Circumstances
On 12 March 2019, at approximately 08:15 local time, a commercial pilot flying an AS350 B3 helicopter (registration HB-ZNZ) was conducting material transport operations in Bissone, Ticino. The helicopter was equipped with a 50-meter longline attached to the central cargo hook. On the morning of the incident, the pilot had already completed two of five planned loads between a loading point at the municipal parking lot south of Bissone and a drop-off point in the town center.
After dropping the second load, the pilot flew back toward the parking lot to collect the next load. The longline was fitted with straps for securing cargo. While overflying the Church of San Carpoforo at low speed, approximately 20–30 meters west of the steeple, a dangling strap became entangled with the cross at the top of the steeple. According to the pilot, this likely occurred due to strong wind gusts that displaced the longline out of the helicopter's vertical axis.
Upon noticing abnormal resistance, the pilot halted in a hover. The cross detached from the steeple, and a stone immediately beneath it fell, rolling across the church roof and causing damage. The ground crew at the loading point became aware of the incident when they heard a loud bang as the cross was torn away.
The pilot then placed the cross in the church parking lot, where a ground assistant detached the straps and the cross from the longline. The pilot subsequently flew to a landing site in Maroggia, south of Bissone, to inspect the helicopter for damage. Finding none, he reported the occurrence to his company and asked them to contact the municipal authorities of Bissone. The Federal Office of Civil Aviation (FOCA) was later informed.
Findings
GPS flight path data showed that the pilot consistently flew west of the steeple on all rotations. The flight during which the strap caught was the easternmost among the empty return flights, indicating that the longline and straps were displaced eastward, possibly due to pendulum motion or wind gusts. Meteorological data indicated a northerly foehn wind with gusts reaching 10 knots in nearby stations. At Bissone, wind conditions may have been stronger due to local orography.
The serious incident was reported to FOCA but not initially to the Swiss Transportation Safety Investigation Board (SISI). The pilot submitted an occurrence report via the EU system on March 25, 2019, after which SISI became aware of the event. Under Swiss regulations, such incidents must be notified immediately to the REGA alarm center.
No injuries were reported among the pilot, passengers, or ground personnel. The helicopter remained undamaged. Damage to third parties consisted of damage to the church steeple cross and roof.