Algorithm and operational concept for resolving short-range conflicts

The article describes an algorithm for computing horizontal resolution trajectories with a limit on bank angle. If loss of separation can be avoided, the algorithm generates a set of manoeuvres that achieves or exceeds the specified minimum separation. The manoeuvres consist of turns to a specified heading followed by straight-line flight. Both single aircraft and cooperative manoeuvres are generated. In cooperative manoeuvres, both conflict aircraft simultaneously execute resolution manoeuvres, which expedite the resolution process compared to single aircraft manoeuvres. If loss of separation is unavoidable for a specified bank angle limit, the method chooses the manoeuvre that maximizes the minimum separation during the turns. The characteristics of the resolution trajectories have been analysed in a parameter space comprising initial positions, encounter angle, airspeed, predicted minimum separation, and bank angle. Analysis of resolutions for sets of initial conditions provided a road map for the design of an algorithm. The conceptual design of a system is described that resolves close-in conflicts automatically by uplinking resolution advisories to aircraft. Controllers have the option to assign detected conflicts to be resolved by the system. The system also has the authority to uplink resolution advisories to the aircraft without prior controller approval if time to loss of separation falls below a threshold value. The Mode S Specific Services data link is well suited for uplinking resolution advisories to the conflict aircraft. Deployment of the system could be an initial step in building the next-generation air traffic control system.