What happened
On May 1, 1966, a flight student was conducting landing practice at the Wangen-Lachen airfield in Switzerland. Operating a Piper PA-22-150 Tri-Pacer, registration HB-OPL, the student was performing a series of external landings under the supervision of an instructor. Due to ongoing drainage and leveling work at the airfield, the usable runway area was restricted, with a landing marker placed 150 meters from the eastern end of the strip.
Following an initial takeoff attempt that barely cleared the end of the runway near the lake, the instructor inspected the eastern section of the field on foot. Believing the ground was sufficiently firm, the instructor signaled the student to begin a second takeoff from this eastern section. As the aircraft accelerated, the main wheels began to sink into soft, sandy, and saturated patches of ground. The sudden braking caused the nose wheel to dig approximately 30 cm into the surface. The impact buckled the nose gear strut, causing the propeller, nose, and left wing to strike the ground. The aircraft slid for approximately 110 meters before coming to a halt. The pilot remained uninjured, though the aircraft sustained heavy damage.
The investigation
The investigation examined the ground conditions, the airfield's operational status, and the decision-making process of the flight crew. Investigators noted that while a NOTAM was in effect restricting much of the airfield, the western two-thirds were usable. However, the eastern section was subject to recent heavy rainfall, with significant precipitation recorded in the days leading up to the accident. The investigation also looked into the communication between the visiting crew and the local airfield personnel regarding the availability of the landing area and the specific condition of the eastern runway extension.