Using a radar to detect a known target likely to be positioned at approximately a predetermined height close to other targets, these other targets also being positioned at approximately the predetermined height. A first phase of detecting the known target is carried out by performing an azimuth scan. When the known target has been detected at a certain distance Di at a certain azimuth angle θaz, a second detection phase is carried out at said azimuth angle θaz and at an elevation angle θEL corresponding to that of an object situated at said distance Di at the predetermined height. The target is said to be detected if it is detected at the elevation angle θEL at a distance D approximately equal to the distance Di.