Lt. Gen. Carl Mundy, who conducted the Marine Corps investigation, wrote that the 15th Marine Expeditionary Unit “did not receive forces that were optimally trained and equipped to the required standards.” But rather than pointing to any one failure or decision that led to the accident, Mundy highlighted a “confluence of factors” that contributed to the fatal incident.
The coronavirus pandemic created a series of changing and often confusing COVID precautions and restrictions and forced the cancellation of exercises in the months before the accident.
It was one of a series of factors that combined to ultimately lead to the sinking of the AAV on July 30, 2020.
A group of AAVs were moving from the USS Somerset to San Clemente Island and on the return trip, four AAVs were delayed for five hours because of a mechanical failure on one of the vehicles, a previous investigation found. When the AAVs did enter the ocean, one began taking on water from multiple spots, as the transmission failed and bilge pumps were overwhelmed, causing the vehicle to sink.
The vehicle commander issued a distress signal, but it took 45 minutes for another AAV to pull alongside to assist. The two AAVs collided, which forced the accident vehicle to turn towards a swell. A wave swept over the vehicle, into the open hatch, and the vehicle sank rapidly.
In the 4-month period leading up to the accident, 11 del 14 AAVs were not operational at some point, highlighting the need for additional maintenance and inspections. Nel frattempo, Mundy said a formal evaluation of waterborne operations of the 15th Marine Expeditionary Unit “would likely have revealed training gaps and deficiencies.” Not all of the Marines had completed underwater egress training before the accident.
The readiness of the platoon was “below the expectations of a platoon preparing to deploy with a MEU, largely due to a lack of time to receive and work on their vehicles prior to composite.”
The Navy investigation led to clarifications on the requirements for safety boats, which took too long to reach the sinking AAV at the time, as well as improvements to communication between the Marines and the Navy.
“The Navy and Marine Corps learned from this tragedy and we are codifying the lessons we have learned as an organization so that the deaths of these Marines and Sailor are not in vain,” said Vice Adm. Roy Kitchener, Commander, Naval Surface Force, US Pacific Fleet. “We are reworking procedures and doctrine, clarifying aspects of amphibious operations, and instituting new training requirements to prevent future tragedies.”