Over the past two decades there has been a steady increase in the amount of electronic equipment carried by transport aircraft. This reflects the expenditure of a large amount of research and development effort, particularly in the automatic flight control field. Yet despite these developments complete automation has not been applied to air transport in the sense that it has been applied to some industrial processes. The attempts made to introduce partial automation have not always had complete success either operationally or economically.

The reasons for this somewhat piece-meal growth of automation in civil transport aircraft are varied. The most important seems to be that any new aircraft represents an evolutionary step forward. Much of the equipment must either be carried forward from a previous generation or based on it, for a mixture of operational and engineering reasons. Inter-fleet standardization in the interests of maintenance and the need to achieve safety by building on past experience are contributory factors.