At what time will ATC begin a telephone search if the flight plan has not been closed, assuming the actual departure time was 1930Z?

To determine the time at which Air Traffic Control (ATC) will initiate a telephone search for a flight plan that has not been closed, it's essential to understand the protocols governing flight plan follow-up procedures.

When a flight plan is filed, ATC monitors the aircraft's progress based on the planned departure time and estimated time of arrival (ETA). If the flight has not been closed by the flight crew, ATC takes action to ensure safety and determine the aircraft's whereabouts.

In your scenario, the actual departure time of the flight was 1930Z. Typically, the standard protocol is that after 1 hour past the planned departure time without communication or updates from the flight, ATC will start a follow-up process. Therefore, adding the 1-hour grace period to the departure time of 1930Z results in a time of 2030Z.

However, ATC typically will check in with the area and potentially escalate actions based on additional elapsed time. In most cases, the next procedure step might occur significantly later. According to general aviation procedures and regulations, if the flight is still unaccounted for, ATC may escalate their search efforts. Given common practices, a search might commence around 2240Z for a flight