Collin Pumpa had been working the night shift with Mr Watson on July 22, 2014 at Bradken Resources' Wodonga factory.

He was about 100 metres away from where his workmate was operating a skid steer loader, when he spotted the flames and raised the alarm.

"As I approached, I looked to see if Peter was out of the skid steer, I couldn't see him," Mr Pumpa said.

"As I got closer, in amongst the flames I could see Peter ... Pete was in a charred state and there was no sign of life."

He and others tried to deal with the flames with a fire extinguisher, before it was finally put out with a fire hose and emergency services arrived. "I wasn't any use to anybody because I didn't feel like leaving him," Mr Pumpa said.

Bradken Resources has been charged under the Occupational Health and Safety Act with failing to provide a safe workplace and faced the first day of a trial at Wangaratta County Court on Wednesday.

Executive general manager Brad Ward appeared on behalf of the company and entered a plea of not guilty.

Crown prosecutor Andrew Palmer told the jury the death of Mr Watson, 42, could have been avoided because the skid steer loader should never have been used to lift heavy metal castings.

"One of those castings had come into the cabin and was effectively on Mr Watson's lap. That is not an event that you can survive, and Mr Watson didn't survive," he said.

"He died from burns when the casting came into the cabin."

There were no witnesses to the incident, but Mr Palmer said the only explanation was that the metal casting, which weighed 300 kilograms and was about 500 degrees celsius, fell out of the bucket and crashed through the windscreen.

He said Bradken failed to take reasonable steps to provide a safe workplace because a series of incidents before Mr Watson's death showed the skid steer loader was not right for the task.

These included a casting falling out of the bucket, falling metal cracking the windscreen and examples of the machinery being unstable.

"It is an inherently unstable piece of machinery," Mr Palmer said.

"Having something so unstable when you're carrying something so heavy and hot is potentially risky."

The jury has been asked to use their heads, not their hearts, when it comes to deciding if Bradken Resources provided a safe workplace for staff.

Judge Julie Condon took a moment to address the jury of nine women and five men on Wednesday after they learnt the case involved the death of a man.

"Hearing that (Peter Watson died) may have evoked some emotion and that's fair enough because it's sad," she said.

"No such emotion has any role to play."

Defence barrister Robert Taylor said the case was about what was "reasonable and practical" for Bradken to have done.

"Nothing that happens today can take away the fact that Mr Watson lost his life ... This case is not about finding someone to blame," he said.

He said Mr Watson had been an experienced and competent worker and urged the jury to make their own decision based on the evidence presented.

One of the key issues will be the position of the bucket on the skid steer loader, which prosecutor Andrew Palmer said was too close to the machine operator to be safe for the task of lifting heavy and hot metal.

He said a rock escalator would have been more appropriate.

Three police officers who gave evidence in court on Wednesday said they saw the bucket was lifted above the height of the machine operator when they attended the scene of the fire after 11.15pm on the night.

Sergeant Stewart Smith said it took firefighters at least 45 minutes to put out the fire because they struggled to get close enough.

"The heat was so intense that the water was just splashing off as steam," he said.

"At least an hour after I arrived was when I could see the deceased inside."

He saw smashed glass where the metal casting had crashed through the windscreen and landed on Mr Watson.

The extreme heat meant emergency service workers and Bradken staff had to use a forklift and chains to remove the casting before paramedics could reach Mr Watson and confirm he had died.

The trial is expected to involve up to 11 witnesses and run into next week.

Evidence will continue in court on Thursday.

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