Analysis of Instrument Landing System Glide Slope Performance Sensitivity to Sideband-Only Phase Variances

摘要

Derivations are provided showing that the glide path on the Instrument Landing System glide slope can change with sideband-only(SBO)phase variances if the SBO null is not well defined. Some of the readily identifiable causes of SBO null softening are identified, and their effects are related to the performance of the more commonly used glide slopes. The most serious case occurs for SBO phase variances on the image-type glide slope in the presence of dry snow, which can cause out-of-tolerance variations in path angle that go undetected by existing monitors.