Who is directly responsible for the final authority regarding the operation of the airplane?

The pilot-in-command holds the final authority over the operation of the aircraft. This role entails making critical decisions regarding the safety and management of the flight, from pre-flight planning to in-flight emergencies. The pilot-in-command is tasked with ensuring compliance with all regulations and procedures, and has the ultimate responsibility for the crew and passengers on board. In situations where quick and decisive action is needed, such as in the event of an emergency, the pilot-in-command must make judgment calls that can significantly affect the outcome of the flight.

The first officer, while trained and experienced, supports the pilot-in-command and assists with the operation, though they do not have the final authority. The flight engineer's role primarily revolves around monitoring and managing aircraft systems but does not entail decision-making authority. The flight dispatcher, meanwhile, is responsible for the overall flight planning and ensuring the flight can operate within regulations, but they do not have operational control of the aircraft once the flight is airborne.