Cessna 172 N8518B accident near Sutter Creek, California

Probable cause

The noninstrument-rated pilot's encounter with instrument meteorological conditions (IMC) while maneuvering, which resulted in a loss of airplane control due to spatial disorientation. Contributing to the accident was the pilot's decision to attempt to descend into an area of widespread IMC.

NTSB analysis

The noninstrument-rated private pilot was conducting a personal cross-country flight. Upon return to his home airport, the pilot encountered forecast low ceilings and poor visibility; based on radar data, he was likely maneuvering in an attempt to locate the airport to land. The airplane impacted near the top of a hill at an elevation of 1,590 ft. A couple reported hearing a low-flying airplane with an engine that seemed like it was "struggling" or not producing power. Another witness in the area stated that she heard, but did not see, a low-flying airplane circling overhead and that the engine sounded like it was cutting out. The airplane then descended below a cloud layer, and she saw it heading in an eastbound direction. Although the weather conditions were conducive to the accumulation of carburetor and structural icing, based on the available evidence, the investigation could not determine whether this occurred. Examination of the airplane and engine revealed no evidence of a mechanical anomaly that would have precluded normal operation.

Instrument flight rule conditions with ceilings below 1,000 ft above ground level (agl), visibility below 3 miles in precipitation and mist, and mountain obscuration were forecast in the area at the time of the accident. However, a search of official weather sources revealed that the pilot had obtained no weather briefings. Reported observations at the destination airport (about 2 miles from the accident site) showed overcast ceilings of about 100 ft agl with a visibility of 1/4 mile about the time of the accident. Radar data showed that the accident airplane approached the area from the southwest (from the departure airport), overflew the destination airport about 4,000 ft agl, and continued tracking to the northeast for about 6 miles before descending and turning back toward the airport. In the minutes before the accident, radar data showed the airplane circling near the accident area at a low altitude. It is likely that the pilot encountered instrument meteorological conditions while maneuvering, which would have been conducive to spatial disorientation, and that the pilot subsequently lost airplane control due to spatial disorientation.

Text from the NTSB. Open the NTSB docket for WPR15FA070 for the full record.