Abstract: The so-called flight path of an aircraft is defined in the form of a set of successive target points (B.sub.i -1, B.sub.i, B.sub.i +1) with a target circle (CB.sub.i) associated with each target point. A navigation envelope (DN) is determined in she direction to this target, and a guidance envelope (DH) is determined in the direction of the next target, for each target point. Normally, the aircraft is in the navigation envelope, and reenters the guidance envelope, then the target circle (B.sub.i) after which it heads in the direction of the navigation envelope associated with the next target. In the contrary case, a mandatory switching envelope (DCF) determines the instant when the aircraft is to orient itself on the next target (B.sub.i +1).