Flight Sequence
On 7 February 1995, at 1502 local time, a Piper PA-18-150 (registration HB-PAW) departed from Fricktal-Schupfart airfield for a training flight. After refueling, the pilot performed three touch-and-go landings and a pleasure flight over the Jura mountains. Returning to the airfield, the pilot entered the downwind leg for runway 25 to conduct a fourth touch-and-go followed by a landing. In the downwind, the pilot activated carburetor heating, then deactivated it on short final.
During the landing, the aircraft touched down within 150 meters of the runway threshold. The pilot applied full power, noted the engine initially ran slightly irregularly but normally, and allowed the aircraft to climb and accelerate to 105 km/h. He retracted the flaps. After switching off the landing light, the engine power suddenly dropped at an altitude of about 50 meters above ground. The pilot immediately lowered the nose and instinctively reduced then reapplied full throttle.
While attempting to flare for an emergency landing beyond the runway end, the pilot could not pull the control stick fully aft. The aircraft struck the ground with a high sink rate, approximately 91 meters beyond the runway end, and came to a stop after about 13 meters. The time of the accident was 1615 local time.
Findings
The pilot held a valid private pilot license. The aircraft was certified for flight. Weight and balance were within limits. The left fuel tank contained 28 liters and the right 32 liters of gasoline. The pilot was not wearing shoulder harnesses.
Technical examination of the airframe, control cables, pulleys, rudder connections, engine, and components revealed no pre-existing defects that could have caused the elevator blockage or engine failure. Propeller deformation and ground marks indicated the engine was producing power at impact.
On 13 March 1995, a cockpit reconstruction was performed with the pilot. It was found that due to the pilot's height, operating the landing light switch (located on the upper right side of the cockpit) could inadvertently move the throttle (on the left cockpit wall) with the left elbow without the pilot's awareness. The reconstruction also confirmed that the backpack used by the pilot, containing items and placed on the rear shelf, could fall between the rear seat and the control stick and block the elevator in a neutral position.
Weather at the time: scattered clouds base around 15,000 feet, visibility more than 10 km, temperature 13°C, dew point 5°C, QNH 1015 hPa.
Probable Cause
The accident was probably due to:
- unnecessary manipulation of a switch (landing light) with a hand change shortly after takeoff;
- inadvertent and unnoticed operation of the throttle during this manipulation;
- blockage of the elevator by an unsecured piece of luggage.