In Deadliest US Sub Tragedy, 'No Cover-Up' Is Found

The release of about 3,000 pages of documents delving into the deadliest submarine disaster in US history has not yielded any sinister effort to hide the truth, a retired Navy skipper says. Instead, documents show the Navy’s policies and procedures failed to keep pace with fast-moving technological advances during the Cold War, allowing a series of failures that led to the sinking of the USS Thresher on April 10, 1963, said retired Capt. James Bryant, per the AP. He sued for release of the documents under the Freedom of Information Act. "There’s no cover-up. No smoking gun," he said. That doesn't make it any less tragic, though. The loss of the nuclear-powered submarine and all 129 sailors and civilians aboard during a test dive in the Atlantic Ocean was both a tragedy for the families and a blow to national pride during the Cold War.

• The Thresher was the first of a new class of attack submarines that could travel farther and dive deeper than any previous sub. But the documents suggest the nuclear-powered submarine's capabilities outstripped the Navy's best practices based on older-generation subs. For example, the ballast system used to surface in an emergency was a legacy system that was never tested at greater depths, and proved to be inadequate, the documents show.
• The Navy believes the Thresher's sinking was likely caused by a burst pipe and electrical problems that led to a nuclear reactor shutdown.
• Bryant, himself the skipper of a Thresher-class submarine, agreed that a series of events led to the sinking: The sub descended far too quickly without stopping to assess for leaks from previous shock testing months earlier; there were training concerns because the location of valves had changed while in dock; and ice buildup prevented the crew from effectively blowing the ballast tanks to resurface.
• No one will know for sure exactly how the disaster played out. But it’s clear that precious minutes went by as the crew became aware of their dire situation. At one point, a message from the submarine to a rescue ship referred to “900 north” suggesting the sub was 900 feet beyond its test depth, according to the documents.
• Another 4,000 pages of Thresher-related documents are due to be released by the Navy.

(More submarine stories.)