The NSW coroner is investigating the Upper Murray fires which started in December 2019, and the death of expectant father Samuel McPaul.

Counsel assisting the inquest, Adam Casselden, said while Mr McPaul's now 15-month-old son had never had the chance to meet his father, he would no doubt learn of his heroic behaviour.

Mr McPaul was on the back of a Culcairn fire truck with Rodney O'Keeffe on December 30 when the vehicle, driven by Andrew Godde, was struck by a fire tornado at Jingellic.

He was crushed underneath the truck and Mr O'Keeffe suffered serious burns and broken ribs.

Mr Godde had only asked Mr McPaul hours earlier if he wanted to help with the fire fight, and picked him up from his Holbrook home.

He became emotional on Wednesday when asked what the late 29-year-old was like as a person.

"Terrific young man and had the world at his feet," Mr Godde said.

"He'd do anything for anyone.

"As soon as I asked him if he'd come on the fire truck, he didn't hesitate.

"That's the way Sam was."

Mr Godde said when they arrived at the scene, he realised how serious the incident was and told his crew to put on all the protective equipment they could.

He said the fire was making its own weather.

Mr O'Keeffe on Wednesday said the conditions in the lead up to the rollover hadn't been too bad, but had quickly changed.

The fire had been several hundred metres from the trio's vehicle, but "just travelled that distance in seconds".

The crew had been heading out of a paddock to protect a home before the situation erupted.

Mr O' Keeffe said they "realised danger was coming and had to get out desperately".

Mr Godde shouted at them to take cover.

Mr McPaul and Mr O'Keeffe were in the rear of the vehicle, behind the cabin, and Mr McPaul grabbed Mr O'Keeffe as the temperature spiked to take shelter.

"This is when the whole paddock seemed to explode in flames," Mr O'Keeffe said.

"I looked around and saw we were surrounded by fire coming from all directions."

Mr Godde described what he thought was a spot fire flaring up in front of the truck as they went to leave the paddock.

As he went to drive through it, as he had done many times before, he realised something was wrong.

"I was in the eye of a tornado full of flame," he said.

He was thrown around in the cabin.

"I remember thinking I'm going to die at Jingellic," Mr Godde later told police, and said he was unable to control the vehicle.

Mr O'Keeffe doesn't remember the rollover.

"I knew I was under the truck but I didn't know how," he said.

Everything turned black and he realised Mr McPaul, who was crushed under the truck, was dead.

Mr O'Keeffe was airlifted to hospital and spent 17 days receiving treatment, including skin grafts.

He only stopped wearing bandages about six months ago and told the inquest he was doing well.

When police arrived at the scene, Mr Godde was distraught.

"He kept saying there was nothing I could do," a policewoman who attended the incident said in a statement.

The inquest heard there was no suggestion Mr Godde had done anything wrong at the property on River Road.

The inquest heard an emergency warning had been sent out to firefighters on their radio system warning of the fire vortex.

Mutliple people said they didn't hear it, including Mr Godde, who said he was probably out of the truck and wished he'd heard it.

"There is a pyrocumulous column that has been created by this fire," the warning said.

"The column is unstable and may collapse.

"If this occurs, the fire will extend in all directions with erratic fire behaviour and extreme winds."

Those at the scene were told to move away from the fire.

Firefighter Mark Reeves said it had been raining embers.

He believes he was the first firefighter at the scene of the blaze with another member when it started on December 29.

While he was hopeful the crews would have the fire under control by the following morning, the conditions deteriorated.

"It was a s---ty day," he said.

"Stinking hot and the wind was really gusty

"A really gusty, terrible day."

The area near the rollover scene caught fire within minutes, he said, and despite having a face mask he was struggling to breathe.

The wind was so fierce, it pushed the strap of his helmet into his throat and made the water hoses extremely hard to control.

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Mr McPaul's wife Megan and mother Chris listened in to the proceedings.

Coroner Teresa O'Sullivan said multiple people would give evidence in the matter.

"I would like to acknowledge that everyone here, certainly everyone involved in these proceedings, understands how difficult that must be," she said.

"We hope that some of your questions will be answered by going through this evidence and through these proceedings.

"And i just wanted you to know our thoughts are very much with you today."

The inquest will continue on Thursday.

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