When the periscope of the USS Montpelier rose from the water during training off the coast of Florida on Oct. 13, 2012, the submarine crew saw a Navy cruiser approaching a mere 100 to 200 yards away.

The cruiser USS San Jacinto tried to reverse, but it was too late.

The Montpelier-San Jacinto collision was one of 906 submarine accidents from late 2004 through 2013, according to data obtained from the Naval Safety Center by The Day through a Freedom of Information Act request.

The submarine's commanding officer was relieved of duty, and the costly mistake also led to changes in the way the submarine force trains, plans for, and executes complex maneuvers.

The data provided by the Navy show that the most severe accidents, including this collision, account for only 2 percent of submarine mishaps over the past decade, however. In far more cases, someone was electrically shocked while working on a submarine or hurt while repairing it. Some submarines lost expensive equipment.

Vice Adm. Michael J. Connor, the commander of the submarine force, said in a recent interview that the Montpelier-San Jacinto collision and other "near misses" around that time got his attention "in a very big way." But, Connor said, "on the whole, the submarine force is one of the most safe work environments in the country, when you consider the heavy amount of industrial work that we do in construction, overhaul, maintenance, ships in dry dock, that sort of thing, and the number of people we have doing that work."

A fleet of 71 submarines, about 17 of which are typically deployed each day, are maintained and operated by 17,000 people.

The number of accidents ranged from 67 to 154 a year since fiscal 2005, according to the data from the safety center. Out of a total of 906 accidents, 18 were considered the most severe, "Class A," because someone was killed or permanently disabled, or there were damages of $2 million or more. Another 18 were "Class B" because someone was partially disabled, several people were hospitalized, or there were damages of $500,000 to $2 million.

Ninety-six percent of the accidents were less severe. There were 264 in the Class C category, with $50,000 to $500,000 in damages or an injury that caused someone to take a day or more off from work, and 606 in the Class D category, with $20,000 to $50,000 in damages or a recordable injury or illness not otherwise classified.

Connor said he has made changes in the past year based on what the submarine force learned from the Montpelier-San Jacinto collision, to make sure the risk of operating a submarine is at an "absolute minimum, given the fact that we do not operate in a risk-free business."

Fiscal 2011 was the worst year for submarine accidents, with 154. Three were in the most severe category, including the USS Ohio hitting a sonar array when the order to abort was given during acoustic testing. That same day, Dec. 18, 2010, the Ohio hit a buoy, according to the data.

U.S. Sen. Richard Blumenthal, D-Conn., questioned why there would be a spike in 2011, two years after the USS Hartford, a Groton-based submarine, hit a Navy amphibious ship in the Strait of Hormuz, and leaders of the submarine force said they would use the lessons learned from that accident to prevent other accidents.

"Whatever they did in the wake of the Hartford apparently was not enough," Blumenthal said after looking at the data obtained by The Day. "I guess that's the conclusion because the mishaps, both serious and otherwise, continue to happen. I think the overall takeaway is that whatever has been done so far has to be revisited and upgraded.

"Ideally what we should be seeing is a trend down," he added, "but we're not seeing that trend."

After the Hartford collided with the USS New Orleans on March 20, 2009, it rolled about 85 degrees, damaging its sail, hull and port bow plane. The Navy paid Electric Boat in Groton about $120 million for the repairs and Navy investigators concluded the crew of the Hartford was at fault.

U.S. Rep. Joe Courtney, D-2nd District, said he, and many others in Congress, felt confident the Navy took the Hartford incident seriously.

"It takes some time to really absorb what happened and develop new best practices," he said. "I think in fairness, it just takes a while for the process to sort of get into the bloodstream of the workforce."

Both the senator and the congressman, however, surmised that the submarine force's decision, around the same time as the increase in incidents, to extend some deployments beyond six months could be a factor in the 2011 spike. That decision was made to compensate for fewer submarines in the fleet.

If submariners are at sea longer, without time to refresh, Courtney said, "it would just seem, intuitively, that would increase the potential, if for no other reason than fatigue, the potential for problems." But, Courtney said, he did not have a way to quantify that.

