In June 1958 the writer submitted to the Ministry of Aviation a paper, summarized below, on the avoidance of collisions in the air. The views expressed are his own and not necessarily those of the Company for which he works.

1. The rules of the air should recognize that the information available to the pilot, whether obtained by visual or ‘electronic’ means, is likely to be limited by the following:

(a) the pilot's ‘field of view’ is at most ± 90° in azimuth and some ± 20° in elevation relative to his aircraft heading.

(b) a collision course can be recognized, but not the heading, course or speed of the other aircraft.