The Flight Design System was developed at NASA Johnson Space Center (JSC) as a flight planning computer system built to provide extensive flight design and mission planning capabilities to users of the Space Transportation System (STS). Originally designed for generation of NASA/JSC flight products for each space shuttle flight, it is now in use by the Air Force Space Division for long-range flight planning and real-time mission support. In addition, FDS capability is required for Space Command's Shuttle Operations and Planning Complex (SOPC). Typical applications of the FDS are trajectory design, attitude and pointing timelines, launch window analysis, separation sequence design, and target-of-opportunity analysis for payload operations. This paper describes the FDS hardware and software configuration, presents the flight design environment in which it operates, and provides specific examples of FDS capabilities.