In-Trail Sequence Stability in Closed Path Continuous Descent Operations

Abstract

Closed path Continuous Descent Operations are only feasible in night time hours, due to the loss in capacity caused by the variations in trajectories of descending and decelerating aircraft. Existing air traffic controller support tools givea quantifiable indication for the probability of a successful, uninterrupted approach. These support tools, however, do not assist the controller in choosing which strategy should be applied to maximize throughput and minimize intervention. In this research five spacing strategies at the Initial Approach Fix have been assessed for their effect on stability of an aircraft arrival stream performing a Continuous Descent Operation at several throughput levels. Monte-Carlo simulations are run with either the possibility to make only speed changes or to allow stretching of the descent path. The results show that by spacing the aircraft with an equal time spacing, the lowest average delay is achieved. The number of conflicts, as well as the extra distance flown, were lowest for the equal time-spacing strategy as well. The simulation results indicated that performing closed path Continuous Descent Operations is possible up until at least 25 aircraft per hour, for the given fleet and procedures, without stretching of the Along Track Distance.