Incident
On 20 June 2023 at approximately 15:30 local time, an Airbus Helicopters AS350 B3, registered HB-ZMK, was in cruise flight at an indicated altitude of about 4800 ft AMSL (approximately 270 m above ground) when it collided with a bird of prey. The helicopter had departed from Alp Nera and was en route to Thusis. On board were the pilot, seated in the front right seat, and a flight assistant (task specialist) on the rear bench.
According to the pilot, he observed a bird of prey roughly in the flight path and attempted to avoid the collision by maneuvering. Despite his input, the bird struck the windshield, penetrating it and hitting the back of the instrument console before impacting the pilot's head. The pilot stated he momentarily lost sight but regained control, righted the helicopter from a right-upward turn, reduced speed, and landed at a suitable location near Zillis.
The pilot sustained minor head injuries; the flight assistant was unharmed.
Findings
Examination revealed that the right windshield, made of acrylic glass, was shattered by the impact, and fragments were thrown into the cockpit. Traces of bird strike were found on one main rotor blade, but no damage occurred to the blade. The bird was identified as a goshawk weighing approximately 800 grams.
At the time of the incident, the pilot was not wearing a protective helmet.
Certification and Statistics
The AS350 B3 is categorized as a 'small rotorcraft' under CS-27 certification specifications. The European Union Aviation Safety Agency (EASA) issued the type certificate data sheet for this model on 28 September 2003. For existing small rotorcraft type designs, there are no airworthiness requirements for structural protection against bird strikes. For new type designs of small rotorcraft with a maximum of five passenger seats, certification specifications still do not require bird strike protection. However, since CS-27 Amendment 9 (17 December 2021), small rotorcraft with six or more passenger seats must be designed to ensure a safe landing after impact of a 1.0 kg bird on the windshield.
Between 2016 and 2023, the Swiss Federal Office of Civil Aviation (BAZL) recorded 41 bird strikes involving helicopters of the CS-27 class in Swiss airspace, with an increasing trend over the years. A 2016 study commissioned by the Federal Aviation Administration (FAA) indicated that approximately 75% of reported bird strikes with small rotorcraft occurred at indicated airspeeds above 80 kt, and 93% occurred below 3500 ft above ground level.