Collision avoidance effectiveness: the past two decades

The author reviews maritime accident statistics during the last two decades and their correlation with the use of collision avoidance equipment, which was mandated for ships larger than 10000 tons by the International Maritime Organization a decade ago. The author assumed that there have been no ships totally lost as a result of a collision with automatic radar plotting assist (ARPA) equipment aboard, because he does not know of any. It is known that approximately 80000 ship years of experience with ARPA equipment have been logged. It is pointed out that, if even one ship were totally lost since 1980, the improvement would be a factor of 49:1 in comparison to the previous decade. This improvement becomes 21:1 with a 90% confidence level. Some of the data obtained are based on discussions between ship owners and equipment manufacturers, not information reported formally through official channels. Based upon this information, the improvement factor could be as high as 150:1 in comparison to 1980. The improvement becomes 95:1 with a 90% confidence level