Flight Time Limitations, explained

acclimatised

A state in which a crew member’s circadian biological clock is synchronised to the time zone where the crew member is. A crew member is considered to be acclimatised to a 2-hour wide time zone surrounding the local time at the point of departure. When the local time at the place where a duty commences differs by more than 2 hours from the local time at the place where the next duty starts, the crew member, for the calculation of the maximum daily flight duty period, is considered to be acclimatised in accordance with the values in Table 1 of ORO.FTL.105 (reproduced under acclimatisation above).

reference time

The local time at the reporting point situated in a 2-hour wide time zone band around the local time where a crew member is acclimatised.

accommodation

For the purpose of standby and split duty, a quiet and comfortable place not open to the public with the ability to control light and temperature, equipped with adequate furniture that provides a crew member with the possibility to sleep, with enough capacity to accommodate all crew members present at the same time and with access to food and drink.

suitable accommodation

For the purpose of standby, split duty and rest, a separate room for each crew member located in a quiet environment and equipped with a bed, which is sufficiently ventilated, has a device for regulating temperature and light intensity, and access to food and drink.

augmented flight crew

A flight crew which comprises more than the minimum number required to operate the aircraft, allowing each flight crew member to leave the assigned post, for the purpose of in-flight rest, and to be replaced by another appropriately qualified flight crew member.

break

A period of time within a flight duty period, shorter than a rest period, counting as duty and during which a crew member is free of all tasks.

delayed reporting

The postponement of a scheduled FDP by the operator before a crew member has left the place of rest.

disruptive schedule

A crew member’s roster which disrupts the sleep opportunity during the optimal sleep time window by comprising an FDP or a combination of FDPs which encroach, start or finish during any portion of the day or of the night where a crew member is acclimatised. A schedule may be disruptive due to early starts, late finishes or night duties.

early type (of disruptive schedule)

An “early start” is a duty period starting in the period between 05:00 and 05:59 in the time zone to which a crew member is acclimatised; a “late finish” is a duty period finishing in the period between 23:00 and 01:59 in the time zone to which a crew member is acclimatised.

late type (of disruptive schedule)

An “early start” is a duty period starting in the period between 05:00 and 06:59 in the time zone to which a crew member is acclimatised; a “late finish” is a duty period finishing in the period between 00:00 and 01:59 in the time zone to which a crew member is acclimatised.

night duty

A duty period encroaching any portion of the period between 02:00 and 04:59 in the time zone to which the crew is acclimatised.

duty

Any task that a crew member performs for the operator, including flight duty, administrative work, giving or receiving training and checking, positioning, and some elements of standby.

duty period

A period which starts when a crew member is required by an operator to report for or to commence a duty and ends when that person is free of all duties, including post-flight duty.

flight duty period (FDP)

A period that commences when a crew member is required to report for duty, which includes a sector or a series of sectors, and finishes when the aircraft finally comes to rest and the engines are shut down, at the end of the last sector on which the crew member acts as an operating crew member.

flight time

For aeroplanes, the time between an aircraft first moving from its parking place for the purpose of taking off until it comes to rest on the designated parking position and all engines or propellers are shut down.

home base

The location, assigned by the operator to the crew member, from where the crew member normally starts and ends a duty period or a series of duty periods and where, under normal circumstances, the operator is not responsible for the accommodation of the crew member concerned.

local day

A 24-hour period commencing at 00:00 local time.

local night

A period of 8 hours falling between 22:00 and 08:00 local time.

operating crew member

A crew member carrying out duties in an aircraft during a sector.

positioning

The transferring of a non-operating crew member from one place to another, at the behest of the operator, excluding the time of travel from a private place of rest to the designated reporting place at home base and vice versa, and the time for local transfer from a place of rest to the commencement of duty and vice versa.

rest facility

A bunk or seat with leg and foot support suitable for crew members’ sleeping on board an aircraft.

reserve

A period of time during which a crew member is required by the operator to be available to receive an assignment for an FDP, positioning or other duty notified at least 10 hours in advance.

rest period

A continuous, uninterrupted and defined period of time, following duty or prior to duty, during which a crew member is free of all duties, standby and reserve.

rotation

A duty or a series of duties, including at least one flight duty, and rest periods out of home base, starting at home base and ending when returning to home base for a rest period where the operator is no longer responsible for the accommodation of the crew member.

single day free of duty

For the purpose of complying with the provisions of Council Directive 2000/79/EC, a time free of all duties and standby consisting of one day and two local nights, which is notified in advance. A rest period may be included as part of the single day free of duty.

sector

The segment of an FDP between an aircraft first moving for the purpose of taking off until it comes to rest after landing on the designated parking position.

standby

A pre-notified and defined period of time during which a crew member is required by the operator to be available to receive an assignment for a flight, positioning or other duty without an intervening rest period.

airport standby

A standby performed at the airport.

other standby

A standby either at home or in a suitable accommodation.

window of circadian low (WOCL)

The period between 02:00 and 05:59 hours in the time zone to which a crew member is acclimatised.

No definition matches that filter.

A Fatigue Risk Management System (FRMS) is the data-driven counterpart. It uses scientific principles, operational experience and measurement to manage fatigue risk continuously, and it can support variations from the prescriptive limits where an operator can demonstrate an equivalent or better level of safety. Under EASA rules, operators must manage fatigue risk within their management system regardless of whether they hold an FRMS approval.

In practice that means collecting duty and rest data, reported fatigue, and roster stability metrics — then acting on them. The guidance material below, from ICAO, EASA, Eurocontrol and the UK and Australian authorities, is the standard starting point.