Air Traffic Conflict Resolution and Recovery

An essential element in the Free Flight concept is the detection and avoidance of air tra c con icts. A con ict occurs when the required separation between two aircraft, namely the ownship and the intruder, is lost. Con ict detection and resolution systems predict loss of separation and output con ict avoidance maneuvers that divert the ownship from its original trajectory. In this paper, we address the problem of redirecting the ownship to its original path, in a geometric optimal way, without introducing new con icts. We call this concept Resolution and Recovery. Given the current 3-dimensional position and velocity vectors of two aircraft in predicted con ict and the ownship's required time of arrival at the target point, the resolution and recovery algorithm outputs a choice of maneuvers. Each maneuver comprises an escape course and a recovery course to be followed by the ownship. The escape course brings the ownship o the predicted con ict and the recovery course returns it to the original target point. We provide a rigorous mathematical description of the problem and show that the algorithm is correct, i.e., no matter which of the proposed maneuvers the ownship picks, it will arrive at the target point at the scheduled time while maintaining the minimum required separation to the intruder at all times.