The 22 March 2009 fatal crash of a Pilatus PC-12 at Butte, Montana was the result of a series of operational errors by the pilot, according to the US National Transportation Safety Board.
The pilot did not ensure that a fuel-system icing-inhibitor was added to the fuel, which it must be in surface temperatures below 0?C. The single-engine turboprop, owned by Oregon-based Eagle Cap Leasing, was operating as a private flight flight from Oroville, California, to Bozeman, Montana, but the flight diverted to Bert Mooney airport at Butte for a unknown reason. On the approach there the pilot lost control.
The PC-12 developed ice in the fuel system that restricted the flow of fuel from the left tank to the engine, which led to a serious lateral fuel tank imbalance. The Board questioned the pilot's failure to divert when low fuel pressure warnings originally enunciated, and for failing to take account of the lateral fuel imbalance in his management of the aircraft on final approach.
All 14 people on board were killed in the crash.