Optimal Strategies for Free-Flight Air Traffic Conflict Resolution

Recent advances in navigation and data communication technologies make it feasible for individual aircraft to plan and fly their trajectories in the presence of other aircraft in the airspace. This way, each aircraft can take advantage of the atmospheric and traffic conditions to optimally plan its path. This capability is termed the free-flight concept. Whereas the free-flight concept provides new degrees of freedom to the aircraft operators, it also brings in complexities not present in the current air traffic control system. In this concept, each aircraft has the responsibility for navigating around other aircraft in the airspace. Although this is not a difficult task under low-speed, low-traffic-density conditions, the complexities of dealing with potential conflicts with multiple aircraft in other flight conditions can significantly increase the pilot's work load. The development of conflict resolution algorithms is presented based on trajectory optimization methods that will the enable the practical implementation of the free-flight concept. These algorithms use nonlinear point-mass aircraft models and include realistic operational constraints on individual aircraft. Several conflict resolution scenarios are illustrated. The present analytical framework can also incorporate information about ambient atmospheric conditions. These conflict resolution algorithms are suitable for implementation onboard aircraft.