'Tragic Mishap Was Preventable': How the Marines Failed 9 Troops Whose 35-Year-Old AAV Sank in the Pacific

U.S. Marines and Sailors memorial service Marine Corps Base Camp Pendleton
Memorial service at Marine Corps Base Camp Pendleton on Aug. 21, 2020 in remembrance of the eight Marines and one sailor from Bravo Company, BLT 1/4, 15th MEU, who died in an assault amphibious vehicle mishap off the coast of California, July 30, 2020. (U.S. Marine Corps/Cpl. Dalton S. Swanbeck)

When the water sloshing around the inside of the 26-ton Marine Corps assault amphibious vehicle carrying 16 troops reached the tops of the men's boots, the rear crewman was alarmed.

"Where's my staff sergeant?" he asked the dozen infantry Marines and a Navy corpsman riding inside as the AAV headed back to a ship off California's coast.

The crewman grabbed one of the grunts' rifles, sticking the buttstock into the oily water to gauge how deep it was. He knew that once it hit their ankles, they needed to prepare to bail.

"Where's my staff sergeant?" the crewman asked again, sounding more worried than before. The vehicle commander was up in the turret as the AAV hit rougher seas on its way back to the amphibious transport dock Somerset, having left a cove on San Clemente Island's west side.

One of the infantry Marines later recalled telling the crewman to calm down.

"We're going to make it back to the ship," he said. "Just do me a favor and take a deep breath."

That the troops inside the vehicle weren't trained to recognize the dire situation they were in is just one of many failures revealed in a months-long investigation into what would be the Marine Corps' deadliest AAV training accident. A mix of mechanical problems, leadership failures and training gaps cost eight Marines and a sailor their lives -- all of whom drowned after the decades-old amphibious vehicle filled with water, tipped and sank 385 feet beneath the ocean's surface.

One of the troops was found inside the vehicle. The other seven who went missing were found in its vicinity.

"Ultimately, this tragic mishap was preventable," Lt. Gen. Steven Rudder, who assumed command of Marine Corps Forces Pacific two weeks before the July 30, 2020 accident off San Diego's coast, wrote in a letter endorsing the investigation's findings. "The actions directed in this document are intended to prevent future incidents of this kind."

Cpls. Wesley Rodd and Cesar Villanueva; Lance Cpls. Marco Barranco, Guillermo Perez and Chase Sweetwood; Pfcs. Bryan Baltierra, Evan Bath and Jack Ryan Ostrovsky; and Navy Hospitalman Christopher Gnem were killed in the accident. They were assigned to Bravo Company, Battalion Landing Team, 1st Battalion, 4th Marines. Their unit was training to deploy with the 15th Marine Expeditionary Unit.

No single problem caused the AAV to sink that day, one of two investigations into the accident found. (A second investigation conducted by the Naval Safety Center will not be publicly released.) Rather, "a sequence of mechanical failures" contributed, it states. The vehicle, one of more than 800 like it in the Marine Corps' inventory, was built 17 years before the youngest Marine killed in the tragic mishap was born.

Problems that allowed the most significant amounts of water to seep into the vehicle included faulty seals on a plenum grill at the front of the vehicle, which controls airflow, and a wrongly installed headlight.

There were no safety boats in the water, which goes against Navy and Marine Corps policies. Unit leaders also failed to ensure their Marines completed egress training, which teaches them to get out of a sinking vehicle or aircraft, before their amphibious vehicle left a Navy ship for a morning raid exercise.

Most of the infantry Marines had only ridden in one of the tracked vehicles on land, never in water. Eight of the nine killed in the accident had only been trained to get out of the vehicle in shallow water, the investigation found. The Marines also weren't given a standard safety briefing that's supposed to occur anytime an AAV heads into the water. That briefing would've helped familiarize them with escape hatches and other protocols.

The Marine commanding the AAV also failed to order the troops to evacuate the sinking vehicle early enough, the investigation found. Procedures call for the vehicle commander to evacuate troops riding in their AAV when water reaches ankle level, and for the crew to bail if water reaches the benches inside.

Since there was no safety boat present, and most of the other AAVs nearby were back on the ship or close to it, the vehicle commander faced a tough choice, a Marine leader familiar with the investigation told reporters Thursday. The former Marine Expeditionary Unit, or MEU, commander was one of four experts to weigh in on the findings, though they did so anonymously to speak candidly about the results.

