CASCADE, Idaho -- A small plane crash that killed one man and badly injured another near Cascade earlier this month occurred after the pilot inadvertently flew into a box canyon, the National Transportation Safety Board determined.

NTSB investigators say the pilot realized the plane was unable to climb out of the terrain, and attempted a "course reversal turn" to get out of the canyon. During the maneuver, the plane stalled, and the aircraft plummeted to the ground.

The crash happened Sept. 2 near in a remote mountain area near the Sulfur Creek Air Strip.

The pilot, 54-year-old Andrew D. Akin of Griffin, Georgia, had come to Idaho to pick the plane up from a seller in the Nampa area, and fly it back to Georgia to deliver it to the buyer, a friend of his. Flying with Akin was his cousin, 50-year-old David R. Henderson of Boise, who was also certified as a pilot.

Henderson was killed in the crash, while Akin had to be airlifted to a hospital by helicopter.

According to the NTSB's preliminary report, the plane was an experimental amateur-built Glastar GS-1, N65EW. The seller met with Akin the day before the crash, and provided a flight instructor to fly with him so that Akin could familiarize himself with the plane before flying to Georgia.

According to FAA records, Akin had 998 hours of flight experience when he applied for his certificate in February. However, the plane's previous owner said Akin told him he did not have much backcountry flying experience.

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The seller said Akin and the flight instructor flew together for about an hour and a half, after which the seller transferred ownership of the plane to the new owner. The seller told investigators he texted the pilot the next evening to ask how the return trip was going, at which point he learned about the crash.

According to the NTSB report, Akin told investigators he and Henderson has planned to fly the plane to the Sulfur Creek Ranch Airstrip near Cascade. He was about 15 miles southeast of Cascade when he flew into the canyon and ultimately crashed.

Akin used his cell phone to call the Valley County Sheriff's Office, telling dispatchers that Henderson was dead and that he was in need of medical attention. The sheriff's office pinged his cell phone and used GPS information for the plane's emergency radiobeacon to find the wreckage, then lifted Akin to safety.

NTSB investigators say the plane crashed in a rocky clearing in the forest. The helicopter pilot who helped rescue Akin said smoke from nearby wildfires somewhat reduced visibility, but that the smoke was "not an issue" of concern or impediment for flying.

The crash remains under investigation.