Carl Westin

4-3 Method 69 inal simulation speed of four time real speed was reduced to two times real speed. As such, the two minute scenarios reflected four minutes of traffic movement in real time. This change was made to allow participants more time to assess the traf- fic situation, as the 4x multiplier might have unnecessarily increased participants’ temporal demands (and thus stress). Aircraft interaction and conflict solution was facilitated by means of a modified ATC Solution Space Diagram (SSD). 102 The SSD is a support tool that visualizes conflict regions (“no-go” regions) imposed by the relative position of other traf- fic. In doings so, the SSD explicitly show conflict-free regions (“go” regions) that represent the available solution space for avoiding conflict (i.e., loosing separation between two or more aircraft). Appendix B further describes the SSD. Figure 4-1 shows the modified heading band SSD tailored for en-route control, developed in an earlier study of ours. 101 The heading band SSD is shown for aircraft QS and highlights a conflict with OM. In contrast to the ATC SSD, the heading band SSD is integrated with the radar plan view display and the performance envelope is only shown for the heading plane at the aircraft’s current speed. 4-3-3 Task Participants were instructed to control the sector by clearing aircraft to their as- signed exit points (indicated by their flight-label), and preventing separation losses (defined as 5 nmi horizontally). A safety net function provided conflict warnings 60 and 30 seconds prior to separation loss. The affected aircraft would first turn amber and then red (at 60 seconds and 30 seconds look-ahead respectively), with the latter warning being accompanied by an aural alert. A performance algorithm continuously provided participants with feedback on their scenario performance. Performance penalties were based on the average track angle errors of each aircraft (i.e., deviation from route) and occurrence of conflicts. Velocity vector Protected zone Safe zone Intruder aircraft Controlled aircraft Red no-go zone Yellow no-go zone QS OM F IGURE 4-1: Right angle conflict with heading band SSD shown for QS.