FAR Part 117 — Flight and Duty Limitations and Rest Requirements

Part 117 replaced the legacy Part 121 Subpart Q / R / S flight-time limits for Part 121 passenger operations with a science-based, fatigue-aware framework. Cargo operations remained under the legacy rules — a controversial cargo carve-out that the cargo airlines argued for and the pilot unions still oppose. The rule's framework derives from the FAA's Fatigue Risk Management Working Group recommendations and significant scientific input on circadian biology, cumulative fatigue, and rest requirements.

Key limits under Part 117. Flight Duty Period (FDP) — the period from report time to engine-shutdown after the final flight of the duty — is limited based on the time of day the duty begins, the number of flight segments, and whether the operation is augmented. A 0500-0559 local report with 1-2 segments allows a 13-hour FDP; the same report with 7+ segments allows only 9 hours. An augmented crew (3 pilots with rest provisions in flight) extends the limit substantially.

Flight time within the FDP — the actual time the aircraft is flying — is limited to 9 hours unaugmented, 13 hours augmented (single rest seat), 17 hours augmented (multiple rest seats). Cumulative limits: 100 flight hours in any 28 consecutive days, 1,000 in any 365 consecutive days, 60 flight duty hours in any 7 consecutive days.

Minimum rest before duty: 10 consecutive hours, of which 8 must be uninterrupted sleep opportunity (this is the rule that resolved the legacy ambiguity about whether commute-time counted as rest). Cumulative rest: 30 consecutive hours free from duty in any 168 consecutive hours (one full day off per week, on the 7-day rolling cycle).

The Fatigue Risk Management System (FRMS) provision (§117.7) allows operators to deviate from specific Part 117 limits where the operator demonstrates through safety analysis that an alternate approach delivers equivalent or better fatigue management. FRMS approvals are operator-specific and require specific FAA approval — not a blanket relaxation of the rules.

Part 117 applies to FAA Part 121 scheduled passenger operations. Part 135 (charter / commuter) operations have their own duty/rest framework under §135.263-§135.273; supplemental Part 121 cargo operations remain under the legacy Subpart S; Part 91 corporate operations are covered by company policy but not by federal duty-time regulation per se.

For Part 121 operators, Part 117 compliance is one of the most heavily monitored regulatory areas. Crew rosters must be built within the cumulative limits, scheduling software must compute the FDP table for every duty, and dispatch / crew control must enforce the rules in real time when delays push duties past their planned limits. Technology vendors (Sabre, Lufthansa Systems, Jeppesen Crew Resources) build entire products around Part 117 compliance.

For pilots, Part 117 is the regulatory backstop against management pressure to fly fatigued. The fitness-for-duty determination (§117.5) puts the legal responsibility on the pilot to refuse a duty assignment if not adequately rested — a safeguard that many pilots have invoked over the rule's lifetime. Schools training airline-track cadets need to teach Part 117 alongside type ratings — graduates who show up to airline new-hire training without understanding duty/rest rules have a learning curve their classmates don't.

Aviatize's compliance and auditing module tracks each pilot's flight time and duty time against the Part 117 cumulative and per-period limits. The system maintains the rolling 7-day, 28-day, and 365-day flight-time totals; alerts on approach to limits; and refuses to dispatch a pilot whose next leg would exceed the limit. The 30-consecutive-hours-free-from-duty rule is enforced as a hard constraint on roster generation.

For combined ATO + AOC operators, the same tracking infrastructure supports Part 121 line operations alongside Part 141 instructor scheduling, with the cumulative rules properly applied across both functions when an instructor flies as line-pilot also. The audit trail produced is exactly what the FAA POI inspects during surveillance.