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US submarine that crashed into an underwater mountain in the South China Sea ran into a pier months earlier

Seawolf-class attack submarine USS Connecticut in the Pacific Ocean with a US Navy HH-60H Sea Hawk helicopter and aircraft carrier USS George Washington and Japanese Maritime Self-Defense Force helicopter destroyer JS Hyuga, November 17, 2009.
US Navy/MCS1 John M. Hageman
  • The US Navy submarine USS Connecticut ran into an underwater mountain in the South China Sea last October.
  • Months earlier, in April 2021, the submarine hit a pier in San Diego.
  • The command investigation said the submarine's leadership failed to learn from the first incident.

A US Navy nuclear-powered fast-attack submarine that crashed into an underwater mountain in the South China Sea last October, damaging the boat and injuring members of the crew, ran into a pier in San Diego months earlier, according to a Navy investigation.

The powerful Seawolf-class submarine USS Connecticut ran into an object later revealed to be an uncharted seamount on October 2, 2021. The grounding, which saw 11 sailors injured, was the result of a number of failings, a newly released command investigation found.

"No single action or inaction caused this mishap, but it was preventable," said the investigation, which was conducted by Rear Adm. Christopher Cavanaugh, the Maritime Headquarters director at Pacific Fleet, and signed off on by 7th Fleet commander Vice Adm. Karl Thomas.

"A grounding at this speed and depth had the potential for more serious injuries, fatalities, and even loss of the ship," the report said, characterizing the incident as "an accumulation of errors and omissions in navigation planning, watch team execution, and risk management."

The incident in October was not the first time the sub had run into something either.

In April 2021, the Connecticut allided with a pier while mooring at Naval Base Point Loma in San Diego, the investigation said.

In the aftermath, a safety stand-down was held to address deficiencies, but "it was not adequately focused on addressing the root causes of the allision," the investigating officer wrote in the new report on the October crash.

A follow-on command investigation into that earlier incident said that the "allision could have been prevented with early, decisive action and recommended the CO [commanding officer], XO [executive officer], NAV [Navigator], OOD [Officer of the Deck], and ANAV [Assistant Navigator] receive administrative or disciplinary action for dereliction of duty."

The commanding officer who endorsed that investigation argued that "while this investigation revealed degraded standards in navigation, planning, poor seamanship, and ineffective command and control, it represented an anomalous performance and not systematic failure."

The officers identified as being responsible for the allision were counseled on the need to correct problems that led to the troubling incident, but there does not appear to have been any further corrective actions taken. The boat was then cleared for deployment.

The command investigation into the October incident involving the Connecticut stated that "the CO, XO, COB, NAV, and ANAV missed a significant opportunity for self-reflection and improvement following the pier allision in April 2021."

The reported noted that the April 2021 "mishap resulted from multiple errors and omissions by the navigation team, failure of the OOD to take decisive action upon recognizing danger, and lack of CO involvement."

In November 2021, the Navy removed the entire command leadership of the Connecticut due to a loss of confidence in their abilities. A 7th Fleet statement at the time said that "sound judgement, prudent decision-making and adherence to required procedures" could have prevented the grounding in the Indo-Pacific.

After stopping in Guam for preliminary damage evaluations following the October crash, the Connecticut, one of only three Seawolf-class attack submarines built to hunt enemy submarines in deep waters, headed state-side for repairs.