The subject of Decision Making for collision avoidance is strict requirements in terms of risk mitigation. There are three steps in the process of decision making. The first step is information collection, where various information like as AIS data, radar data, chart data and many other voyage related data used for ship operation are collecting. The second step is information processing, where all collected information would be processed and analyzed by the team on duty at bridge to recognize about the own ship current situation, for instance, encountering collision risk and the performance of own ship in a current navigation environment. The third step is the decision of own ship action, where captain and/or navigator select own ship action that satisfies safety, legality and efficiency. According to the near miss cause surveyed done in the past [1] , 43% of cause by the navigator themselves, 17% for teamwork and 23% for supporter, so most of the cause of near miss exists in humans. So, there is need to review the function of decision making process. Improvement for the information collection has been made, such as loading AIS. And with appearance of GPS, it became easy to know the true motion of target. But nothing has been improved for the information processing and overall improvement of decision making has not progressed. Among the information processing, it is necessary to improve the evaluation method of collision risk. The conventional collision risk evaluation method use the Distance of Closest Point of Approach (DCPA) and Time to CPA (TCPA) of target which are related to relative motion (see Figure 1). Evaluation Method of Collision Risk by Using True Motion H. ImazuTokyo University of Marine Science & Technology, Tokyo, Japan ABSTRACT: It is necessary to develop a useful application to use big data like as AIS for safety and efficiency of ship operation. AIS is very useful system to collect targets information, but this information is not effective use yet. The evaluation method of collision risk is one of the cause disturb. Usually the collision risk of ship is evaluated by the value of the Closest Point of Approach (CPA) which is related to a relative motion. So, it becomes difficult to find out a safety pass in a congested water. Here, Line of Predicted Collision (LOPC) and Obstacle Zone by Target (OZT) for evaluation of collision risk are introduced, these values are related to a true motion and it became visible of dangerous place, so it will make easy to find out a safety pass in a congested water.

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The subj t of this study is to make a standard of judgement for

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The subject of this study is to rロ ake an optimum criterion for coUision avoidance action deciding by navigator