Officials from the Japanese Maritime Self-Defense Force (MSDF) said Tuesday that one of their submarines that collided on Monday with a commercial vessel off the western coast of the country was damaged more than initially thought, with sources saying human error may have been the cause.
According to the officials, the 84-meter-long Souryu class submarine sustained damage to its conning tower and its hydroplane in the collision in the Pacific Ocean, off the western main island of Shikoku.
Damage was also caused to the sub's communications equipment in the collision, leading to a more than three-hour delay in the collision being reported after it occurred at 10:55 a.m. local time off Cape Ashizuri in Kochi Prefecture.
Japan's top government spokesperson Chief Cabinet Secretary Katsunobu Kato told a press briefing on the matter that steps by the MSDF should be taken to ensure that such communications delays do not occur again.
MSDF Chief of Staff Adm. Hiroshi Yamamura offered his apologies and said the communications delay was inexcusable.
Japan's Defense Minister Nobuo Kishi on Tuesday also apologized for the incident in which three crew members on the submarine were injured, saying that he was sorry for the worry caused to the general public.
On Monday, Kishi said that despite the commercial vessels being visible in the sub's periscope, it was unable to avoid the collision.
But, according to informed sources within the Defense Ministry, the collision may have been a result of human error on the MSDF's part, with personnel on the sub failing to properly check the surroundings using sonar before surfacing.
Kishi also said that the Japan Coast Guard has launched a probe into the collision with the full cooperation of the MSDF and the Defense Ministry.
The investigation was launched Tuesday morning by the 5th Regional Coast Guard Headquarter at Kochi Port, where the submarine arrived late Monday after it had been conducting routine exercises.
Japan's Transport Minister Kazuyoshi Akaba said Tuesday that no one aboard the commercial vessel was injured and it was able to navigate away from the collision with no problem.
He also said the Japan Transport Safety Board will conduct an independent investigation into the incident.
