How is the time frame defined for an aircraft to be considered overdue?

An aircraft is considered overdue when it has not arrived at its destination or made contact with air traffic control for a specific period of time, which is generally 30 minutes or 1 hour beyond its expected arrival time. This timeframe is critical for ensuring the safety of flights, as it allows for prompt search and rescue efforts if an aircraft fails to arrive as scheduled.

The 30 minutes threshold often serves as an immediate indicator that the aircraft may be experiencing difficulties, prompting ATC to initiate procedures to locate it. On the other hand, the 1-hour threshold may apply to flights operating under less restrictive operational conditions, where the initial 30 minutes has elapsed without any communication.

Understanding this timeframe justifies the option that correctly identifies the period for considering an aircraft as overdue. It is a standard practice that prioritizes safety and ensures that appropriate measures are taken to locate the aircraft.