Amateur-built RV-6A N992KS accident near Preston, Idaho

Probable cause

The non-instrument-rated pilot’s continued visual flight into instrument meteorological conditions, which resulted in a loss of control due to spatial disorientation.

NTSB analysis

Two pilots departed on a visual-flight-rules cross-country flight as a flight of two airplanes, with the non-instrument-rated accident pilot in the lead position. About one hour into the flight, the pilots encountered clouds at their cruise altitude of 9,500 ft and climbed above the clouds to an altitude of 11,500 ft mean sea level (msl). The pilot of the second airplane reported that he visually acquired the accident airplane after it climbed to 11,500 ft, then lost visual contact as he obtained weather information for the destination airport. ADS-B information revealed that the accident pilot began a gradual descent from about 11,500 ft to about 9,800 ft before climbing back up to about 11,000 ft before the data ended. About this time, the accident pilot transmitted to the other pilot that he was “in a cloud and doing a 180°.”

The second pilot recorded a short video of the accident airplane while the two airplanes were cruising at 11,500 ft. The footage showed the accident airplane flying over a broken to overcast cloud ceiling with cumulus and standing lenticular clouds present. A pilot report near the accident site issued about 15 minutes before the accident included clouds from 9,000 ft to 12,000 ft msl.

The airplane impacted mountainous terrain about 2 nautical miles south of the last recorded ADS-B location at an elevation about 9,200 ft msl on a heading about 180° from its last recorded heading. The airplane was significantly fragmented. Postaccident examination of the airframe and engine revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation of the airplane. The airplane was not equipped with an attitude indicator, as the pilot had removed and replaced it with a unit capable of displaying artificial horizon data, in addition to other information, on a tablet computer. The extent of his operational experience with the unit and its display options was not determined.

The reason for the pilot’s unannounced descent into the clouds could not be determined based on the available information; however, his lack of an instrument rating increased his susceptibility to spatial disorientation following the loss of visual reference to the horizon that he would have experienced upon entering clouds. The turning descent toward the accident site, as well as the fragmentation of the wreckage, which suggests a high-energy impact, are both consistent with a loss of control due to spatial disorientation.

Text from the NTSB. Open the NTSB docket for WPR22FA347 for the full record.