Vertical Trajectory Optimization to Minimize Environmental Impact in the Presence of Wind

Abstract

The vertical trajectory optimization for the en route descent phase is studied in the presence of both along-track and cross winds, which are both modeled as functions of altitude. The flight range covers some portion of a cruise segment and ends at a meter fix. The descent trajectory is assumed as a flight idle descent. The problem is formulated as an optimal control problem with both mixed state path constraints and pure state constraints. For minimizing environmental impacts, we optimize descent trajectory with respect to two cost functionals: fuel and emissions costs. We analyze both singular arc and boundary arc using the necessary conditions of the optimality. From the analysis result, we propose the optimal trajectory generation method, in which the optimal trajectory is generated by the backward and forward integration. The trajectory from the proposed algorithm is compared with the numerical optimal solution of the original optimal control problem. The result shows that the proposed algorithm generates the same solution as the numerical optimal solution. The wind speed, windshear, and cross-wind effects on the optimal trajectory are analyzed with two aircraft type, Boeing 737-500 and Boeing 767-400.