Until the 1970s, the walls of civil airliner cockpits – in fact every surface that was within the pilots’ reach – were studded with indicators, instruments and electromechanical controls. The controls, with their arrays of complicated dials, were generally designed for a three-man crew: two pilots and an engineer. A typical trans-port aircraft from this period had more than 100 instruments and controls, the most important of which were packed with bars, needles and symbols. All of these displays jostled for space on the various instrument panels, and competed for the pilot’s attention. Research aimed at finding a solution to this problem, conducted in particular by NASA in the United States, led to the development of display devices capable of processing flight data, and the raw information provided by aircraft systems, and integrating it into an easily understandable synthetic image.
This development was only possible be-cause of a fundamental change in the type of information processed by onboard systems. Earlier instruments, based on analogue information, provided indications that were directly linked to the associated physical phenomena (for example air pressure, airspeed, or the position of a gyroscope). Digital information, on the other hand, results from the conversion of a physical measurement into binary code by means of an analogue-digital converter.
The digitisation of the physical data required for flight control and navigation, as well as for more general operational and informational purposes, led to a profound change in aircraft cockpits from the 1970s onwards. Thanks to improvements in electronics and computer technology, data could now be converted from analogue to digital format, processed by computers, and displayed on computer-type screens in the cockpit.