Manual selection of the active reference of a flight plan for the guidance of an aircraft

Method for managing the flight plan intended for managing the flight of an aircraft, the aircraft possessing a flight management system furnished with a flight plan comprising waypoints and with an original trajectory consisting of legs and of transitions between legs calculated in such a way that the trajectory passes as close as possible to the said waypoints of the flight plan and that the aircraft is able to follow the said trajectory, an active reference, which may be the active leg, that is to say flown by the aircraft, or the From waypoint of the aircraft, being defined at each instant, comprising a step of manually selecting the active reference used for guiding the aircraft.