On Airborne Collision Avoidance System’s Compatibility with Segmented Independent Parallel Approach Procedures

Abstract

Curved or segmented approach procedures are considered beneficial for reducing or shifting the impact of aircraft noise in the approach phase of flight. Considering airports with parallel runway systems, the usage of segmented approaches, however, no longer allows simultaneous and independent approach operations according to current guidelines and therefore reduces capacity. In previous work a safety concept was developed to pave the way towards conducting independent approach operations while utilizing segmented approaches. Although the Airborne Collision Avoidance System (ACAS) is by definition not part of this kind of safety concept, an important question to answer is whether the current ACAS implementation can be characterized as compatible to the proposed approach geometry. Because classical approaches towards parallel runways are already critical with respect to generating nuisanceACAS alerts, this issue might even be exacerbated due to the segmented routing. Therefore, an approach geometrydependent critical runway spacing that will not result in nuisance ACAS alerts will be determined in this work. The obtained value can be compared to a given runway layout to determine whether ACAS may be used or should be deactivated for a given segmented approach procedure.