Near-Optimal Methodology for In-Flight Synthesis of Trajectory Options Set

Abstract

This paper presents an algorithm for in-flight synthesis of near-optimal trajectory options sets in the presence of time-varying airspace constraints during the en route phase of an aircraft flight to support NextGen trajectory-based operations. The en route structure of the National Airspace System is modeled as a graph with airports, waypoints, and navigational aids as the vertices, and en route airways representing the edges between them. To represent a more realistic situation, the network is subject to constraints due to factors such as convective weather and prevailing winds, which are assumed to vary with time. Furthermore, Federal Aviation Administration imposed flight restrictions and protocols such as temporary flight restrictions, and special use airspaces are also introduced as the network constraints. The costs for traversing each link are evaluated based on a user-defined, wind-dependent cost function. A novel near-optimal route generation methodology, based on A* algorithm, is developed to deal with the time-varying nature of the network constraints. The algorithm is fast enough to allow in-flight synthesis of trajectory options set. Further, it is sufficiently robust in adapting to varying severity of weather. These characteristics are demonstrated in the paper with trajectory generation examples.