At the warning, Michael Ryan, then 63, returned the Warrigal Care minibus safely to the overtaking lane as he drove northward on the M1 shortly before midday on January 25 last year. 

But moments later, he again veered left. 

Dashcam footage played at Ryan’s Wollongong District Court trial on Monday showed the bus crossing into the path of an 18.5-tonne B Double that was carrying almost 49,000 litres of highly flammable ethanol. 

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The truck nudged the back left of the bus, spinning it so its side momentarily pressed flat against the driving force of the truck’s nose. The bus then continued off onto the roadside and flipped onto a guardrail. 

Margaret Russell, 78, suffered multiple blunt force injuries in the crash and did not survive. 

It is the prosecution’s case that Ryan drove dangerously by leaving the overtaking manoeuvre too late – until both vehicles were within about 500 metres of the exit to Dapto, where the occupants of the minibus were to attend a picnic hosted by Warrigal Care. 

On Monday the Crown prosecutor told the jury the truck was gaining speed on a downward slope and the bus, fitted with a device that limited its speed to 100kmh in a 100kmh zone, was ill-equipped to overtake in the circumstances. 

Tony Forshaw, who was transporting the fuel load from Bomaderry to Port Botany for Ron Finemore Transport, told the court the truck was also fitted with a speed-limiting (100kmh) device.

He said he did not sound the truck’s horn at the minibus’s first veering – “I didn’t feel it was necessary at the time” - or the second – “I was hanging on to the steering wheel”.

Mr Forshaw gave evidence he did not did not see the bus’s indicator light up before it veered left.

“I continued checking my mirrors and next thing I know, the little purple bus has clipped the right hand side of my vehicle,” he said. 

He said he pulled the truck safely to a halt after the collision, pushed an isolation switch to safeguard the ethanol then walked to the bus to help some of the 11 injured passengers.

Ryan, of Berkeley, answered in a loud, clear voice – “not guilty” – as the indictment was read out on Monday. 

He was accompanied by a large group of supporters. 

His lawyer, Josh Brock, told the jury his client had not been speeding, texting or drink driving when the collision occurred, and that his behaviour fell short of the legal definition of dangerous driving. 

“No driver can make the right judgement call 100 per cent of the time,” he said. 

“[Overtaking] is a maneuver that is likely undertaken by hundreds of cars on a daily basis. It will be the defence case that [Ryan] did so with care,” he said, adding that something had admittedly “gone horribly wrong”.  

Mr Forshaw is expected to return to the stand as the trial continues before Judge John Pickering on Tuesday. 

CORRECTION: In an earlier version of this story, Margaret Russell was referred to as an 88-year-old woman. In fact, Ms Russell was aged 78.