Flight Time Limitations/ Commander's Discretion Calculation Guide V2 (09.01.2014)
Extension of FDP
a. In-Flight Relief An additional flight crew member can be carried to provide in-flight relief with the intent of extending the MAX Allowable FDP. The division of duty and rest must be kept balanced between the flight crew members.
The FDP shall only be extended if the total in-flight rest exceeds 3 hours for each flight crew member. The rest is not required to be consecutive.
For rest in a bunk: Half the total rest taken can be added to the MAX allowable FDP; on condition that the MAX FDP does not exceed 18 hours
For rest in a seat: One third the total rest taken can be added to the MAX allowable FDP; on condition that the MAX FDP does not exceed 15 hours