Aircraft Disintegrates After Entering Embedded Thunderstorm (N59DB)

Incident Overview and Weather Conditions The aircraft entered an embedded thunderstorm after air traffic control (ATC) advised the pilot of several large areas of heavy precipitation in the area and along the vicinity of the flight path. The pilot responded that the aircraft's radar showed no build-ups or returns. According to the recorded taped conversation, ATC allowed deviations at the pilot's discretion. The pilot continued the flight path and was lost on radar shortly thereafter in a descending right turn at 16,800 feet MSL. Witnesses observed the aircraft exit the bottom of the cloud at about 1,000 feet AGL. The wings were seen to separate from the fuselage. Other witnesses saw the fuselage descend inverted, minus the wings, empennage, and engines, to impact in a corn field. The wreckage was scattered over an area 1 and 1/2 miles long and 1/2 mile wide. All four occupants were killed. ## Pre-Departure Observations Witnesses who had observed the aircraft's preparations for departure described it as 'mass confusion' in the cockpit. The aircraft reportedly crept forward six times during an extended 10-15 minute checklist while the engines were running at a high rpm setting on a ramp with other aircraft and people around. ## Official Findings The official findings identified three occurrences. Occurrence #1 was loss of control in flight during the normal cruise phase, with findings including inadequate preflight planning/preparation by the pilot in command, inadequate in-flight planning/decision by the pilot in command, flight into known adverse weather initiated by the pilot in command, thunderstorm weather condition, flight advisories not followed by the pilot in command, visual/aural perception by the pilot in command, and lack of total experience by the pilot in command. Occurrence #2 was airframe/component/system failure/malfunction during the uncontrolled descent phase, with findings including design stress limits of the aircraft exceeded by the pilot in command, wing separation, flight control surfaces/attachments separation, and engine assembly separation. Occurrence #3 was in flight collision with terrain/water during the uncontrolled descent phase, with the terrain condition being an open field.