Assisting Air Traffic Controllers in Planning and Monitoring Continuous-Descent Approaches

An interface was developed to assist controllers in metering, sequencing, and merging aircraft flying a continuous-descent approach. This time-space diagram displays predicted aircraft approach trajectories in a way that allows controllers a better insight into the separation between aircraft flying continuous descents. The paper discusses how a baseline time-space diagram display can be enhanced with "what-if?" predictions, providing support for routine controller-spacing techniques such as speed instructions and the use of direct-to commands. An experiment with eight professional air traffic controllers compared the time-space diagram to a conventional plan-view display in low- and high-traffic-rate scenarios. Use of the time-space diagram display yielded a significant reduction in controller workload. It also reduced the number of instructions to the pilots, suggesting a reduced workload for the flight deck as well. Controllers' opinions on the usefulness of the what-if predictions were mixed, and these additions did not lead to any significant performance improvements.