Head-Down Display [HDD] The Collection
These are displays located in the cockpit such that the pilot has to look down to the instrument panel to observe them. They are distinguished from the instruments in that they show, in part or entirely, a computer generated image. The information may be a replication of the traditional instruments showing attitude , speed altitude or navigation data for example. Other formats might show engine data or stores management. More sophisticated systems display a map with superimposed steering cues and waypoints. Radar, FLIR and Low Light TV pictures may also be presented with overlaid data.
Originally HDD used monochrome Cathode Ray Tubes and later colour CRT were used but modern HDD will use LCD panels with significant advantage for installation depth.