Flight and Weather Briefing
The pilot of N9143B requested and received a weather briefing before departure. The briefing indicated that an area forecast for the route of flight predicted thunderstorm activity and cumulonimbus clouds with tops as high as FL450. A weather system impacting the Florida Gulf Coast consisted of "looming thunderstorms" in that area. During the flight, the pilot contacted the Enroute Flight Advisory Service (EFAS) for enroute weather advisories. The EFAS advised of "cells" east of St. Augustine and issued convective SIGMET 05E for southern Florida, recommending a routing toward the Tampa/St. Petersburg area and then southward to avoid an area of thunderstorms.
Thunderstorm Encounter
During the flight, the pilot asked the controller if he could deviate about 12 miles west, citing that he thought he saw "a hole" in the weather. Radar ground track plots showed that the pilot observed a 3 to 5 mile gap between two thunderstorm clusters and attempted to fly through an area of light radar echoes between two larger areas of heavier echoes. N9143B departed level flight, and radar indicated that a cluster of thunderstorms, level three to four, were present in the vicinity of the ground track position. Radar data showed that N9143B started an uncontrolled descent from FL260 (about 27,500 feet msl).
Witness Observations
Witnesses reported hearing the engine make a winding noise, then observed the airplane come out of the clouds about 300 feet above the ground, in a nose-low spiral, and noted that the right wing was missing.
Wreckage Distribution
The right wing was not found at the crash site but was located 1.62 miles from the main wreckage. The aircraft impacted the ground during the uncontrolled descent.