When must a preflight be conducted?

A preflight inspection is a crucial safety protocol conducted to ensure that an aircraft is in a safe and airworthy condition before each flight. The correct timing for this inspection is specifically mandated to occur prior to boarding the flight, whenever there is a change in aircraft, and after returning to an unattended aircraft. This ensures that any potential issues that could affect the safety of the flight are identified and addressed.

Conducting a preflight before boarding the flight allows the crew to verify that safety equipment is functional, that the aircraft systems are operational, and that there are no visible problems. Moreover, if an aircraft is changed, the crew must perform a preflight inspection to account for any differences in systems or configurations. Finally, returning to an unattended aircraft allows the crew to check for any unauthorized access or changes that may have occurred while the aircraft was not in use.

This comprehensive approach ensures that safety is prioritized under varying circumstances, promoting a culture of vigilance within aviation operations.