What happened
Prior to the commencement of the flight, the pilot received a weather briefing that warned of convective activity, instrument meteorological conditions, and moderate-to-severe icing along the intended path. During the flight, the pilot utilized the autopilot to assist with maneuvering while attempting to navigate around weather systems. After notifying air traffic control of an intention to turn directly toward the destination, the aircraft began a slight left turn of approximately 10 degrees, which aligned with the planned route.
Shortly after this initial maneuver, the aircraft's flight path reversed, and it began a right-hand bank. The aircraft reached a bank angle of roughly 120 degrees with the right wing down over the following 70 seconds, accompanied by slow oscillations in pitch. Satellite imagery suggested the aircraft was operating in instrument meteorological conditions when it entered a rapid descent, with a descent rate reaching approximately 7,000 feet per minute.
Findings
Post-accident inspections of the aircraft and the right engine showed no mechanical failures or malfunctions that would have prevented normal operation. The left engine was not recovered from the site. Analysis of the flight dynamics suggests the aircraft was likely not under active control once it deviated from its intended course. The evidence indicates the pilot may have failed to realize that the autopilot had disengaged. While the pilot's specific focus during the navigation phase could not be determined, the presence of turbulence and restricted visibility likely increased the pilot's workload and prevented the use of external visual cues to detect the developing bank. The initial roll rates may have been too subtle to alert the pilot to the developing unusual attitude, and the convective weather conditions likely hindered any attempt at recovery.