After a second American SSN (nuclear powered sub) collided with a sea mount in October 2021, the leadership of the U.S. Navy SSN force realized they had a serious problem. In mid-November the commander of all American subs and the commander of subs based in the Pacific agreed that an emergency stand-down (halt in regular operations) to assess the state of navigation training among SSN crews was in order. The second collision investigation is not yet complete but enough is known to attribute the collision to poor training and supervision of the officers and sailors who handle underwater navigation.
On October 2nd the Connecticut became the second American SSN to collide with an underwater seamount. The damage was so severe that it had to surface immediately. The ballast tanks were damaged so the sub could not remain underwater. It was also feared that there might have been a radiation leak but none of the radiation monitoring sensors on the sub detected any. The navy has already relieved the captain of the Connecticut along with the executive officer (second in command), and the COB (Chief of the Boat, the senior NCO on the sub). These key personnel were relieved for poor navigation procedures and failure to train the crew to do it right. Now the submarine command wants to find out the extent of the problem by similarly scrutinizing the status of navigation training and capabilities on all SSNs.
The first such collision occurred in 2006 and the reason was a lack of updated charts (nautical maps showing underwater obstacles) on all SSNs in 2006. That was thought to be remedied after the 2006 collision and all ships are supposed to have the electronic charts that are part of the new VMS (Voyage Management System) that not only uses electronic copies of charts, but quickly updates charts when new underwater obstacles are detected. This is done via space satellites or various seagoing data collection systems. In 2016 the navy installed a new VMS system (version 9.3) in American SSNs and it is not yet known if this was an issue. Crews are given initial training on these new systems before they depart on a cruise, where the two senior officers, and especially the COB, are responsible for ensuring that all sailors involved with navigation are properly trained to handle the VMS and the new charts. The navy has not yet released all the details it has on how the recent seamount collision and whether the sea mount the Connecticut ran into was in current VMS charts. It is also unclear how extensive the damage to the Connecticut is and whether the navy can afford to repair the sub or will have to retire it.