ONE moment everything was "perfect" but within seconds Rodger Hannemann's crane had become an uncontrollable colossus.
The former crane driver is giving evidence in Brisbane Coroners Court, at an inquest into the death of Christine Leonardi and her six year-old son Samuel.
The crane smashed into the Leonardi's ute near Toowoomba in 2013.
It was unprecedented when the crane kicked to the left that day, Mr Hannemann told Coroner John Hutton on Tuesday.
"When I lifted my foot off, it went to the left," he said.
Only moments earlier "everything was perfect, fine," he told the court.
Mr Hannemann applied the brakes softly. Then the Franna AT20 crane driver began fishtailing "significantly" side to side.
He thought accelerating would apply more hydraulic pressure and help him regain control.
"Would it surprise you to know that the experts who've reviewed this case said you should never accelerate in this situation?" counsel for the coroner Peter de Waard asked.
"It would," Hannemann replied.
The former driver said he tried to apply the brakes and that did not work.
"I hit a bump or something," the crane driver added. "It was almost back under control again."
Then he felt a noticeable jolt. Soon after, he heard "a massive explosion" and travelled another 60m before stopping after the fatal accident.
The driver said he still did not know why he did not phone 000 immediately.
"I couldn't tell her where I was or what happened," Mr Hannemann said.
"You would have been shocked. Absolutely shocked," Mr Hutton told the driver.
The coroner said Mr Hannemann did actually brake as experts advised, but that did not work.
Asked how he handled the situation, Mr Hannemann said he would do the same thing again "except not go there that day".
A friend of his in Mt Isa who operated similar cranes complained of handling and fishtailing problems, Mr Hannemann said.
But the cranes were generally good machines, he added.
"They're not designed for high-speed road use," Coroner Hutton added.
Mr Hannemann stopped working as a crane driver about a year after the tragic accident.
The inquest continues.
Crane deaths: "She had nowhere to go. Absolutely nowhere"
THE crane that smashed into the Leonardi family car "catapulted" itself off the road and could have easily caused even more tragedy, a coronial inquest has heard.
Christine Leonardi and her six-year-old son Samuel died after the 2013 crash on the New England Highway near Toowoomba.
It was "a miracle" anybody survived, Coroner John Hutton said on Tuesday.
The coroner shook his head as he was shown what he labelled "distressing" pictures of the devastating crash.
"She was trying to get out of the way," he said, as the routes of the 20 tonne Franna AT20 crane and the Leonardi's vehicle were explained.
"She had nowhere to go. Absolutely nowhere," he said at Brisbane Coroners Court.
Mrs Leonardi was driving. Her two other children were injured that day, but survived, as did Mrs Leonardi's husband John.
The crane's engine brake kicked in at 95kmh, which was the crane's fastest possible speed, counsel assisting the coroner Peter De Waard said.
The crane carried on for 60m after the crash, smashing through a fence and some trees.
"So there's a massive inertia, uncontrolled inertia after the crash [which] carries the vehicle quite some distance," Mr Hutton said.
"Not only is it dangerous on the road if there's a crash. It's also dangerous to surrounding third parties who live adjacent to the road."
The coroner was also concerned at the proximity of power lines to the crash scene.
Mr De Waard said a deflated inside right rear tyre and some handling issues were identified with the crane a few weeks before the crash.
The crane driver, Rodger Douglas Hannemann, arrived to give evidence on Tuesday morning.
He told the court most formal testing carried out before he was licensed to drive cranes did not involve driving on public roads.
Mr Hannemann had been driving cranes for several years elsewhere, including the Chinchilla region, before getting a job with Loughlin Crane Hire in 2012.
He said after joining Loughlin, his new employer seemed happy with his crane driving skills.
Mr Hannemann said no issues or advice related to crane handling or stability were mentioned.
Mr De Waard said there was an "8% gradient" down the hill where the crash happened.
There was a dip at the bottom, then a gradient up of about 2.5% for a short distance before the point of impact.
Mr De Waard said one expert described it as a "moderate" slope, in contrast with an earlier comment from Mr Hannemann that it was a steep slope.
The court heard of some differences between handling trucks and cranes, and the "death wobble" which could affect cranes.
Mr Hannemann said "a death wobble" occurred when a crane fishtailed and the driver was left with no control.
"I found the best way to pull them out of that was acceleration," he said.
The driver was now a self-employed artist.
Mr and Mrs Leonardi had lived in Toowoomba since 1999.
EARLIER: IT WAS a crash that took the lives of a mum and her six-year-old son.
Now, three years after a runway crane ploughed into a car Christine Leonardi and her son Samuel were travelling in, a coronial inquest will seek answers.
The impact of the runaway crane in September 2013 left Mrs Leonardi's car unrecognisable, a pre-inquest conference heard at an earlier date.
The incident happened on the New England Highway. Mrs Leonardi was driving her three children to school in Toowoomba.
A coronial inquest in Brisbane today will begin examining how the crane driver lost control of the vehicle - and what might be done to make driving cranes on public roads safer.
In May, a pre-inquest conference in Brisbane heard the crane began to swerve as it drove slightly downhill around Top Camp.
The court heard physical evidence showed driver Rodger Douglas Hannemann began to brake - but he could not stop the swerving.
He accelerated to try and regain control but the fishtailing increased.
He eventually lost control of the vehicle, colliding with Mrs Leonardi's Ford dual cab ute despite her efforts to avoid him.
Mrs Leonardi died instantly and Samuel died in hospital days later. Her two other children were injured but lived.