What happened
During the flight, the pilot was operating under progressive altitude clearances, eventually climbing to FL200. While cruising at this level, the crew reported experiencing moderate chop. At approximately 1025 CDT, the aircraft was cleared to climb to FL220. Shortly after reaching this altitude, the pilot noted that the aircraft was positioned within a cloud layer between flight levels 200 and 210.
Following this report, the aircraft began experiencing significant altitude deviations. The plane climbed above its assigned level of FL220 before descending to approximately 20,500 feet. This was followed by an upward pitch to roughly 23,000 feet and a subsequent steep descent. As the aircraft emerged from the cloud layer near 2,000 feet, it underwent an in-flight breakup.
Search efforts located wreckage across a broad area. The left wing was discovered approximately 0.2 miles from the main fuselage, while fragments of the rudder and stabilizers were found within 100 yards of the wreckage center. Both occupants were killed in the accident.
Findings
Investigation into the structural failures revealed that fractures on major components were consistent with overstress separation, though no pre-existing cracks were identified. Environmental forecasts for the area had indicated potential thunderstorms, icing, and IFR conditions. Notably, the pitot heat switch was discovered in the 'off' position.
The failure to activate pitot heat while flying in icing conditions led to blocked airspeed indications, which contributed to the loss of control.