Part 91K duty and rest rules for fractional program flights are in 14 CFR 91.1057 through 91.1062. For a one- or two-pilot crew, a flight crewmember needs at least 10 hours of rest before duty, may be on duty up to 14 hours, may fly up to 8 hours (one pilot) or 10 hours (two pilots), and needs at least 10 hours of rest after duty, or 14 after a multi-time zone flight (91.1059). Weather or other circumstances outside anyone’s control can stretch flight time to 9 or 12 hours, and then the rest after duty grows to 12 hours (18 after a multi-time zone flight). On top of that, every assignment needs 10 consecutive hours of rest in the 24 hours before it ends, and each crewmember gets 13 rest periods of 24 hours every calendar quarter (91.1057).
If you’re still working out whether a flight is Part 91, 91K or 135 in the first place, start with Part 91 vs Part 135 vs Part 91K.
Which sections cover Part 91K duty and rest?
| Section | What it covers |
|---|---|
| 91.1057 | Definitions, rules that apply to every crewmember, and the option to use Part 121 or 135 limits |
| 91.1059 | Quarterly and yearly caps, the 24-hour flight time limit, and the duty and rest table |
| 91.1061 | Augmented crews of three or four pilots: who must be on board, sleeping facilities, a separate table |
| 91.1062 | Flight attendants, or an approved alternative |
Section 91.1057(b) ties them together: a program manager may assign a crewmember, and a crewmember may accept an assignment, for flight time “only when the applicable requirements of this section and §§ 91.1059-91.1062 are met.” The duty falls on the crewmember who accepts as well as the program manager who assigns.
What do the 91.1057 definitions mean?
Section 91.1057(a) defines the terms that decide which bucket a block of time falls into.
- Duty period. “The period of elapsed time between reporting for an assignment involving flight time and release from that assignment by the program manager.” Everything between report and release counts, “even if flight time is interrupted by nonflight-related duties.”
- Rest period. Time “free of all responsibility for work or duty” before or after a duty period, during which the crewmember “cannot be required to receive contact from the program manager.” If the program manager imposes “any duty or restraint, including any actual work or present responsibility for work should the occasion arise,” that time isn’t rest.
- Standby. The part of a duty period when the crewmember is under the program manager’s control and ready to fly. “Standby is not part of any rest period.”
- Reserve status. The crewmember stays fit to fly, within a reasonable response time of the aircraft, and reachable. “Reserve status is not part of any duty period or rest period.”
- Extension of flight time. An increase in flight time “because of circumstances beyond the control of the program manager or flight crewmember (such as adverse weather) that are not known at the time of departure.”
- Multi-time zone flight. An easterly or westerly flight, or several flights in one direction in the same duty period, that “results in a time zone difference of 5 or more hours” and is flown south of 60 degrees north latitude and north of 60 degrees south latitude.
Standby is duty. Reserve is neither duty nor rest, so a day on reserve doesn’t count toward the 13 rest periods, and it doesn’t add to the duty period either.
What else does 91.1057 require of every crewmember?
These rules sit on top of the tables in 91.1059 and 91.1061.
- No duty during rest. “No program manager may assign any crewmember to any duty during any required rest period” (91.1057(c)).
- Positioning isn’t rest. Transportation “not local in character” that the program manager requires and provides, to an airport where the crewmember will fly or home after being relieved, “is not considered part of a rest period” (91.1057(d)).
- Extensions have a ceiling. A flight crewmember may continue an assignment that runs long because of circumstances beyond anyone’s control, but the extension “may not exceed the maximum time limits set forth in § 91.1059” (91.1057(e)).
- Ten in twenty-four. “Each flight assignment must provide for at least 10 consecutive hours of rest during the 24-hour period that precedes the completion time of the assignment” (91.1057(f)).
- Thirteen days off a quarter. The program manager “must provide each crewmember at least 13 rest periods of at least 24 consecutive hours each in each calendar quarter” (91.1057(g)).
- The right to decline. A flight crewmember “may decline a flight assignment” if, in their own determination, flying it wouldn’t be consistent with the standard of safe operation the regulations require (91.1057(h)).
- Rest can overlap. “Any rest period required by this subpart may occur concurrently with any other rest period” (91.1057(i)). A 24-hour day off can also be the after-duty rest the table requires.
The program manager can’t make a pilot take its call during required rest, because the rest period definition says the crewmember “cannot be required to receive contact from the program manager.”
What are the Part 91K limits for one or two pilot crews?
Section 91.1059 has three layers.
Quarterly and yearly caps
No assignment as a member of a one- or two-pilot crew if the crewmember’s “total flight time in all commercial flying will exceed” 500 hours in any calendar quarter, 800 hours in any two consecutive calendar quarters, or 1,400 hours in any calendar year (91.1059(a)). “All commercial flying” includes a pilot’s paid flying for someone else, so ask for it and record it.
Flight time in any 24 consecutive hours
“Except as provided in paragraph (c),” the flight time of the assigned flight plus any commercial flying in any 24 consecutive hours may not exceed 8 hours for one pilot or 10 hours for two pilots “qualified under this subpart for the operation being conducted” (91.1059(b)). The 24 hours roll forward with each flight rather than resetting at midnight.
