Energy Efficient Trajectory Designs for Minimizing Climate Impact of Aircraft on Various Timescales

Abstract

Future air traffic management systems are developed to enhance safety and efficiency of air traffic operations while accommodating the demand. The impact of aircraft emissions and contrails on the environment adds an additional dimension to aircraft trajectory optimization. This paper describes an optimization module capable of minimizing the climate impact of aircraft emissions and contrails and analyzes the energy efficiency of the trajectory designs and their relationships with the environmental objective. The methodology is used to evaluate the energy efficiency of three designs that each minimizes the total climate impact of aircraft CO 2 emissions and contrails at the end of 25, 50, and 100 years, respectively. Alternatively these designs can be evaluated with respect to how a hypothetical tax on contrail production would influence a stakeholder’s willingness to redefine their respective “optimal” cruise trajectory. The baseline wind-optimal routes and the three designs of climate-optimal trajectories are applied to simulated traffic between 12 city-pairs in the United States. Contrail reduction using both route and altitude changes to aircraft trajectories are more energy efficient than contrail reduction using either route or altitude changes only. Initial results show that climate-optimal trajectories involving lateral changes, which minimize total climate impact at the end of 50 or 100 years, result in smaller amount of contrail formation but have larger temperature reduction per unit fuel burn than that of 25 years. Similar results are obtained for the climate-optimal designs for aircraft trajectories involving altitude changes. The contrail cost that can potentially redefine a stakeholder’s objective to these climate-optimal goals is about 3.7 $/nmi for aircraft trajectories involving altitude changes for a contrail radiative forcing of 30mW/m 2 under current scenario.