When must a flight plan be filed?

A flight plan must be filed for all flights beyond 25 nautical miles from the departure aerodrome to ensure safety and proper management of air traffic. This requirement allows for effective monitoring of aircraft, particularly in case of emergencies. When a flight is planned beyond this distance, it typically enters a more complex airspace system, where traffic control services are essential for maintaining safe distances between aircraft. Filing a flight plan helps authorities to track the aircraft's intended route and manage potential search and rescue operations if the aircraft does not arrive as scheduled.

In contrast, other scenarios do not require a flight plan. For instance, flights under 25 nautical miles, while they may still be flown safely, typically do not need the same level of oversight. Similarly, the requirement is not limited solely to international flights or commercial operations, as many recreational or private flights also necessitate a flight plan when exceeding the specified distance.