← Duty117 / Guides / 117 vs 135

Part 117 vs Part 135 — Different Rulebooks, Different Physics

Pilots move between 121, 91K and 135 operations and the duty rules do not travel with them. Here is the honest, source-backed comparison — neither regime is "looser" everywhere.

Who is covered by what

§117.1(a): Part 117 prescribes limits "for all flightcrew members and certificate holders conducting passenger operations under part 121" — plus 121-directed Part 91 flying when any segment is a passenger operation (§117.1(b)–(c)). Crucially, the rule itself is written for fractional programs too: §117.23(a) counts flying "on behalf of any certificate holder or 91K Program Manager", so subpart K fractional crews live under Part 117, not under a 135-style scheme.

Part 135 (subchapter G, parts 135.261–135.267) governs commuter and on-demand operators. It has no Table B/Table C, no FDP-by-report-time concept, no acclimation rules and no WOCL machinery.

Side by side

	Part 117 (§117.11–117.29)	Part 135 scheduled (§135.265)	Part 135 unscheduled 1–2 pilots (§135.267)
Daily flight time	Table A: 8 h (0000–0459), 9 h (0500–1959), 8 h (2000–2359); 13 h / 17 h with 3/4 pilots	8 h per 24 h (single pilot); 8 h between required rests (two pilots)	8 h per 24 h (one pilot); 10 h (two pilots)
Duty period concept	FDP from report to parked aircraft, with report-time tables	No FDP tables — limits are on flight time + rest sizing	Duty period ≤ 14 h possible (§135.267(c)) if bracketed by 10 h rests and combined duty+rest = 24 h
Rest structure	10 h rest incl. 8 h uninterrupted sleep opportunity, from release (§117.25(e)); 30 h free of duty per 168 h (§117.25(b))	9 h rest for <8 h flying, 10 h for 8–9 h, 11 h for 9+ h; reducible to 8/8/9 h with a compensating 10/11/12 h rest inside 24 h (§135.265(b)–(c)); 24 h free of duty in any 7 days (§135.265(d))	≥10 h rest before completion of assignment (§135.267(d)); 13 rest periods of 24 h each per quarter (§135.267(f))
Monthly / annual caps	100 h per 672 h; 1,000 h per 365 days; 60 h FDP/168 h; 190 h FDP/672 h (§117.23)	1,200 h/calendar year; 120 h/calendar month; 34 h per 7 consecutive days (§135.265(a))	500 h/quarter; 800 h/two consecutive quarters; 1,400 h/year (§135.267(a))
Reserve	Full machinery: long/short-call, RAP ≤ 14 h, 16/17 h combined walls (§117.21)	Standby not separately regulated as FDP — company-dependent	Same — no RAP concept
Circadian protections	WOCL (0200–0559) caps, acclimation, 56 h post-trip rest	None	None (graded post-overage rests 11/12/16 h, §135.267(e))
After-takeoff relief	§117.11(b) / §117.19(b): as far as needed to land safely + 10-day report	Not similarly codified	§135.267(e): graded rests after exceeding daily limits

Three things worth knowing

Rest can be traded in 135, not in 117. §135.265(c) lets a carrier schedule reduced rest with a payback rest inside 24 hours. Part 117 has no reduced rest at all: 10 h with 8 uninterrupted sleep hours, full stop.
135 counts months, 117 counts rolling hours. 120 h/calendar month (135.265(a)(2)) resets on the calendar; 60/168 and 100/672 are rolling windows that can bite mid-month.
91K is 117 territory. If you fly fractional under a Program Manager, your limits are Table B/C and §117.23 counts every hour you fly for anyone. "135 rules" do not apply to the crew just because the airplane is smaller.

Commuter operations under §135.261/135.263 (scheduled with ≥5 round trips/week, etc.) follow the scheduled-ops table above; charter and air-ambulance flying follows the unscheduled columns. Check which section your operator's ops spec cites before assuming.

Check a 121/91K duty day in the calculator

Verified against eCFR 14 CFR 117.1, 117.23 and 14 CFR 135.265/135.267 (current). Educational only — ops specs and CBAs add layers on both sides.