Background
On Sunday, June 19, 1988, a SOCATA TB-10 Tobago, registration HB-EZV, departed from Birrfeld Airport at 1706 hours local time for a private sightseeing flight with three passengers. The pilot, born in 1963, held a private pilot license issued on May 5, 1981, with a total flight experience of 154 hours, including 8 hours and 22 minutes on the accident aircraft type.
Flight Sequence
According to witness accounts, the pilot taxied from the fuel station to the beginning of runway 08, positioning the aircraft approximately 90–100 meters after the runway start. The takeoff acceleration was relatively low, and the aircraft became airborne near the end of the paved runway. Immediately after liftoff, the aircraft rolled and yawed left and right; one roll was so pronounced that a passenger thought the wingtip touched the ground. The climb was shallow with a high angle of attack, and the stall warning horn sounded continuously from liftoff until impact. The aircraft narrowly cleared a highway and power lines—a passenger estimated the clearance above the power lines at 3–5 meters. After crossing the power lines, the pilot initiated a left turn. The left wing struck tree tops at about 10 meters above ground level, and the aircraft fell into a forest at a 45° angle, coming to rest after approximately 80 meters. A fire broke out.
Wreckage and Rescue
The three passengers escaped the burning aircraft by themselves: one was uninjured, one seriously injured, and one slightly injured. The pilot died in the aircraft. The aircraft was destroyed, and forest damage occurred.
Cause and Contributing Factors
The investigation determined that the accident was caused by an aerodynamic stall: after takeoff and during the climb, the pilot never managed to gain sufficient speed by reducing the angle of attack. Contributing factors included:
- Not using the full available runway length.
- A high takeoff weight, possibly exceeding the maximum limit (actual weight was approximately 1156 kg, slightly above the 1150 kg maximum).
- High probability that the engine did not deliver full takeoff power, possibly due to a pre-existing undetectable defect.
- Failure to abort the takeoff in time.
Additionally, the aircraft's fuel tanks could contain more fuel than indicated (about 30 liters more per wing). The aircraft had been refueled to approximately 3/4 capacity on advice of the pilot's father. A professional pilot had experienced climb difficulties with the same aircraft on a previous flight and had reported it.