When must pilots file a flight plan?

Filing a flight plan is essential for maintaining safety and ensuring proper air traffic management. Pilots are required to file a flight plan when operating under Instrument Flight Rules (IFR) because this provides air traffic control with necessary information about the flight, including route, aircraft type, and expected time of arrival. This is crucial as it allows for the effective management of air traffic and enhances the safety of all aircraft in the airspace.

For VFR (Visual Flight Rules) flights, the requirement to file a flight plan depends on specific factors such as the airspace being operated within and the distance being traveled. For instance, flights in controlled airspace or flights that are over a certain distance from the departure point often necessitate a flight plan for communication and safety purposes. Additionally, VFR flight plans can be beneficial, even if not required, as they provide a means for search and rescue operations in case of emergencies.

The other options do not capture the nuanced requirements of when a flight plan is mandatory. While training flights might require a plan for instructional purposes, it is not universally mandated. Flying at night or before every takeoff is also not a blanket requirement, as there are certain conditions under which pilots may operate without a filed flight plan. The correct