Cessna S550 Citation S/II, Dillon, Mont., May 3, 2007–The NTSB did not determine the reason for the in-flight loss of control of the Citation, which crashed on descent to Dillon Airport, killing the ATP-rated pilot and a passenger. The aircraft was destroyed.

When the pilot canceled radar service, he was at 14,000 feet, out of FL380. The jet descended at a steady rate to 13,000 feet then began turning right for the procedure turn outbound and descended to 12,900. The airplane lost 1,600 feet in the next 10 seconds and radar contact was lost. Witnesses heard a loud engine noise, then a “plop” noise, and the airplane was seen turning to the right with its nose down about 75 to 80 degrees, turning six to seven times before disappearing from sight.

Anti-ice fluid was found on the leading edges of the wing and tail anti-ice panels. An airmet indicated the freezing level was from 4,000 to 10,000 feet, with icing potential up to 20,000 feet.

The aircraft was registered to Hamilton Ranches of Itasca, Ill.