Benefits of Continuous Descent Operations in High-Density Terminal Airspace Considering Scheduling Constraints

This study estimates the potential benefits of continuous descents for more than 480,000 flights to 25 major airports in the National Airspace System. While reduced fuel consumption and greenhouse gas emissions are expected for these procedures, the benefits during periods of congestion are not well understood. To address this gap, baseline trajectories were constructed from flight plan and track data for flights arriving at 8 busy terminal areas. Two types of continuous descent trajectories were modeled. One enforced a constant distance-to-fly constraint to simulate uncongested operations. The other enforced a constant time-to-fly constraint to simulate congested operations. Potential fuel savings were calculated for different continuous descent scenarios. Analysis of the distance-constrained trajectories showed that fuel savings was distributed unevenly among the flights. The estimated savings was less than 25 kg for over 45% of the flights, and less than 100 kg for over 87% of the flights. The time-constrained trajectories showed 70-85% less potential savings than the distance -constrained trajectories. Prioritization of the improvements necessary to execute continuous descents during periods of congestion must rely upon analysis of a sufficient sample of operations, representative of many days, aircraft types, and traffic demand levels.