Airborne Collision Alerting Logic for Closely Spaced Parallel Approach

Abstract

A prototype airborne collision alerting logic was developed for simultaneous approach to closely spaced parallel runways. A novel design methodology, based on collision probabilities instead of traditional spatial or temporal alerting criteria, was used. With this technique, an alert is issued when the probability of a collision exceeds an acceptable threshold value, set for a level of safety of 1 accident in every 1000 worst-case blunders. Probability contours were constructed through Monte Carlo simulation over a range of aircraft position, speed, ground track, and turn rate conditions. These contours were stored in look-up tables that were accessed in real time for evaluation during numerical and piloted simulation of approaches. Three lateral runway spacings were investigated: 3,400, 2,500, and 1,700 ft. The results show that the “worst-case” blunder may not be that which appears subjectively to be the most severe. Additionally, the methodology can be used as a tool to evaluate alternative alerting systems.