What happened
On August 2, 2011, at approximately 18:49, a TL 96 Sting ultralight aircraft departed from the Rothenburg o. d. Tauber airfield for a private training flight. The crew consisted of a flight instructor and a pilot trainee, both of whom were performing a flight to maintain flight proficiency. After completing a circuit and performing a touch-and-go landing at 18:53, the aircraft departed the airfield area heading north.
Approximately seven minutes later, witnesses observed the aircraft flying at an unusually low altitude in the airspace east of Reichelshofen. Conflicting reports regarding the engine were noted; while some witnesses reported hearing engine sputtering and misfires, others described a normal engine sound. One observer reported seeing the aircraft in a glide with a dead engine before it entered a vertical, spiral-like descent. At approximately 19:00, the aircraft struck a field at a high sink rate and longitudinal pitch, resulting in two fatalities and the total destruction of the aircraft.
The investigation
The BFU investigation examined the aircraft, the flight logs, and the medical findings of the occupants. The aircraft, a 2004 model, was found with significant structural damage to the fuselage, wings, and tail. The engine and cockpit were embedded in the ground, and the fuel tank was ruptured and empty. While the investigation looked for mechanical failures, no evidence of technical defects was found. The investigation also reviewed the medical results of the post-mortem examinations, which included blood alcohol testing.
Findings
- The aircraft was significantly overweight; while the maximum takeoff mass is 472.5 kg, the calculated takeoff mass was at least 567 kg.
- Engine performance issues, specifically reported engine sputtering and misfires, were observed by multiple witnesses prior to the crash.
- The flight instructor had a blood alcohol concentration of 0.37 promille, which was classified as intoxication.
- The pilot trainee had a blood alcohol concentration of 0.29 promille, which was not considered significant intoxication.