Study on Conflict Detection Method with Downlink Aircraft Parameters

Abstract

In order to meet the demand and keep the safety of air traffic, ENRI (Electronic Navigation Research Institute) studies on leveraging data-link function of SSR (Secondary Surveillance Radar) mode S and tries to apply it to the improvements of CA (Conflict Alert) which supports air traffic controller to keep safe separations between aircraft. Our purpose is to develop new DAP-CDM (Downlink Aircraft Parameters-Conflict Detection Method) and evaluate the impacts of its introduction by computer simulations.

First, for considering DAP-CDM, we calculated horizontal and vertical prediction errors of aircraft position estimated by the conventional CDM. As a result, both prediction errors were reduced by using flight data instead of radar data. We also found that it was better to smooth vertical speed for prediction and to utilize selected altitude in DAP-CDM. Then, occurrences of CA were analyzed to understand the effects of prediction error reduction. Currently, a large number of CAs were displayed for less than 20 seconds and often intermittently. When CA happened with a large altitude difference more than 10,000 ft, vertical flight phases of aircraft were the combination of climbing and descending. Under that condition, the changes of flight phase into level flight were rarely observed by judging from their later tracks. Therefore, smoothing vertical speed and utilizing selected altitude in DAP-CDM were considered to be necessary.

For the purpose of comparing DAP-CDM with the conventional CDM, ENRI developed CDES (Conflict Detection Evaluation System). It can simulate both the new and conventional CDMs under air traffic situations and system parameters as almost same as the conventional ones. Finally, the characteristics of DAP-CDM were studied and its advantages were demonstrated. DAP-CDM has the function of predicting aircraft positions by using smoothed aircraft horizontal velocity and vertical speed, and judging aircraft flight phases by using roll angle and selected altitude. As a result of evaluating DAP-CDM by the simulation with CDES, the judgment of vertical flight phases by selected altitude was most effective to reduce the number of unnecessary CA.