A U.S. Navy Attack Submarine Slammed Into an Underwater Mountain at High Speed

Key Points and Summary: The 2005 collision of the USS San Francisco with an ‘underwater mountain’ near Guam highlighted critical navigation challenges in submarine operations.

-The accident, which resulted in one sailor’s death and 97 injuries, was attributed to human error and inadequate charts.

-Since then, significant advances in submarine technology, like the Block III Virginia-class’s “fly-by-wire” system, have improved safety.

-This system integrates automated controls, advanced sonar, and human oversight to enhance navigation.

USS San Francisco: The Submarine Tragedy That Shook the Navy

While passive sonar ensures stealth, it struggles to detect static underwater hazards. This tragedy spurred innovation, underscoring the importance of technological evolution in undersea navigation and naval safety.

Submarine accidents are tragic. In one incident, one sailor died, and as many as 97 United States Navy crew members were injured undersea South of Guam in 2005 when the USS San Francisco submarine “collided” with an undersea “seamount” or mountain.

This tragedy understandably stays in the hearts and minds of US Navy and Pentagon personnel and families and will for several decades. 

Extensive research and investigation revealed the crash may have resulted from a combination of human error and undersea navigational technology challenges. One key reason may have been that the submarine was traveling at a maximum depth of 525 feet, a depth not on the navigational charts used by submarine commanders. 

A 2021 CNN report cited findings from the US Navy analysis indicating that the submarine commanders should have known the undersea mountain was there due to “charts in their possession that indicated a navigational hazard in the area.”

“If San Francisco’s leaders and watch teams had complied with requisite procedures and exercised prudent navigation practices, the grounding would most likely have been avoided,” the Navy report said, as quoted in the CNN article. “Even if not wholly avoided, however, the grounding would not have been as severe and loss of life may have been prevented.”

While such a finding likely raised great concerns, there are also considerations regarding the maturity of undersea navigation. Undersea navigation is regularly full of complexities and challenges, to a considerable extent, because there is no GPS or high-frequency radio beneath the ocean’s surface. 

Block III Virginia-Class Submarine 

Since the accident, however, there have been substantial and arguably defining leaps forward in undersea navigation. Specifically, Block III and beyond US Navy Virginia-class attack submarines are built with a next-generation “fly-by-wire” automated computer technology.

This system, which has now been successfully deployed for many years, uses acoustics, computing, and undersea sensors to automate the depth and speed of a submarine as needed while under human supervision. 

The Virginia-class attack submarine Pre-Commissioning Unit Mississippi (SSN 782) conducts alpha trials in the Atlantic Ocean. (U.S. Navy photo courtesy of General Dynamics Electric Boat)

The system’s navigation does not replace human command and control or decision-making. Yet, the system uses a “joystick” control that operates with automated control to ensure accurate navigation. 

Advanced sonar can detect foreign objects and potential obstacles for submarines, given that it is used regularly to “find” enemy submarines. However, when “active” sonar is used and acoustic “pings” are sent forward, a return rendering can be discerned, but not without emitting a detectable “signature.”

For this reason, submarines performing clandestine missions that require them to remain fully undetected are likely to only use “passive” sonar, which receives signals and does not send forward “pings.” This prevents the submarine from sending out an acoustic signature, which could give away a submarine’s location. 

While passive sonar can detect moving objects, such as enemy threats, by “picking up” movement and acoustic signals, it cannot “see” static objects, such as large fixed undersea structures.

It, therefore, seems likely that the submarine, which was reportedly on the way to Australia, was attempting to remain undetected and went to depths possibly much too dangerous for the kind of submarine being used. 

GROTON, Conn. (May 13, 2009) Being escorted by a tug, Virginia-class attack submarine USS Hawaii (SSN 776) makes its way down the Thames River past the historic ship Nautilus as it departs Naval Submarine Base New London for its new homeport at Naval Station Pearl Harbor. Commissioned May 5, 2007, Hawaii is the third Virginia-class attack submarine constructed and the first submarine to be named after the Aloha state. (U.S. Navy photo by Mass Communication Specialist 2nd Class Peter D. Blair/Released)

About the Author: Kris Osborn 

Kris Osborn is the Military Technology Editor of 19FortyFive and President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a highly qualified expert in the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.