The flight time limitations and rest requirements table
Paragraph (c) says no assignment may be made or accepted “if that crewmember’s flight time or duty period will exceed, or rest time will be less than” the values in this table. The two columns are the regulation’s own headings.
| 91.1059(c) | Normal duty | Extension of flight time |
|---|---|---|
| (1) Minimum rest immediately before duty | 10 hours | 10 hours |
| (2) Duty period | Up to 14 hours | Up to 14 hours |
| (3) Flight time for 1 pilot | Up to 8 hours | Exceeding 8 hours up to 9 hours |
| (4) Flight time for 2 pilots | Up to 10 hours | Exceeding 10 hours up to 12 hours |
| (5) Minimum after duty rest | 10 hours | 12 hours |
| (6) Minimum after duty rest period for multi-time zone flights | 14 hours | 18 hours |
Read the extension column with the definition in 91.1057(a). It applies when flight time grows because of circumstances “not known at the time of departure,” such as weather. A schedule planned past 8 or 10 hours of flight time doesn’t fit that definition. The duty period stays at 14 hours in both columns, and the price of the extra flight time is a longer rest afterward.
How do augmented crews change the limits?
Section 91.1061 applies to crews of three or four pilots. The same 500, 800 and 1,400 hour caps apply (91.1061(a)). Before assigning a pilot to an augmented crew, the program manager must make sure “adequate sleeping facilities are installed on the aircraft for the pilots,” that “no more than 8 hours of flight deck duty is accrued in any 24 consecutive hours,” and that the crew has the right mix of pilots (91.1061(b)).
A three-pilot crew needs a PIC, a second PIC-qualified pilot and an SIC; a four-pilot crew adds a fourth pilot who meets the SIC qualifications. Each seat must meet the subpart’s qualifications, the PIC must also meet 61.57, the second PIC-qualified pilot 61.57(c) and (d), and for IFR the SIC and fourth pilot must meet part 61 recent instrument experience.
The table in 91.1061(c):
| 91.1061(c) | 3-pilot crew | 4-pilot crew |
|---|---|---|
| (1) Minimum rest immediately before duty | 10 hours | 10 hours |
| (2) Duty period | Up to 16 hours | Up to 18 hours |
| (3) Flight time | Up to 12 hours | Up to 16 hours |
| (4) Minimum after duty rest | 12 hours | 18 hours |
| (5) Minimum after duty rest period for multi-time zone flights | 18 hours | 24 hours |
Without sleeping facilities on the aircraft, the program manager may not assign pilots to an augmented crew (91.1061(b)(1)), so the longer limits aren’t available.
What are the Part 91K flight attendant rules?
Section 91.1062(a) limits a flight attendant to a scheduled duty period of 14 hours, followed by at least 9 consecutive hours of rest (reducible to 8 if a 10-hour rest follows within 24 hours). Each extra flight attendant beyond the minimum complement in the management specifications allows a longer duty period: 16 hours with one, 18 with two, and 20 with three on flights that land or take off outside the 48 contiguous states and the District of Columbia. After more than 14 hours of duty, rest is at least 12 hours (reducible to 10 if a 14-hour rest follows).
Under paragraph (b), a program manager may instead apply the flight crewmember limits of 91.1057, 91.1059 and 91.1061 to flight attendants, through written procedures that cover all of them, add a flight attendant for each extra pilot assigned under 91.1061, and “are approved by the Administrator and described or referenced in the program manager’s management specifications.”
Can a 91K program use the Part 135 duty limits instead?
Yes, with authorization. Section 91.1057(j) says: “If authorized by the Administrator, a program manager may use the applicable unscheduled flight time limitations, duty period limitations, and rest requirements of part 121 or part 135 of this chapter instead of the flight time limitations, duty period limitations, and rest requirements of this subpart.”
For Part 135, the unscheduled one- and two-pilot rules are in 135.267. They share the 500, 800 and 1,400 hour caps, the 8 and 10 hour limits in 24 hours and the 13 rest periods a quarter, but handle overruns differently.
| 91.1059 (91K) | 135.267 (Part 135 unscheduled) | |
|---|---|---|
| Duty period | Up to 14 hours | No general cap; a regularly assigned duty period of no more than 14 hours is one condition of 135.267(c) |
| Rest in the 24 hours before the assignment ends | 10 consecutive hours (91.1057(f)) | 10 consecutive hours before the planned completion time (135.267(d)) |
| Flight time running long for reasons outside anyone’s control | Up to 9 or 12 hours, then 12 hours of rest (18 after a multi-time zone flight) | Rest of 11, 12 or 16 hours depending on whether the limit was exceeded by up to 30, up to 60 or more than 60 minutes (135.267(e)) |
| Multi-time zone rest | 14 hours, 18 with an extension | No separate figure in 135.267 |
Without that authorization, program flights stay on 91.1059 and 91.1061. For the Part 135 side in more depth, see Part 135 duty time limits.
