Originally Posted by
bmwe92fan
My question is simple - how often is the spare pilot called upon to enter duty?
The IRO(s) are on-duty for the entire flight per 14 CFR 117. They participate in the pre-flight planning, briefing, and preflight inspection. They are all on the flight deck during takeoff and landing.
During the flight, each pilot will rotate onto break. 14 CFR 117 is very specific about the length and timing of breaks going as far as requiring breaks of specific minimum lengths in the second-half of the duty period for the pilots in the control seats for the landing.
Originally Posted by
bmwe92fan
There are domestic flights just as long that don’t have these requirements - so was curious…. I do realize it is plane dependent however.
The max duty day and flight time restrictions of 14 CFR 117 vary based on the time of day and number of legs flown. An eastbound flight that falls just under the unaugmented limit is likely to be over the limit when flying westbound against the headwinds. In those cases, the flight will be augmented in both directions. A limited number of flights are flown unaugmented in the summer months when winds are less strong and when the departure times allow the longer limits.