The need for an airplane to navigate safely at lower altitudes and low visibility aroused the need for this research. The integrity of terrain and the obstacle models stored in the onboard Synthetic Vision System is demonstrated with the real-time sensor measurements, to detect the hazards. An approach of statistical comparison of the terrain shadowing feature, against the extracted shadow features from the stored terrain model is adopted.
X-band weather radar is used for terrain database integrity monitoring and terrain referenced navigation. Various feature extraction methods are addressed here, to support the correlation process between the weather radar measurements and the stored terrain databases. Furthermore, enhanced weather radar antenna beam models are applied to achieve high performance SHADE (the shadow detection and extraction) functionality. The methods for the aircraft state estimation information such as velocity, from the geometrical changes in the observed terrain imagery are applied for the navigation purposes. The outputs from these methods are compared to the state estimates obtained from the Global Positioning System (GPS) and Inertial Navigation System (INS) readings. All methods discussed in this thesis are evaluated using flight test data collected with NASA’s DC-8 in Reno, NV and with a Gulfstream V in Reno, NV.