Extended Terminal Area Research Articles

Trajectory synthesis algorithms that are key to the center ‐terminal radar approach control automation system (CTAS) developed at NASA Ames Research Center for air trafe c control automation are discussed. CTAS generates computer advisories based on synthesized trajectories that help controllers to produce a safe, efe cient, and expeditious e ow of trafe c over the extended terminal area. Trajectories are synthesized from initial aircraft positionsto ametering e x orrunway, depending on airspace.Thehorizontal pathisconstructed e rstfrom specie ed waypoints using straight lines and constant-radius turns. The vertical trajectory is divided into a series of e ight segments. Three types of e ight proe les are dee ned by connecting selected segments in a predetermined order: fast, nominal, and slow. Each proe lecan produce a certain rangeof arrivaltimes. A second-order Runge ‐Kutta scheme is used for integrating a set of simplie ed point-mass equations to generate vertical trajectories. Then, an iterative scheme is employed to determine the speed that meets a specie ed arrival time. Several special case trajectories are also explained. Two e ight scenarios are used to illustrate the use of trajectory synthesis algorithms.

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