摘要：Many collisions are caused by human factors and are often attributed to errors in situational awareness, such as inadequate lookout. It is therefore necessary to investigate the situational awareness at the time of the accident to analyze the accident, but there has been no evaluation of the validity of the results of this awareness. The National Maritime Research Institute (NMRI) has developed a method of assessing situational awareness using OZT in previous studies for accident analysis. However, since OZT is expressed as positional information, it is not easy to determine collision risk between own ship and a target ship from the OZT positional variation at any given time. In this study, the author developed a method to quantify collision risk from OZT information to apply to collision risk assessment. The collision risk by OZT was based on arrival time to reach the OZT considering the ship's length and speed which is defined as the unsafe rate. And the OZT was calculated by a weighted average which the unsafe rate times a pre- defined weight coefficient against ship's course. To show the validity of the method, it was applied to an example of actual collision accident. The result showed that it could be available to the applicability to validation for cognitive behavior for risk of collision at the accident.
