How is flight time defined for regulatory purposes?

Flight time, for regulatory purposes, is defined as the period from when the aircraft starts moving under its own power for the purpose of flight until it comes to a stop at the end of the flight. This definition is critical as it establishes a clear beginning and end for flight time, ensuring consistency in record-keeping and compliance with regulations governing flight operations.

Understanding this definition is essential for operators and flight crews under Part 135 operations, as it affects various regulatory requirements such as flight time limitations, maintenance scheduling, and crew duty time regulations. Tracking flight time accurately is vital not just for regulatory compliance, but also for safety management, as it relates to crew fatigue and operational readiness.

The other options do not encapsulate the regulatory definition. The period from taxiing to parking includes ground operations which are distinct from actual flight time. The time spent in actual air travel only may exclude crucial phases of flight, and commencing pre-flight checks does not indicate the start of flight time as it pertains to regulatory definition, which is specifically tied to the movement of the aircraft under its power.