Coronial findings have been released into a shocking car crash that claimed three lives on the Midland Highway south of Ross in October 2020.
A red Toyota Celica coupe lost control and veered into an oncoming vehicle after swerving when a solar panel fell off a caravan up ahead of them.
The male driver - known only as AZ, his 15-year-old daughter in the passenger seat and his 71-year-old aunt in the rear seat were all killed instantly, while his 7-year-old son - in the other rear seat - suffered a broken elbow.
All three passengers in the other car sustained non-life threatening injuries.
The driver of the caravan didn't realise the solar panel had come loose until he was contacted by police further up the highway.
Coroner Simon Cooper has found the 48-year-old man behind of the wheel of the Celica was significantly under the influence of marijuana, with pathology results showing he had 35 µg/L of THC in his system at the time of the crash.
Cannabis was also discovered in the boot of the car.
"In the bag, police found a smoking device and 8.4 grams of chopped cannabis," the report states.
"In light of the fact that it was identified that AZ had a substantial level of cannabis in his body at the time the crash occurred (and no other person in the vehicle did), it is reasonable to conclude, and I do, that the cannabis was his,"
Mr Cooper says the evidence as a whole satisfies him that AZ overreacted to the situation he faced that day.
"I am quite satisfied that the solar panel was actually flying over AZ’s vehicle, some distance above it.
"No doubt, AZ’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.
"AZ should not have been driving.
"His inability to react appropriately to the solar panel because of the THC in his body was the principal reason, in my view, he, his 15-year-old daughter and aunt died."
The 71-year-old also wasn't wearing a seatbelt.
"Had she been, then like the other rear seat passenger, she may not have died in the crash."
The solar panel which came off the caravan had been retrospectively fitted by an electrician as per the manufacturers instructions.
Mr Cooper has found it was a significant factor in the crash.
"I note there are no specific regulations governing how solar panels or similar are to be affixed to, or mounted, on caravans or similar in this state.
"In my respectful view there should be."
In the aftermath, the Department of State Growth conducted a full review into current standards, performance measures, legislation and published guidelines regarding the proper fitment of aftermarket equipment and accessories.
The State Registrar of Motor Vehicles has issued a Special Information Bulletin (Security of Attachments) "...to ensure that checks of the security of external equipment and accessories are undertaken as part of preregistration inspections" and further advice has been published in relation to the fitment of aftermarket solar panels.
"Moreover, I am advised by the Department that a National approach is being pursued in relation to the Australian Light Vehicle Standards Rules for the insertion of a new rule addressing ongoing security of aftermarket accessories fitted to any vehicle," Mr Cooper said.