What happens when a submarine runs into an undersea mountain
Just after noon on Jan. 8, 2005, the USS San Francisco, U.S. Navy nuclear-powered Los Angeles-class submarine collided with an undersea mountain while moving at maximum speed. The crew, most of them injured, one of them killed, fought for their lives to get the ship afloat. Someone messed up big time.
The ship was moving at its top submerged speed, anywhere from 20-25 miles per hour. While this may not seem like much, it was more than 6,000 tons of nuclear-powered ship ramming into a mountain, enough to cause significant structural damage, ground the boat, and heavily damage its ballast tanks and sonar dome.
To say that the collision injured 98 people and killed one is somewhat misleading. That is what happened. With a complement of 118 and 12 officers, the ship had 98 injured, 80 of whom were seriously injured and/or bleeding significantly. One sailor, 24-year-old Machinist's Mate Second Class Joseph Allen Ashley was killed by his injuries. The sailor who was able to pull the "chicken switches" (handles that force the submarine to immediately surface – an "emergency blow") did it with two broken arms.
Once the switches are pulled, the submarine's ballast tanks are supposed to fill with high-pressure air, making the sub positively buoyant (up to two million pounds lighter) and pop above the surface of the water.
But the San Fransisco didn't immediately pop up. For a full 60 seconds, she waited before moving to the surface. That may not seem like a lot of time, but it probably felt like forever while waiting to see if your boat was also going to be your underwater tomb. But she did surface. Later, the boat's engineers were able to rig the auxiliary diesel engine to use the exhaust to keep the damaged ballast tanks full, and after making temporary repairs in Guam, she was able to move to Pearl Harbor.
A Navy investigation found the ships crew were not using the most up-to-date charts to plot their course. The charts it did use, however, noted the presence of "discolored water," which was indicative of a seamount. The latest charts did indicate the mountain, though, and the commander should have had the latest charts. Further, when operating in stealth, Navy submarines don't use active sonar, and the sub was going too fast for the passive sonar to be effective.
The ship was still salvageable. After being moved to Puget Sound, her bow was replaced with that of the USS Honolulu, which was being retired later that same year. The San Francisco is now a training ship for the Navy nuclear engineering school in Charleston, South Carolina. The captain, Cmdr. Kevin Mooney was relieved of his command following the collision, and six other sailors were reprimanded with him, receiving reductions in rank.
For the rest of the crew, their quick response to accidentally ramming a mountain at sea and saving the ship along with their own lives while heavily injured, earned them medals from on high.