A Performance Evaluation of Elevation Database Integrity Monitors for Synthetic Vision Systems

Key words: integrity monitoring, terrain elevation database Terrain elevation databases or digital elevation models (DEMs) are used for a wide variety of applications such as surveillance, surveying, mission planning, and environmental planning. This paper focuses on the application of DEMs in Synthetic Vision Systems (SVS). SVS are intended to provide pilots with an advanced display that depicts terrain information as well as other information about the external environment such as obstacles and traffic. When utilizing terrain elevation databases in applications that require higher levels of integrity than an advisory system, it is required to include an integrity monitor that guarantees the specified probability of false alarm (fault-free detection), probability of missed detection, and time-to-alarm. The terrain information displayed to the pilot is synthesized from DEMs. The DEMs in use today are often generated by many different technological sources (remote sensing, photogrammetry, etc.) and pieced together by humans. Several approaches to DEM integrity monitoring are discussed and compared. One of the methods is based on the comparison of the DEM with downward-looking (DWL) sensor information. Flight test results with a real-time prototype DWL integrity monitor are shown.