Oh, for a Good Night's Sleep

By By Ross Detwiler rossdetwiler@gmail.com
Source: Business & Commercial Aviation

Science has shown that an eight-hour rest period during the window of circadian low (WOCL) is the best way to ensure safe and accurate performance for any individual. Putting that sentence into a document that applies to all commercial flight operations must have been a huge undertaking.

And after wading through the FAA's entire “Flight Crew Member Duty and Rest Requirements” (77 FR 330) I came away impressed that it was ever completed. In reading the document's various inputs and considerations, I would have given the authors about the same chance of success as giving a sink full of grown cats a bath.

Nevertheless, the science was acknowledged, the disagreements all heard, and the document was published in the Federal Register on Jan. 4, 2012. Most importantly, decisions were made. The 314-page document displays typical bureaucratic style and length, but the real meat comes down to the final three charts that appear on one of the last pages.

The charts somehow take into consideration the time zone to which the crewmember is acclimated, when the day begins, how many pilots are in the crew, what crew rest facilities are available and the number of hours to be flown and the length of the flight duty period (FDP). The designers accomplished a very worthwhile goal and I can only imagine the frustrations, bickering, cajoling, documenting, pleading and huge effort that went into it by all the parties concerned. In fact, most of the document deals with how those various concerns were raised and handled. Those final three charts represent amazing achievement.

One of the hardest assignments ever given me was to come up with a simple chart that allowed our department dispatchers to schedule crews in international operations without having to review each leg of a trip with me. I eventually succeeded, but reserved the right to examine our toughest international trips in the scheduling phase. Often I cut planned crew rests short and many times I extended them because I knew from experience there were situations where “normal” wasn't enough and others when “crew rest” periods were time spent awake, waiting to go to the airport. The new FAA document creates all-encompassing charts that I was not smart enough to produce.

Even though the new rules were developed for airlines and supplemental carriers, it would be foolish for those of us operating large cabin business jets over extremely long range profiles to ignore them. This new “gold standard” on crew rest has to be considered in any scheduling we do and as it turns out, most of us were probably pretty close to it anyway.

The factors affecting fatigue include:

Time of day — Fatigue is, in part, a function of circadian rhythms. All other factors being equal, fatigue is most likely, and most severe, between the hours of 2:00 a.m. and 6:00 a.m.

Amount of recent sleep — If a person has had significantly less than 8 hr. of sleep in the past 24 hr., he or she is more likely to be fatigued.


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