Summary and Key Points: On October 2, 2021, the USS Connecticut, a Seawolf-class fast attack submarine, struck an unmarked seamount in the South China Sea, causing significant damage and injuries.

-The incident was attributed to a culture of negligence fostered by the command team and multiple failures in navigation and watchstanding procedures.

-Despite the damage, the crew managed to surface and return to Guam. An investigation highlighted several prior incidents and lapses in leadership.

-Following the mishap, the commanding officer, executive officer, and chief of the boat were relieved of their duties, underscoring the risks and challenges of submarine operations.

USS Connecticut Collision: The Seamount Mishap and Its Aftermath

On October 2nd, 2021, the USS Connecticut, a Seawolf-class fast attack submarine was undertaking a submerged transit of the South China Sea enroute to Okinawa when she struck an unmarked seamount causing significant damage and several injuries to the crew. Fortunately, she was able to surface and limp back to Guam, although the investigation notes that the outcome was nearly the tragic loss of the sub with all hands. The investigation report, released on April 20th, 2022, calls the watchstanders on duty at the time of the accident to account while also highlighting the culture of negligence fostered by the command team, detailed in several incidents prior to this deployment and incident.

USS Connecticut History:

The Seawolf-class vessels were designed during the Cold War to combat the newer advanced Soviet subs- the Typhoons and the Akulas. The Connecticut was commissioned on December 11th, 1998 as the second boat of the class. Connecticut, like her sister Seawolf ships, featured improved steel capable of diving deep as well as equipment allowing shallow water operations. They mount a much larger armament than the preceding Los Angeles-class boats as well as being significantly quieter. Ultimately, the high cost associated with building each Seawolf vessel coupled with the dissolution of the Soviet Union led the U.S. to cancel the majority of the order. Only three Seawolf ships were ever constructed.

Over the past three decades, the Connecticut has participated in multiple deployments. She served with the Wasp Expeditionary Strike Group to join the fight in the War on Terror in 2004. She has several times participated in ICEX training exercises in the Arctic, surfacing through the ice in 2003 and more recently in 2011. In 2021, she was homeported at Naval Base Kitsap-Bremerton working up for a Pacific deployment. In May of 2021, she got underway for operations in the Western Pacific.

The Crash:

Leading up to the crash, the Connecticut was headed to Okinawa to conduct a humanitarian evacuation, or HUMEVAC. The heavily redacted report does not give any further specifics or reasons for her location. Throughout the deployment, the boat had been having issues with her forward depth sounder. The crew had tested and troubleshot to the best of their abilities and the report indicates that her captain was working to have spare parts either meet the boat in Okinawa or be waiting for her in Guam. Prior to the crash, the boat was operating on a temporary routing. While the report does not spell out the specifics of submarine navigation, it makes clear this is not the optimal method for route planning on ocean transits. Furthermore, since 2007, the U.S. submarine force has operated under a COSOE which “provides the OOD with unambiguous boundaries within which the watch section may operate without additional CO permission.” The unredacted portion of the investigation takes pains to note that these operating procedures contain yellow and red depth tripwires which the Officer of the Deck (OOD) - in charge of safe and proper operation of the vessel when underway - must act upon.

Beginning in the early hours of the morning, the Quartermaster of the Watch (QMOW) - responsible for safe navigation of the boat - logged several losses of soundings in the log. Basically, the QMOW was unable to determine depth via the fathometer. The report notes that “the QMOW did not take the required actions for a LOS.” Furthermore, around 5:00 a.m. the QMOW noted and logged several depth readings that did not correlate properly with the chart. Although he apparently noted a few consecutive readings that did correlate and reported these to the OOD, he failed to log them. In the next thirty minutes, several watchstanders discussed using a non-secure fathometer mode which may expose the sub but would give more accurate depth readings. While the ODO apparently planned to call the captain and request this change, he did not get the chance.

Sometime around 6:18, the Connecticut collided with a bathymetric feature.  The next ten minutes were a hectic struggle to save the boat. While the crew successfully broached the ship in the minutes immediately following the collision using her forward speed, they soon faced another problem. As the boat came to a stop, she was unable to deballast and she began sinking. A few minutes later, the crew successfully performed an “emergency blow” and surfaced the ship. When the ship resurfaced, the crew managed to get the normal ballast pumps working and began pumping 100,000 pounds of water overboard. During this process, one pump overheated until it “glowed red and smoked” although fortunately this did not cause any further issues. Ultimately, the crew managed to stabilize the ship and transit safely to Guam.

The Investigation and Causes:

The investigation report details the culture aboard the ship that allowed this mishap to occur, noting: “No single action or inaction caused this mishap, but it was preventable.  It resulted from an accumulation of errors and omissions in navigation planning, watch team execution, and risk management.  Prudent decision-making and adherence to standards in any one of these three areas could have prevented the grounding.”

The report further lays out the issues already noted in the Commanding Officer, specifically a counseling and letter of performance in July of 2020, a counseling and letter of instruction in February of 2021, and, perhaps most incredibly, a collision with a pier in April of 2021. This last event led to a separate investigation which recommended yet another counseling however that review wasn’t finalized until the boat was already on deployment. Additionally, the report notes the unusually high optempo for a boat working up for deployment where the crew were at sea for 67% of the time. The Navy Times reported dissatisfaction and low morale among the crew who felt that the command cared only about the mission. In the lead up to the incident, the report notes with painstaking detail the multiple failures of the leadership and watch team in developing an unsafe route, ignoring unsafe indications, and failing to act decisively in the face of such indications.

The Aftermath:

Following the investigation, the Commanding Officer, Executive Officer, and Chief of the Boat (the senior enlisted member) were all relieved of their duties. The report also recommended the NAV, OOD, ANAV, and QMOW be disciplined and separated from the Navy although it’s unclear the ultimate fate of these individuals.

While this mishap was far less tragic than the 2005 collision of the USS San Francisco with an undersea mount that resulted in 98 injuries and one fatality, it was still a sobering reminder of the dangers of submarine operations and the risk the silent service undertakes in fulfilling their missions.

About the Author: Maya Carlin 

Maya Carlin, National Security Writer with The National Interest, is an analyst with the Center for Security Policy and a former Anna Sobol Levy Fellow at IDC Herzliya in Israel. She has by-lines in many publications, including The National Interest, Jerusalem Post, and Times of Israel. You can follow her on Twitter: @MayaCarlin.