Incident Summary
A helicopter, registration ZWK, struck a powerline while maneuvering over a bridge, resulting in a collision with terrain. Earlier that day, the pilot had flown under the same powerline, which spanned a drainage channel. During the accident flight, the pilot momentarily lost awareness of the powerline and unintentionally flew into it.
Pilot Awareness and Distractions
Immediately before the wirestrike, the pilot's attention was diverted towards flying and operating equipment for agricultural spraying. The source notes that such diversion was normal and required for the task. The pilot's limited working memory capacity contributed to the loss of awareness, as responding to immediate demands can cause other hazards to be overlooked.
Environmental Factors
Native vegetation near the power poles obscured additional visual cues that might have indicated the presence of the powerline. The powerline itself was narrow-gauge and had no markings. Due to the limitations of human vision, powerlines can be very difficult to see, especially during low-level flight.
Defenses and Equipment
The operator had defenses in place aimed at reducing wirestrike likelihood by supporting pilot awareness of powerlines. However, the demands of spraying near powerlines kept attention high, and the ability to recover from lapses in awareness was low. The helicopter was fitted with a bladder-type fuel tank, which likely reduced the risk of a fuel leak and post-impact fire following the collision. The source indicates that wirestrike protection systems (WSPS) cannot typically be installed on smaller helicopters such as the R44, and that the pilot was not wearing a helmet at the time of the accident.