Four soldiers died after a Black Hawk helicopter crashed during a training mission on Colorado's second-highest mountain, the Army's Special Operations Command said Thursday.
The helicopter crashed Wednesday afternoon near the summit of 14,421-foot Mount Massive.
The Army initially said two were killed, one was injured and one was missing. The missing man was found dead late Wednesday, and the injured man died on the way to the hospital Wednesday, said Lt. Col. John Clearwater, a spokesman for the command at Fort Bragg, N.C.
All were male soldiers from Fort Campbell, Ky., he said. Their names haven't been released.
The crew was training in high-altitude mountainous conditions, "much like the environment they operate in Afghanistan," Clearwater said, adding that he didn't know whether the crew had served there.
The helicopter was assigned to the 160th Special Operations Aviation Regiment (Airborne) at Fort Campbell. Soldiers in the 160th are known as "night stalkers" because they specialize in nighttime operations. The regiment's Web site says the 160th has carried out combat operations in Iraq and Afghanistan.
Wednesday's flight began at Peterson Air Force Base in Colorado Springs, which is about 90 miles east of Mount Massive.
The cause of the crash hasn't been released. The Black Hawk's flight recorder was recovered and an investigation team from Fort Rucker, Ala., was at the crash site Thursday, Clearwater said.
The MH-60 Black Hawk is frequently used for infiltration missions and to bring supplies to special-operations forces in the field, according to the unit's Web site. The helicopter is also used for rescue and medical evacuations, and an armed version is used for escort and fire support.
Not all helicopters can fly at high altitudes. Only those with powerful engines are able to achieve the lift needed to stay airborne in the thinner air found at higher elevations.
Higher temperatures can compound the problem, making it seem as if the chopper is flying at an even higher elevation than it really is, said Maj. Joshua Day, the commander of the Colorado Army National Guard's High-Altitude Army Aviation Training Site in Gypsum, which helps train pilots for missions to Afghanistan.
"The effects kind of pile on to each other," he said.
At the training site, instructors focus on what's called power management, becoming aware of how much power a chopper's engine is able to produce given conditions and how to operate accordingly. Day said coming in too fast or too slow could cause the rotor to spin slower and the chopper to sink, a big danger for aircraft flying so close to the ground.
Weather conditions reported near the site of the crash weren't unusual for the mountains — temperatures in the 50s and 60s and winds gusting up to 26 mph, according to the National Weather Service.
But those conditions were reported between 2,000 feet and 4,000 feet below where the helicopter crashed, and there can be significant differences in winds and temperatures as altitude increases, said Jim Pringle, a meteorologist with the agency's Grand Junction office.