Event
During the takeoff climb, a twin-engine airplane experienced a strong downdraft and subsequently impacted trees and terrain. The pilot reported that while taxiing to the runway, the monochrome weather radar was set to the 40-mile range. The scan showed no weather behind the runway, but a cell was indicated 15 miles from the runway. The takeoff roll was uneventful, with rotation at 95 knots. Climb out was conducted at 110 knots, with engines at maximum power, propellers at maximum RPM, and manifold pressure indicating maximum. A 10-degree turn was initiated towards the Cotulla VOR when, at 1,500 feet MSL, a sharp descent was felt, with the vertical speed indicator (VSI) showing a rate of descent of 800 feet per minute. The wings were leveled and airspeed reduced to 85 knots. The rate of descent decreased to 400 feet per minute and then to 300 feet per minute until impact. Upon impact, a fire erupted that destroyed the airplane.
Weather
A review of doppler weather radar images indicated thunderstorms in the vicinity of the airport. The pilot's in-cockpit radar had shown a cell 15 miles from the runway prior to takeoff.
Probable Cause
The official probable cause was a downdraft that exceeded the aircraft's climb performance. A contributing factor was the presence of thunderstorms in the vicinity of the airport.