"For a long time, he was by himself as the last vehicle in a column of vehicles, with a ship somewhere between 1,500 and 2,000 yards away and no other vehicle or safety boat anywhere in proximity," the Marine said of the vehicle commander. "He was signaling his distress. He was trying to report his distress on the radio. He had a lot going on, and he was taking the decisions with the information that he had available at the time."

Inside, most of the troops still still wore their heavy protective equipment and helmets, as water continued filling the inside of their vehicle. Two were later found with their M4 service carbines still slung around their bodies.

An emergency evacuation lighting system was found to have been disabled. Chemical lights should've been attached to mark hatch, or door, handles, but weren't. The Marines inside the vehicle resorted to using flashlights on their personal cell phones to find the handles, which they struggled to open since they weren't trained to do so.

Two commanding officers have been removed from their jobs since the accident over a loss of confidence in their abilities to lead.

Lt. Col. Michael J. Regner, commanding officer of Battalion Landing Team, 1st Battalion, 4th Marines, was relieved in October. Col. Christopher Bronzi, the 15th Marine Expeditionary Unit's commanding officer, was relieved of command this week. Bronzi still led the MEU through its training workup and four months of its deployment to the Middle East before he was relieved over the newly released investigation.

The reliefs mark the second time in a year that senior Marine Corps officers have been punished for fatal accidents investigators determined could have been prevented.

"This is not what right looks like," a Marine safety expert said this week. The Marine Corps has been briefing families of the nine killed in the mishap on their findings.

Lt. Gen. Karsten Heckl, I Marine Expeditionary Force's commanding general who carried out the reliefs of the two commanding officers, called the training problems, safety shortcuts and other conditions that led to the fatal mishap "totally unacceptable."

"This serious failure of leadership contributed to the overall events that led to the loss of life and injury of our Marines and Sailor," Heckl added.

A Changed Mission

Little went as planned as Marines and sailors prepared to launch a mechanized raid on San Clemente Island on the morning of July 30.

Fourteen AAVs were supposed to launch from the Somerset. By about 7:45 a.m., 13 of them had left the ship. One stayed back due to maintenance problems.

When they reached the beach, the Marines carried out a mechanized raid and were scheduled to return to the ship by about noon. That return was delayed when another AAV broke down on the island.

The crew of the AAV that later sank performed some maintenance while ashore, according to the investigation. There appeared to be a fluid leak, and they added six gallons of transmission fluid to the vehicle -- something the former MEU commander said should have signaled a big problem.

"The transmission capacity for oil and AAV is 23 gallons," he said. "So they added six gallons -- nearly a quarter the capacity of the tank. … That's pretty significant and it's not normal."

Still, at about 4:45 p.m., that AAV was one of nine that started heading back to the Somerset. Four AAVs stayed back on San Clemente Island, and two more later had to turn back due to problems, leaving seven in the water.

The AAV platoon's first section leader said he'd collected each of the vehicles' operational checks before the vehicles left the beach, but when the investigating officer requested copies, the Marine could not produce them.

The sea state near San Clemente Island was calm, but things got choppier when the vehicle got past the cove. A safety boat was available to escort the AAVs back to the ship, but remained on the Somerset because no one requested it. Marines can use nearly empty AAVs as safety boats in a pinch, but no one planned for that either.

The AAV platoon commander said he assumed the ship would have safety boats out as the vehicles made their way back to the Somerset, but "this assumption was never confirmed ... [and] was never coordinated," the investigation states.

The AAV that was about to hit trouble was the last of the seven headed back to the Somerset. Since they'd been delayed by the maintenance problems on the beach, the Somerset was now conducting flight operations, leaving it heading away from the AAVs' positions.

The last AAV began to show signs of trouble. First the transmission failed. Other mechanical trouble followed.

"Transmission fails, the water drive fails, the engine RPMs drop," the former MEU commanding officer said. "Water is coming into the engine compartment through the plenums. It's also coming into the engine compartment through a headlight that was leaking."

That eventually led the generator to fail, leaving the vehicle operating on battery power alone.

"When the transmission failed, the hydraulic bilge pumps were degraded," the former MEU commander added. "... The electric bilge pumps were not operating at capacity, nor was the radio. So we've got a series of mechanical failures that are compounding the danger this AAV is in."

As the AAV slowly sank, the vehicle commander was on top of the AAV, waving a blue-and-white checkered November flag. Someone on the ship spotted the maritime distress signal, and the two AAVs that hadn't yet reached the Somerset turned back.

