Flight Details
The pilot departed on an instrument flight rules (IFR) flight plan along a route that had been forecast and reported to contain thunderstorm activity with the possibility of icing and turbulence.
In-Flight Events
While at 15,000 feet, the pilot reported encountering rain and icing and requested a lower altitude. After being cleared to 13,000 feet, radar data showed the airplane accelerating to 6,250 feet per minute.
Witness Observation
Shortly thereafter, a ground witness observed the fuselage descending out of a cloud with no wings or tail.
Wreckage Examination
Examination of the wreckage failed to reveal any pre-existing mechanical anomalies.