Sense And Avoid (SAA) Flight Test and Lessons Learned

Abstract

*† ‡ § ** †† ‡‡ Unmanned Aerial Systems (UAS) are being used extensively in the military, government, and private sectors to perform what were once manned missions. However, authorization to operate UAS unrestricted within organized airspace systems among civil air traffic remains virtually nil even though procedures and systems allowing for remote, even transcontinental, control of UAS and communication with air traffic controllers are in place and demonstrate robustness. The major technological barrier is the lack of an onboard sense and avoid (SAA) system capable of providing UAS with the ability to avoid collisions with other aircraft. Two Air Force Research Lab (AFRL) programs were established to address this need. AFRL’s Sensors Directorate and Air Vehicles Directorate are working jointly to develop SAA system components. The Sensors Directorate is developing electro optical (EO) based “sense” or detection sensor technology, and the Air Vehicles Directorate is developing the autonomous “avoid” or maneuvering technology. In addition to the EO system, the Air Vehicles Directorate is incorporating Traffic Alert and Collision Avoidance System (TCAS) information for the detection of conflicting traffic. AFRL recently conducted a series of SAA flight tests to evaluate the performance of these systems during flight. The SAA hardware and software were installed in a Learjet (LJ), which acted as a surrogate High Altitude Long Endurance (HALE) UAS. The LJ was flown in various near-collision encounter scenarios with aircraft representative of general aviation (GA) and commuter transport class platforms acting as intruder aircraft on a collision course. This paper describes the component technologies which comprise the SAA system, the accomplishments achieved and lessons learned from the flight test activities.