According to the Annual report of Maritime Safety Agency (Japanese Coast Guard) , 391 vessels requested the rescue to M.S.A. cause of collision in 1996. The report says that the collision is the major cause of the sea casualties. It is to be supposed that many vessels are not operated appropriately. We researched on those vessels which were not operated appropriately in Japanese teritorial water and found that Japanese pilots encountered such vessels at the rate of 4.4% on their piloting. Also we found that Inland Sea pilots and Yokosuka pilots often encountered such vessels in the Traffic Route.
