Report Finds Human, Mechanical Errors Caused Fatal AAV Sinking in California

Eight U.S. Marines and a sailor died during a training exercise off the coast of San Clemente Island last summer when their AAV sank

Servicemembers killed in AAV accident
15th Marine Expeditionary Unit

A command investigation released by the U.S. Marine Corps Thursday showed a combination of human and mechanical errors led to the sinking of an Amphibious Assault Vehicle (AAV) off San Clemente Island last summer, killing eight Marines and a Navy sailor.

The report, completed by the I Marine Expeditionary Force (MEF), said disregard of maintenance procedures, inaction by AAV crewmen and improper training all played a role in the training mishap last July.

The sunken AAV and 12 others were involved in a training mission on San Clemente Island, about 78 miles off the coast of San Diego, on July 30, 2020.

The first signs of mechanical issues appeared as crews were getting ready to leave the island and go back to USS Somerset, according to the USMC. One of the AAVs had a mechanical failure that caused a five-hour delay and forced four AAVs and several service members to remain on the island.

The U.S. military confirmed it located and recovered the remains of the marines and sailor who died during a training incident off San Clemente Island.

As the other nine AAVs were headed back to the ship, one of them began taking on water from multiple points, the USMC said. The vehicle was equipped with bilge pumps, but due to a transmission failure the pumps couldn't handle the amount of water coming in and the vessel began to sink, according to the report.

A distress signal, known as a "November Flag," was sent out but no safety boats were in the water. The USMC said it took 20 minutes for another AAV to arrive for support.

By the time the second AAV arrived, the mishap AAV had been sinking for approximately 45 minutes, the report said.

As the crew on the sinking AAV began evacuating through a hatch on top of the vehicle, the assisting AAV collided with it and shifted the sinking AAV on its side with the hatch facing a large swell. The swell crashed into the hatch side of the sinking AAV and filled the troop compartment with water, causing it to sink rapidly with 11 service members on board, the report said.

The body of one Marine was recovered at the scene and eight other service members went down with the 26-ton AAV, which sank to a depth of nearly 400 feet.

Following an extensive search, the remains of the missing military members were found on Aug. 3, 2020, when the sunken craft was discovered. The deceased were identified as:

  • Pfc. Bryan J. Baltierra, 18, of Corona, California, a rifleman with Bravo Company, BLT 1/4, 15th MEU.
  • Lance Cpl. Marco A. Barranco, 21, of Montebello, California, a rifleman with Bravo Company, BLT 1/4, 15th MEU.
  • Pfc. Evan A. Bath, 19, of Oak Creek, Wisconsin, a rifleman with Bravo Company, BLT 1/4, 15th MEU.
  • U.S. Navy Hospitalman Christopher Gnem, 22, of Stockton, California, a hospital corpsman with Bravo Company, BLT 1/4, 15th MEU.
  • Pfc. Jack Ryan Ostrovsky, 20, of Bend, Oregon, a rifleman with Bravo Company, BLT 1/4, 15th MEU.
  • Cpl. Wesley A. Rodd, 22, of Harris, Texas, a rifleman with Bravo Company, BLT 1/4, 15th MEU.
  • Lance Cpl. Chase D. Sweetwood, 18, of Portland, Oregon, a rifleman with Bravo Company, BLT 1/4, 15th MEU.
  • Cpl. Cesar A. Villanueva, 21, of Riverside, California, a rifleman with Bravo Company, BLT 1/4, 15th MEU.
  • Lance Cpl. Guillermo S. Perez, 19, of New Braunfels, Texas, a rifleman with Bravo Company, Battalion Landing Team (BLT) 1/4, 15th MEU.

On Tuesday, the Marines Corps announced Col. Christopher J. Bronzi, the former commanding officer of the 15th Marine Expeditionary Unit, was relieved of command by Lieutenant General Steven R. Rudder, commander of the U.S. Marine Corps Forces, Pacific, “due to a loss of trust and confidence in his ability to command."

The decision to relieve Col. Bronzi of command came as a result of the completion of the command investigation, the U.S. Marines said. Col. Fridrik Fridriksson, who previously commanded the 11th Marine Expeditionary Unit, has been placed in command of the 15th MEU.

Col. Bronzi was the second leader in the 15th MEU to be relieved of command in connection to the incident. In October 2020, Lt. Col. Michael J. Regner was relieved of his command.

I MEF has taken administrative or disciplinary action against seven other people "whose failures contributed to the mishap," according to the report.

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