Time-based-fuel-efficient aircraft descents: Thrust-idle descents along re-negotiated routes vs. powered descents along published routes

We address the situation where required times of arrival (RTAs) are assigned outside the feasible time window that allows aircraft to fly energy-neutral continuous descent operations (CDOs). Two strategies to achieve these RTAs are compared by means of simulated optimal trajectories and in terms of fuel consumption: powered descents along the published arrival route vs. energy-neutral CDOs along re-negotiated routes. A sensitivity study to different parameters led to results primarily for RTAs later than the estimated time of arrival. With strong-tailwind, stretching the route and flying neutral CDOs improves the efficiency of the operation. Light aircraft also benefit from being assigned longer pre-defined routes, while for heavy aircraft it is more efficient to fly powered descents along the published route. This paper could contribute to enhance ground-based decision support tools for air traffic controllers, aiming to manage arrival traffic more efficiently and reducing the overall environmental impact of arrival operations.