What happened
On May 11, 1962, two Agusta-Bell 47-J3 helicopters were returning to Italy from the 1962 Hanover Air Show. The flight formation, consisting of a lead aircraft (I-264) and a second aircraft (I-243), departed Zurich. Despite receiving weather briefings indicating that the Gotthard route would be difficult due to low clouds and numerous obstacles, the pilots chose to proceed via the Gotthard Pass.
As the formation entered the narrow Schöllenen Gorge near Göschenen, the aircraft were flying at an altitude of approximately 100 to 150 meters above ground level. The lead pilot, spotting a high-voltage power line ahead, performed a sudden descent of about 20 to 30 meters to warn the second aircraft. The pilot of I-2-43 attempted a similar maneuver but was unable to arrest the descent. During the maneuver, the main rotor struck a rock wall, causing the helicopter to crash violently into a rock in the Reuss riverbed. The pilot sustained minor injuries, but the passenger was killed when the seatbelts tore from the airframe upon impact.
The investigation
The investigation examined the flight conditions, the aircraft's performance capabilities, and the pilots' decision-making. Investigators analyzed the terrain of the Schöllenen Gorge, noting the presence of high-voltage lines and the narrow, steep-sided nature of the canyon. The technical investigation of the wreckage confirmed that the aircraft's components met construction standards and that the passenger's seatbelts failed only due to extreme overstress during the crash.
Findings
- The flight formation entered a narrow, obstacle-dense gorge at a low altitude during unfavorable weather conditions.
- The second helicopter was operating with critically low power reserves due to its high altitude and the reduction of forward airspeed during the avoidance maneuver.
- The pilot's attempt to avoid the power line, while necessary, led to a loss of altitude that could not be recovered.
- The pilots had been specifically warned about the hazards of the Gotthard route, including low cloud ceilings and obstacles, yet proceeded with the flight plan.