Worked example: one two-pilot duty day (illustrative)
The times and numbers are made up. Assume a two-pilot crew on program flights in one time zone.
The plan. The crew was released at 19:30 the evening before and reports at 06:30, so rest before duty is 11 hours, above the 10 required by 91.1059(c)(1). Three legs are planned with 8 hours 30 minutes of flight time and release at 18:30, a 12-hour duty period. Neither pilot did any other commercial flying in the 24 hours before.
What happened. On the last leg, weather at the destination that wasn’t forecast when the leg departed brings holding and a diversion. The crew lands with 10 hours 40 minutes of flight time for the day and is released at 20:00.
| Check | Rule | Limit | Actual | Result |
|---|---|---|---|---|
| Rest before duty | 91.1059(c)(1) | 10 hours | 11 hours | Within |
| Duty period | 91.1059(c)(2) | 14 hours | 13 hours 30 minutes | Within |
| Flight time, two pilots | 91.1059(c)(4) | 10 hours normal, up to 12 with an extension | 10 hours 40 minutes | Within only as an extension |
| Rest after duty | 91.1059(c)(5) | 12 hours after an extension | Next report no earlier than 08:00 | Next day moves |
| Rest in 24 hours before tomorrow’s assignment ends | 91.1057(f) | 10 consecutive hours | 12 hours, 20:00 to 08:00 | Within |
What it does to tomorrow. Because flight time went past 10 hours, the minimum after-duty rest is 12 hours instead of 10, so tomorrow’s 07:00 departure needs another crew or a later start. If the day had been a multi-time zone flight, the after-duty rest would have been 18 hours (14 without the extension).
The quarter. Say one of the pilots had 492 hours of flight time this quarter, including hours flown for another commercial operator. Today’s 10 hours 40 minutes takes them past the 500-hour cap in 91.1059(a). The program manager couldn’t assign that trip, and the pilot couldn’t accept it, so other commercial flying has to be in your records before the schedule is built.
A checklist for each 91K crew assignment
Run this before assigning a crew, and again whenever a trip moves.
- Which table applies: one or two pilots, or an augmented crew with sleeping facilities installed? And is the program on subpart K limits, or authorized to use Part 121 or 135?
- Did each crewmember get the minimum rest immediately before duty?
- Does the duty period, from report to release by the program manager, stay inside the table?
- Does flight time, plus any commercial flying, stay inside the limit in every rolling 24 hours?
- Is there 10 consecutive hours of rest in the 24 hours before the assignment ends?
- Is any of the planned rest really positioning the program manager provides, reserve or standby?
- Is any leg part of a multi-time zone flight, which raises the rest after duty?
- Does anyone pass 500 hours in the quarter, 800 in two quarters or 1,400 in the year, counting all commercial flying?
- Is each crewmember on track for 13 rest periods of 24 consecutive hours this quarter?
- If a flight ran long as an extension under 91.1057(e), has the next duty period moved for the longer rest?
Keep the evidence. Section 91.1027 requires a record of each pilot’s flight time “in sufficient detail to determine compliance with the flight time limitations of this subpart,” kept for at least 12 months. If you also track qualifications and recency, our post on pilot training and currency tracking covers that side.
Part 91K duty and rest in Avion Desk
On the plan for charter operators, Avion Desk checks Part 91K duty and rest under 91.1057 to 91.1059, and Part 135 under 135.267 as well. Every save of a trip is checked, duty included, and you see the result each time you save; a problem is named, and when an admin overrides one, the override is recorded with a note. Standby, days off and positioning are entered as crew events, and a crew duty view shows where each person stands. See the crew, duty and rest features and pricing. To try it, start a free trial on the plan for charter operators, enter a week of program trips with your crews’ standby, days off and positioning, and see the 91K checks run, or request a demo.
Frequently asked questions
What is the maximum duty period under Part 91K?
For a one- or two-pilot crew, 14 hours, whether or not flight time was extended (91.1059(c)(2)). An augmented crew may be on duty up to 16 hours with three pilots or 18 hours with four (91.1061(c)).
How much rest does a Part 91K pilot need?
At least 10 hours immediately before duty. After duty, at least 10 hours, or 12 if flight time was extended; after a multi-time zone flight, 14 hours, or 18 if extended (91.1059(c)). Every assignment also needs 10 consecutive hours of rest in the 24 hours before it ends (91.1057(f)).
Does reserve count as rest under Part 91K?
No. Section 91.1057(a) says “reserve status is not part of any duty period or rest period,” and “standby is not part of any rest period.”
Does flying for another operator count toward the 91K limits?
Yes. The quarterly, two-quarter and yearly caps count “total flight time in all commercial flying,” and the 24-hour limit adds “any commercial flying by that flight crewmember” (91.1059(a) and (b)).
Can a fractional program use the Part 135 duty rules?
Only if authorized by the Administrator. Then it may use the applicable unscheduled limits of Part 121 or Part 135 instead of subpart K’s (91.1057(j)).
This article explains the rules in plain language and isn’t legal advice; the regulation text governs.
