Probability-based collision alerting logic for closely-spaced parallel approach

Abstract

A prototype airborne collision alerting logic was developed for aircraft on approach to closely-spaced parallel runways. A novel design methodology was used based on collision probabilities instead of traditional spatial or temporal alerting criteria. With this technique, an alert is issued when the probability of a collision exceeds an acceptable threshold value. The logic was based on a hazard level corresponding to the current Precision Runway Monitor System of one accident in every one thousand worst-case blunders. Probability contours were constructed through Monte Carlo simulation over a range of aircraft position, speed, heading, and turn rate conditions. These contours were stored in look-up tables that were accessed in real time for evaluation during numerical simulation of approaches. Three runway spacings were investigated: 3,400, 2,500, and 1,700 ft. The results show that the unnecessary alert rate at 1,700 ft runway spacing was double that at 3,400 ft runway spacing. Additionally, the logic induced collisions in two low-closure-rate situations, suggesting that the worst case blunder may not be a drastic heading change. (Author)