Cessna U206G N71BS accident near Yellow Pine, Idaho

Probable cause

The pilot's failure to maintain clearance from the trees while taking off in a high-density altitude. Contributing to the accident were the pilot's failure to perform pre-takeoff performance calculations, his positioning of the elevator trim in a nose-down position, and the discrepancy between the airplane's flap positioning lever and the actual position of the flaps.

NTSB analysis

During a biennial flight review, at the suggestion of the evaluating instructor pilot, the Pilot-In-Command elected to land at a remote back-country airstrip where he had not made prior plans to land. After landing at the 800- to 900-foot-long strip, the pilot took off in the high-density-altitude environment without having first completed an aircraft performance calculation or checking his airplane's outside air temperature gauge. Although the pilot reported that there did not seem to be any issues with the engine producing full power, soon after liftoff the airplane struck a number of pine trees and descended into the terrain. A postaccident inspection of the airplane did not find any evidence of powerplant anomalies, but did reveal that the elevator trim was set at a five degrees tap up (airplane nose down) position, and that the flaps were extended 25 degrees even though the cockpit indicator indicated that they were at 20 degrees.

Text from the NTSB. Open the NTSB docket for WPR09LA343 for the full record.