Availability estimation of navigation aids

Ground network of waypoints has been commonly used for different navigation tasks. The most important of them are detection of aircraft location line in 3D space and positioning in airspace. Aircraft location determination by signals from ground-based waypoints is a part of alternative positioning algorithms in flight management system. A new method of radio navigation aids availability in particular airspace volume has been represented in paper. It includes cylindrical model of NAVAIDS service volume according to three basic types: Terminal, Low altitude and High Altitude. Proposed method uses digital elevation model of terrain data for detection of radio sight line and availability estimation in 3D space of NAVAIDS. The simple model of diffraction process was considered to increase accuracy of the method. However, diffraction model has been used only for peaks of relief. Represented method has been used for availability areas estimation of VOR and DME waypoints network for Ukrainian airspace. Availability areas of waypoints were highlighted in contour lines according to data in Aeronautical Information Publication. Also, the total number of NAVAIDS combination was estimated and indicated in contour graph for region.