Assessment of radar altimeter performance when used for integrity monitoring in a synthetic vision system

Synthetic Vision Systems (SVS) are being developed to support a wide variety of operations. These operations include tactical or critical applications of the SVS. To enable certification of an SVS as a flight-critical system several requirements must be met with regards to accuracy, integrity, availability, and continuity. Ohio University has been developing a prototype SVS as part of NASA´s aviation safety program that includes a real-time terrain database integrity monitor to guarantee the required integrity. Ohio University´s integrity monitor provides a consistency check between a terrain database profile and a synthesized terrain profile. The synthesized terrain profile is generated from information from Global Positioning System (GPS) and a radar altimeter. This paper explores the radar altimeter performance for use in a SVS terrain database integrity monitor. This data will be used in this paper to assess the various radar altimeters. Data from two different radar altimeters and highly accurate photogrammetry digital elevation models (DEM) are used to evaluate the performance of the radar altimeters. The effects of the terrain variation underneath the aircraft and the radar altimeter antenna beamwidth on the performance of the radar altimeter are discussed