Implementing Time-Based Spacing for Decelerating Approaches

Abstract

The three-degree decelerating approach is a promising noise abatement procedure shown to significantly reduce noise impact on communities surrounding airports. However, a limitation to a widespread implementation of this and other noise abatement procedures is that runway capacity is compromised. The reason for this is that air traffic controllers increase spacing between in-trail aircraft to compensate for the uncertainties in the descent trajectory. The research presented in this paper focuses on simplifying the task of the controller by requiring aircraft to accurately hit a required time of arrival over the runway. A key component in the development of the associated pilot support interface necessary to help pilots in their new task is a wind profile prediction algorithm that estimates the actual wind profile and predicts how it will evolve in time along the descent trajectory. Rather than using a boundary layer model for estimating the wind profile, the wind prediction algorithm uses historical wind measurement data from preceding aircraft. By incorporating the wind prediction algorithm in an advanced flap scheduler algorithm, accurate time-to-fly estimates can be made for the three-degree decelerating approach. Monte Carlo simulations were conducted to test the robustness of the algorithm and analyze the control space for various wind conditions. Maximum feasible deviations in terms of time while satisfying noise goals are shown to be between 8 and 30 s. The pilot support interface was designed and tested in a piloted experiment Performance in terms of noise and time goals as well as workload is consistent and significantly better with respect to the nonsupported condition, for all wind conditions, but, in particular, for more complex wind conditions.