The sense and avoid (S&A) capability is crucial for the unmanned aerial vehicles (UAVs). It is due to the necessity of integrating civilian and governmental UAVs into the common airspace. In a S&A scenario, the ego-UAV is the observer, which estimates the probability and/or the possibility of collision. Based on this estimation, it initiates an avoidance maneuver, if and when it is required. The probability of collision can be determined through the estimation of direction and distance of the other aircraft or UAV (called in this context the intruder).