En-route descent trajectory synthesis for air traffic control automation

This paper discusses en-route trajectory synthesis that is key to the Center-TRACON Automation System developed at NASA Ames for air traffic control automation. Based on trajectories produced in the Trajectory Synthesizer (TS) module, computer advisories are generated that help controllers to produce a safe, efficient, and expeditious flow of traffic for the extended terminal area. TS synthesizes trajectories from the initial position to the final position in the en-route area for one aircraft at a time by integrating a set of simplified point-mass equations. Specifically, TS separates the horizontal path from the vertical trajectory. The horizontal path is constructed from specified waypoints using straight lines and constant-radius turns. The vertical trajectory is divided into a series of flight segments. Three types of flight profiles are defined by connecting selected segments in a pre-determined order: fast, nominal and slow. Each profile can produce a certain range of arrival times. In numerical computations, a second-order Runge-Kutta scheme is used for integrating equations of motion. A regula falsi iterative scheme is employed to determine the speed that will meet a specified arrival time. Two flight scenarios are used to illustrate the TS solution procedure