A fast and low-cost validation technique for ILS and MLS

A feasibility study of evaluating site effects on ILS (instrument landing system) and MLS (microwave landing system) using analytical and computational techniques is presented. The problem of site effect evaluation is divided into three stages: terrain modeling, ray tracing, and field evaluation. Innovative techniques are introduced at each stage to make the model versatile enough to handle most general terrain contours and surface conditions and also reduce computational requirements to a minimum. The result is a scheme that can be used to evaluate most terrain types on a mini/microcomputer. Specifically, it is shown that, using a simple two-dimensional multiwedge model of the terrain (i.e. no variation of terrain height in the third dimension), it is possible to obtain accurate estimates of the glideslope parameters by simulating procedures similar to those specified by ICAO (the International Civil Aviation Organization). The computational results have been visualized by comparison with actual data from flight tests. A summary of results for actual sites is presented