An Assessment of Unmanned Aircraft System Level-Turn Maneuver Performance Requirements In Relation to a Quantified Well-Clear Definition

Abstract

Demands for access of Unmanned Aircraft Systems (UAS) to the United States National Airspace System continue to increase. Per Title 14 of the Code of Federal Regulations part 91, §91.113, “vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft. When a rule of this section gives another aircraft the right-of-way, the pilot shall give way to that aircraft and may not pass over, under, or ahead of it unless well clear.” In lieu of an onboard pilot’s practical judgement and ability to see and avoid other aircraft, UAS must possess the capability of remaining equivalently separated based upon a quantified definition of “well clear.” This separation will be quantified using the Detect and Avoid (DAA) Well Clear definition. Before DAA systems can be developed for this purpose, the requirements for the DAA systems must be determined. To fill this gap, RTCA, Inc., Special Committee 228 is currently working to develop Minimum Operational Performance Standards for UAS that will include DAA system requirements. For a manned aircraft to remain well clear of another aircraft, the pilot uses both visually estimated distance from the traffic aircraft as well as his judgement of how quickly and responsively his aircraft can maneuver to plan when to initiate an avoidance maneuver. Likewise, aircraft maneuver performance and its impact on avoidance maneuver timing will be important factors in the quantified DAA system requirements. To support RTCA in developing these requirements, NASA has tasked Adaptive Aerospace Group, Inc., with conducting a series of trade studies to evaluate the impact of aircraft maneuver capability across an array of commanded avoidance maneuvers and encounter geometries on DAA across a wide range of UAS aircraft performance capabilities. This paper discusses efforts to determine maneuver performance requirements and associated time and range requirements needed for level-turn maneuvers to avoid violating the specified DAA Well Clear volume. Insight to this process, proposed requirements, and associated implications are presented in this paper.