Airline crew scheduling is the process of assigning pilots and cabin crew to flights. It runs in stages: build pairings from the flight schedule, assign them to named crew as rosters, publish the rosters, then track and repair them on the day of operation. Every assignment must respect the flight time, duty, and rest limits set by the operator's regulator.
The four stages of crew scheduling
| Stage | What happens | Output |
|---|---|---|
| Pairing | Flights are grouped into sequences that a crew can legally operate, from reporting for duty until release at the end of the trip. | Pairings, also called trips or rotations. |
| Rostering | Pairings, standby, leave, and training are assigned to named crew for the roster period, often using crew bids or preferences. | An individual roster, or line, for each crew member. |
| Publication | The roster is validated against the rules and published so that crew can plan their rest. | The published roster and its notifications. |
| Tracking and recovery | Sickness, delays, and cancellations break the plan. Controllers reassign crew while staying within the limits. | An updated roster with a record of each change. |
A note on terminology
ICAO's fatigue management manual defines a pairing as "a scheduling expression describing the time from when a flight crew member initially reports for duty until he/she returns home from the sequence of flights and is released from duty", and notes that it is also called a trip. EASA guidance uses "crew pairing" for the rostered positioning and flights of crew members within one duty period, and "rotation" for the multi-day sequence. Terms such as crew tracking and crew control are industry usage and have no regulatory definition.
The limits a roster must respect
ICAO Annex 6 requires each State to "establish regulations for the purpose of managing fatigue". Regulators do so with flight time limitation (FTL) schemes. The table shows headline values from three schemes. The limits that apply to a specific duty also depend on its start time, the number of sectors, acclimatisation, and crew augmentation.
| Limit | FAA Part 117 | EASA Subpart FTL | OTAR Appendix F (aeroplanes) |
|---|---|---|---|
| Applies to | Flightcrew in Part 121 passenger operations. | Aircrew in commercial air transport with aeroplanes. | Operators under OTAR Parts 121 and 135 in the UK Overseas Territories. |
| Cumulative duty | 60 flight duty period hours in any 168 consecutive hours; 190 in any 672 consecutive hours. | 60 duty hours in 7 consecutive days; 110 in 14; 190 in 28. | 55 duty hours in 7 consecutive days, which may be increased to 60; 95 in 14; 190 in 28. |
| Cumulative flight time | 100 hours in any 672 consecutive hours; 1,000 hours in any 365 consecutive calendar days. | 100 hours in 28 consecutive days; 900 in a calendar year; 1,000 in 12 consecutive calendar months. | 100 hours in 28 days; 900 hours in 12 months. |
| Maximum daily flight duty period | 9 to 14 hours, by scheduled start time and number of segments. | Up to 13 hours for acclimatised crew starting between 0600 and 1329 with one or two sectors. | Up to 14 hours. |
| Minimum rest | 10 consecutive hours with an 8-hour sleep opportunity; 30 consecutive hours free from duty in any 168 hours. | At home base, the preceding duty period or 12 hours, whichever is greater; away from base, the preceding duty period or 10 hours, whichever is greater. | Set out in Appendix F. |
The units differ between schemes. The FAA counts flight duty period hours in rolling windows of hours, while EASA and the OTARs count duty hours in consecutive days. A roster that is legal under one scheme is not automatically legal under another.
In the EU, operators must also "publish duty rosters sufficiently in advance to provide the opportunity for crew members to plan adequate rest". The acceptable means of compliance say rosters should be published 14 days in advance.
Why crew scheduling is an optimization problem
Even a small schedule produces more legal combinations of flights and crew than a planner can enumerate by hand. Scheduling software therefore separates two kinds of rule.
- Hard constraints cannot be broken: every flight needs its crew complement, each crew member must be qualified for the aircraft and route, and no assignment may breach the flight time limitation scheme.
- Objectives are traded against each other: crew preferences and bids, a fair spread of workload, cost, and how well the roster absorbs disruption.
A sound tool treats legality as a hard constraint, reports the duties it could not cover, and shows the rule behind each rejected assignment.
Disruption recovery on the day of operation
A published roster starts to drift as soon as the operation begins. A recovery process works from three principles.
- Change as little as possible. Keep the assignments the disruption did not touch and repair only the affected duties.
- Check legality with real duty history. Cumulative limits depend on what each crew member has already worked, not only on the planned month.
- Keep a person in the decision. A controller reviews the proposed change, approves it, and the change is recorded.
Fatigue risk management
Prescriptive limits are one way to manage fatigue. ICAO also defines the fatigue risk management system (FRMS): "a data-driven means of continuously monitoring and managing fatigue-related safety risks, based upon scientific principles and knowledge as well as operational experience that aims to ensure relevant personnel are performing at adequate levels of alertness." Under FAA Part 117, an operator may exceed a provision of the part only when the FAA has approved it under an FRMS.
What to check in crew scheduling software
The airline crew scheduling software overview sets out an evaluation checklist: the rules engine, the source of cumulative duty history, how uncovered work is reported, qualification and currency checks, human authority over publication, and the crew's own view of the roster.
CREW AI is FlightAtom's crew scheduling and management software. Its implemented flight time limitation engine follows the OTAR scheme; another scheme is scoped and validated for the operation as part of an implementation.
Official references and scope
These sources define the limits and terms described above. Table values are headline figures; the full rules contain conditions that change the limit for a specific duty.
- 14 CFR Part 117: FAA flight and duty limitations and rest requirements for flightcrew members.
- EASA Easy Access Rules for Air Operations: Regulation (EU) No 965/2012, including Subpart FTL of Part-ORO and its acceptable means of compliance.
- ICAO fatigue management: ICAO material on fatigue management approaches and the FRMS definition.
- Overseas Territories Aviation Requirements: Air Safety Support International's OTAR Parts 121 and 135, including the fatigue management scheme in Appendix F.
Crew scheduling FAQs
What is crew scheduling in an airline?
Crew scheduling is the process of assigning pilots and cabin crew to flights. It covers building pairings from the flight schedule, assigning them to named crew as rosters, publishing the rosters, and repairing them when the operation changes.
What is the difference between crew pairing and crew rostering?
A pairing is a sequence of flights that a crew can legally operate, from reporting for duty until release at the end of the trip. Rostering assigns pairings, standby, leave, and training to named crew members for the roster period. Pairing is usually solved first, then rostering.
How many hours can airline pilots fly?
It depends on the regulator. Under FAA Part 117, a pilot in Part 121 passenger operations is limited to 100 flight hours in any 672 consecutive hours and 1,000 hours in any 365 consecutive calendar days. Under EASA rules the limits are 100 hours in 28 days, 900 hours in a calendar year, and 1,000 hours in 12 consecutive calendar months.
How far in advance must rosters be published?
EASA rule ORO.FTL.110 requires operators to publish duty rosters sufficiently in advance for crew to plan adequate rest, and its acceptable means of compliance say rosters should be published 14 days in advance. Other regulators and operator agreements set their own periods.
What is an FRMS?
A fatigue risk management system is, in the ICAO definition, a data-driven means of continuously monitoring and managing fatigue-related safety risks, based on scientific principles, knowledge, and operational experience, so that personnel perform at adequate levels of alertness.
What does crew scheduling software do?
It generates pairings, builds rosters within flight time, rest, and qualification constraints, publishes them to crew, and proposes recovery options when a disruption breaks the plan. CREW AI is FlightAtom's crew scheduling and management software.
Bring a roster problem you can verify
Use a representative roster period, your current rules, and a real disruption to compare your present process with CREW AI.