Carl Westin

B Solution Space Diagram B-1 Background This appendix provides the theoretical foundation of the Solution Space Diagram (SSD), and the development of the baseline SSD as used in this thesis. The ATC SSD visualizes the safe “go” areas and contained “no-go” areas within a horizon- tal representation of an aircraft’s control space in terms of heading and speed. The shape and size of these areas are defined by constraints affecting the aircraft’s flight path, such as the aircraft’s own flight-technical performance and environmental ob- structions representing other aircraft, terrain, and weather. The inspiration for the SSD, as a representation of an aircraft’s safe fields of travel, was inspired by Gibson’s work in the context of automobile driving. 291 These principles were further cultivated into guidelines for interface design driven by the Cognitive Systems Engineering and Ecological Interface Design (EID) paradigms. 292 A first prototype, incorporating the SSD with an enhanced navigation display, was used by Stijn van Dam to support pilots in self-separation activities in a futuristic free-flight environment (Figure B-1(a)). 232 A first version for ATC was used by Mercado Velasco to support controllers in CD&R, and potentially reduce their workload (Figure B-1(b)). 102 B-2 Constructing the solution space The SSD representation utilizes the (relative) velocity plane of aircraft to provide an easily observable overview of how the current position, track, and speed of aircraft interact. A basic understanding of the SSD, and the information visualized, is best conveyed by considering the diagram in its simplest form. Consider the situation in Figure B-2 that illustrates a conflict between two aircraft on straight paths.