A great deal has already been written about the navigational problems presented by the appearance in the near future of supersonic civil aircraft; in this paper I shall try to give a quick description of the methods that will be available in the supersonic Concorde in 1970, with an account of the chief considerations that governed their choice. While there is no doubt that there is a specific navigational problem proper to supersonic aircraft, it does not present itself in as critical a form as some writers believe. When the present-day jets came into service there was not, strictly speaking, any real gap to be bridged. The conventional methods and means used in prop-driven aircraft were taken over, with whatever further adaptations were required for particular cases—such, for example, as polar navigation. In spite of the increase in speed, there was still sufficient time for the navigator to check position and heading at regular intervals.

However, the 300 per cent increase in speeds now envisaged (1300 knots = mach 2.2 for the Concorde) introduces a more formidable discontinuity in relation to the standards of today. At a speed of 22 miles a minute it becomes impossible for the navigator to work as rapidly as he must if he is to deal with the information provided by his sensors and carry out the necessary corrections.