At about 1253 Eastern Standard Time on 20 May 2010, a Bell
Helicopter 206L LongRanger III helicopter, registered VH-OSU,
commenced forestry spraying operations about 37 km south-south-west
of Latrobe Valley Airport, Victoria. At about 1354 the pilot
commenced a final spray run that resulted in the helicopter's
flightpath crossing a powerline that was known to the pilot. The
helicopter contacted the wire, seriously damaging the helicopter's
flight control system and main rotor mast, which likely rendered it
uncontrollable. The helicopter subsequently impacted the ground.
The pilot was fatally injured.
The investigation found that it was likely that the pilot failed to recall the existence of the wire. The inherent difficulty of visually detecting the wire, combined with the operating groundspeed, meant that the pilot would not have had sufficient time to avoid the wire after seeing it. An examination of the wreckage of the helicopter did not find any mechanical abnormalities that might have contributed to the accident.
No permanent or temporary high visibility devices were attached to the powerlines, nor were they required to be. The helicopter was not fitted with wirestrike protection system (WSPS) equipment, nor was it required to be by aviation regulation. The investigation was unable to determine if a WSPS might have altered the outcome of the wirestrike.
As a result of this accident, Energy Safe Victoria issued a wire safety alert to aerial work operators and infrastructure providers. The Australian Transport Safety Bureau (ATSB) issued a Safety Advisory Notice to Energy Networks Australia and operators and pilots that are involved in low-level operations. The notice suggested that, where wires exist in areas where low-level activity occurs, operators and pilots consider the need for any powerlines to be marked in accordance with AS 3891.2, 2008, Part 2: Marking of overhead cables for planned low level flying operations. In addition, the ATSB has published an educational report aimed at increasing awareness among low-level operators and those agencies organising such activities. The ATSB has also commenced a research investigation that seeks to more fully understand the wirestrike risk in Australia.