Accident Overview
On August 31, 2008, at approximately 1418 central daylight time, a Schleicher ASW-20B glider, registration N30WK, was substantially damaged when it struck terrain near Cleburne, Texas. The commercial pilot, who was the sole occupant, sustained fatal injuries. The glider was owned and operated by a private individual. The flight was conducted under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed from TSA Gliderport (TA11) in Midlothian, Texas, around 1326 as a local flight.
A resident in the area alerted emergency services after observing the crash. An FAA inspector also arrived and documented the accident site. The glider came to rest in an open field near a residence. The flaps were set to position "2," corresponding to -6 degrees of flaps (flaps up 6 degrees). The wreckage was later moved to a secure location for examination.
Investigation
An examination conducted by the NTSB Investigator-in-Charge confirmed flight control continuity to the rudder, elevator, ailerons, airbrakes, and flaps. No pre-impact anomalies were identified in the airframe.
Flight Data
A Cambridge Aero Instruments data recording device was recovered from the glider. Data analysis showed that after being towed from TA11, the glider flew southwest of the airport. The pilot made several attempts to gain thermal lift. At approximately 1355, the glider began maneuvering for thermal lift but continued descending. The flight proceeded over a field and entered what appeared to be a normal left traffic pattern. The final recorded data point, at 1417, placed the glider at 895 feet mean sea level (approximately 150 feet above ground level), traveling at 29 miles per hour, descending at about 390 feet per minute on the "final approach" leg.
Pilot Information
The pilot held a commercial certificate and had logged over 5,279 hours of flight time in various military and civilian aircraft, including approximately 399 hours in gliders, with at least 7.5 hours in the accident glider.
Medical and Toxicology
An autopsy performed by the Tarrant County Medical Examiner's Office determined the cause of death to be multiple blunt force trauma. Forensic toxicology by the FAA Bioaeronautical Sciences Research Laboratory detected carbon monoxide and cyanide, but no ethanol. Additionally, diphenhydramine was found in the pilot's blood and liver, and ibuprofen was present in the blood. According to the FAA Forensic Toxicology Research Team chief, the diphenhydramine level in the blood was below the laboratory's calibration curve and therefore not quantified.
Weather
At 1425, an automated weather station at Cleburne Municipal Airport (CPT), about 9 miles northwest of the accident site, reported wind from 120 degrees at 4 knots, visibility 10 miles, clear skies, temperature 90°F, dew point 72°F, and barometric pressure 29.96 inches of Mercury.