Regulations
FAA Part 117 vs EASA ORO.FTL: flight time limitations compared
FAA Part 117 and EASA ORO.FTL pursue the same objective, bounding flight time, duty and rest to control fatigue, through two very different architectures. Part 117 is a uniform, directly applicable set of tables; ORO.FTL is a European framework that each operator implements through a flight time specification scheme approved by its authority.
Three kinds of people need this comparison for practical rather than academic reasons: groups holding certificates on both sides of the Atlantic, planners who move from one regime to the other through a career change or an acquisition, and the teams that have to encode both in a single tool. For them the question is down to earth: which rules to configure, and which ones do not carry across.
What is the architectural difference between the two regimes?
This is the most consequential difference, and it usually gets lost behind the comparison of numbers.
Part 117 (14 CFR Part 117) is a directly applicable federal rule. Its tables are the same for every operator in scope; there is no operator-specific limits scheme to get approved. The trade-off is little flexibility in exchange for maximum legibility, since two Part 117 carriers work to the same ceilings.
ORO.FTL is a framework. The regulation and its certification specifications set the boundaries, but each operator implements them through a flight time specification scheme approved by its national authority, and collective agreements almost always add another layer on top. Two equally compliant European operators can therefore run materially different internal rules.
The tooling consequence is direct. Under the FAA rule, encoding the regulation gets you most of the way. Under EASA, a tool that can only encode the European text has encoded nothing usable, which makes per-operator configuration the condition of use rather than a convenience.
Who does each rule apply to?
| FAA Part 117 | EASA ORO.FTL | |
|---|---|---|
| Operations covered | Flightcrew members in Part 121 passenger operations (domestic, flag, supplemental) | Commercial air transport (CAT) by aeroplane |
| Out of scope or separate regimes | Part 135, Part 91 subpart K; all-cargo operations unless the carrier opts in (§117.1(d)) | Air taxi, aeroplane EMS, single-pilot: national rules and Subpart Q of Regulation (EEC) No 3922/91, by derogation |
| Cabin crew | Separate rule (§121.467) | Covered by the same FTL subpart |
| Operator-specific implementation | No, uniform rule | Yes, authority-approved specification scheme |
This is the first thing that goes wrong in transatlantic conversations. A US business aviation operator flying under Part 135 is not under Part 117, exactly as a European air taxi operator is not under ORO.FTL. Both sit under a neighbouring but distinct regime, and the tables below do not apply to them.
The European perimeter is about to move. The delegated regulation adopted by the Commission on 8 September 2026 splits the FTL subpart in two: FTL (A) for scheduled and charter operations, FTL (B) for air taxi and aeroplane EMS, from 15 October 2028 (see our article on charter crew rostering). Part 117, for its part, has applied since 14 January 2014.
How do the numerical limits compare?
| Limit | FAA Part 117 | EASA ORO.FTL |
|---|---|---|
| Flight time over 28 days | 100 h in any 672 consecutive hours | 100 h in any 28 consecutive days |
| Annual flight time | 1,000 h in any 365 consecutive days | 900 h per calendar year and 1,000 h in any 12 consecutive calendar months |
| 7-day cumulative | 60 FDP hours in any 168 consecutive hours | 60 duty hours in any 7 consecutive days |
| 14-day cumulative | No equivalent | 110 duty hours |
| 28-day cumulative | 190 FDP hours in any 672 consecutive hours | 190 duty hours |
| Flight time per duty period | 8 or 9 h depending on report time (Table A); 13 h with three pilots, 17 h with four | No separate cap: the FDP bounds the day |
| Maximum FDP, unaugmented | 9 to 14 h by report time and number of flight segments (Table B) | 9 to 13 h by report time and number of sectors |
| Maximum FDP, augmented | 13 to 19 h by rest facility class and number of pilots (Table C) | 14 to 17 h by rest facility class and number of additional crew (CS FTL.1.205) |
| Crew not acclimatised | FDP reduced by 30 minutes | Separate tables by acclimatisation state |
| Minimum rest before duty | 10 consecutive hours, including an 8-hour uninterrupted sleep opportunity | 12 h at home base, 10 h away (including an 8-hour sleep opportunity), or the length of the preceding duty if longer |
| Weekly rest | 30 consecutive hours free from all duty in the past 168 hours | 36 consecutive hours including 2 local nights, never more than 168 h apart |
| Window of circadian low (WOCL) | 02:00 to 05:59 | 02:00 to 05:59 |
The convergences are genuine: the same 100 flight hours per 28 days, the same WOCL, the same 9-hour floor and the same logic of an FDP table indexed on report time and sector count. One difference in vocabulary still changes the arithmetic: Part 117's cumulative caps count FDP hours, while ORO.FTL's count duty hours, a broader notion that includes simulator sessions, ground training and office work. Beyond that, the divergences cluster around rest and the weekly rhythm.
Which differences actually shape a roster?
Five gaps matter far more day to day than the annual ceilings.
- Minimum rest. Part 117 sets a single 10-hour value wherever the crew is, including 8 hours of uninterrupted sleep opportunity; a pilot who will not get them must tell the carrier and cannot report until that rest has been given. ORO.FTL also requires an 8-hour sleep opportunity away from base, but demands 12 hours at home base and indexes rest on the length of the preceding duty. On a layover-heavy programme, it is home base that binds harder under EASA.
- The weekly rhythm. 30 duty-free hours under the FAA rule against 36 hours including two local nights under EASA. The local-nights wording is what does the work: it prevents weekly rest from being paid in daytime hours, and it effectively dictates the skeleton of every European monthly roster. Part 117 has its own rule with no direct equivalent: 56 hours of rest, covering three physiological nights, on returning home from a trip of more than 168 hours that crossed more than 60° of longitude.
