Incident Overview
On Sunday, June 25, 1972, at 17:25 TU, a Piper PA-28 Cherokee with registration HB-OKF crashed in the commune of Allos, located in the High Alps of Provence, France. The aircraft was operated by the Aéro-Club de Genève and was on a private tour flight from Cannes to Geneva. The crash resulted in the deaths of all four occupants: one pilot and three passengers.
Flight Circumstances
The aircraft departed Cannes at 16:23 TU on June 24, 1972, carrying the pilot and three passengers. Approximately forty minutes into the flight, the plane overflew Allos at an altitude of 1,425 meters. The pilot encountered mountain peaks obscured by clouds to the north, blocking the direct route. Upon attempting a turn back toward the coast, the valley to the south also became obstructed by rising cloud layers.
Trapped in the cirque with excellent visibility but no clear exit, the pilot spent ten to fifteen minutes searching for a suitable landing site. He ultimately selected a sloping meadow on a plateau for an engine-on landing. However, during the final approach, the aircraft struck a 220-volt power line running along the slope. The impact severed three copper wires, causing the plane to deviate leftward.
Crash Sequence and Investigation
After passing under a high-tension line without contact, the aircraft clipped the tops of two trees, which further destabilized it. The Cherokee then descended approximately one hundred meters before colliding with the near-vertical wall of the Ubac ravine at speeds exceeding 100 km/h. The impact caused the aircraft to catch fire and slide fifteen meters to the bottom of the ravine.
Forensic analysis by the Centre d’Essais des Propulseurs de Saclay examined a propeller blade broken at 50% of its radius. The investigation concluded that the blade fracture resulted from torsional stress during the ground impact, not from contact with the power lines. The primary cause of the accident was identified as rapidly deteriorating weather conditions in the mountains, which trapped the aircraft and forced an emergency landing where a hidden power line caused loss of control.