Duty period is defined as the period of time between reporting for an assignment involving flight time and what other milestone?

The definition of "duty period" in aviation regulations specifically refers to the total time a pilot or flight crew member is on assignment, starting from when they report for their duty until they are officially released from that assignment. This includes time spent preparing for the flight, performing pre-flight checks, and any time spent in-flight, continuing until the duties have been officially completed and the crew is relieved of their responsibilities.

Choosing the point of "release from the assignment" as the endpoint of a duty period is crucial because it encompasses the entire scope of the flight crew's responsibilities, including all preparatory work and the potential management of any post-flight responsibilities. This definition ensures that all aspects of duty that can affect a crew member's operational readiness and fatigue are considered, aligning with regulations designed for safety and well-being in aviation operations.