What happened
On July 12, 1961, a student pilot was conducting local training flights at Basel-Mulhouse Airport in a Piper Cub HB-OEF. After successfully completing an initial circuit, the pilot took off for a second circuit. During this period, a sudden and violent thunderstorm developed in the vicinity, causing wind speeds to surge from approximately 9 knots to over 30 knots in a matter of minutes.
As the wind shifted, air traffic control and ground instructors attempted to redirect all arriving aircraft to runway 26 to avoid a dangerous tailwind component on the grass runway 34. While other aircraft successfully transitioned to the new runway, the student pilot ignored signals from the control tower and ground instructors. The pilot attempted two landings on runway 34 despite explicit prohibitions. On the third attempt, the aircraft veered sharply to the right, following a trajectory aligned with the gusting wind. The aircraft traveled 200 meters across the grass before the wind caught the control surfaces, causing the aircraft to capsize onto its back.
The investigation
The investigation examined the meteorological conditions, the aircraft's mechanical state, and the actions of the flight crew and ground personnel. Investigators found that the engine and fuel systems were functioning normally, and the aircraft had sufficient fuel for the flight. The investigation also reviewed the rapid change in wind direction and velocity recorded at the airport.
While the pilot was unavailable for formal questioning, the investigation analyzed the actions of the Balair flight instructors and the airport's air traffic control services. The investigation also noted the physical damage to the HB-OEF, which included significant destruction to the upper wing surfaces, a deformed fuselage, and a broken propeller.