Effect of ADS-B Characteristics on Airborne Conflict Detection and Resolution

Most Free-Flight concepts rely on self-separation by means of airborne Conflict Detection and Resolution (CD&R) algorithms. A key enabling technology for airborne CD&R is the Automatic Dependent Surveillance-Broadcast (ADS-B) system, which is used for direct state information exchange between aircraft. Similar to other communication systems, ADS-B is affected by a number of limitations which can be broadly classified as system and situation related deficiencies. This re- search investigates the impact of these limitations on the viability of using ADS-B for airborne CD&R within the Free-Flight context. Here, ‘state-based’ conflict detection and the modified voltage potential conflict resolution algorithm are used as a case- study. An ADS-B model is developed, and its effect on the aforementioned CD&R method is measured using three fast- time simulation experiments. The experiments studied overall safety with ADS-B, as well as the specific effect of situation related characteristics, i.e., transmission range and interference, on safety. The results indicated that the overall safety with ADS- B was comparable to the case where perfect state information was assumed. Additionally, it was found that increasing ADS- B transmission range also increased signal interference, which in turn lowered safety. This suggests that the degrading effect of ADS-B signal interference should be considered in future airborne CD&R research, particularly for high traffic densities.