Carl Westin

B-5 Modified SSD 199 3. Incorporate a conflict zone (i.e., no-go areas) look-ahead time of eight min- utes as controllers tend to resolve conflicts en-route on a short time frame. 4. Simplify the visual representation of the SSD, in particular the triangle- shaped no-go areas, to reduce information complexity and overload. 5. Visualize how critical no-go areas are (i.e., time-to-conflict) through color coding. The integration of the SSD and radar display support controllers in relating no- go areas for aircraft to their spatial positions (first comment). In addressing the second comment, simple state-based predictions were used to determine aircraft in conflict and highlight them on the radar display. This modification increased the SSD’s level of information analysis (Stage 2). The third comment was addressed by introducing a time-horizon that affected the triangle-shaped visualization. By defining a finite time-horizon (set to five minutes), the tip of the triangle is rounded off. The smaller the look-ahead time, the more the triangle tip is cut off. Prior to this modification, when there was no limit to the time-horizon, pointing the velocity vector to the tip of the triangle would postpone a conflict indefinitely (T= ∞ ) as the controlled aircraft would end up flying parallel to the other aircraft. The change is reflected in Figure B-5. In Figure B-5(b) the velocity vector is outside the constrained no-go area, indicating that separation is maintained for the time being. However, caution is needed since the current situation only ascer- tains that a conflict will not occur within the next eight minutes. As time progress, however, the current track will result in a conflict provided both aircraft leave their velocity vectors unchanged. The fifth and final comment was addressed by limiting the maneuver envelope to the aircraft’s current speed. Figure B-6 shows (a) the full SSD, which shows the (a) SSD without time-horizon (b) SSD with time-horizon F IGURE B-5: The effect of time look-ahead on SSD no-go area.