Continuous Descent Approaches Continuous Descent Approaches (CDA) have shown to result in considerable reductions of aircraft noise during the approach phase of the flight (Erkelens, 2002). Due to uncertainties in aircraft behaviour, Air Traffic Control (ATC) tends to increase the minimum spacing interval in these approaches, leading to considerable reductions of runway capacity (Clarke, 2000). To enable the application of such procedures in higher traffic volumes, research has advanced in the creation of airborne tools and 4-dimensional prediction algorithms. Little research has addressed the problem of sequencing and merging aircraft in such an ap- proach, however. In this chapter we present the Time-Space Diagram (TSD) display that shows the aircraft along-track distance to the runway versus the time. On this display, the in-trail separation is presented as the horizontal distance between two predictions. It is hy- pothesised that this display will enable the air traffic controller to meter, sequence and merge aircraft flying a CDA at higher traffic volumes. In this chapter, the TSD will be introduced and the effects of various common separation techniques on the predictions of the display are discussed in detail. The display is currently being evaluated by actual air traffic controllers in a simulated traffic scenario to provide an initial validation of the design. Problem statement ATC in CDA procedures According to Annex 11 to the Convention on Civil Aviation (ICAO, 2003), the primary goal of ATC is to provide service for the purpose of safe, orderly and expeditious flow of traffic. In approach control, this task can be described as minimising delays while maintaining suf- ficient separation between the aircraft. During the TDDA, the in-trail distance between two approaching aircraft should therefore reach, but not go below, the minimal distance required. To achieve this, the primary tool common to all approach controllers is the two-dimensional…