Amateur-built Lancair 360 MK-II N989TT accident near Milford, Utah

Probable cause

The pilot's loss of control of the airplane due to spatial disorientation after inadvertently entering instrument meteorological conditions. Contributing to the accident were the pilot's inadequate preflight preparation, his en route decision-making, and his distraction due to a partial loss of engine power due to a restriction in a fuel injection nozzle.

NTSB analysis

The pilot, who was not instrument rated, intended to fly to his destination while remaining in visual meteorological conditions (VMC). While en route, he entered an area where the clouds started to close in on him. Although the air traffic controller whom he was communicating with advised the pilot that there was an airport with VMC a short distance behind him, the pilot elected to attempt to proceed to his destination. As he continued, weather conditions became such that the pilot elected to land at an alternate airport. While being vectored to the alternate airport, the airplane's engine began to run rough, which, according to recorded engine analyzer data, was due to a restriction of the fuel flow in the orifice of the no. 1 cylinder injector nozzle. While attempting to deal with the rough running engine and maneuvering toward the alternate airport, the pilot inadvertently entered the clouds, and most likely lost control of the airplane due to spatial disorientation. The airplane then descended near vertically into the terrain. There was no record of the pilot receiving a weather briefing either from an FAA-contracted Flight Service Station or from either Direct User Access Terminal Service (DUATS) provider.

Text from the NTSB. Open the NTSB docket for WPR11FA147 for the full record.