URClearED - Defining the Remain Well Clear concept for airspace D-G classes in the European airspace

Remotely Piloted Aircraft Systems (RPAS) are increasingly becoming a part of our day-to-day life, and the wide range of their possible applications is creating a new industry with a large economic potential that is pushing the technological developments at a much faster pace than that for manned aviation. However, due to constraints arising from safety and operational considerations, RPAS can currently only fly in segregated airspace, making their integration in the civil airspace an unsolved challenge. RPAS have to guarantee a level of safety at least equal to that of manned aircraft. Manned aviation follows the rules of the air. The notion "well-clear" is used in ICAO rules without giving exact definition of the term. Here, rules rely on the perception and judgement of the pilot. The capability to perform RWC and DAA is required for the full integration of RPAS with General Air Traffic (GAT). To this end, several rule-making bodies are working to define the required safety and performance objectives. An RPAS needs proper mathematical definitions of Remain-Well-Clear (RWC) in order to operate safely. When implementing RPAS into civil airspace, exact well-clear parameters have to be determined. In 2013, the second FAA workshop on Unmanned Aerial Systems (UAS) concluded that "there is a need for establishing an unambiguous and quantitative definition for well clear that can be used as a separation performance standard for an aircraft system". In 2014, the SAA Science and Research Panel (SARP) provided a Well Clear Recommendation to RTCA SC-228, which was subsequently used in the first Minimum Operational Performance Standards for Detect and Avoid (DAA) systems, DO-365. The URClearED project intends to define the requirements and capabilities for the RWC function of a DAA system of an RPAS operating in Class D-G airspace also interacting with VFR flights. Particularly in airspace classes F-G IFR aircraft will not receive ATC-provided separation. Different European countries may define airspace classes and rules differently. Further, the congestion of the airspace and the characteristics of the VFR traffic may complicate the situation. When crossing state border airspace class and rules may change. This paper will report the definition of scenarios and use cases selected to evaluate the RWC function under the aforementioned conditions. RWC volume and threshold selection will be evaluated in a subsequent simulation and assessment phase. Scenarios will encompass all the relevant elements under analysis. The type of encounter are a primary factor, not only in terms of its geometry but also in terms of the rules under which the conflicting aircraft are operating and the specific airspace classes involved. This will impact the roles and responsibilities of involved actors. Transitions between different classes of airspace will also be considered, including states cross-border situations