The Japan Maritime Self-Defense Force’s (JMSDF) Soryu-class submarine was involved in a collision with a commercial vessel in waters off Cape Ashizuri in Kochi Prefecture, western Japan. The impact left parts of the upper part of the submarine bent, and three of its crew sustained minor injuries.
There were almost no traces of damage on the commercial vessel, and reportedly no one on it was hurt. But a small fishing boat probably wouldn’t have survived the encounter. This is an unacceptable accident, and thorough investigations into its cause must be made.
Submarines use sonar technology to ascertain the shape of the land and the potential presence of other vessels. When they approach the ocean’s surface, a periscope can also be deployed to visually confirm the state of the waters above.
The accident took place during drills on the Soryu submarine, when it was coming up to the ocean surface. It’s reported that the crew only became aware of the commercial vessel when they used the periscope, and that the collision happened despite them scrambling to dodge the boat.
The Soryu is a conventionally powered submarine with world-class capabilities. Why did a submarine of this level end up crashing into a freight vessel right in front of it?
Details of the situation are not known, but there has reportedly been no information saying the sonar was faulty. It’s possible that it was a case of human error, and that whoever was in charge of sonar monitoring had not fully confirmed the state of the area around them for surfacing, a time when the utmost care must be taken.
The accident was not reported to the submarine’s commanding headquarters until some 3 1/2 hours after it took place. Why did it take this long for communication in the case of such a major emergency?
Reportedly it was because all of the submarine’s communications equipment was damaged, and it had to continue moving until it reached a point where crew could get a mobile phone signal. But if there hadn’t been another means of communication, this would have been a problem from a crisis management point of view.
The waters where the accident took place are part of a traffic zone frequently used by commercial vessels. It is also questionable whether the decision to ascend so close to the water’s surface in this area was an appropriate one.
A thorough investigation into the cause of the accident by the Japan Safety Transport Board, run by the Japan Coast Guard and the Ministry of Land, Infrastructure, Transport and Tourism, is necessary. The JMSDF must provide its full cooperation with this.
In the past, the JMSDF’s Nadashio submarine collided with the Daiichi Fuji Maru, a pleasure fishing boat, and in waters off Hawaii, the training ship Ehime Maru sank after it was struck by the USS Greeneville, a nuclear-powered U.S. Navy submarine.
Another accident where a vessel with defense capabilities collided with a commercial ship has taken place. There must also be investigations into whether the lessons of the past have been fully learned.