Aviat A1 N236AM accident near Santa Ynez, California

Probable cause

The pilot’s failure to maintain clearance from mountainous terrain during cruise flight in low visibility and mountainous obscuration conditions.

NTSB analysis

Before the accident flight, the private pilot had flown to a ranch. The ranch owner reported that, after the pilot decided to return home and once, they had walked about halfway back (about 100 yards) to the airplane, the pilot sat down and told him that he was “kind of tired today.” A few minutes later, they continued walking to the airplane. Subsequently, the ranch owner watched the pilot board the airplane, taxi out, and take off. According to local law enforcement personnel, concerned friends and family notified them that the pilot had not returned. Shortly after, the Federal Aviation Administration issued an alert notice. A law enforcement air unit found the airplane wreckage the following morning on steep, rising, mountainous terrain about 8.8 miles northeast of the intended destination.

Recorded radar data showed a radar target consistent with the accident airplane about 6 miles west of the ranch on a west-northwesterly heading for about 6 minutes. The airplane then turned right to a northwesterly heading and began descending. The airplane continued along this heading for about 2 minutes until the last recorded radar target, which showed the airplane was about 0.2 mile south of the accident site at 2,725 ft mean sea level.

Satellite imagery around the time of the accident showed an extensive cloud layer that obscured the departure and intended destination areas. The imagery also showed that a broken layer of low stratiform-type clouds obscured the accident site and the lower terrain west of the site around the time of the accident. A TAF issued 4 minutes before the accident forecast scattered clouds at 2,500 ft above ground level at the destination airport. At the time of the accident, AIRMET Sierra was valid for mountain obscuration near the accident site.

Examination of the airplane and engine revealed no preaccident mechanical malfunctions or failures that would have precluded normal operation. Therefore, based on the evidence, it’s likely that the pilot encountered reduced visibility and mountain obscuration conditions, which likely led him to turn the airplane away from his intended destination and subsequently collide with mountainous terrain.

Toxicology tests detected zolpidem, which is used for the short-term treatment of insomnia and is impairing, in the pilot’s specimens. The pilot’s wife reported that her husband was taking blood pressure medication and that he suffered from insomnia. However, despite the ranch owner’s statement that the pilot felt tired and the pilot’s history of insomnia and use of zolpidem, the available medical evidence was insufficient to determine whether he was impaired by inadequate sleep, an acute medical condition, or his use of zolpidem.

Text from the NTSB. Open the NTSB docket for WPR19FA146 for the full record.