A methodology for estimating the probability of potential secondary conflicts

In a distributed separation assurance system, each aircraft is equipped with its own conflict detection and resolution capability. An aircraft that is resolving an initial primary conflict has complete state information of all nearby aircraft, so is able to choose a resolution trajectory that is conflict-free from all other aircraft. However, because the update of state information is not instantaneous, it is possible that two distinct conflicts, if resolved in a near-simultaneous manner, may result in a downstream secondary conflict. Also an intent error in the state information may lead to a potential secondary conflict. This paper presents a methodology and sample results to analyze the frequency of potential secondary conflicts using output from a NAS-wide simulation. The events considered are not secondary conflicts themselves, but rather potential secondary conflicts, or situations in which there is an increased likelihood of a secondary conflict.