What happened
On October 31, 1977, a Piper PA-28-180 G Cherokee, registration HB-OKZ, departed Agno airport on a VFR flight destined for Venezia-Tessera. During the flight, the pilot communicated with Milano Information, stating the aircraft was flying along the highway and was abeam Varese at 1,500 feet. At approximately 09:13 GMT, the pilot notified air traffic services of his intention to divert and return to Agno.
Shortly after this final communication, the aircraft struck a high-voltage power line near Origgio, Italy. The impact was severe enough to sever the right wing from the fuselage. The wing struck the ground approximately 80 meters away, while the remaining fuselage continued for another 180 meters before impacting the ground, catching fire, and coming to a halt. The accident resulted in 4 fatalities, including the pilot and three passengers.
The investigation
The investigation examined the wreckage, radio transcripts, and weather conditions. Technical analysis of the debris confirmed that the aircraft struck the Cislago-Arese-Parabiable power line with significant speed, causing several strands of the cable to break. The investigation found no mechanical defects in the aircraft, which had been well-maintained.
Investigators also reviewed the pilot's flying experience and the meteorological conditions. At the time of the accident, the area was experiencing low visibility due to fog and stratus clouds, with visibility in some areas dropping below 300 meters. Radio transcripts were analyzed to determine the pilot's last known intentions, though some parts of the final transmission were deemed unintelligible.
Findings
- The primary cause of the accident was attributed to inadequate flight planning and the pilot's failure to properly assess the deteriorating weather conditions.
- The pilot's lack of experience in low-visibility conditions contributed to the accident.
- There was a failure to accurately judge altitude and distance from ground obstacles during the flight.
- The pilot's decision to continue or divert in marginal VFR conditions, combined with difficulty maintaining altitude and precision in turns, played a critical role.