By the time the first of those two vehicles reached the AAV in peril, it was only about 6 inches above water. The water inside was at bench level when the vehicle commander told his rear crewman to open the side cargo hatch, instructing everyone to "drop their stuff" and get out. But the Marines were struggling to operate the handle to open the latch. It was dark. Some held up cell phones for light, since no other light sources were available.

The troops inside started to panic, witnesses recalled. One worried about his swimming skills.

The vehicle that approached to help accidentally bumped into the sinking AAV due to the choppy sea state, and the impact turned it sideways into the waves. When the hatch was opened, a wave quickly swept over the top of the AAV.

"This wave rapidly filled the troop compartment with water and caused AAV ... to assume a nose high pitch angle and rapidly sink," the investigation states with 11 still in the vehicle.

The AAV that pulled up to help was able to recover the vehicle commander, rear crewman and three embarked personnel. The AAV driver then came up to the surface. An officer from a third vehicle that was now at the scene dove into the water to save the driver.

Perez and another Marine also emerged from the water. They attempted lifesaving aid, but Perez could not be saved.

Baltierra, Barranco, Bath, Gnem, Ostrovsky, Rodd, Sweetwood and Villanueva were missing. Rodd, at 23 years old, was the oldest of the nine killed in the accident.

Two rigid-hull inflatable boats were launched from the Somerset to assist with the search at 6:25 p.m. Coast Guard vessels and other ships were tasked with search-and-rescue operations.

The AAV was found on Aug. 3. The Marine Corps announced four days later that Navy salvage teams had recovered the bodies of the missing sailor and seven Marines.

'We Will Get Better'

The Marine Corps is in the process of replacing its fleet of aging AAVs with the new Amphibious Combat Vehicle, but the rollout will take years. Marines in California are currently testing and evaluating the new amphibious vehicles that will carry troops between ships and land.

That means the Marine Corps will continue using AAVs for years to come. For now though, their water operations remain halted pending fleet-wide safety inspections. Commandant Gen. David Berger ordered the pause the day after the AAV sank.

"What we learned about this mishap vehicle is that there were problems with its watertight integrity, and that we may have similar problems elsewhere in the fleet," a Marine leader who previously commanded a division said Thursday. "As it turns out, we did."

Most of the inspections are complete, the Marine added, though they're still checking some AAVs in prepositioned stocks around the globe. The most common problems, an AAV expert said, were problems with cargo hatches and the plenum -- the grill at the front of the vehicle.

"Since this mishap, these detailed depot-level maintenance inspections are now required annually for every vehicle, regardless of where they're located," the AAV expert said. "So every vehicle will go through this watertight integrity inspection annually."

That inspection now involves pouring water onto a vehicle to check for leaks, rather than just the visual checks crews usually completed in the past, he said.

But operating the aging vehicles will require "ruthless adherence to maintenance procedures, use of checklists, and operating policies and procedures," the investigation notes. AAV units must be well led and trained, it adds, and "disciplined in their approach to maintenance and operations."

When the 15th Marine Expeditionary Unit began to assemble before its fall deployment, the AAVs selected were far from mission-ready, the investigation found. They came from something Heckl called "the deadline lot," and experts said 12 of the 13 chosen were inoperable.

"They had significant maintenance difficulties," the former MEU commander said.

Once those AAVs were assigned to the MEU though, it was up to Bronzi to make sure they were maintained, Heckl wrote. The MEU's commanding officer did not make the AAV maintenance deficiencies a priority, he added.

That finding needs attention across his Marine expeditionary force, Heckl noted. He called the general operation of training and safety standards for ground vehicles "inadequate."

"There should be a concerted Marine Corps effort to ensure ground vehicle safety procedures and checks are conducted in a manner more akin to the vigorous aviation procedures and checks," he wrote. "In short, there can be no laxity with regard to safety checklists of any kind. This will be a focus of effort within I MEF and its subordinate units, including MEUs."

As the Marine Corps shifts its focus to combat threats from China, ship-based operations are being highly prioritized. Leaders acknowledged shortfalls in some areas after 20 years of land-based missions in the Middle East.

"We will get better," the former division commander said. "... We're aware of [the problems] and we're going to fix it."

-- Gina Harkins can be reached at gina.harkins@military.com. Follow her on Twitter @ginaaharkins.

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