This method uses for the estimation of a distance, a propagation distance transform considering only the paths which are both accessible to the aircraft taking account of its vertical flight profile and complying with air regulations. The propagated distance Dp is accompanied by a propagated altitude Ap which at all points follows the vertical flight profile of the aircraft, whilst being greater than the altitudes of these points and complying with the air regulation constraints at these points. This is obtained by subjecting the propagation to compliance with the vertical flight profile of the aircraft, constraints of the elevations of the points of the relief and air regulation constraints.