4.2 Flightcrew Duty & Rest Requirements (14 CFR Part 117)

4.2 Flightcrew Duty & Rest Requirements (14 CFR Part 117)

Commercial aviation safety depends fundamentally on alert, well-rested flightcrews. For decades, pilot flight time limitations were governed by rigid, prescriptive rules under 14 CFR Part 121 Subparts Q, R, and S. In response to the crash of Colgan Air Flight 3407 near Buffalo, New York, and subsequent congressional mandates in the Airline Safety and Federal Aviation Administration Extension Act of 2010, the FAA promulgated 14 CFR Part 117—a modern, science-based regulatory framework incorporating circadian biology, sleep science, and bio-mathematical fatigue modeling.

For aircraft dispatchers, mastering Part 117 is not optional. Because dispatchers share joint operational control with the Pilot-in-Command, a dispatcher cannot legally release a flight if the planned flight time or Flight Duty Period will exceed Part 117 limits. Furthermore, when en route delays, holding, or weather diversions occur, dispatchers must evaluate in real time whether the crew will exceed their maximum legal Flight Duty Period before takeoff.

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Applicability: Part 121 Passenger vs. Cargo Operations (§ 117.1)

Under 14 CFR § 117.1, Part 117 applies to:

1. All certificate holders conducting operations under 14 CFR Part 121 with passenger-carrying operations.
2. All flightcrew members who perform duties in Part 121 passenger operations.
3. All-Cargo Operations (Voluntary Opt-In): All-cargo operations are generally exempt from mandatory Part 117 compliance and may continue operating under the legacy flight time and rest rules of Part 121 (§ 121.471 for domestic, § 121.503–525 for flag/supplemental). However, under § 117.1(c), an all-cargo certificate holder may voluntarily elect to opt into Part 117, provided the entire cargo operation complies with Part 117 in its entirety.

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Critical Regulatory Definitions (§ 117.3)

Understanding Part 117 requires mastering five foundational statutory definitions defined in 14 CFR § 117.3:

1. Flight Duty Period (FDP)

A period that begins when a flightcrew member is required to report for duty with the intention of conducting a flight, a series of flights, or positioning or ferrying flights, and ends when the aircraft is parked after the last flight and there is no intention for further flight by the same flightcrew member.

• Start of FDP: The mandatory report time (typically 45–60 minutes prior to scheduled departure).
• End of FDP: Aircraft block-in (engines shut down and parking brakes set at the gate) on the final flight segment.
• Duty vs. FDP: Total "Duty" is broader than FDP. Duty includes any task a flightcrew member performs on behalf of the certificate holder (administrative work, training, deadhead travel, post-flight debriefs). FDP specifically includes duty associated with flight operations.

2. Flight Time (Block Time)

The time that begins when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest at the next point of landing (block-in).

Flight time is the actual block-to-block flight duration. Table A governs maximum flight time, while Table B governs maximum FDP.

3. Window of Circadian Low (WOCL)

A period of maximum sleepiness that occurs between 0200 and 0559 during a physiological day.

• The WOCL is determined by the flightcrew member's acclimatized local time.
• Duty performed within the WOCL carries the highest risk of acute cognitive impairment and microsleeps. Consequently, Table B imposes severe FDP penalties for duty periods that overlap the WOCL.

4. Theater and Acclimatization

• Theater: A geographical area in which the distance between the flightcrew member's flight departure point and arrival point differs by no more than 60 degrees of longitude (approximately 4 standard time zones).
• Acclimatized: A flightcrew member is considered acclimatized to a local time zone if:
  1. The crewmember has had at least 36 consecutive hours of rest in a new theater, or
  2. The crewmember has remained in the new theater for at least 72 continuous hours.
• If a flightcrew member is not acclimatized to the local time zone where duty begins, their Table A, B, and C limits must be calculated using the time zone of the location to which they are currently acclimatized!

5. Deadhead Transportation Rules

• Deadhead Before Flight: If an air carrier transports a crewmember (deadheads) to an airport to conduct a flight without an intervening legal rest period, the deadhead travel counts as duty and is included in the FDP.
• Deadhead After Flight: If a crewmember completes their last flight and then deadheads to home base, the deadhead is duty, but does NOT count toward the FDP. However, deadhead travel cannot infringe upon the mandatory 10-hour rest period that follows.

Deadhead Scenario Analysis under Part 117
1. Deadhead ──> Flight Segment ──> Flight Segment ──> Block-in
   └────────────────────── All Counted in FDP ──────────────────────┘

2. Report ──> Flight Segment ──> Block-in ──> Deadhead to Base
   └────── Counts as FDP ──────┘ └─ Duty only (NOT FDP) ─┘

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Table A: Maximum Flight Time Limits (Unaugmented Operations)

Under 14 CFR § 117.11, no certificate holder may schedule and no flightcrew member may accept an assignment if the scheduled total flight time will exceed the limits in Table A:

Key Principle: For an unaugmented two-pilot crew, the maximum block flight time is either 8 hours or 9 hours, depending entirely on the acclimatized report time. If a crew reports at 0445, their maximum allowable flight time is 8 hours; if they report at 0500, it expands to 9 hours.

