Optimal flight paths for engine-out emergency landing

Loss of engine power constitutes a major emergency situation in General Aviation (GA) aircraft, requiring the location of a safe-to-land strip within reach, and thereupon planning and executing an effective gliding path towards it. These critical tasks are currently entrusted with the pilot. In recent years, technological advances in avionics (GPS, GIS and computing capabilities) have reached the GA cockpit - clearing the way for safety enhancements that utilize these resources. In this paper we consider the problem of 3D trajectory planning for an engine-cut GA aircraft towards a specified airstrip, while avoiding natural or man-made obstacles. We emphasize energy efficiency, which allows the aircraft to maximally extend its reach. To that end we employ a dynamic model of the aircraft, which leads to a six-dimensional optimal control problem. We propose a computation approach that is aimed at approximating the globally optimal solution in real-time. Our approach is based on motion primitives, or basic maneuvers, which are parameterized flight segments of specified shapes which are locally optimized for energy efficiency. These basic maneuvers enable a coarse discretization of the search space, and the planning problem is reduced to a graph-search problem of tractable size which may be efficiently solved using an optimal graph search algorithm. Important computational enhancements include the use of pre-compiled basic maneuver dictionaries. The effectiveness of the proposed solution is demonstrated via simulation results.