13/3/19: Bool Lagoon South Australia
Wirestrike involving a Robinson R44, VH-ZWK, 20 km from Naracoorte, South Australia, on 13 March 2019
On 13 March 2019, a Robinson R44 helicopter, registered VH-ZWK and operated by Helifarm, was conducting aerial spraying operations at Bool Lagoon, around 20 km south of Naracoorte, South Australia.
While spraying along a drainage channel, the helicopter pilot momentarily forgot about the location of a powerline spanning the channel, as he manoeuvred the helicopter over a bridge. The helicopter collided with the powerline, then crashed into the ground. The helicopter was destroyed and the pilot sustained minor injuries.
What the ATSB found
The helicopter pilot momentarily lost awareness of the powerline as he manoeuvred over the bridge. Nearby vegetation, which reduced the pilot’s ability to see the power poles and visually identify the powerline, probably reduced the pilot’s ability to maintain this awareness. The operator had a number of policies and procedures to support pilots’ powerline awareness, and it may not be possible to completely mitigate the risk of wirestrike during repeated low-level flying near powerlines.
As a result of this momentary loss of awareness, the helicopter collided with the powerline, which led to a collision with terrain. The bladder-type fuel tank installed in the accident helicopter, as compared to an all-aluminium fuel tank, probably reduced the risk of a post-accident fire.
What’s been done as a result
The operator has implemented new policies and procedures to increase pilots’ awareness of powerlines during spraying operations, particularly spraying of drains. These include improved maps and other planning documents for drain spraying operations involving flying near powerlines, and increased training of helicopter pilots engaged in these operations.
This accident provides another reminder of the dangers posed by powerlines during low-level spraying operations.
The ATSB has released, in association with the Aerial Application Association of Australia (AAAA), an educational booklet, Wirestrikes involving known wires: A manageable aerial agriculture hazard (AR-2011-028). This booklet contains numerous wirestrike accidents and lessons learned from them. The AAAA has now launched its Powerline Safety Program that aims to encourage and facilitate power companies to improve aviation safety. The program includes marking of powerlines by powerline network operators (with a marker in accordance with Australian Standard AS 3891-2) wherever it is requested by a pilot, aviation company or landholder.
As this accident highlights, there may be limits to the extent to which operators can mitigate the risk of wirestrike during repeated low-level operations near powerlines. Helicopter wirestrike protection (WSPS) can provide a last line of defence in the event of a wirestrike. Some aircraft selected for aerial agriculture operations can be configured to include WSPS. However, this technology is not currently available on smaller helicopters such as the R44.
Pilots and operators involved in low-level spraying are also reminded that flight helmets can reduce the risk of serious injury in the event of an accident.