Circumstances
On Friday, 25 June 1965, at 1140 MEZ, a pilot departed Beromünster airfield in a Piper PA-28-180 Cherokee, registration HB-OVX, accompanied by three passengers. The intended destination was Wangen-Lachen airfield, located near Lake Zurich, where the group planned to swim. Prior to departure, the pilot telephoned an outdated contact number to inquire about field conditions. The recipient of the call stated that no one was present at the airfield and that she was unaware of its current state.
Arrival and Landing
Upon arriving over Wangen-Lachen around midday, the pilot performed two low passes at approximately 30 meters to assess the strip. He observed a signal laid out on the ground: a red square with a single yellow diagonal stripe. This signal is officially defined as 'caution during approach and landing due to poor field condition or other reasons.' However, the actual signal displayed was a red square with two yellow diagonal stripes, which indicates 'landing prohibited for an extended period.' Despite this, the pilot landed at 1200 on runway 09.
After landing, the pilot and one passenger inspected the runway. They found that the first 300 meters were dry, firm, and mowed, while the remainder was uncut and soft. The pilot noted that the third runway marker (at about 220 meters from the threshold) could serve as a reference for the latest lift-off point. He then joined the others for swimming.
Departure and Accident
At 1315, the pilot and passengers returned to the aircraft for the flight back to Beromünster. The pilot initiated a rolling takeoff on runway 09. For the initial part of the roll, the flaps were fully retracted; after approximately 200 meters, he extended them to 10°. According to his account, the airspeed reached 60 mph at the third marker, at which point he lifted off successfully. However, the aircraft did not transition into a proper climb and instead settled back to the ground in uneven terrain. The landing gear collapsed, and the aircraft sustained severe damage. All four occupants were uninjured.
Investigation
The investigation was hindered by a delayed start and conflicting testimony. No technical defects were found on the aircraft. The pilot held a private pilot license issued in 1959 and a restricted commercial pilot license valid through 13 February 1966, with a type rating for the accident aircraft added on 14 March 1965. His total experience was approximately 460 hours, with 55:22 hours on type. The three passengers were all holders of pilot licenses or student permits. The aircraft's weight at the time of the accident was about 980 kg, within the maximum allowed 1089 kg, and the center of gravity was within limits.
Meteorological Conditions
At the time of the accident, the weather was clear and nearly calm, with occasional thermal activity. Temperature was 32°C and pressure 627 mmHg.
Site Information
The accident occurred at the eastern end of runway 09, near a drainage ditch about 70 cm wide and 100 cm deep, located approximately 150 meters beyond the runway end. The field elevation is 410 m. The runway is 440 meters long, but only about 300 meters were mowed and usable on the day of the accident.
Regulatory Context
The pilot had been fined on 24 August 1965 for landing without permission and despite a landing prohibition signal. The airfield required prior permission (PPR) as listed in the AIP. The pilot’s pre-flight inquiry was made to an unauthorized individual.