Coordination Between Multiple Ground-Based Separation Assurance Agents

Spatial separation between aircraft in the current air-transportation system is maintained in a distributed, ground-based fashion with multiple regional air-traffic controllers providing separation across the national airspace system (NAS). These controllers have different areas of specialization including airport tower controllers, Terminal Radar Approach controllers, and enroute controllers. Separation assurance is handled differently in each of these regions, with the most structure and constraints for aircraft approaching the runway and the least structure for aircraft in enroute airspace. Regardless of their area of specialization, each controller is responsible for maintaining separation for all aircraft under their control, and they must ensure that hand-offs to downstream controllers are done safely. 1 The current system is divided into these multiple regions because a single person could not provide separation for the thousands of aircraft in the air at any given time. In a future fully automated separation assurance system, however, it is theoretically possible that a single agent could be responsible for maintaining separation for all aircraft, providing a global, centralized control system. Since this system could prioritize conflicts and proceed through them sequentially, it could be internally coordinated, and this would remove the need for constraints on resolutions to ensure coordination. The computation power required for a single agent to control the entire airspace might be significant, so the solution may need to be parallelized in an efficient way that still maintains safety. 2 A key insight in this parallelization is that, since the time scale for separation assurance is on the order of tens of minutes, a resolution in one area will not have an impact on the separation assurance problem beyond a few hundred miles. Therefore, the problem can be decomposed geographically, similar to how it is decomposed in the current system, while minimizing the synchronization and coordination required to ensure efficient solutions. The Advanced Airspace Concept (AAC) 3 seeks to automate separation assurance for enroute, center