A collision that killed seven Marines in one of the Marine Corps' deadliest aviation training accidents in years occurred over a sprawling desert range favored by the U.S. military because its craggy mountains and hot, dusty conditions are similar to Afghanistan's harsh environment.
Officials were scrambling Thursday to determine what caused the AH-1W Cobra and UH-1 Huey to crash during a routine exercise Wednesday night when skies were clear and the weather was mild.
There were no survivors in the accident near the Chocolate Mountains along the California-Arizona border.
It was the fifth aviation accident since March involving the 3rd Marine Aircraft Wing headquartered at Miramar Marine Corps Air Station in San Diego. Throughout the Navy and Marine Corps, there have only been two other aviation training accidents in the last five years involving seven or more deaths, according to the military's Naval Safety Center.
"It's an unfortunate consequence of the high tempo of operations," said retired Marine Col. J.F. Joseph, an aviation safety consultant. "They're out there working on the edge trying to exploit the maximum capabilities of the aircraft and their tactics. Just by the virtue of that, in becoming combat ready, these unfortunately are not uncommon occurrences."
The Marine Corps and the Navy, nonetheless, stand out in their efforts to mitigate that risk and make training as safe as possible, he said.
With 17,500 Marines and sailors, including personnel stationed at Camp Pendleton and Marine Corps Air Station Yuma in Arizona, the 3rd Marine Aircraft Wing conducts hundreds of aviation training exercises a year so troops can get as much experience as possible before they go to war.
The number of Marines killed in the latest crash shook the military community. Chaplains and counselors were called in to talk with members of the units. Six of the Marines killed were from Pendleton -- the West Coast's largest base -- and one was from the base in Yuma.
Their identities will not be released until their families have all been notified.
Two of the Marines were aboard an AH-1W Cobra, and the rest were in a UH-1 Huey utility helicopter. They were flying in a remote section of the 1.2 million-acre Yuma Training Range Complex as part of a two-week standard training called "Scorpion Fire" that involved a 450-member squadron from the 3rd Marine Aircraft Wing.
The helicopters collided near dunes at the edge of the Yuma range about an hour before the range was to shut down for the evening.
Ground troops were in the area, but they were not affected, said Gunnery Sgt. Dustin Dunk, a spokesman at the Yuma base, which is a 90-minute drive from the accident site.