In-Flight Breakup After Pitot Tube Icing (N22EK)

Flight Progression and Weather Conditions After takeoff, the pilot received progressive altitude clearances up to flight level 200 (FL200). While cruising at FL200, the pilot reported moderate chop. At approximately 1025 Central Daylight Time, the pilot requested and received clearance to FL220. About three minutes later, the pilot inquired about cloud tops and stated that the aircraft was in a layer between FL200 and FL210. An area forecast had predicted instrument flight rules (IFR) conditions, thunderstorms, and icing in the vicinity of convective activity in the area. The pitot heat switch was later found in the off position. ## Aircraft Behavior and Breakup Soon after the pilot's report, the aircraft began deviating from its assigned altitude of FL220 (22,000 feet). It climbed above the assigned altitude, then descended to approximately 20,500 feet before pitching up to about 23,000 feet. The aircraft then entered a steep descent. An in-flight breakup occurred around the time the aircraft emerged from the clouds near the 2,000-foot level. Wreckage was scattered over a wide area. The left wing was found about 0.2 mile from the fuselage, while pieces of the rudder and stabilizers were located about 100 yards from the fuselage. Examination of fractures on major structural components showed features typical of overstress separation, with no preexisting cracks found. Both occupants were killed.