Performance Evaluation of Airborne Separation Assurance for Free Flight

Airborne separation assurance is a key requirement for free flight operations. This paper investigates the feasibility of airborne separation assurance for free flight by evaluating the performance of Conflict Detection and Resolution (CD&R) schemes in a simulated air traffic environment. Two qualitatively different CD&R methods were evaluated in an air traffic simulation environment provided by the Future ATM Concepts Evaluation Tool (FACET). The evaluation was based on a horizontal-plane free flight traffic scenario constructed with initial conditions from actual air traffic data; nearly a thousand aircraft were modeled in this 6-hour scenario. The results of the performance evaluation indicate that airborne separation assurance performed quite well in the free flight evaluations: (1) All of the conflicts were resolved; (2) The impact on flight efficiency, as measured by path-length and flight-time changes, was quite small; and, (3) The impact on system stability, as measured by additional aircraft experiencing conflicts due to the “domino effect,” was modest.