What happened
During a departure from a property, a helicopter entered a shallow climb down a valley and struck a distribution powerline approximately 400 m from the take-off site. The pilot had previously consulted with the property owner regarding potential hazards, such as powerlines, but the owner was unaware of the specific distribution line spanning the valley. Because the pilot departed in the same direction as the initial landing, the flight path did not involve overflying the wires, which prevented an opportunity to identify the hazard during the arrival phase.
The investigation
The investigation examined the pilot's pre-flight planning and the visibility of the electrical infrastructure. It was noted that, unlike in other Australian states, accessible electricity network maps were unavailable to assist the pilot in identifying hazards. While the pilot was aware of low-hanging lines on a neighboring property from previous road visits, this information did not aid in detecting the airborne hazard. The investigation found that the pole on the hill was visible from the take-off location, but the wires themselves were not seen and lacked any visual markers to increase their detectability. Furthermore, the pilot did not perform aerial reconnaissance of the intended departure track.
Findings
- The pilot did not expect powerlines to be positioned at an altitude greater than 150 ft above the ground.
- The distribution powerline was not fitted with any visual markers.
- The pilot's departure track and shallow climb gradient led to controlled flight into an unseen powerline.
- A lack of available, usable electricity network maps hindered effective pre-flight hazard identification.
- The pilot did not conduct an aerial survey of the departure path to check for obstacles.