The purpose of this research was to determine how different pilot types perceived the subjective concept of the Well Clear Boundary (WCB) and to observe if that boundary changed when dealing with manned versus unmanned aircraft systems (UAS) as well as the effects of other variables. Pilots\u27 perceptions of the WCB were collected objectively through simulator recordings and subjectively through questionnaires. Together, these metrics provided quantitative and qualitative data about pilot WCB perception. The objective results of this study showed significant differences in WCB perception between two different pilot types, as well as WCB significant differences when comparing two different intruder types (manned versus unmanned aircraft). These differences were dependent on other manipulated variables, including intruder approach angle, ownship speed, and background traffic levels. Subjectively, there were evident differences in WCB perception across pilot types; general aviation (GA) pilots appeared to trust UAS aircraft slightly more than did the more experienced Airline Transport Pilots (ATPs). Overall, it is concluded that pilots\u27 mental models of the WCB are more easily perceived as time-based boundaries in front of ownship, while being more easily perceived as distance-based boundaries to the rear of ownship
