What happened
On October 26, 2009, a Beech B100 King Air, registration N729MS, crashed near Benavides, Texas, while flying under instrument flight rules from Uvalde, Texas, to Leesburg, Florida. Prior to departure, the pilot received weather briefings indicating significant convective activity and a moving squall line along the planned route. To avoid these conditions, the pilot altered the flight path further south to seek "holes" in the weather.
During the flight, the pilot requested a heading change to navigate through a perceived gap in the weather. The air traffic controller issued a heading of 120 degrees, believing a clear area existed. However, the aircraft subsequently entered a line of very heavy to intense thunderstorms. At 1140, the pilot reported encountering "pretty good turbulence" and noted a descent from 25,00 and 24,000 feet. This was the final communication from the crew. Shortly after, an expletive and the sound of a stuck microphone were heard on the frequency. Radar data showed the aircraft entered a rapid descent, reaching a peak descent rate of over 40,000 feet per minute, before the radar track was lost. The aircraft impacted terrain, resulting in 4 fatal injuries.
The investigation
Investigators recovered the main wreckage in a shallow impact crater approximately 6.5 miles north of Benavides. The wreckage distribution was consistent with an in-flight break-up. Examination of the flight control surfaces, including the vertical stabilizer, rudder, and elevators, revealed fractures consistent with overstress failure, with no evidence of pre-existing cracks.
Both engines exhibited heavy impact damage. The left engine's gearbox housing was cracked, and the fuel pump housing was fractured. The right engine's gearbox housing was also cracked, and the fuel pump and fuel control were pushed toward the engine. The propeller blades on both engines showed various forms of bending and separation due to impact.
Data retrieved from the aircraft's Enhanced Ground Proximity Warning System (EGPWS) confirmed that the unit recorded a "Terrain Caution" and "Terrain Pull-up" alert. Performance data from the EGPWS indicated the aircraft was descending at a rate of 1,871 feet per minute during the pilot's last transmission, which later increased to extreme rates during the final descent.