Background
The flight was conducted under instrument flight rules. A preflight weather briefing had identified hazardous thunderstorm activity along the intended route.
Event
The pilot attempted to penetrate a line of thunderstorms, which had tops reaching 45,000 feet. During his final radio transmission, the pilot reported encountering severe turbulence. Shortly thereafter, witnesses observed pieces of the airplane falling to the ground, scattered across an area of 10 square miles.
Weather Conditions
At the time of the accident, surface winds were estimated at 40 miles per hour, gusting to 60 miles per hour. Heavy rain was also reported at the site.
Preflight Briefing
The preflight weather briefing explicitly identified the hazardous weather conditions. The briefer advised the pilot to remain on the ground until the weather had passed.