A method for aiding navigation for an aircraft between a descent start point and a computation end point, comprises the computation steps of: collecting a flight plan consisting of a succession of waypoints and of the associated vertical constraints; determining a corridor consisting of a floor trajectory and of a ceiling trajectory defining the minimum and maximum altitudes permitted to the aircraft; splitting the corridor into several cells defined between two waypoints furthest apart and between which the ceiling trajectory is distinct from the floor trajectory; determining for at least one cell a vertical trajectory complying with the altitude constraints and comprising the longest possible IDLE segment; and a step consisting in determining and displaying maneuvering points of the aircraft making it possible to follow the target vertical trajectory.