- Flight time within the day. Part 117 caps the flight time of each duty period at 8 or 9 hours for a minimum crew. ORO.FTL has no equivalent limit, so a dense short-haul programme can fit more flying hours into the same FDP under EASA.
- The calendar-year cap. ORO.FTL's 900 hours per calendar year has no FAA counterpart, where the annual ceiling rolls over 365 days. In Europe this produces a year-end effect unknown in the US: the most-used crew members become unavailable in November and December unless their hours were levelled across the year.
- Extension mechanisms. ORO.FTL provides a planned extension of one hour, at most twice in 7 consecutive days, on top of commander's discretion (2 hours, 3 with an augmented crew). Part 117 has no planned extension: an extension of up to 2 hours is a joint decision of the pilot in command and the carrier when unforeseen circumstances arise before take-off (§117.19), allowed only once beyond 30 minutes before the next 30-hour rest period, and any overrun of more than 30 minutes is reported to the FAA within 10 days. A European planner therefore holds a construction lever a US planner does not, which is not the same as a lever to use routinely.
Night flying shows the difference in method well. Part 117 puts a number on it: no more than three consecutive duty periods infringing the WOCL, five if each includes a rest opportunity of at least 2 hours in suitable accommodation (§117.27). ORO.FTL handles these duties through its certification specifications and an appropriate, operator-specific fatigue risk management.
Can one planning tool handle both regimes?
Yes, on one condition: the rules must be configurable data, not code.
The applicable regime follows the certificate, not the geography: a group running a European AOC and a US certificate rosters two populations under two rule sets, often with the same planners. What must change from one roster to the other is the rule set applied to the computation, not the tool. And that rule set has to coexist with in-house rules and labour agreements, which are neither European nor American but specific to the company.
Rules also change over time, and a botched transition carries a real price. In December 2025, IndiGo cancelled more than 4,500 flights in ten days after failing to adapt its rosters to India's revised FDTL rules, introduced back in January 2024 (Kumar, 2025, IJFMR); the airline later put the quarterly impact of those disruptions at ₹577.2 crore, around USD 65m (ThePrint, 2026). A tool where rules are data gets reconfigured. A tool where rules are buried in code gets rewritten. Europe's 2028 switch will put the same question to every air taxi and aeroplane EMS operator.
That is the principle SkAI Tech is built on: FTL, Part 91 and Part 135 form the regulatory base, extended by regional and in-house rules configured per operator. The platform connects by API to the operations system already in place, without replacing it, and checks every assignment against the applicable rule set.
Running contracts under several rule sets? See how SkAI Tech rosters crews for ACMI operators.
FAQ
Is a US business aviation operator subject to Part 117?
Generally not, if it operates under Part 135 or Part 91 subpart K: those regimes carry their own flight time and rest limitations. For a one- or two-pilot crew in unscheduled Part 135 operations, for instance, the cap is 1,400 flight hours per calendar year, with 10 consecutive hours of rest in the 24 hours before each assignment ends (§135.267). What applies is determined by the certificate, not by the aircraft type.
Which regime is stricter?
Neither, in the abstract: they are stricter on different dimensions. ORO.FTL binds harder on home-base rest, weekly rest, the 14-day cumulative and the calendar-year cap; Part 117 binds harder on flight time per duty period, consecutive nights and the absence of planned extension, but is more permissive on maximum FDP (14 hours against 13 unaugmented, 19 against 17 augmented). A useful comparison is done programme by programme, not row by row.
Which rules apply on a transatlantic flight?
The operator's regime, tied to its certificate, not the geography of the flight. A European operator remains under its approved ORO.FTL scheme when serving US destinations. Acclimatisation arises in both regimes through different mechanisms: EASA acclimatisation tables on one side, the FAA's theater on the other, an area in which departure and arrival differ by no more than 60° of longitude, a pilot being acclimated after 72 hours in a theater or 36 consecutive hours free from duty.
Do both texts address fatigue beyond the limits?
Yes, and this is where they converge. Part 117 requires every pilot to affirm fitness for duty before flight and bars the carrier from flying a pilot who reports being too fatigued (§117.5); it allows its limits to be exceeded under an FAA-approved FRMS that provides at least an equivalent level of safety (§117.7). ORO.FTL requires the operator to build schedules that protect crews from fatigue, and a fatigue risk management process where the rules call for one or to support a derogation. That is the subject of our FRMS article.
Sources
- 14 CFR Part 117, Flight and Duty Limitations and Rest Requirements: Flightcrew Members, eCFR consolidated text up to date as of 8 October 2026: §§117.1, 117.3, 117.5, 117.7, 117.11, 117.13, 117.17, 117.19, 117.21, 117.23, 117.25, 117.27 and Tables A, B and C.
- 14 CFR §121.467 (flight attendant duty limitations and rest) and §135.267 (unscheduled one- and two-pilot crews), eCFR, same date.
- EASA, Easy Access Rules for Air Operations, Part-ORO Subpart FTL (ORO.FTL.105, 205, 210, 235) and CS FTL.1.205; Regulations (EU) No 965/2012 and No 83/2014.
- European Commission (2026, 8 September), Delegated Regulation C(2026) 6142 final amending Regulation (EU) No 965/2012 for air taxi, emergency medical service and single-pilot operations: Subparts FTL (A) and FTL (B), applicable from 15 October 2028.
- Kumar, S. (2025), IndiGo Airlines Crisis 2025 — A Critical Analysis of India's Largest Aviation Disruption, IJFMR 7(6).
- ThePrint / PTI (2026), IndiGo Q3 profit plunges 78 pc to Rs 549 cr; ops disruptions cause Rs 577 cr financial impact.
