It is necessary to make numerous improvements to the Marine Operation System to increase the safety. Here, we try to find out the issues to improve on the Marine Operation System by a method of questionnaire. We expected that there were many near misses that had occurred at the work of ship's navigation bridge, as it seems to be especially related to human element in serious maritime casualties. So we tried to collect instance of near miss incident on board. The investigation was carried out in co-operation with a great number of seafarers (captains, officers and pilots) that belong to the Japanese flag ships and Pilot Association through their companies and associations. They were permitted to answer the questionnaire with keeping their name unmentioned and plural answers per an item. Some two thousand respondents participated in the investigation. The result of the investigation consists of both the instances of near miss incidents on board and personal matters of the respondents.
