Probing the atmosphere using certain wavelengths of high-intensity visible and non-visible light (LIDAR) presents a visual hazard to pilots of aircraft at close range. In order to safely operate the LEANDRE lidar during the International H2O Project (IHOP 2002) a small marine radar was used to detect nearby aircraft and disable the lidar before the aircraft encountered the lidar beam. This magnetron based radar was operated in pseudo-coherent (coherent-on-receive) mode in order to derive both non-coherent and coherent parameters for use by the aircraft detection algorithm. The detection algorithm and the parameters required by the algorithm are discussed in detail in this paper.