US troops had to use their phones as flashlights to try to escape a sinking assault amphibious vehicle that killed 9 of them

• The Marine Corps has released the investigation into the AAV that sank and killed nine last summer.
• The investigation shows that failure after failure led to tragedy.
• At one point, troops used phones to open the escape hatch because the emergency lights were out.

The US Marine Corps assault amphibious vehicle (AAV) accident last summer that killed nine service members was a disaster, one in which failure after failure led to tragedy, a newly-released investigation has revealed.

A lot of things went wrong. At one point, just minutes before the vehicle sank, troops on board were using their cell phones as flashlights to try and open one of the escape hatches because the emergency lighting system wasn't working. That was just one of many problems the investigation found.

An AAV is a heavy fully-tracked amphibious landing vehicle commonly known as an "amtrac" or "track" that transports as many as two dozen troops between ships at sea and shore.

Last July, an AAV assigned to Bravo Company, Battalion Landing Team 1st Battalion, 4th Marines, part of the 15th Marine Expeditionary Unit, sank off the coast of California as it returned to the amphibious transport dock USS Somerset from San Clemente Island.

The mishap vehicle was carrying three AAV crewmembers, 12 Marines, and one Navy corpsman. Eight embarked Marines and the Navy sailor died, making this incident the deadliest AAV training accident in the vehicle's history.

In the aftermath, the Marine Corps grounded its entire fleet of AAVs as it launched an investigation into exactly what happened. Waterborne operations have yet to resume.

The commander of US Marine Corps Pacific blamed the sinking and the resulting deaths on "a confluence of human and mechanical failures" in a statement attached to the investigation. He added that "this tragic mishap was preventable."

'Human and mechanical failures'

The command investigation found that the accident was caused by maintenance failures, delayed evacuation orders, and a failure to properly train embarked personnel on AAV safety procedures, among other issues.

As the 26-ton amphibious vehicle returned to the Somerset following a shore exercise on July 30, water was leaking into the hull of the AAV from multiple locations. All AAVs leak, but more water than normal was leaking in due to various maintenance failings.

Around 5:30 p.m. local time, the rear crewman informed the vehicle commander that the water inside the AAV had reached the deck plate. The commander is said to have replied: "Thanks for letting me know."

Standard operating procedure is that embarked personnel prepare for water operations when water hits the deck plate. Evacuation should begin when water reaches boot ankle level, but that did not happen and the results were fatal.

In addition to multiple watertight integrity failures, the vehicle also suffered several other serious mechanical failures, from the transmission to the generator, which impacted the four bilge pumps in place to push water out of the vehicle. The communications system was also affected.

When water hit boot ankle level, the vehicle commander began waving the November flag, a blue and white banner signaling that a waterborne vehicle is in distress and in need of immediate assistance, but no order to evacuate was given, the investigation said.

As for the embarked personnel who were riding in the back, the investigation said that they "were not trained appropriately and did not realize how dire the situation was ... when the water was at boot ankle level."

Not only did they not receive a proper safety briefing prior to waterborne operations, but the investigation also found that many of the embarked troops had not completed the necessary training to know how to exit the vehicle in an emergency.

The commander waved the blue and white distress flag for 20 minutes but did not make use of the pyrotechnic signaling options available.

Due to a miscommunication, there were no safety boats nor support AAVs in the water at the time of the accident, though two other AAVs did eventually maneuver to assist.

By around 6:05 p.m., water in the AAV was about calf-high, and the rear crewman was recommending evacuation to the vehicle commander. The order to open the starboard cargo hatch and start evacuation did not come until water hit the bench seats.

Troops in the back moved to open the cargo hatch on top, but things did not go smoothly due to a lack of training and decreased visibility. It was "extremely dark" inside the AAV.

The command investigation said that the "embarked personnel were using personal cell phones as a lighting source due to the Emergency Egress Lighting System not functioning and the fact that no chemical lights had been used to mark the hatch handles." The EELS had been inexplicably disabled.

By the time they got the hatch open and started getting people out, the AAV was only about six inches out of the water, leaving it extremely vulnerable. Making matters worse, an assisting AAV ran into the mishap vehicle, knocking it sideways.

When a wave washed over the struggling AAV, water came pouring in through the open hatch, flooding the vehicle.

Some troops were standing on the bench seats that run along the inside of the vehicle when "the force of the water rushing in knocked all personnel off their feet," leaving troops inside shocked and disoriented, the investigation said.

Minutes later, around 6:15 p.m., the vehicle, which had been sinking slowly for about 45 minutes, tilted up and slipped beneath the surface, plunging to a depth of 385 feet.

All but one service member made it out of the AAV, but seven troops who made it out drowned before reaching the surface. One service member made it to the surface but died of drowning injuries.

The command investigation said that all of the deceased service members were wearing body armor. Some troops appear to have tried to remove their gear, but the life preserver negatively impacted those efforts.

For those that never made it to the surface, the life preservers were less effective at depth, especially given the excess weight troops were carrying.

The service members who died when their vehicle sank last summer were Lance Cpl. Guillermo Perez, Pfc. Bryan Baltierra, Lance Cpl. Marco Barranco, Pfc. Evan Bath, Pfc. Jack Ryan Ostrovsky, Cpl. Wesley Rodd, Lance Cpl. Chase Sweetwood, and Cpl. Cesar Villanueva, and Hospitalman Christopher Gnem.

The Marine Corps said in a statement Thursday that their loss continues to be felt across the service.

'Tragic mishap was preventable'

The I Marine Expeditionary Force commander said in a statement that "this entire mishap could have been averted and lives saved if the vehicle commander had followed [standard operating procedures] and ordered the embarked personnel to take off their gear and evacuate the mishap AAV at the appropriate time."

But, there were problems at other levels as well. He noted that at the platoon level "discipline and combat effectiveness were seriously compromised."

The Marine Corps has already removed the senior commanders of BLT 1st Battalion, 4th Marines and the 15th MEU. The commander of Bravo Company has also been fired. Unspecified disciplinary action has also been recommended for some others in the chain of command.

In the wake of the deadly accident last summer, the Corps adjusted the inspection standards for its AAVs. It also halted all AAV waterborne operations until the entire fleet of roughly 800 vehicles could be inspected. The investigation said that "a majority of the AAVs failed to meet the new inspection criteria."

The AAV that sank and killed eight Marines and a sailor was not the only vehicle that encountered troubles during last summer's training exercise.

A little over a dozen AAVs were involved in the training. One had to be left on the ship because it was inoperable, another had to be picked up from San Clemente Island by a Landing Craft Air Cushion after it malfunctioned, and one lost the ability to maneuver and had to be towed back to the island.

An inspection of the participating vehicles after the accident found that most were in "poor condition."

One Marine veteran Insider spoke to previously about the problems with AAVs said that the vehicles "are death traps and need to be updated if not completely eradicated from the Marine Corps."

Marine Corps officials insist the vehicles are safe as long as procedures are properly followed.

The Corps is in the process of phasing out its AAVs and replacing them with the new Amphibious Combat Vehicle (ACV). The service is also making dozens of changes to the way it maintains and operates amphibious vehicles to make sure that nothing like what happened last summer happens again.