Crew, Logs and Records — Page 112, Lesson 176

I want to walk you through the definitions that form the foundation of crew duty and rest regulations. These are the precise terms you'll see in every operator's flight-time limitation scheme, so let's take them one by one. First, duty period. A duty period starts when an operator requires you to begin any duty — that could be a briefing, a check, or administrative work — and it ends only when you are completely free from all duties. The key point is that it covers any work the operator assigns, not just flying. Next, flight duty period, or FDP. This is a subset of duty period. An FDP is any time during which you operate in an aircraft as a member of its crew. It starts when the operator requires you to report for a flight or a series of flights, and it finishes at the end of the last flight on which you are an operating crew member. So the FDP is specifically the window from report time to the end of the last flight — it does not include ground duties before or after that flying window. Home base is the location the operator nominates for you, from which you normally start and end a duty period or a series of duty periods. Under normal conditions, the operator is not responsible for your accommodation at home base — that's your own responsibility. Local day is simply a 24-hour period starting at 00.00 local time. Local night is a period of eight hours falling between 22.00 and 08.00 local time. Notice it's defined by the clock, not by sunset. A single day free of duty must include two local nights. A rest period may be included as part of that day off. So if you get a full calendar day off, it has to span two local night periods — that ensures you get proper overnight rest. Operating crew member means a crew member who carries out duties in an aircraft during a flight or any part of a flight. If you're in the cockpit or cabin performing your assigned role while the aircraft is in motion, you're an operating crew member. Positioning is the transfer of a non-operating crew member from place to place at the operator's request. Importantly, positioning excludes travelling time. Travelling time is defined separately as: time from home to a designated reporting place and vice versa, and time for local transfer from a place of rest to the commencement of duty and vice versa. So if you're deadheading as a passenger to another airport to start a duty, that's positioning — but your commute from home to the airport is travelling time, not positioning. Rest period is an uninterrupted and defined period of time during which you are free from all duties and airport standby. No phone calls, no assignments, no standby — just genuine rest. Standby is a defined period during which the operator requires you to be available to receive an assignment for a flight, positioning, or other duty without an intervening rest period. You're on call, but you're not yet on duty — though standby itself is not rest. Now, a critical fatigue-related term: Window of Circadian Low, or WOCL. The WOCL is the period between 02.00 and 05.59. Within a band of three time zones, the WOCL refers to home base time. Beyond three time zones, the WOCL refers to home base time for the first 48 hours after departure from the home base time zone, and to local time thereafter. This is the period when your body is most prone to fatigue, and regulations are designed to minimise flying during this window. Moving into flight and duty limitations — these are hard numerical limits. Cumulative duty hours: The operator must ensure that your total duty periods do not exceed 190 duty hours in any 28 consecutive days, spread as evenly as practicable throughout that period. Additionally, you cannot exceed 60 duty hours in any seven consecutive days. These are cumulative caps on all duty, not just flying. Finally, there is a limit on total block times. The operator must ensure that the total block times of the flights on which you are assigned as an operating crew member does not exceed — and the excerpt cuts off there, but you can see the principle: there is a maximum amount of actual flying time, measured as block time, that you can accrue as an operating crew member over a given period. That figure shows records for other operations personnel, but the definitions I've just given you are the vocabulary you'll use every time you fill out a crew log or check your duty limits. Take them in, because every subsequent limitation and scheme builds on these exact terms.