When must a civil or military tower close a flight plan?

A flight plan must be closed for both Instrument Flight Rules (IFR) and Visual Flight Rules (VFR) flights to ensure the safety and accountability of all aircraft in the airspace. Closing a flight plan is essential because it informs air traffic control that the aircraft has completed its journey safely. For IFR flights, this closure is typically done automatically by air traffic control when the aircraft lands, but pilots have the responsibility to ensure that VFR flight plans are also closed upon arrival or when the flight is terminated.

This systematic approach allows air traffic controllers to maintain accurate situational awareness of all aircraft operations, preventing misunderstandings or potential search and rescue missions for aircraft that have already safely landed but whose flight plans remain open. Hence, the requirement for both IFR and VFR plans to be closed highlights the emphasis on safety in aviation operations.