File photo of a Cobra helicopter gunship and UH-1 Huey searching for insurgents after a U.S. Marine patrol in Falluja

 
File photo of a Cobra helicopter gunship  and UH-1 Huey searching for insurgents after a U.S. Marine patrol in Falluja
A Cobra helicopter gunship (L) and UH-1 Huey search for insurgents after a U.S. Marine patrol from the 2nd Battalion of the 1st Marine Division was attacked near Falluja in this file image from June 24, 2004. Two U.S. military helicopters collided over a training range in Arizona on February 22, 2012 killing seven Marines, the Marines said on February 23. The aircraft, an AH-1W "Cobra" and a UH-1Y "Huey," were conducting routine training operations when the accident occurred. REUTERS/Bob Strong/Files (IRAQ - Tags: MILITARY DISASTER)