History of Flight
On 30 May 1978, the pilot flew from Lommis to Vienna with one passenger in the Piper PA-24-260 HB-OYV. Two days later, on the morning of 1 June 1978, the crew began the return flight via Klagenfurt, Friedrichshafen, and Altenrhein. At 1705 local time, HB-OYV landed in Friedrichshafen from Klagenfurt, where the aircraft was refueled with duty-free aviation gasoline. The flight continued to Altenrhein (customs airport). Ten minutes after landing in Altenrhein, the pilot departed at 1755 for Lommis.
Approximately from Bischofszell-Affeltrangen onward, HB-OYV flew through a thunderstorm rain zone. Via radio, the pilot received information from Lommis that runway 25 was in use. He initiated a direct landing approach in light rain. During final approach, the pilot noticed several puddles on runway 25 and decided to land beyond them, correcting the approach by increasing engine power. The aircraft touched down 200 to 250 meters after the runway threshold with an overspeed of about 10 mph. The pilot immediately applied full braking but noted rapidly decreasing braking effectiveness on the wet grass runway. Realizing he could not stop before the end of the runway and an obstacle beyond it, he applied full power approximately 150 meters before the runway end. In a steep nose-up attitude, the aircraft lifted off just before the runway end, overflew the access road, and at 1825 struck a wire mesh fence (2.25 m high) with the tail and outer right wing, then a woodpile (1.80 m high), before coming to a stop after a left turn. The occupants exited the wreckage uninjured.
Findings
- The pilot held a valid private pilot license and was authorized to conduct the flight. His conversion training on the accident aircraft took place between late June and early July 1976, comprising 5 flight hours with 55 landings at Lommis.
- No relevant health issues were known; the pilot was not under the influence of alcohol.
- The aircraft was certified for non-commercial IFR and VFR operations, and according to the pilot, no technical defects influenced the accident. The braking system was in order.
- Maximum permissible landing weight was 1338 kg; actual weight at the time was approximately 1200 kg, within limits. Center of gravity was within the permissible range.
- HB-OYV was fully refueled in Friedrichshafen with 340 liters (90 US gal). Assuming an average consumption of 48 L/h, about 300 liters remained after 40 minutes flight time.
- During impact with the woodpile, fuel from the two tanks in the right wing was dispersed.
- Last 100-hour inspection: 17 October 1977; last annual inspection: 15 December 1977. Total aircraft flight time: 1456:24 hours.
- Weather at accident time (from Swiss Meteorological Institute): flat high-pressure area with a thunderstorm passage in the evening; clouds: 2-8/8 Cb base ~2100 m, 4-8/8 Ac base ~3000 m; visibility 8 km; wind variable around 5 kt; temperature 14°C; dew point 13°C; QNH 1022 hPa; sun azimuth 286°, elevation 16°. Around 1740, a thunderstorm passed over the airfield.
- During the thunderstorm, puddles formed on the runway 150-200 m after threshold 25. The aircraft landed beyond them, leaving about 400-450 m for landing roll. The grass runway (mowed the previous day) was wet.
- According to the PA-24-260 flight manual, for a weight of 1200 kg and temperature 14°C on hard surface: takeoff distance over 50 ft obstacle (flaps 15°) approx. 275 m (900 ft); landing roll (approach speed 90 mph, flaps 32°) approx. 215 m (700 ft). No data on increased landing roll on wet grass.
- About 150 m before the runway end and 180 m before the obstacle, the pilot applied full power. Left of the runway centerline was a stream embankment, right were airfield buildings.
- A 5.40 m long skid mark from the tailwheel, 20 m before the woodpile, indicates the aircraft was in an extreme nose-up attitude.
- The fence height was 2.25 m, woodpile height 1.80 m. The fence was pushed over about 25 m; wood parts were shattered. The aircraft came to rest after a left turn in front of a construction crane placed across the runway axis.
- Aircraft damage: propeller at low pitch, both blades severely bent; main landing gear, tail empennage, and right outer wing torn off; front fuselage and left wing heavily deformed. Flaps extended 15-20°; flap switch in cockpit was in "Off" position.
- A Swiss Federal Court ruling of 17 February 1978 noted that the Thurgau Building Department had ordered on 13 June 1977 that the construction crane be removed immediately and the stored wood by 20 June 1977. The appeal by the owner was only partially granted. The court reasoned that if the planned construction is not carried out, the crane and wood must be removed.
Probable Cause
Failure to initiate a timely go-around. Contributing factors: late touchdown, excessive landing speed, and wet grass runway.
Remarks
The recommended approach speed for this aircraft type is 90 mph. The pilot increased engine power too much to overfly the puddles, touching down with overspeed. Possibly there was also light tailwind unnoticed by the pilot. Given the known obstacles at the runway end, the pilot should have decided to go around immediately after the long and fast landing.