Abstract: A landing zone landing assistance system for a rotary wing aircraft, the system includes a computer, an HMI for interacting with the pilot of the aircraft, an optical assembly provided with at least one optical sensor, a radar assembly provided with at least one radar detector and an inertial unit, wherein the computer is configured to implement the following steps: a first step (Step1) consisting in determining an optical image of the possible landing zone; a second step (Step2) consisting in determining the relative position of the landing zone with respect to said system in the terrestrial reference frame; a third step (Step3) consisting in determining a landing zone approach path; and a fourth step (Step4) consisting in supplying to the HMI a deviation between the position of the system and the approach path.