How would you design a Detect and Avoid (DAA) system for large UAS integration into civil airspace?

DAA enables unmanned aircraft to maintain safe separation from other aircraft, replacing see-and-avoid. Architecture: Sensors - ADS-B In (cooperative traffic), active radar for non-cooperative traffic, and electro-optical/infrared for terminal operations. Tracking: Multi-sensor fusion for comprehensive air picture, Track initiation, maintenance, and classification, and Uncertainty estimation for decision making. Alerting: Remain Well Clear (self-separation) and Collision Avoidance (last resort) thresholds per RTCA DO-365. Guidance: Maneuver recommendations considering UAS performance, Conflict resolution coordinated with TCAS-equipped traffic, and Pilot-in-loop for manned operations or autonomous for BVLOS. Standards: RTCA DO-365 (MOPS), DO-366 (radar MOPS), and ASTM standards for smaller UAS. Challenges: Non-cooperative traffic detection range/reliability, Latency in command link for piloted response, and Certification of autonomy for collision avoidance.