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Table B: Maximum Flight Duty Period (FDP) for Unaugmented Operations

Under 14 CFR § 117.13, the maximum unaugmented FDP is determined by a dual-axis matrix: scheduled report time (acclimatized local time) and number of scheduled flight segments.

Table B Matrix (14 CFR Part 117)

Analytical Insights from Table B

1. Circadian Peak: The maximum allowable FDP is 14 hours, available only for crews reporting between 0700 and 1159 with 1 or 2 flight segments.
2. Circadian Trough (WOCL): Crews reporting between 0000 and 0359 are restricted to a flat 9-hour FDP, regardless of whether they fly 1 segment or 7 segments.
3. Multi-Segment Penalties: Each additional takeoff and landing imposes mental workload and task saturation. For an 0700 report, 1–2 segments allow 14 hours FDP, while 7+ segments compress allowable FDP to 11.5 hours.

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Table C: Augmented Flightcrews & Rest Facility Classifications (§ 117.17)

An augmented flightcrew is a flightcrew that has been supplemented by one or more additional flightcrew members (typically 3 or 4 pilots total), allowing individual pilots to rotate out of the flight deck and sleep in an onboard rest facility during en route cruise.

Rest Facility Classifications (§ 117.3)

Table C Maximum FDP Limits (Augmented Operations)

Maximum Augmented Duration: A 4-pilot crew utilizing a Class 1 rest facility reporting between 0700 and 1259 can legally operate a Flight Duty Period of up to 19 consecutive hours.

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Cumulative Flight Time & Duty Limitations (§ 117.23)

Part 117 enforces four distinct rolling cumulative caps to protect against long-term chronic fatigue:

Part 117 Cumulative Limitations Summary (§ 117.23)
├── Flight Time Caps:
│   ├── ≤ 100 Flight Hours in any 672 Consecutive Hours (Rolling 28 Days)
│   └── ≤ 1,000 Flight Hours in any 365 Consecutive Calendar Days (Rolling 1 Year)
└── Flight Duty Period (FDP) Caps:
    ├── ≤ 60 FDP Hours in any 168 Consecutive Hours (Rolling 7 Days)
    └── ≤ 190 FDP Hours in any 672 Consecutive Hours (Rolling 28 Days)

Every time a dispatcher generates a release, the airline's automated flight operating system evaluates the crew's projected cumulative flight time and FDP over rolling 168-hour, 672-hour, and 365-day windows. If any boundary will be breached before final block-in, the release cannot be authorized.

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Mandatory Rest Requirements (§ 117.25)

1. Pre-FDP / Pre-Reserve Rest Period (§ 117.25(e))

No certificate holder may schedule, and no flightcrew member may accept, an assignment for an FDP or reserve duty unless the crewmember is given at least 10 consecutive hours of rest immediately before beginning the assignment.

• Uninterrupted Sleep Opportunity: Within that 10-hour rest period, the crewmember must be provided at least 8 uninterrupted hours of sleep opportunity.
• Transportation / Travel Time: If an airline transports a crewmember to a hotel, travel time does not count toward the 8-hour sleep opportunity. The 8-hour clock begins only when the pilot arrives at the suitable accommodation (hotel room).

2. Mandatory Weekly Rest (§ 117.25(b))

No certificate holder may schedule and no flightcrew member may accept an assignment unless the crewmember has received at least 30 consecutive hours of rest within the 168 consecutive hours (7 days) preceding the start of any reserve or FDP.

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FDP Extensions: Unforeseen Operational Circumstances (§ 117.19)

When delays occur on the day of operation due to adverse weather, ATC ground delays, or mechanical issues, Part 117 permits strictly circumscribed FDP extensions:

1. Pre-Takeoff Extensions (§ 117.19(a))

• If unforeseen circumstances arise before takeoff on the first or subsequent segment, the PIC and dispatcher may mutually agree to extend the maximum FDP by up to 2 hours.
• The 30-Minute Threshold: If the extension exceeds 30 minutes, it can only be utilized once before the crewmember receives the mandatory 30-hour rest period under § 117.25(b).
• Regulatory Reporting: Any pre-takeoff extension exceeding 30 minutes requires the carrier to submit a formal written report to the FAA within 10 days, detailing the operational reasons and corrective actions taken.

2. Post-Takeoff Extensions (§ 117.19(b))

• If unforeseen circumstances arise after takeoff, the flightcrew may continue the flight to the planned destination or alternate airport, and the FDP may be extended without limitation until the aircraft safely lands and parks.

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Common ADX Exam Traps & Practical Scenarios

1. The Deadhead FDP Trap: An exam question asks: "A pilot reports at 0600, deadheads on a 2-hour flight to Chicago, and immediately conducts two scheduled passenger flights. Does the deadhead count as FDP?" YES. Because the deadhead occurs prior to a flight segment without intervening rest, it is part of the FDP.
2. Table A vs. Table B Limits: Table A limits Flight Time (8 or 9 hours). Table B limits Flight Duty Period (9 to 14 hours). Do not confuse the two! A crew reporting at 0800 can have an FDP up to 14 hours, but their total flight time during that FDP cannot exceed 9 hours.
3. Rolling Lookback vs. Calendar Days: 672 consecutive hours is exactly 28 days (28 × 24 = 672). It is not the calendar month of February, March, or April. A rolling calculation evaluates every minute looking backwards exactly 672 hours.