periods starting between 19:00 and 04:00 [local time] on the outward leg, and between 18:00 and 01:00 on the return leg. ..."

"Crews generally slept well on the night before a flight, and they made considerable use of naps later in the day prior to an evening or an early morning departure. ..."

"There were many instances of in-flight napping, particularly on the return leg, which helped to moderate the development of fatigue. However, the amount of sleep the crews obtained in flight was insufficient to sustain levels of alertness at the most critical times of day. ..."

There are obvious implications here for ultra-long range flights (see ASW, Dec. 22, 2003).

Elsewhere in the report, it is observed that noise affects sleep in a hotel far more than light. In any event, the study authors conclude that as a result of the findings, the SAFE model has been "improved considerably."

Pilots are skeptical of SAFE results. For one thing, they say, it does not give estimates of cumulative fatigue. For another, it does not give an allowance for fatigue during one's time off (e.g., poor sleep because it's daytime when you're trying to sleep at home, because you're jet-lagged, or because the new baby is sick). One pilot opines that proper answers to the fatigue issue would create an aircrew shortage and would impact the bottom line so horrendously that the airlines would revolt. (The full CAA Paper 2005/04 may be viewed at www.caa.co.uk/docs/33/CAAPaper2005_04.pdf)

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