Terrain following and terrain avoidance with synthetic vision

Abstract

The basis for synthetic vision was established long before the term was coined. During the Eighties, extensive simulator evaluation using displays that presented a computer-generated, spatially integrated depiction of the environment, the planned path and threat areas, was performed. The anticipated advantages that were pursued comprised a reduction in signature made possible by a reduction in the use of active sensors and an increase in pilot situation awareness because of the integration of information regarding threat areas. In the early nineties, a proof-of-concept demonstrator was realized in which the combined use of database technology, advanced displays and forward-looking sensors has been explored to provide aircraft a nap-to-earth navigation capability. This paper describes the design and evaluation of a synthetic and enhanced vision system that has been extended with functions to provide a database derived terrain following capability, both on planned routes and off path. It will discuss the guidance cues implemented to provide both on-path and off-path TF guidance, illustrate how the integration of real-time imaging sensor data is ised to compensate for the limitations of the terrain elevation database, and show how information regarding known threats is integrated into the different displays. Furthermore, initial results from a flight test performed with the FAA 727 are presented.