How maximum Flight Duty Periods and maximum Flight Times will affect Airlines FAR 121 subpart Q versus FAR 117 – Split Duty


By

Garret Healy, Software Engineer, Jeppesen Inc.

Joshua Foltz, First Officer, Allegiant Air

Abstract:

The author’s developed the following tables as a crew planning tool. These tables demonstrate how strict FAR Part 117 work rules are in relation to allowed duty time when compared to FAR part 121 subpart Q.

Airlines must schedule efficient Flight Duty Periods and carefully plan when Flight Duty Periods begin as well as how many segments are involved.

In order to schedule efficient pairings the Airlines should consider looking at productive hours (block time) versus non-productive hours (FDP time).

Split duties have been used in the industry under many different names, High-Speed Over Night, Continuous Duty Over Night, Night Turn, Stand-up Overnight, etc. These operations all have the same characteristics, relatively low, flight time and duty time with a duty break of 3 to 6 hours.

Most split duty operations have been utilizing regional jets, where the turn time is smaller.

Until FAR 117 was created, carriers had constraints for split duties mostly within CBA’s.

Definitions:

Duty:

Is defined in FAR part 117.

Means any task that a flightcrew member performs as required by the certificate holder, including but not limited to flight duty period, flight duty, pre- and post-flight duties, administrative work, training, deadhead transportation, aircraft positioning on the ground, aircraft loading, and aircraft servicing.

Pre-Flight Duties:

Includes reporting for an assignment, acknowledging flights to be performed while on duty, will be operated in accordance to FAA regulations, including understanding of the expected conditions that will affect the flight(s) to be performed. Inspections of the aircraft for flight readiness, etc.

Flight Duty Period (FDP):

Is defined in FAR part 117.

Means 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 aircraft movement by the same flightcrew member. A flight duty period includes the duties performed by the flightcrew member on behalf of the certificate holder that occur before a flight segment or between flight segments without a required intervening rest period. Examples of tasks that are part of the flight duty period include deadhead transportation, training conducted in an aircraft or flight simulator, and airport/standby reserve, if the above tasks occur before a flight segment or between flight segments without an intervening required rest period.

Flight Time:

Is defined in FAR part 1.

Commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing.

Flightcrew Member (FCM):

Is defined in FAR part 1.

Is a pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time.

Duty Break:

Must meet the following criteria:

  1. Is scheduled before the start of the FDP.
  2. Is at least 3 hours.
  3. Is not provided until after the first segment In the FDP has been completed.
  4. Is provided between 22:00 and 05:00 local time.
  5. Is measured from the time that the flightcrew member reaches the suitable accommodation.
  6. Duty breaks cannot be reducible from scheduled. Even during delays, the scheduled duty  break cannot be reduced

Suitable Accommodation:

means a temperature-controlled facility with sound mitigation and the ability to control light that provides a flightcrew member with the ability to sleep either in a bed, bunk or in a chair that allows for flat or near flat sleeping position. Suitable accommodation only applies to ground facilities and does not apply to aircraft on-board rest facilities.

Assumptions:

Brief time:

The amount of pre-flight duty before the flight departs the gate. Typically ranges between 0:45 to 1:00; generally contained within a CBA; for the purposes of this paper we will use 1:00.

Debrief time:

The amount of post-flight duty after the flight arrives at the gate. Typically ranges between 0:15 to 0:30; generally contained within a CBA; for the purposes of this paper we will use 0:15.

Flight Time Buffer:

The amount of time used to schedule a FCM within the permissible limitations of FAR part 117.11, for the purposes of this paper we will use 0:30.

Minimum Connect Time:

The minimum time from when an aircraft arrives at the gate, to the time when the aircraft moves away from the gate to allow for sufficient to unload/load passengers and baggage, and make any required service needs for the aircraft before departure as well as performance of pre-flight checklists, for the purposes of this paper we will use 0:30.

Permissible Extensions to FDP:

Under FAR 117.19, it is permissible to operate beyond the scheduled limitations in FAR 117.13 by 0:30, extensions up 2:00 may be conducted before departure under certain conditions, for the purposes of this paper we will use 0:00.

Cumulative Flight Time Limitations:

For the purposes of this paper, a FCM will not be exceeding any of the following limitations:

  1. Under 117.23, FCM’s are limited to 100 hours in 672 consecutive hours and 1000 hours in 365 calendar days.
  2. Under 121 subpart Q, FCM’s are limited to 30 hours in 7 calendar days, 100 hours in a calendar months and 1000 hours in a calendar year.

Cumulative Flight Duty Time Limitations:

For the purposes of this paper, a FCM will not be exceeding any of the following limitations:

  1. Under 117.23, FCM’s are limited to 60 hours in 168 consecutive hours and 190 hours in 672 consecutive hours.
  2. Under 121 subpart Q, FCM’s are presently not limited by FDP time.

