Analysis of downlink aircraft parameters monitored by SSR mode S in ENRI

In order to prepare for future deployment of SSR (secondary surveillance radar) mode S with DAPs (downlink aircraft parameters) function in Japan, ENRI (Electronic Navigation Research Institute) has started research and development of new SSR mode S. DAPs function enables ground station to obtain aircraft information such as selected altitude, rollangle, magnetic heading and so on. When DAPs function is employed as a means of ATC (air traffic control), reliability of DAPs data is critically important. The purpose of this paper is to compare DAPs data with original FMS (flight management system) source data to validate radar system function and to test the reliability of DAPs data. This time, we picked up B737-800 and B747-400 and selected aircraft parameters in GICB (Ground Initiated Comm-B) 40, 50 and 60 as an analysis target of DAPs data. These are known as Mode S EHS (enhanced surveillance) which becomes mandatory in the part of Europe. In this paper, we first describe our experimental mode S system with DAPs function. Then, DAPs data have been compared with the data stored in aircraft flight recorder. As a result, we presented that the values of DAPs agreed with those of airborne stored data except in a few parameters.