Radar was fitted to merchant ships after the last war in the belief that, amongst other things, it would help to reduce collision casualties. However, by the early 1950s people were talking about ‘radar assisted collisions’ and today, in spite of improved radar equipment and training facilities, we read all too often of collisions between radar equipped ships. The question remains why such collisions occur; in part the answer lies in the fact that modern merchant ships have limited manpower so that the officer of the watch is often the only man on the bridge for long periods, and plotting ships' tracks from radar information is a time consuming business. The result is that, although radar provides the information required to avoid a collision, it is not in a form readily assimilated by the operator and incorrect interpretations can occur. The obvious solution is automatic extraction and processing of the radar information so that it can be presented to the operator in a form which will enable him to assess the situation rapidly. This would eliminate the tedious process of plotting, but retain the information normally obtained from a plot.