The Calculator determines Flight Duty Period legality based on flight operation characteristics and flight crew status. It also determines cumulative FDP hours, cumulative Flight Time hours, and remaining hours against each Part 117 limitation.
GatedFTDTCalculationEngine — the remote switch is the FTDTRestRulesEngine row of /api/settings/list genericSettings (ALPAMobile/Helpers/FTDTFeatureFlagsOptionsConfigurator.cs; precedence in ALPAMobile/Helpers/AppPropertiesFeatureFlags.cs, AB#2969). A missing row or off means the legacy engine for every member (no rest violations); shadow keeps members on legacy results while the new engine runs alongside for divergence logs; on makes the engine available, and it runs only for members who turn on Settings → FTDT Rest Rules Engine (off by default). The row is on only on gatewayapi (production); gatewayapiqa has no row, so builds pointed at QA never get the engine. The §117.25(d) is live: the gateway airports API ships each airport's IANA zone as timeZoneId (AB#2371), read through ALPAMobile/Services/FlightSearchAirportLookup.cs; an airport without one keeps the timezone-dependent checks dormant there.For unaugmented operations the maximum FTL is determined by the acclimated time of report per Table A to Part 117.
| Time of Report (Acclimated) | Maximum Flight Time (hours) |
|---|---|
| 0000–0459 | 8 |
| 0500–1959 | 9 |
| 2000–2359 | 8 |
For augmented operations the maximum FTL is determined by Table C to Part 117, based on scheduled start time, total crew count (3 or 4 pilots), and rest facility class (1, 2, or 3). Limits range from 13 to 19 hours.
The Maximum FDP is reduced by 30 minutes if the flight crew member is not acclimated.
| Scheduled Start Time (Acclimated) | 1 seg | 2 seg | 3 seg | 4 seg | 5 seg | 6 seg | 7+ seg |
|---|---|---|---|---|---|---|---|
| 0000–0359 | 9 | 9 | 9 | 9 | 9 | 9 | 9 |
| 0400–0459 | 10 | 10 | 10 | 10 | 9 | 9 | 9 |
| 0500–0559 | 12 | 12 | 12 | 12 | 11.5 | 11 | 10.5 |
| 0600–0659 | 13 | 13 | 12 | 12 | 11.5 | 11 | 10.5 |
| 0700–1159 | 14 | 14 | 13 | 13 | 12.5 | 12 | 11.5 |
| 1200–1259 | 13 | 13 | 13 | 13 | 12.5 | 12 | 11.5 |
| 1300–1659 | 12 | 12 | 12 | 12 | 11.5 | 11 | 10.5 |
| 1700–2159 | 12 | 12 | 11 | 11 | 10 | 9 | 9 |
| 2200–2259 | 11 | 11 | 10 | 10 | 9 | 9 | 9 |
| 2300–2359 | 10 | 10 | 10 | 9 | 9 | 9 | 9 |
All values in hours.
For augmented operations, FDP is determined by three factors: (1) acclimated scheduled start time, (2) total crew count (3 or 4 pilots), and (3) rest facility class (1, 2, or 3).
| Start Time (Acclimated) | Class 1 / 3 crew | Class 1 / 4 crew | Class 2 / 3 crew | Class 2 / 4 crew | Class 3 / 3 crew | Class 3 / 4 crew |
|---|---|---|---|---|---|---|
| 0000–0559 | 15 | 17 | 14 | 15.5 | 13 | 13.5 |
| 0600–0659 | 16 | 18.5 | 15 | 16.5 | 14 | 14.5 |
| 0700–1259 | 17 | 19 | 16.5 | 18 | 15 | 15.5 |
| 1300–1659 | 16 | 18.5 | 15 | 16.5 | 14 | 14.5 |
| 1700–2359 | 15 | 17 | 14 | 15.5 | 13 | 13.5 |
All values in hours. Rest facility class definitions: see definitions.html.
Unaugmented: Total hours in FDP + RAP may not exceed the lesser of: (Table B FDP) + 4 hours, or 16 hours — measured from the beginning of the RAP.
Augmented: Total hours in FDP + RAP = (Table C FDP) + 4 hours — measured from the beginning of the RAP. No 16-hour absolute cap for augmented.
To determine when the FDP reaches its maximum: add the maximum FDP (from Table B or C) to the FDP start time.
The actual flight time equals the sum of durations of all city-pair segments flown.
| Window | Type | Maximum |
|---|---|---|
| Last 672 hours (28 days) | Cumulative Flight Time (§117.23(b)) | 100 hours |
| Last 365 days | Cumulative Flight Time (§117.23(b)) | 1,000 hours |
| Last 168 hours (7 days) | Cumulative FDP hours (§117.23(c)) | 60 hours |
| Last 672 hours (28 days) | Cumulative FDP hours (§117.23(c)) | 190 hours |
FDP hours run from the report to the last flight's Block In (§117.3: the FDP "ends when the aircraft is parked after the last flight"), not to the release (work item 3191, José 2026-10-07; AB#3386). Interim, pending the SME: a duty period whose legs are all deadhead or positioning counts nothing, and so does a deadhead after the last flight (interpretation I-29); a duty period with a Duty leg and no flight counts to its release, because the app cannot tell airport/standby reserve from ground duty, while a Duty leg after the last flight is not counted (open with the SME); a leg dated outside the duty period is not read; one with no legs logged counts to its release. A duty period not concluded counts up to now or its calculated max end. Each duty period starts at its own report: ground duty logged as its own duty period before a flight is not yet joined to that FDP (S-15).
No certificate holder may assign and no flightcrew member may accept assignment to any reserve or duty during any required rest period.
Before beginning any reserve or flight duty period, a flightcrew member must be given at least 30 consecutive hours free from all duty within the past 168 consecutive hour period.
If a flightcrew member operating in a new theater has received 36 consecutive hours of rest, that flightcrew member is considered acclimated and the rest meets the requirements of §117.25(b).
A flightcrew member must receive a minimum of 56 consecutive hours rest upon return to home base if:
A flightcrew member must be given a rest period of at least 10 consecutive hours immediately before beginning the reserve or flight duty period (measured from release from duty). The 10-hour rest period must provide at least 8 uninterrupted hours of sleep opportunity.
If a flightcrew member determines that the rest period under §117.25(e) will not provide 8 uninterrupted hours of sleep opportunity, the flightcrew member must notify the certificate holder and cannot report for the assigned FDP until a proper rest period is received.
If a flightcrew member engaged in deadhead transportation exceeds the applicable Table B FDP, the flightcrew member must be given a rest period equal to the length of the deadhead transportation (but not less than the 10-hour minimum under §117.25(e)) before beginning a flight duty period.