Two A-10C Thunderbolt IIs collided last year over the Nevada desert due to insufficient communication over altitude, according to a newly released investigation report.
During a night close air support training mission in the Nevada Test and Training Range on Sept. 6, the first mishap pilot, called "Pilot One" in the investigation, did not hear he had climbed too high above his assigned "altitude block," entering space that was designated for "Pilot Two," according to the Accident Investigation Board report published by Air Combat Command on Thursday.
"Pilot One climbed above the assigned altitude block during a series of commands and did not hear the audible notification signaling the altitude climb and therefore did not radio-in to deconflict established altitude blocks," ACC said in a release.
Pilot Two "did not have line of sight on [Pilot One] when the collision occurred. The midair collision rendered both aircraft uncontrollable and both pilots ejected," the release said.
The crash occurred roughly 50 miles away from Nellis Air Force Base.
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The night training was designated to get part of the weapons instructor course qualification for Pilot One; Pilot Two was the instructor, ACC said.
Both pilots remain in the Air Force and have "returned to flying status" since the mishap, ACC spokeswoman Maj. Docleia M. Gibson told Military.com on Friday.
Both pilots, with the 66th Weapons Squadron, 57th Wing at Nellis, sustained minor injuries. Both A-10C aircraft were destroyed upon impact. The cost of the accident is estimated at over $30 million.
According to the report, Pilot One said he would fly below 10,000 feet while Pilot Two would stay at 11,000 feet and above. Both pilots had appropriate equipment and gear, including night vision goggles, the report said.
But just before 8 p.m. local time, Pilot One climbed roughly 1,500 feet in a 15 minute span into Pilot Two's airspace. The task was to put targets on range during a simulated close-air support mission.
According to the report, Pilot One was cross-checking various factors, such as proper weapons delivery for the mission, as well as other aircraft parameters, without noticing he was too high.
The collision occurred at about 11,400 feet, the report said.
Additional factors were at play, the report said. They included "task over-saturation, misperception of changing environment, breakdown in visual scan, and environmental conditions affecting vision."
There were broken clouds in the area, but well above the altitude each pilot was flying, the report concluded.
"Based upon the forecast and prevailing conditions, the weather was within pilot limits," it said.
"The amount of time or attention spent performing a visual scan of aircraft instruments was not sufficient and did not allow [mishap pilot 1] to identify that an altitude deviation had occurred," Air Force Col. Bruce Munger, president of the Aircraft Accident Investigation Board, wrote in his summary.
Munger and investigators also determined Pilot Two could not see Pilot One's approach and therefore could not avoid the unintentional collision.
The crash occurred the same week as a classified aircraft crash on the same training range.
Lt. Col. Eric Schultz, 44, died from injuries sustained in an accident in which an unidentified aircraft crashed at the range, located about 100 miles northwest of Nellis. The aircraft was assigned to Air Force Materiel Command and was flying a training mission at the time of the mishap, according to a release at the time. The Air Force has never identified the type of aircraft involved in September's crash. Air Force Chief of Staff. Gen David Goldfein would say only that it was not an F-35 Joint Strike Fighter.
-- Oriana Pawlyk can be reached at email@example.com. Follow her on Twitter at @oriana0214.