Managing Idle Descent Trajectory Uncertainties at Schiphol
Idle descents are continuous descent operations flown at almost zero thrust. These descents are more fuel efficient and cause less noise compared to normal powered descents. However, air traffic control cannot intervene during such descents, or the additional efficiency will be lost. Change in wind, pilot inputs and other factors, normally compensated with thrust, cause these descents to be less predictable. Therefore, an additional spacing buffer of two till four minutes is required to safely fly idle descents. This has a large impact on the landing capacity of Schiphol, hence only nighttime operations incorporate idle descents when possible. This research aims to provide insight into the trajectory uncertainties of idle descents by analysing flight recorder data. Quantifying and reducing the trajectory uncertainties of idle descents can potentially reduce the required spacing buffer and help with flying more idle descents.