NAVAID Support of High-Altitude Area Navigation Routes.

A study was conducted to determine the capability of the present system of navigational aids NAVAIDs to support an area navigation RNAV route structure. Coverage contours for each NAVAID were derived through application of radio line-of-sight LOS angles from the antenna to the surrounding terrain. A hypothetical high altitude RNAV structure was tested against the coverage contours of the NAVAIDs presently used in the airspace at 18,000 feet and above. Each parent route and its related parallel offsets were checked for areas of excessive route width as well as for areas of noncoverage at a flight altitude of 18,000 feet. Based on these results, it is concluded that the present NAVAID system will support a high altitude RNAV route structure with only minor problems, principally in connection with route widths. But the extent of this problem depends upon air traffic control requirements and the assumed cross-course navigational errors. With definite information regarding these factors, the methodology developed at NAFEC can be effectively used to isolate and identify specific NAVAID coverage problems.