Connor, the sub force commander, said the submarine force has become "increasingly sensitive over the years" to the time a submarine is deployed and how busy the crew is during the deployment, and carefully manages how long a submarine works in a challenging environment "to manage just that type of factor."

"The submarine force did react to 2011 because we drove the rate down to near zero for major mishaps in 2012," he added.

There were no Class A mishaps in fiscal 2012 and only one Class B. But there were four Class A mishaps in fiscal 2013, including the Montpelier-San Jacinto collision, and one Class B.

Because of that collision, submarine crews must now train more often on how to operate in more challenging scenarios than they would likely encounter at sea, Connor said.

Junior officers now stay on submarines for 36 months instead of 32 for their first tour, to gain more experience at sea. The submarine force is changing the work rotation aboard submarines so sailors sleep for eight hours at about the same time every day instead of six, based on findings from the Naval Submarine Medical Research Laboratory in Groton, he said.

It is easier for submariners to report small issues that didn't seem quite right but did not lead to a mishap, he added, and the planning process for exercises with multiple ships was improved to ensure everyone involved has a detailed understanding of the safety plan and "we know that they know it."

The submarine force, Connor said, is doing everything it can to prevent accidents.

Broken fingers, lacerations

The Navy's data showed that nearly 22 percent of the reports were about personnel - about 200 of them - who were electrically shocked. In other accidents, hatches fell on heads and hands.

On the USS Toledo in 2009, a sailor who was getting food out of storage caught his hand in a hatch. Two fingers were broken and his pinky finger was cut badly.

Chief Hospital Corpsman Aaron McKnight was the independent duty corpsman, the sole medical provider, on the Toledo at the time. McKnight said he immobilized the hand and stopped the bleeding. He started an IV and gave the sailor medication for the pain.

The submarine was at sea but not far from Groton. A small boat quickly arrived to take the sailor to shore for surgery.

That was the worst injury McKnight said he has treated at sea. In port, he helped someone who fell in a bathroom on the pier and fractured his skull, and another sailor whose hand got caught in a periscope.

Most often, McKnight, who was the Submarine Independent Duty Corpsman of the Year for 2011, said he sutures lacerations because people bump their heads while working.

McKnight has treated sailors who were electrically shocked by doing an electrocardiogram to make sure the rhythm of the heart was not disturbed and checking vital signs. The cases were not severe, he said.

Overall, McKnight, who has also deployed on the USS Springfield, said he feels a submarine is a safe place to work. There is an in-depth safety brief before any procedure to prevent injuries, and the submarine force "takes lessons learned really seriously," said McKnight, who is assigned to the Naval Submarine Support Center in Groton.

But, McKnight said, while he has never dealt with a rash of injuries, in an industrial workplace "the potential is always there."

Mistakes can be costly

The USS Philadelphia lost an exercise torpedo at the Atlantic Undersea Test and Evaluation Center range in the western Atlantic on July 10, 2008. Seven submarines damaged or lost the sonar array that trails behind a submarine.

Each incident cost the Navy between $500,000 and $2 million.

Mishaps throughout the Navy, including in aviation, cost the service a total of $441 million in fiscal 2013, according to the safety center. The center's data does not include the damages to the USS Miami that caused the Navy to scrap the submarine. The May 23, 2012, fire was deliberately set, rather than an accident.

Courtney said the Navy is operating in a "challenging budget environment" and has "every incentive in the world" to reduce the number of accidents. While some are unavoidable, Blumenthal said, the Navy should be able to prevent more of them, particularly the electric shock injuries.

"I'm perplexed and deeply interested in the data that I've seen because we ought to focus very intensely and immediately on trying to reduce those numbers," Blumenthal said.

As a member of the Senate Armed Services Committee, Blumenthal said he will ask Navy leaders whether they have consulted an occupational health safety specialist. He said he wants to know how the submarine data compares with similar records for other Navy ships.

Connor said the submarine force has a process to review workplace safety.

"We have valuable ships and very valuable people working on those ships," he said. "Because of that, we need to make sure they're all ready to perform."

Explore the data

The Day worked with Visible Government Online Inc., an information technology and services company in Brunswick, Maine, to create a searchable database using data obtained from the Naval Safety Center by The Day through a Freedom of Information Act request. Explore the data below.