The Primary Flight Display

The Primary Flight Display (PFD) looks in many ways like a HUD, but it is located in the aircraft's control panel. PFDs are common on modern business jets and airliners [Lon01]. Both the PFD and the HUD are computerized instrumentation systems; this similarity in their display capabilities allows many analogous elements to be used in both devices.

PFDs offer many excellent ideas on how a computerized instrument can present a large amount of information in a compact yet user-friendly way. These devices combine analog and digital outputs in ways that maximize the benefits of both types of display [Nas00, Mac03].

One specific element that is being designed for Flightdeck-UI is styled after a PFD airspeed indicator. This virtual instrument combines a columnar analog gauge (including color bands) with a pointer that also serves as a window for the digital output of the measured value [Mac03]. The least significant digits of the digital output are represented as a moving tape, making it easy to read the display even if the numbers are changing quickly (this is a significant problem with conventional digital displays).

The Flightdeck-UI PFD-airspeed-style element will include annunciator features, with the background of the pointer changing color when it moves into the warning region of the gauge. The pointer will also flash if it moves into the critical region.