Analysis of advanced flight management systems: PBN to xLS

█ A continuously descending path definition for these procedures would be problematic operationally. For high ISA deviations, captures necessarily will be from above, which is behavior that flight crews deem unsatisfactory. █ Some systems automatically insert a shallower vertical path segment prior to the expected GS capture point, which allows for deceleration. This segment allows even hot day GS captures to be from below the GS, widening the temperature range over which capture can occur. █ Most systems are configured to prevent GS capture prior to LOC capture to prevent the possibility of descending on the GS while off the centerline of the localizer. █ In spite of the differences in capture logic across systems, the localizer capture points were remarkably consistent. █ GS capture locations were more spatially consistent than predicted by the MITRE due to small differences in capture logic. █ One of the systems captured when it was predicted not to capture the GS. The manufacturer revealed that it not only incorporates a proximity rule for GS capture, but adds a minimum amount of time for which the proximity rule must be satisfied before capture occurs.