Rest Requirements:

For the purposes of this paper, a FCM will always be in compliance with the following requirements:

  1. Under 117.25, FCM’s are required to have been scheduled for and have been given a rest period of no less than 30 hours in the 168 consecutive hours preceding the start of a FDP.
  2. Under 121 subpart Q, FCM’s are required to have been scheduled for and have been given a rest period of no less than 24 hours in the 7 calendar days preceding the scheduled completion of any flight subject to this subpart.

Minimum Duty Break:

FAR 117.15 mandates that the minimum time spent in a suitable accommodation is 3:00.

Travel Time:

FAR 117.15, mandates that the time to travel to/from the location used as a suitable accommodation is not part of the required duty beak, generally, the location is relatively close-by; for the purposes of this paper we will use 0:15 each way for travel time, this will equate to 0:30.

FAA rational for Split-Duty:

When a FCM is assigned a FDP during the Overnight Period (a FDP that infringes on any portion of the WOCL), the rest period and associated sleep opportunity immediately before the FDP will provide less beneficial rest as it is during the daytime. In order to allow for longer FDPs during the Overnight Period, it was determined that by providing a Duty Break between 22:00 and 05:00 will allow for the FCM to gain some sleep during the WOCL. As the Duty Break is to be scheduled, this allows a FCM to plan as to how best to prepare for the break and take advantage of the sleep opportunity, ie) caffeine intake.

Specific regulatory provisions applied:

Daily Flight Time Limitations (FTL):

1        Part 117 has Daily FTL’s governed under 117.11.

  • Based upon FDP start time, the limitation is either 8:00 or 9:00 as defined in Table A.
  • Evaluated on a leg by leg basis, FCM may not continue a flight if before takeoff it is known that the FTL will be violated.

 table A

Table A

      2        Part 121 has Daily FTL’s governed under 121.471(a)(4).

  • The scheduled limitation is 8:00.
  • A FCM may continue the assigned FDP as long as the flight itinerary is the same as what the FCM began with no further constraints (legal to start, legal to finish), else a reevaluation at the point of rescheduling must take place.

Daily FDP Limitations:

  1. Part 117 has Daily FDP limits governed under 117.13, however under 117.15 we have simplified the table to account for the application of the required duty break as well as the max permissible combined FDP and Duty Break.

split1

Table B (Modified)

  1. Part 121 does not actually have FDP limitations, instead a complicated system based upon 121.471(b) and (c):
    • A scheduled flight time in the 24 hours preceding the scheduled completion of a flight segment.
    • A required rest period in the 24 hours preceding the actual expected completion of a flight segment. The may be reduced due to operational contingencies before takeoff.
    • A compensatory rest period will be required following the release of a duty period that is preceded by a reduced rest period, this will effectively limit the duty period to a maximum of 16 or 15 hours dependent upon the scheduled flight time in the 24 hour period, and the compensatory rest period must commence within 24 hours of the start of the reduced rest period.

121.471(a)(b)

Objective comparisons of specific regulatory provisions:

split2

FAR 121 Subpart Q

(Max Skd FDP + Max Extension) – ((Max Flight Time – FT Buffer) + Brief + Min Break+ (Segments – 2) * Turn) = Allowed Delay within FDP

split3

Relative Efficiency of the FDP

100 * (Max Flight Time)/(Max Duty time – Debrief) + Allowed Delay within FDP)

split4

FAR 117 Split Duty

(Max Skd FDP + Max Extension) – ((Max Flight Time – FT Buffer) + Brief + Min Break+ (Segments – 2) * Turn) = Allowed Delay within FDP

(Max Skd FDP + Max Extension + Min Break) – ((Max Flight Time) + Brief + Min Break + (Segments – 2) * Turn) = Required Reduction of Flight Time

split5

split6

Relative FDP Efficiency

100 * (Max Flight Time- Required reduction of Flight Time)/(Max Skd FDP + Allowed Delay within FDP)

split7

Conclusions:

FAR 121 subpart Q is generally more efficient, however there are cases where FAR 117 will be more efficient, from 1300 to 1959 with less than 5 segments, and increase in efficiency of 1.54 percent over operation under 121 with less than 9 hours flight time in 24 hours, this is due to the higher flight time permitted under FAR 117.

FAR 121 overall allows for greater absorption of delays, however FAR 117 will permit absorption of delays with less than 4 segments, with permitted delays greater than or equal to 2 hours with 2 or 3 segments during the 2000 to 2259 FDP starts.

We also examined FDP’s under FAR 117 without applying the Split-Duty rules:

  1. Split duties were capable of absorbing delays with 3 and 4 segments by 0:30 more over non-split duties
  2. Efficiencies are less with split-duties than with non-split duties, this is primarily due to the longer Combined FDP’s with split duties.

An additional benefit to Split-Duties is that a FCM may be assigned 4 to 5 consecutive FDP’s that overlap the WOCL when each FDP has a min duty break of 2:00. Reference is FAR 117.27.

Recommendations:

The application of split duty under FAR 117, is best when the duties have 4 or fewer segments, and is best applied to FDP’s starting between 20:00 and 21:59, this allows for the highest average leg lengths.

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