Cessna 172 N5781A accident near Veneta, Oregon

Probable cause

The pilot’s failure to maintain adequate airspeed and altitude to clear trees during the initial climb after takeoff.

NTSB analysis

Witnesses located at their residences adjacent to the accident site reported hearing the airplane takeoff from the airport and that the engine sounded normal. Shortly after, the sound of the engine stopped. One witness reported that while he was outside his home, he saw the accident airplane fly over 100-foot tall trees north of his position at an altitude of about 200 feet above ground level (agl) and that the engine sounded normal. The witness said that while he directed his attention away from the airplane momentarily, he heard the engine suddenly stop and he immediately looked back and observed the airplane descend into 100-foot tall trees.

An iPhone was located within the wreckage and contained a 23-second video recording inside the accident airplane. Review of the video revealed that it began as the airplane initiated takeoff roll on the grass runway. The video briefly captured the engine tachometer gauge, which displayed 2,300 revolutions per minute (RPM). Throughout the video, the engine sound was consistent and did not increase or decrease. During the final 8 seconds of the video, after the airplane became airborne, a sound, similar to a stall warning horn was heard until the end of the recording.

Postaccident examination of the airframe and engine run revealed no evidence of any preimpact mechanical malfunction or failure that would have preluced normal operation. Cockpit documentation revealed that the throttle was in the fully extended or idle position, and was bent downwards. Given the idle position of the throttle and downward bend, it is likely that the pilot reduced power prior to impacting trees. The sound of the stall warning horn within the recorded video suggests that the airplane was traveling at a slow airspeed immediately after takeoff and most likely continued in this state throughout the climb. While witnesses reported hearing the engine lose power, it is possible that the witnesses heard the reduction of engine power from a high power setting to an idle power setting prior to impact with trees, thus being similar to a loss of engine power.

Toxicology tests on the pilot were found positive for metabolites of marijuana within the pilot’s blood and lung tissue. Most behavioral and physiological effects return to baseline levels within 3-5 hours after drug use, although some residual effects in specific behaviors have been demonstrated up to 24 hours, such as complex divided attention tasks. Psychomotor impairment can persist after the perceived high has dissipated. In long term users, even after periods of abstinence, selective attention has been shown to be adversely affected with increasing duration of use, and speed of information processing has been shown to be impaired with increasing frequency of use. The exact degree of impairments in cognition, judgment, and motor function were unable to be determined. The pilot’s use of marijuana was likely more than five hours before the accident and may have contributed to his failure to successfully manage this flight.

Text from the NTSB. Open the NTSB docket for WPR12FA274 for the full record.