WASHINGTON - Suddenly, listeners on USS Skylark (ASR 20) heard a noise "like air rushing into a tank." Five minutes later they heard the unmistakable sound of a submarine imploding.
In 1963, USS Thresher (SSN 593), the first of her class, was a state-of-the-art submarine with the most modern technology of the day, allowing her to be fast, quiet and deep diving. However, on April 10, none of that would matter when, in less than 20 minutes, deficient specifications, deficient shipbuilding practices, deficient maintenance practices and deficient operational procedures would cause an event that would permanently change how the Navy designs, builds, maintains, and operates submarines.
ONE MOMENT IN TIME CHANGED IT ALL
On April 10, Thresher was off the coast of Massachusetts conducting sea trials after a nine-month maintenance period. The seas were calm. Wind was seven knots and visibility was about 10 miles. Save for the submarine rescue ship Skylark which accompanied Thresher during the sea trials, no ships were in the vicinity. Aboard Thresher were 16 officers, 96 enlisted sailors, plus 17 civilian technicians to support the at sea tests.
According to the official documents, this is the short, but dramatic, chain of events:
7:45 a.m. - The two vessels were in close proximity and were communicating. Shortly thereafter, Thresher began a deep dive which according to Skylark personnel appeared to "proceed satisfactorily."
9:13 a.m. (approximately) - Thresher sends a garbled report to Skylark saying, "Experiencing minor difficulties. Have positive up angle. Am attempting to blow. Will keep you informed." In the background could be heard the sound of high-pressure air being blown into the submarine's ballast tanks.
9:15 a.m. - On the surface, Skylark's crew tried to re-establish communications by underwater telephone, using the query, "Are you in control?"
9:17 a.m. - Skylark receives another mostly unintelligible message from Thresher in which the words, "exceeding test depth" are heard.
9:18 a.m. - Skylark detects the sound of an underwater implosion.
10:40 a.m. - Skylark dropped a series of hand grenades indicating to Thresher that she should surface.
10:45 a.m. - Skylark's commanding officer ordered a message reporting the loss of contact. Transmission difficulties held up the communication.
12:45 p.m. - Radio New London received the message that communication had been lost.
While the exact cause of the loss is not known, a thorough investigation revealed significant deficiencies. In a 2003 brief to the House Science Committee, Rear Adm. Paul E. Sullivan, NAVSEA's deputy commander for ship design, integration and engineering, briefed the following issues:
-Thresher had about 3000 silver-brazed piping joints exposed to full submergence pressure. During her last shipyard maintenance period 145 of these joints were inspected on a not-to-delay vessel basis using a new technique called Ultrasonic Testing. Fourteen percent of the joints tested showed sub-standard joint integrity. Extrapolating these test results to the entire population of 3000 silver-brazed joints indicates that possibly more than 400 joints on Thresher could have been sub-standard. One or more of these joints is believed to have failed, resulting in flooding in the engine room.
-The crew was unable to access vital equipment to stop the flooding.
-Saltwater spray on electrical components caused short circuits and loss of propulsion power.
-The main ballast tank blow system failed to operate properly at test depth. Investigators believe that various restrictions within the system coupled with excessive moisture in the compressed air led to ice formation which prevented the air from reaching the ballast tanks. Consequently, the submarine was unable to overcome the increasing weight of water rushing into the engine room.
SUBSAFE IS BORN
Thresher changed the face of the submarine service. It drilled into our collective minds how critically vital every specification was to the safety and successful operation of that essential national asset and the work it was required to accomplish.
The Judge Advocate General Court of Inquiry Report contained 166 Findings of Fact, 55 Opinions and 19 Recommendations. In June 1963, not quite two months after Thresher sank, the SUBSAFE Program was created. The SUBSAFE Certification Criterion was issued by BUSHIPS letter Ser 525-0462 of 20 December 1963, formally implementing the program.
The Submarine Safety Certification Criterion provided the basic foundation and structure of the program that is still in place today. The program established:
* Submarine design requirements
* Initial SUBSAFE certification requirements with a supporting process, and
* Certification continuity requirements with a supporting process.
LEST WE FORGET
This is about history, right? Far from it. If anything, this lesson from 50 years ago is even more relevant now because of a real danger that we all must battle.
"Ignorance, arrogance, and complacency prove the three biggest threats facing the SUBSAFE Program," said Cdr. Daniel Ettlich, director of the Submarine Safety and Quality Assurance Division at NAVSEA. "These threats continually attack and erode the long established safety culture."
Staying conscious of that and forcing ourselves to stay vigilant is what will continue to make SUBSAFE more than just a program born from tragedy. It must be a mantra of sorts.with a drumbeat that constantly reminds us nothing is more important than doing the job right.
"The pressures of cost and schedule are great," said Ettlich, "thus requiring us to ensure standards are upheld, even under the harshest of pressures." Because, after all, he said, "an honest mistake can kill someone just as dead as malpractice."
- NAVSEA -