Abstract
This paper proposes an analytical method for establishing a separation minimum for air traffic control (ATC) using a monopulse SSR (secondary surveillance radar) of which coverage is extended to 250NM. The azimuth estimation accuracy of the monopulse SSR, what we call, the long range SSR (LSSR), was significantly improved compared with that of conventional SSR. As an index of a collision risk due to azimuth errors of the LSSR, the close approach probability (CAP) associated with the probability of overlap of aircraft in azimuthal direction is used for evaluating the safety of the surveillance system. The CAPs for both the LSSR and the conventional SSR are estimated through modeling distributions of azimuth errors and these are compared each other. The results show that the CAP for the LSSR is significantly smaller than that for the conventional one under 5NM radar separation minimum.
