Tactical Separation Algorithms and Their Interaction with Collision Avoidance Systems

The nation’s air transportation system is currently unable to support the forecasted demand for air travel. New airborne and ground-based capabilities are being investigated to address the myriad of challenges that pilots, operators, and air navigation service providers will face. One approach being studied considers a layered architecture involving a strategic and a tactical system to provide automated separation assurance. Because the tactical system will operate in a time horizon that may overlap with on-board collision-avoidance systems, it must be designed not to interfere with these systems. This paper presents a new set of vertical conflict resolutions for a conflict aircraft pair. Heuristics are presented which govern the use of the new vertical and recently-developed horizontal conflict resolution algorithms to minimize interference with an on-board collision-avoidance system. To address the expected increase in traffic density, an algorithm for globally resolving conflicts involving multiple aircraft is also presented. Evaluation using real-world encounters in both en route and terminal airspace demonstrates the effectiveness of both the vertical algorithm and the heuristics used to reduce the interference.