In 1972 civil sales formed some 30% of the US aerospace industry. Although in 1973 there was a swing back to defence products, civil sales retain an important position. Not surprisingly, aerospace industries without sizeable civil projects on hand, such as Britain's and Canada's, are looking with concern at their future prospects.

Such increasing dependence brings its own problems, for civil sales have been characterised by large fluctuations in the past. Predictions have often been wrong and costly, yet accuracy is a prerequisite of the industry's steady development. The heavy research and development and expenditure involved in a major civil programme necessitates a forecasting horizon of up to a decade.