Human Systems Integration Division @ NASA Ames

Recent standards development efforts for the integration of Unmanned Aircraft Systems (UAS) into the National Airspace System (NAS), such as those in RTCA Inc. Special Committee 228 (SC-228), have focused on relatively large UAS transitioning to and from Class A airspace. To expand the range of vehicle classes that can access the NAS, the NASA UAS Integration in the NAS project has investigated Low Size, Weight, and Power (Low SWaP) technologies that would allow smaller UAS to detect-and-avoid (DAA) traffic. Through batch and human in the loop (HITL) simulation studies, the UAS Integration in the NAS DAA subproject has identified candidate performance standards that would contribute to enabling extended Low SWaP, UAS operations under 10,000 feet. These candidate performance standards include minimum field of regard (FOR) values for Low SWaP air surveillance sensors as well as a DAA well-clear (DWC) definition which can be applied to non-cooperative traffic to reduce the required maneuver initiation range.

To test the assumptions of the project’s simulation studies and validate the candidate performance standards, a live flight research event was executed at NASA Armstrong Flight Research Center. The UAS Integration in the NAS Project Flight Test 6 Full Mission sought to characterize UAS pilot responses to traffic conflicts using a representative Low SWAP DAA system in an operational NAS environment. To achieve this live, virtual and constructive distributed environment (LVC-DE), elements were combined to simulate a sector of Oakland center airspace and induce encounters with a live, manned aircraft A NAVMAR Applied Sciences Tigershark XP was used as the UAS ownship and was integrated into the test architecture to enable it to be controlled from a Vigilant Spirit Control Station (VSCS) research ground control station. Qualified UAS pilots were recruited to act as subject pilots under test (SPUT) to control the Tigershark XP in a simulated mission while coordinating with a participating air traffic controller in simulated airspace. The intruder speed, intruder equipage and encounter geometry were varied between six scripted encounters per SPUT. Various metrics were collected including pilot reaction time from the onset of DAA alert, ATC coordination rate, probability and severity of losses of DAA well clear, and subjective ratings of system acceptability.

Flight Test 6 Full Mission was successfully executed in October and November 2019. Results indicated that the subject pilots completed the simulated missions with zero losses of well-clear and generally low workload ratings, although avoidance maneuvers were larger and reaction times were longer than was found in HITL lab studies. In the post-flight subjective questionnaire, subject pilots indicated that the sensor FOR would not allow coordination with ATC and would have preferred a longer sensor range if flying in the NAS. The implications of these results on the development of standards for Low SWAP DAA systems will be discussed.