A proximity radar method for a rotary-wing aircraft includes a sequence of phases T(k) of steps. In a first phase T(1), the electronic computer of the radar system computes unambiguous synthetic patterns on the basis of a first activated interferometric pattern M(1) of N unitary radiating groups. In the following phases T(k) of steps, executed successively in increasing order of k, the electronic computer computes synthetic patterns on the basis of interferometric patterns M(k) of rank k, wherein the N unitary radiating groups of a series deviate simultaneously in terms of azimuth and in terms of elevation as k increases, and establishes maps of rank k of the surroundings in terms of azimuth distance/direction and/or elevation distance/direction cells wherein the detected obstacle ambiguities, associated with the network lobes, are removed by virtue of the map(s) provided in the preceding phase or phases.