Background
The airplane was operated by the manufacturer and was on a sales demonstration itinerary. At the time of the accident, it was being repositioned following a demonstration. The two pilots on board included a commercially licensed manufacturer's sales pilot and a private licensed regional sales distributor.
Flight and Weather
Prior to departure, one of the pilots requested and received an abbreviated weather briefing, which included an airman's meteorological information notice (AIRMET) for occasional moderate rime ice. The pilot then filed an instrument flight rules (IFR) flight plan for a route over mountainous terrain, with a published Minimum En route Altitude (MEA) for the airway that was above the predicted icing level. However, the flight plan was not activated. The pilots informed a TRACON controller who was providing VFR advisories that they intended to continue under visual flight rules (VFR) through a mountain pass and open their IFR flight plan after reaching the other side, where the MEA was lower.
Accident Sequence
A review of mode C altitude reports and analysis of cloud bases and tops indicated that the flight was likely in at least intermittent, if not mostly solid, instrument meteorological conditions (IMC) as it flew through the pass. As the flight approached the other end of the pass, the controller advised the pilots that radar showed they were heading into rising terrain and asked, "Do you have the terrain in sight?" One pilot responded, "we're maneuvering away from the terrain right now." After that, radar contact was lost.
Recorded radar data showed that the airplane made a right-hand turn toward rising terrain while continuing to climb to an approximate altitude of 8,800 feet mean sea level (msl). During the last minute of radar data, the airplane was recorded at altitudes of 8,000 feet msl, 8,800 feet msl, and 8,600 feet msl, with the last return at 7,300 feet msl. A performance study using radar data and aerodynamic data from Cessna revealed that as the aircraft turned, the bank angle steadily increased until a very abrupt change in pitch consistent with a stall occurred. The airplane then departed controlled flight and descended at a very steep nose-down attitude into mountainous terrain. Wreckage was later located at an elevation of 6,073 feet.
Wreckage and Investigation
Nearby ground witnesses first noticed the sound of the airplane, which suddenly changed to a high-pitched, increasing rpm. They then saw the accident airplane coming out of the clouds almost straight nose down. The weather was described as cold with drizzling rain and reduced visibility due to clouds. Examination of the wreckage revealed no evidence of mechanical malfunction or failure.
Probable cause was determined to be the pilot's continued flight into instrument meteorological weather conditions and his subsequent failure to maintain an adequate airspeed while maneuvering, leading to a stall/spin.