Lessons From the Loss of USS Thresher (SSN 593) on April 10, 1963

You are currently viewing Lessons From the Loss of USS Thresher (SSN 593) on April 10, 1963

​Photo by EB Employee Patrick “Pat” M. McCarthy, Principal Program Representative, Quality (D421).

Electric Boat Shipbuilders,

On the morning of April 10,1963, USS Thresher began her deep dive in 8,400 feet of water 220 miles off Cape Cod. During the dive, an unexpected message was received by USS Skylark, her escort ship: “Experiencing minor difficulties, have positive up angle, am attempting to blow.” This message was followed by additional garbled transmissions, and at approximately 9:18 a.m., silence. USS Thresher and her crew were lost.

Although several details of the actual events will never be known, it’s likely a brazed pipe joint in one or more seawater pipes failed. This failure would have caused saltwater impingement on propulsion plant electrical equipment, shorting out critical functions and shutting down the reactor plant. Without propulsion, the ship lost its means to drive to the surface and was forced to conduct an emergency main ballast tank (EMBT) blow. The EMBT blow is the last line of defense for a submarine to get to the surface in a casualty. Unfortunately, it’s likely that the high-pressure air in the main ballast tank air flasks had high moisture content that froze in pipes and filters, blocking air flow and preventing it from reaching the main ballast tanks, dooming the ship and her crew. This sequence of events prevented 129 sailors, contractors and shipyard workers from returning to their families and loved ones.

The Judge Advocate General Court of Inquiry convened following the loss of Thresher, and concluded design and construction activities were not keeping pace with the complexity of newer ship design and materials, as well as newer operational capabilities. Additionally, inadequate quality assurance, overconfidence in existing fabrication methods, lack of approved documentation, inadequate training and schedule pressure were contributors to the tragedy.

The compilation of learning from the loss of USS Thresher led to the inception of the SUBSAFE Program, the first of the three special emphasis programs (SEPs) designed to add safeguards including more robust oversight of critical systems and components where failure could jeopardize the safety of the ship, its personnel and the mission. The robust material condition we design into our ships, as well as the expert craftsmanship, technical rigor, comprehensive testing and certified documentation, combined with the requirements of the SEPs (SUBSAFE, DSS-SOC and Fly-by-Wire Ship Control System), provide the assurances we owe to the crew and their families. The quality of our work forms the crew’s trust in us that they can depend on their ship to carry out its mission.

Take a moment to revisit what we have learned from the loss of USS Thresher, and consider how we are tackling problems that arise on a daily basis. Unplanned event learning sessions provide an essential opportunity to pause, reflect and learn when things don’t go to plan, and ensure we don’t make the same or similar mistakes. Our willingness and ability to attack and resolve problems when they are small is a foundational and critical part of our culture, and one that requires work and commitment from all shipbuilders. Understanding the root cause of the problem and implementing corrective actions to correct deficiencies and prevent recurrence ensures that we can confidently certify each ship we deliver to the Navy.

I ask each of you to reflect on this tragedy and relate learning from this event to the work you do today as we execute in this historic shipbuilding environment. No matter how you contribute to our product, the quality and verification of your work is vital to the safety of the ship, its crew and the success of its mission. This focus is especially important as we transition from our core Virginia Block I-IV design and construction programs to the new Virginia Block V (Virginia Payload Module), Block VI and Columbia programs. The unique capabilities of our products, coupled with the world security environment, are driving us to deliver at a much quicker pace. As we all face this pressure to deliver at a more rapid rate, it’s vital we remember our commitment to first-time quality. Lives hang in the balance.

As we grow as a business and onboard new shipbuilders, we need to ensure that we convey this duty and our culture of quality to the next generation.

Throughout the week you will see displays at each site to commemorate the loss of USS Thresher. Please take a moment to recognize each of the 129 flags representing a sailor, contractor or shipyard worker who never came home because of the tragedy. Consider how each flag carries with it the weight of the impact the individual losses had on their families

Thank you for your continued commitment to honoring the lives lost aboard USS Thresher through the thoughtful work you do each day to prevent a similar tragedy.​

Sean Reith
Quality Assurance and Special Emphasis Programs Director

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