National Maritime Research Institute (NMRI) conducted an accident analysis involved in two container ships at Hanshin Port in 2016 at a part of investigation by Japan Transport Safety Board (JTSB). A purpose of the analysis was to investigate backgrounds of the accident systematically with a different way from the traditional survey.
The investigation was mainly conducted from two view points, i.e.
1) assessment of situation awareness based on evaluations of the collision likelihood level using AIS data and
2) CREAM (Cognitive Reliability and Error Analysis Method) analysis which is a method of Human Reliability Analysis.
This paper describes the result from the former view point. In order to evaluate situation awareness at the incident, the authors analysed time variations of the ships' state quantity and collision likelihood between collided two ships. Collision likelihood was estimated by indices as CJ (Collision Judgement), SJ (Subjective Judgment), CR (Collision Risk), BC (Blocking Coefficient) and OZT (Obstacle Zone by Target). From the results, it deems that operators of the ships could aware the likelihood of collision at some timing before the collision. Besides, it indicates that estimated value by CPA (Closest Point of Approach) analysis might cause delay in awareness of the collision likelihood of operators because the larger ship length is, the larger difference between CPA analysis and actual value becomes.
