What caused the Marine amphibious assault vehicle sinking tragedy?

By Philip Athey



“It’s alright, just calm down — we’re going to make it back to the ship. Just do me a favor and take a deep breath.”

These were the words a Marine told his ­amphibious assault vehicle rear crewman on July 30, 2020, as reality hit that the AAV they were in was actually sinking.

The water was up to top-of-the-boot level at that point, and the Marines and sailor trapped inside were nervous.

The platoon had been finishing a training raid and was coming from San Clemente Island, California.

Before the mission had even started that ­morning another AAV had been pulled for maintenance issues.

By the end of the mission four out of the 13 AAVs assigned to the 15th Marine Expeditionary Unit had broken down.

And, by the end of the day, the AAV these ­Marines and sailor were in would never make it back to the ship nor the shore.

Catastrophic failures led to its sinking, resulting in the deaths of eight Marines and one sailor.

Their deaths were the result of a series of failures, the 2,002 page Marine Corps investigation into the accident found.

Failures that day included the choice to use previously deadlined vehicles, the failure to notice significant mechanical issues with the AAV that sank, the failure to properly train the Marines and sailor who died, and the repeated failure to follow standard operating procedures during the exercise, the command investigation found.

The vehicle that sank that day was 36 years old — more than 14 years older than the oldest Marine killed in the accident. They were Pfc. Bryan J. Baltierra, 18, of Corona, California, a rifleman. Lance Cpl. Marco A. Barranco, 21, of Montebello, California, a rifleman. Pfc. Evan A. Bath, 19, of Oak Creek, Wisconsin, a rifleman. U.S. Navy Hospitalman Christopher Gnem, 22, of Stockton, California, a hospital corpsman. Pfc. Jack Ryan Ostrovsky, 20, of Bend, Oregon, a rifleman. Cpl. Wesley A. Rodd, 22, of Cypress, Texas, a rifleman. Lance Cpl. Chase D. Sweetwood, 18, of Portland, Oregon, a rifleman. Cpl. Cesar A. ­Villanueva, 21, of Riverside, California, a rifleman. And Lance Cpl. Guillermo S. Perez, 19, of New Braunfels, Texas, a rifleman.

The Marines and sailor who died were all ­assigned to Battalion Landing Team 1/4.

“The investigation reveals a confluence of human and mechanical failures caused the sinking … and contributed to a delayed rescue effort,” Lt. Gen. Steven Rudder, commander of Marine Forces Pacific, said in the investigation.

“Ultimately, this tragic mishap was preventable,” he said.

Mechanical problems

On the day of the incident the vehicle that sank ran into its first mechanical problem while still on the beach of San Clemente Island, California.

It was there on the beach that the AAV crew had discovered oil leaking out of the engine. They eventually added six gallons of oil to the ­transmission, roughly a quarter of the 23 gallons required for it to operate correctly.

“During the time we were on the island I remember … the driver had mentioned that his transmission oil was running low,” the rear ­crewman in the AAV that day told investigators.

The rear crewman, whose name was redacted from the investigation, normally was an AAV mechanic, but was assigned to the AAV that day because the usual rear crewman had tested positive for COVID-19.

After refilling the vehicle with oil, the crew set off on its return trip to the Somerset, according to the investigation.

No safety boat was in the water that day.

In the morning the safety boat offered by the crew of the Somerset had mechanical issues and was unable to deploy. But, because AAVs can operate as safety boats when no other vehicle is available, the platoon commander designated one of the AAVs as the safety boat for the trip to shore. Though one AAV was designated, two were required by the standard operating procedures —one of the first violations of the day.

For the return trip the commander said he assumed the Navy would be providing safety boats and did not designate any of the vehicles as a ­safety boat, the investigation found.

As the AAVs headed out to sea they started to experience rougher waters than were permitted by mission’s no-go standards.

“As soon as we splashed again you knew almost immediately that the sea state was worse,” one of the Marines on the AAV told investigators. “We were rocking back and forth really hard. We were getting so much water through the hatches on top that I thought it was raining.”

Prior to any exercise, AAV leadership is supposed to observe the water to ensure Marines are not operating in unsafe conditions.

The last sea state observation that day took place around 12:23 p.m., more than four hours before the AAVs headed back to the Somerset. Though there is no definitive evidence, it is suspected that the sea state “exceeded the no-go decision criteria,” the investigation found.


To read more about this preventable tragedy – https://www.marinecorpstimes.com/news/your-marine-corps/2021/04/15/what-caused-the-marine-amphibious-assault-sinking-tragedy/

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