The continual increase in the complexity and performance of modern aircraft give rise to the need for improved accuracy and versatility in the electronic aids available to the crew. The system described is an example of digital computing techniques applied to the problems of air navigation. Navigation was chosen as a typical problem but the flexibility of the computer would allow it to be applied to other in-flight problems, such as the calculation of fuel and air data.

Dexan (Digital Experimental Airborne Navigator) is the outcome of some three years' work at the Applied Electronics Laboratories of the General Electric Company at Stanmore and the Royal Aircraft Establishment, Farnborough. The calculations performed by the computer to carry out a particular navigation process are shown schematically in Fig. 1.