What happened
On August 14, 1982, a pilot based in Ticino invited a passenger for a scenic flight using the SF 28A "Tandem Falke" motor glider HB-2024. After completing the necessary flight plan at Locarno airfield, the aircraft departed around 12:30 local time. Approximately twenty-five minutes into the flight, witnesses located on Monte di Moneda observed the motor glider flying low along the valley wall of Val Morobbia. The pilot signaled to the observers before continuing toward Carena.
Subsequently, another witness reported seeing HB-2024 collide with an agricultural transport cable spanning the valley. The aircraft struck the cable with its propeller spinner, which was found embedded in the line. The impact sheared off the right aileron and left deep grooves along the leading edge of the right wing. The glider then nosed down into the forest below at coordinates 727,000/113,800, at an altitude of 950 meters. The crash resulted in the total destruction of the aircraft and minor damage to the surrounding woods.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the flight history, weather conditions, and physical evidence from the wreckage. Medical examinations revealed that the pilot had died from his injuries, while the passenger sustained severe trauma. A toxicology report on the pilot's muscle tissue indicated an alcohol concentration of 0.74 per mille.
Investigation into the transport cable confirmed it was legally permitted and properly registered by its owner. The cable spanned approximately 1,000 meters between Melera and a mountain station, reaching a maximum height of 200 meters above the valley floor. Weather reports from Locarno-Magadino showed clear visibility earlier in the day, but conditions at the accident site included strong haze or mist, with scattered clouds and variable winds.
Findings
The investigation determined that the primary cause of the accident was a combination of navigational error and poor tactical decision-making. The pilot likely lost orientation due to the strong haze present in the valley, leading him to fly into an area known for overhead cables. Despite having flown in the region previously, the choice to navigate deep within a narrow, cable-filled mountain gorge was deemed tactically incorrect.
Contributing significantly to the loss of situational awareness was the pilot's alcohol consumption prior to flight. The high power setting required to maintain altitude in the valley likely caused the propeller spinner to strike the cable first, initiating the catastrophic failure sequence. No technical defects were found in the aircraft that could have caused the incident.
Safety action
The report highlighted the dangers of flying in valleys with overhead agricultural cables, particularly under conditions of reduced visibility or haze. It emphasized that even experienced pilots must maintain strict orientation and avoid low-altitude flight in cable-saturated areas when impaired by alcohol.