The influence of cannabis caused a driver to overreact to an airborne solar panel on the Midland Highway south of Ross before a horrific triple fatality, the coroner has found.
The male driver, 48, his daughter, 15, and aunt, 71, were all killed when their Toyota Celica collided with an oncoming Holden Commodore on October 2, 2020.
Just before the crash, a Ford Ranger towing a caravan was travelling north on the highway when a solar panel on its roof came loose and blew in the general direction of the southbound lane.
The Commodore was following behind.
The driver of the Celica swerved into the gravel verge and lost control, crossing into the northbound lane and colliding with the Commodore.
Dashcam footage showed "the solar panel flying high in the air well over the southbound lane" and that it was not heading towards the Celica but over it.
Coroner Simon Cooper found that the solar panel had been added to the caravan as an aftermarket addition and fitted by a qualified electrician as per manufacturers instructions using Sikaflex 252 adhesive.
The adhesive had failed, he said, and the area was experiencing strong winds at the time.
Since the crash, the Department of State Growth has made it a requirement for checks on external equipment and accessories to be carried out as part of registration inspections.
A national approach is also being pursued, including for a new rule to address ongoing security of aftermarket accessories.
As a result, Mr Cooper made no formal recommendation regarding the solar panel, apart from mentioning the need for specific regulations about how solar panels are affixed to caravans in Tasmania.
He did, however, comment upon the presence of 35 micrograms of cannabis per litre in the bloodstream of the driver of the Celica, who died at the scene.
Mr Cooper said this resulted an "overreaction" by the driver to the risk posed by the airborne solar panel.
"I am quite satisfied that the solar panel was actually flying over [the] vehicle, some distance above it," he wrote in his findings.
"No doubt, [the driver's] perception of what was occurring was different. However, I am also satisfied that both his perception and reaction time were very likely to have been affected by the THC found in his body at autopsy.
"His response to the circumstances which confronted him is to be contrasted with that of [the driver of the Commodore]. She was able to perceive the presence of the Celica in her lane and apply her brakes heavily to reduce the speed of her vehicle and thus lessen the impact of the collision."
Mr Cooper expressed his sympathies to all involved in the crash.
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