Max-Range Glides in Engine Cutoff Emergencies Under Severe Wind

Abstract

Engine cutoff is a recurring emergency in general aviation. It may be caused by an engine malfunction, fuel leak, or improper aircraft maintenance. Such an event, coupled with adverse weather, may endanger passengers and crew. This work obtains max-range optimal trajectories that exploit to the utmost the airframe dynamic capability, accounting for intense in-plane and crosswinds. This study proves that the optimal trajectory in terms of minimal altitude loss must maintain constant heading and velocity. A novel equation for the optimal glide velocity is then derived, whose unique solution depends only on the aircraft’s optimal velocity in still air and the wind vector. An explicit analytical expression is obtained for the optimal velocity in strict crosswinds. The results are demonstrated by applying them to the Cessna 172 airframe, in realistic engine cutoff scenarios, and it is shown that using these results can significantly increase the maximal glide range in scenarios combining strong crosswinds and in-plane winds. This paper formulates a range-maximization algorithm that yields the reachability envelope, the optimal landing site, and flight instructions that enable the pilot to follow the optimal path. These results can also enhance the common charts in glider manuals to account for non-negligible crosswinds.