What happened
The pilot of N9143B requested permission from air traffic control to deviate approximately 12 miles west, believing a gap existed in the prevailing weather. Radar ground track analysis indicated the pilot attempted to fly through an area of light radar echoes located between two larger thunderstorm clusters. During this maneuver, the aircraft departed level flight at FL260 (approximately 27,500 feet MSL).
Radar data confirmed that a cluster of thunderstorms, rated level three to four, was present near the aircraft's ground track. The aircraft then entered an uncontrolled descent. Witnesses reported hearing the engine produce a winding noise and observed the Cessna (type not specified in source, but following registration) emerge from the clouds approximately 300 feet above the ground in a nose-low spiral. During this phase, the right wing separated from the aircraft; while the main wreckage was located at the crash site, the right wing was discovered 1.62 miles away.
The investigation
The investigation examined radar data and weather briefings. Prior to the flight, the pilot had received a weather briefing that predicted thunderstorm activity and cumulonimbus clouds with tops reaching FL450. The briefing also noted a weather system impacting the Florida Gulf Coast characterized by looming thunderstorms. The pilot had also contacted the Enroute Flight Advisory Service (EFAS) and was informed of convective SIGMET 05E in effect for southern Florida, as well as specific cells east of St. Augustine. Based on this information, the pilot was advised that routing toward Tampa/St. Petersburg and then southward would avoid the thunderstorm areas.