Three-Degree Decelerating Approaches in High-Density Arrival Streams

Abstract

The positive effects of continuous descent approac h (CDA) on aircraft noise, fuel consumption and emissions are evident. Nevertheless, the negative effect on capacity restrains continuous descent approaches from being used in high density traffic. A solution to this problem is the transfer of the separation t ask from the air traffic controller to the pilot. This paper discusses the feasibility of impl ementing the Three-Degree Decelerating Approach (TDDA) at high density traffic airports in a distance- or time-based self-spacing environment. In other research, time-based separation was implemented in the TDDA to prevent transient motions in the arrival stream res ulting in possible loss of separation caused by trajectory predictions of the leading aircraft b ased on previous states. For the same reason aircraft intent-based trajectory prediction of the lead aircraft in a distance-based scenario was introduced in this research. A fast-ti me simulation tool was developed to simulate arrival streams of different aircraft type s and weights that execute the TDDA in both self-spacing scenarios under actual wind condi tions. The simulation tool was used to quantify the performance differences between distance- and time-based self-spacing in terms of capacity, noise reduction, and loss of separatio n. For the time-based scenario no effects of leading aircraft on trailing aircraft could be iden tified. However, an increase in separation with a negative effect on the airport capacity to a ssure safe separation was required. In the distance-based self-spacing scenario a slow-down ef fect was observed, leading to a decrease in the noise reduction towards the end of the arriv al stream. The deteriorating noise reduction was solved by altering the initial separa tion between aircraft in the arrival stream. A sensitivity study showed that the TDDA performance in a distance-based scenario is not degraded dramatically by realistic deviations from the desired situation.