FAR 117: Rules that Govern Rest, Flight and Duty Times for Pilots

In January of 2014, one of the biggest regulatory changes in history went live.  It was FAR 117: Flight and Duty Time Limitations: Flight Crewmember.  This section is a complete rewrite of the rest and flight time limitations that apply to most pilots under section FAR 121, which are the rules governing airlines.  Under the 121 rules, a confusing hodge podge of rules that basically centered around a concept of being legal to finish if you the pilot was legal to start their duty.  There were a few exceptions to that but that’s a synopsis.  It applied the same rest requirements to all domestic operations, allowed benefit for additional pilots only when flying out side the continental US (because pilots get tired differently when flying outside the US).

FAR 117 had been in the works after the Colgan Air Flight 3407 accident outside of Buffalo.  This was largely driven family members of passengers who died in that accident and was mandated by Congress in 2010.  The new rules have longer rest periods, with a mandated opportunity or sleep, a change in limits based on when the pilot started their duty and cumulative limits for flight time and a new concept called a flight duty period, which also has cumulative limits.  It also limits the number of consecutive duty periods that a pilot can fly in the Window of Circadian Low (WOCL) which is basically the middle of the night.  The new rules do not apply to cargo carriers, which is a result of a complicated cost-benefit analysis that the FAA has to do before publishing a rule.  Cargo carriers are still governed by the previous rules under FAR 121., separated by domestic operations and flag operations.

Unfortunately, the new rules are more complicated than the previous rules.  Because they are based on actual times and not scheduled times, combined with one of the limits being flight time driven, it’s impossible for a pilot (or the airline) to truly complicate crew legality until the aircraft pushes back from the gate, thus starting their “flight time.”  For many schedules, this is just fine.  There is plenty of buffer left.  However, for days where there are long delays, this can be a difficult calculation taken right down to the wire.

Also, because of legal interpretations issued after the rule and a number of unofficial explanations of the rules, the rule has become even more opaque for pilots who are legally responsible, in conjunction with the airline, for ensuring legality.



Here are some references to help you understand FAR 117 and how it applies.  If you have a question, please let us know!

FAR 117 Regulations – The actual text of the regulations from the FAA.

FAA Legal Interpretations – Legal interpretations that impact FAR 117 and how it is applied.

FAR 117 Table A – Flight time limits under FAR 117

FAR 117 Table B – Flight duty period limits for unagumented crews (crews that don’t have more pilots than normally required for the airplane)

FAR 117 Table C – Flight duty period limits for augmented crews (crews that have extra pilots assigned for the flight)