Evaluation of image-type glide slope performance in the presence of snow cover

A formulation for the effects that the ground-reflected signal has on the far-field performance of image-type glide slope is developed using geometrical optics. The effects of snow cover are then related to the formulation and analyzed. Results indicate that it is possible for certain types of dry snow to cause glide slope system performance to exceed U.S. Flight Inspection Manual (USFIM) tolerances at depths below existing Federal Aviation Administration (FAA) plowing criteria.