Analysis of DAA Well Clear Criteria Using the Flown Trajectories

This paper proposes an airborne conflict and collision risk metric that is a modified version of the Detect and Avoid Well Clear (DWC) alerts. Previous works that directly applied DWC calculations to assess risk were able to identify regions and situations where the risks are relatively higher. However, because DWC assumes a constant velocity for all flights at each time step to represent the future position, it cannot reflect future maneuvers caused by the inherent route structure or controller instructions. When applying DWC criteria to historical manned aircraft trajectories, it was discovered that a large number of false alerts were detected due to this extrapolation. In order to study the effects of maneuvers, this paper proposes a method to calculate equivalent DWC alert levels using actual flown trajectories as future positions. This redefined method is referred to as Trajectory DWC (TDWC). Horizontal Miss Distance, vertical separation, and modified tau, parameters used in the calculation of DWC, are redefined using the actual flown trajectories from the current time step. To test this new metric, DWC, and TDWC alerts are calculated using Automatic Dependent Surveillance-Broadcast data from aircraft that passed through the Incheon Flight Information Region in 2018. Based on the results, the number of pairs and duration of DWC and TDWC alert events are analyzed. Depending on the DWC criteria or alert levels, TDWC resulted in 20 to 80 percent fewer alert pairs and duration. It was confirmed that TDWC can correctly exclude false risk situations and can be a better risk metric.