The Command Investigation into the assault amphibious vehicle mishap off the coast of Southern California on July 30, 2020, has been completed by the I Marine Expeditionary Force investigating officer and endorsed by the Commanding General of I MEF and the Commander of U.S. Marine Corps Forces, Pacific.

The loss of Corporals Wesley A. Rodd and Cesar A. Villanueva; Navy Hospital Corpsman 3rd Class (Fleet Marine Force) Christopher Gnem; Lance Corporals Marco A. Barranco, Jack-Ryan Ostrovsky, Guillermo S. Perez, and Chase D. Sweetwood; and Privates First Class Bryan J. Baltierra and Evan A. Bath continues to be felt across the Marine Corps.

The investigation revealed a confluence of human and mechanical failures caused the sinking of the mishap AAV, and contributed to a delayed rescue effort. The investigation determined the cause of the mishap was a combination of maintenance failures due to disregard of maintenance procedures, AAV crewmen not evacuating personnel when the situation demanded for such actions, and improper training of embarked personnel on AAV safety procedures.  In the closing endorsement, COMMARFORPAC found contributing factors included lack of training, the material condition of the AAVs assigned to 15th Marine Expeditionary Unit, lack of safety boats in the water, a higher-than-anticipated sea state, and insufficient buoyancy provided by personal flotation devices at depth.

On the morning of July 30, 2020, thirteen AAVs with embarked personnel conducted a movement from USS Somerset to San Clemente Island.  Due to the mechanical failure of an AAV on San Clemente Island, which produced a five-hour delay and required some personnel and AAVs to remain on the island, only nine AAVs departed to return to USS Somerset on the afternoon of July 30.  During the return transit, water began to enter the mishap AAV through multiple points of leakage, the transmission failed, bilge pumps were unable to expel water rapidly enough due to the transmission failure, and the AAV began to sink.  The vehicle commander gave the distress signal, known as a “November flag,” but no safety boats were in the water, and it took approximately 20 minutes for another AAV to arrive to assist.  The mishap AAV was slowly sinking for approximately 45 minutes before the other AAV with embarked personnel pulled alongside.  The mishap AAV crew prepared to evacuate embarked personnel by opening a hatch on the top of the vehicle.  The AAVs collided, causing the mishap AAV to turn broadside to a swell.  A large wave swept over the mishap AAV, in which water entered the troop compartment through the open hatch, and caused the mishap AAV to rapidly sink with eleven personnel on board.

Despite an extensive search-and-rescue effort, eight Marines and one Sailor perished at sea.  We offer our sincere gratitude to the men and women of the U.S. Coast Guard, U.S. Navy, and all those involved in the search, rescue, and recovery efforts.

As a result of the investigation, actions have been taken, directed, or recommended to prevent a future mishap and to hold Marines accountable.

Responsive Actions:

• The Commandant of the Marine Corps ordered an immediate suspension of all AAV waterborne operations on July 31, 2020, pending a comprehensive review of equipment, procedures, and training pertaining to safety during waterborne operations.  This suspension does not apply to land-based training or regular maintenance of the vehicles. 
• Program Executive Office, Land Systems, ordered all assault amphibian units to conduct additional inspections of every AAV with new criteria for hull watertight integrity, bilge pump function, and emergency egress lighting systems.
• Commanding General, Training and Education Command conducted a course curriculum review board for the Marine Corps underwater egress training program, which trains service members to conduct emergency egress from a sinking vehicle or aircraft.

Commander, Marine Corps Forces Pacific directed the commanding generals of I MEF and III MEF to:

• Review all safety practices and procedures associated with waterborne operations, ensure commanders are directly responsible for safety structure, and require general or flag officer notification prior to use of AAVs as safety boats.
• Clarify guidance on the provision of ready equipment and trained personnel to MEUs.
• Ensure AAV waterborne operations are trained and evaluated during pre-deployment workup periods.
• Ensure personnel receive appropriate rest prior to high-risk training and operations.
• Require all AAV and mechanized unit leaders to review a study on emergency egress of AAVs conducted by a student at Naval Postgraduate School.
• Ensure positive communications between AAV leaders and ship personnel, and ensure appropriate ship personnel grant permission to launch AAVs to or from a ship.
• Provide 90-day updates on execution of these directed tasks.

Commander, Marine Corps Forces Pacific requested appropriate agencies at Headquarters, U.S. Marine Corps to:

• Review the utility and effectiveness of the Life Preserver Unit 41.
• Review underwater egress training and procedures.
• In coordination with the U.S. Navy, review employment of safety boats during waterborne operations, including whether the AAV is suitable for employment as a safety boat.
• In coordination with the U.S. Navy, review the Common Standard Operating Procedures for Assault Amphibian Operations and develop it into an applicable directive.
• Review the Amphibious Combat Vehicle program to ensure lessons learned from AAV mishaps are incorporated into training, operations, and maintenance when the ACV is fielded, and current ACV safety features adequately support emergency egress.
• Continue sustained funding of the AAV program for as long as the vehicle is in service.
• Standardize water integrity testing procedures.

Disciplinary action:

• Commander, Marine Corps Forces Pacific relieved the commanding officer of 15th MEU on March 23, 2021.
• CG, I MEF relieved the Commanding Officer of BLT 1/4 and the Company Commander of Bravo Company, BLT 1/4 on Oct. 13, 2020.  CG, I MEF has taken appropriate administrative or disciplinary action against seven other personnel whose failures contributed to the mishap.
• Commander, Marine Corps Forces Pacific has forwarded a copy of the investigation to CG, TECOM, recommending appropriate administrative or disciplinary action to address failures by the former commanding officer of 3rd Assault Amphibian Battalion.