What does 'flight time' refer to?

The term 'flight time' specifically refers to the duration of the flight as measured from when the aircraft begins its movement for takeoff, which is often referred to as 'block out,' until it comes to a complete stop at the destination, known as 'block in.' This includes the time spent in the air but excludes other phases such as taxiing or preparing for takeoff prior to departure and after landing. Because of this standard definition, the answer that encompasses the total period of flight operation, including taxi times at both ends, is the correct choice. Understanding this definition is crucial for aviation operations and for accurately interpreting flight duration for scheduling and operational purposes.