Cessna 172M N1186U accident near Laytonville, California

Probable cause

The pilot’s impairment due to alcohol ingestion, which resulted in his failure to maintain clearance from trees during a low-altitude flyby.

NTSB analysis

The private pilot was conducting a local personal flight. Witnesses reported that they observed the airplane making several low passes over an open field. During the last pass, they observed the airplane's right wing contact a tree and then separate from the airplane. The airplane subsequently came to rest in a wooded area.

According to the autopsy report, the pilot had coronary artery maximum occlusion of 50 percent, and there was no evidence of preexisting heart muscle scarring. This amount of occlusion likely would not have caused acute symptoms and would not have impaired the pilot's judgment; therefore, the pilot's coronary artery disease likely did not impair his ability to operate the airplane or contribute to the accident.

Toxicology reports identified ethanol in the pilot's heart blood, iliac blood, vitreous, and urine. The distribution of the ethanol in the pilot's tissue was consistent with ingestion, not postmortem production. Although there was some variation, all of the pilot's tissues tested positive for ethanol well above 0.040 gram per deciliter, which indicates that the pilot had ingested sufficient ethanol to impair his ability to safety operate the airplane.

Text from the NTSB. Open the NTSB docket for WPR14LA230 for the full record.