When should an ALNOT be issued for an overdue aircraft?

The correct choice is based on established procedures for managing overdue aircraft situations. An ALNOT, which stands for Alert Notice, is a communication that alerts relevant parties about a potential emergency involving an aircraft that may not have arrived at its destination as scheduled.

The issuance of an ALNOT is typically mandated when there are significant indicators that an aircraft is overdue, and the combination of lost communications and radar contact serves as critical criteria in these situations. Specifically, when there is a complete loss of both radio communications and radar contact for a period of 30 minutes, it raises concerns for the safety of the aircraft and its occupants. This timeframe allows for the possibility that an aircraft may have experienced difficulties, and notifying appropriate agencies can facilitate a timely search and rescue operation.

While the other options may suggest various situations that could be concerning, they do not align with the recognized protocol that combines both the duration of communication loss and the type of contact (radar and radio) that is necessary to determine when an ALNOT should be issued. Thus, the 30-minute window marks a threshold that prompts immediate action in coordination with safety procedures.