A computer known as the Radio Track Guide, of which both air and ground trials have been held, is described. As a system it can provide accurate automatic guidance for all anticipated operational conditions in a manner which is of value for both navigational and movement-control purposes. Mr. Britnell's paper was presented at the Paris convention on automatic navigation.

The criterion for assessing the efficiency of a navigational aid must include a reference to the ease and precision with which it enables a vehicle to maintain a specified track. In aircraft navigation the most accurate tracks are, of necessity, those made in the vicinity of the runway during the landing and take-off phases. At such times the errors must be limited to a few feet and such small values are a result of the pilot using an ideal reference frame for lateral guidance purposes. This is centred upon the runway and within it he is able to detect, with a high degree of accuracy, the two quantities necessary for precise track keeping. These two quantities are the displacement and rate of displacement from the required track.