What happened
While cruising at approximately 900 ft above mean sea level, a helicopter collided with a white-bellied sea eagle. The impact was severe enough that the bird passed through the aircraft's windscreen, subsequently striking a passenger. Despite the sudden disruption and the damage to the windscreen, the pilot maintained control of the aircraft. The pilot successfully identified a nearby landing site with access to medical services and performed a controlled descent and landing to ensure the injured passenger could receive prompt medical attention.
The investigation
Investigators examined the circumstances of the collision and the physical evidence at the site. The analysis determined that the pilot had limited opportunity to detect the bird, as their gaze was directed down and to the left of the flight path, placing the bird in their peripheral vision. The investigation noted that even with a forward gaze, the high closure rate of approximately 94 kt and the direct relative trajectory of the soaring bird made the collision likely unavoidable due to the limitations of the see-and-avoid principle.
Furthermore, the investigation assessed the structural integrity of the windscreen. While manufacturers like Robinson and Bell produce birdstrike-rated windshields, these are typically rated for a 1 kg impact at maximum speed. The collision involved a bird weighing approximately 3 kg, which likely exceeded the design limits of the windscreen, allowing for penetration.
Findings
- The primary cause of the incident was the collision with a white-bellied sea eagle.
- The bird's mass and the speed of impact caused the windscreen to fail.
- The passenger sustained injuries from the impact of the bird following the windscreen breach.
- The pilot's effective emergency response and adherence to procedures prevented further loss of aircraft control.