Collision Avoidance System Optimization for Closely Spaced Parallel Operations through Surrogate Modeling

Abstract

The Traffic Alert and Collision Avoidance System (TCAS) has been mandated worldwide to protect against aircraft mid-air collisions. One drawback of the current TCAS design is limited support for certain closely spaced parallel runway operations. TCAS alerts too frequently, leading pilots to often inhibit Resolution Advisories during approach. Research is underway on ACAS X, a next-generation collision avoidance system that will support new surveillance systems and air traffic control procedures. ACAS X has been shown to outperform TCAS for en route encounter scenarios. However, the design parameters that are tuned for the en route environment are not appropriate for closely spaced parallel operations. One concept to allow for closely spaced parallel operations is a procedure-specific mode of the logic that reduces the nuisance alert rate while still providing collision protection. This paper describes the application of surrogate modeling for the purpose of tuning ACAS X for parallel operations. The performance of the tuned system is assessed using a data-driven blunder model and an operational performance model. The tuned ACAS X logic is found to outperform TCAS for each model in terms of both safety and operational suitability.