Flight Diversion and Final Approach
A pilot en route from Cleburne, Texas, to McAllen, Texas, believed his navigation equipment was malfunctioning and landed at Marble Falls, Texas. He subsequently decided to return to Cleburne at night. After further difficulties with the navigation equipment, the flight ended at Lufkin, Texas.
Witnesses observing the airplane's approach to Runway 25 at Lufkin Airport reported that it crossed the runway threshold approximately 20 feet above ground level and flew level down the runway centerline. One witness stated that about one-third of the way down the runway, the airplane "dropped its left wing, spun, and hit the ground." Another witness described an "abrupt left dive" before impact.
Aircraft and Toxicology Findings
An examination of the airplane revealed no preaccident anomalies with the airframe, engine, or equipment. Toxicology tests detected 0.20 mg/L (0.20 mcg/mL) of diazepam (Valium), 0.55 mg/L (0.55 mcg/mL) of nordiazepam (a metabolite of Valium), and 6.9 mg/L (6.9 mcg/mL) of butalbital in the pilot's blood. Valium is an antianxiety agent and muscle relaxant, while butalbital is a barbiturate sedative. Neither drug is approved for use while flying.