Field Evaluation of the Tailored Arrivals Concept for Datalink-Enabled Continuous Descent Approach

Abstract

Allowing aircraft to descend uninterrupted at low engine power, continuous descent operations promise to maximize fuel efficiency while minimizing environmental impact. Tailored arrivals is a concept for enabling continuous descents under constrained airspace conditions by integrating advanced air and ground automation through digital datalink. Operational trials were completed in January 2007 involving transpacific flights into San Francisco during early morning hours. Leveraging newly deployed Federal Aviation Administration automation in the oceanic environment, trajectory-based clearances were transmitted by datalink to Boeing 777 aircraft equipped with future air navigation system avionics. NASA's prototype ground-based automation for high-density arrival management tailored trajectory clearances to accommodate artificially imposed metering constraints. Upon sharing wind and descent-speed-intent data, ground-based and airborne automation were found to predict meter-fix arrival times to within a mean accuracy of 3 s over a 25 min prediction horizon. Corresponding mean altitude and along-track prediction errors of ground-based automation were -500 ft and -1.3 n mile, respectively, in comparison with surveillance truth. A benefits analysis suggests Boeing 777 fuel savings of between 200 and 3000 1b per flight (depending highly upon baseline traffic conditions) together with a corresponding reduction in CO 2 emissions of between 700 and 10,000 1b per flight.