1. An aircraft instrument display system for imaging, on a bit-mapped display formed of a multiplicity of individually addressable pixels at locations throughout the display and actuatable to create images on the display, aircraft flight information based on aircraft and environmental sensor data that is input to the display system, the system comprising a primary video graphics processor for generating graphics video imaging information; said primary video graphics processor having an associated potential failure thread; a graphics rendering processor means operatively connected to said primary graphics processor for providing a graphics rendering function; an integrity checking processor means operatively connected to said graphics rendering processor for providing an integrity checking function verifying proper functionality of said primary video graphics processor, said primary video graphics processor generating a graphical display of said aircraft flight information for use by flight crew of the aircraft in operating the aircraft from said graphics video imaging information, said integrity checking processor means providing a switching control signal output based on the integrity of said graphical display; video switch means having first and second inputs and an output, said first input being operatively connected to said integrity checking processor means for receiving said control signal there from and being responsive thereto and said second input being operatively connected to said primary video graphics processor for receiving said graphics video imaging information there from, and said output being operatively connected to said display for providing graphical displayable information to said display for providing said graphical display in response to said switching control signal; and a secondary video graphics processor operatively connected between said integrity checking processor means and an input to said video switch means for generating graphics video imaging information, said secondary video graphics processor having a different potential failure thread from said primary video graphics processor said video switch output switching between said primary video graphics imaging information and said secondary video graphics imaging information in response to said control signal for avoiding a common failure thread and providing said graphical display even when said integrity checking processor means detects a mismatch condition for said primary video graphics processor; whereby critical display data availability is maintained.