A pilot's "overconfidence," coupled with his lack of situational awareness regarding altitude and airspeed, contributed to the 2016 crash of an unmanned MQ-9A Reaper in Afghanistan when a flame-out training approach went wrong.

The Reaper, which was being operated by a launch and recovery element in the 62nd Expeditionary Reconnaissance Squadron in Afghanistan, crashed about 900 feet short of the runway at Kandahar Airfield while returning from a combat support mission on Feb. 20, 2016. The crash cost the government $12.3 million, but didn't cause any injuries, deaths or damage to private property.

In the Accident Investigation Board report released Thursday. Air Force investigators found that the Reaper pilot was trying to simulate a flame-out for training purposes, but set the power below the recommended setting for such approaches. The pilot failed to maintain the proper altitude, the report said, which led to a steeper descent path short of the runway.

Flame-out training requires a pilot to simulate the loss of an engine and then manage his descent to arrive at the runway at the appropriate altitude. Under such a training exercise, the remotely piloted aircraft doesn't land, but instead performs a low approach after ending the simulated flame-out.

As the pilot began his approach and reduced his power, he acknowledged that his speed was slow, the report stated. At the next point of the approach, he lowered the Reaper's nose, began to turn it toward the runway, and again noted the RPA was flying slow, commenting, "Power's too low. Now it's too high," as the power fluctuated.

The sensor operator announced the Reaper's altitude was low as it completed the turn toward the runway, the report said, and the pilot said the drone's airspeed was coming back up and he was looking for the runway. The sensor operator alerted the pilot that the RPA was approaching the runway, and the runway was visible in the pilot's display, but the pilot didn't see it, the report said.

"The [pilot] then stated, 'I do not see the runway. Is that it right there?' and the [sensor operator] responded, 'It's way out in front of you,' " the report said.

The pilot then decided to discontinue his approach and tried to increase the Reaper's power. But by that point, the RPA was about 17 knots below approach speed and descending at 880 feet per minute. Because it was going so slow, the pilot couldn't pull it out of its descent and it crashed. The aircraft was damaged beyond repair, the report said.

The investigators found no maintenance problems or malfunctions, and said the weather — which was clear with calm winds — did not contribute to the accident.

The pilot was current and qualified on the Reaper at the time of the accident, with 9.4 total instructor hours, 53.4 simulator hours, and 373 total flight hours in the MQ-9, the report said.

But the report said the pilot "flew significantly less than typical." He had flown twice in the 30-day period preceding the crash, which was enough to maintain currency. But the report said that all witnesses — including the pilot himself — acknowledged that was "well below 'normal' crew flying levels." The pilot felt it was enough to stay proficient, but his squadron commander disagreed.

As a result, the report said the pilot's overconfidence contributed to the crash. He didn't tell his sensor operator he was planning to discontinue his approach until the sensor operator prompted him. His decision to discontinue the approach was largely based on his "internal clock" and the lack of expected visual references, rather  relying on regular altitude updates or a pre-briefed altitude.

The investigation board found that the pilot's "inadequate real-time assessment" and "failure to maintain appropriate situational awareness of his altitude and airspeed" caused the crash. The pilot's overconfidence — "which led to an over-estimation of his proficiency and excessive reliance on previous experience" — also substantially contributed to the crash.