What happened
On August 12, 1972, a Piper Tri Pacer PA-22-150, registration HB-OTM, departed Altenrhein airfield for a sightseeing flight over the Rhine Valley accompanied by three passengers. During the return to the airfield, the pilot initiated a long final approach from the east sector at approximately 1,200 feet.
As the aircraft descended to 1,000 feet, the pilot reduced power to idle and extended the flaps fully, maintaining an approach speed of 80 mph. Approximately 300 meters before the runway threshold, the pilot encountered moderate gusts that drifted the aircraft slightly to the right of the approach centerline. In an attempt to correct the flight path, the pilot maneuvered over a nearby cornfield. During this maneuver, the aircraft lost altitude, prompting the pilot to apply power and use the elevator to stretch the glide path. However, the aircraft lost lift very close to the ground, resulting in a sudden drop and a hard landing that brought the aircraft to a halt.
The investigation
The investigation confirmed that the pilot held a valid private pilot license with an endorsement for aircraft equipped with flaps. The Piper Tri Pacer was properly registered, and the investigation found no pre-existing technical defects. The airspeed indicator was found to be within required tolerances, and the aircraft's weight and center of gravity were within prescribed limits.
Meteorological conditions at the time included light haze and visibility of approximately 10 km. Winds were recorded from the north-east at 5 knots, with a slight tendency toward a breeze. The ground temperature was 22°C.
Findings
The investigation established that the 1 fatality and 1 injury occurred as a result of the aircraft's inability to maintain flying speed during the final stages of the approach. The primary cause was that the pilot underestimated the required height and distance to the runway. In an attempt to compensate for the wind and correct the approach path, the pilot allowed the airspeed to drop below the minimum flying speed, causing the aircraft to sink abruptly and strike the ground with significant force. The impact caused heavy damage to the landing gear, propeller, and engine.