The crew from the Edinglassie Rural Fire Brigade, based at Muswellbrook, was patrolling along Commission Road in the Wollemi National Park on Wednesday night.

According to John Cox, a district coordinator for the NSW Rural Fire Service, the crew members heard a "crack".

An ironbark tree, fire-damaged and more than 30 metres high, was falling towards their tanker. The firefighter in the passenger seat yelled, "Go!".

The tree's trunk clipped the back of the cabin then bounced and smashed down on the back of the tanker. The firefighters emerged "cheerful but shaken".

"We were so relieved they were safe, considering the damage done to the truck, and considering they were in a remote location," John Cox said.

The tanker was badly damaged. The tree smashed into lockers, a pump and two hose reels, and it tore off a part of the back of the truck. John Cox said the force had bent the tray.

"It almost looks like a banana," Mr Cox said. "There's a big bow from the weight of the tree."

The tanker is now out of service. The crew, however, headed back out to battle fires on Friday in a replacement tanker.

"They were very, very lucky," said John Cox of the Edinglassie crew's near miss. "No injuries, extremely lucky."

Just a day later, the RFS suffered a tragedy, with two firefighters killed and another three injured, after their tanker hit a falling tree and rolled near Buxton, south-west of Sydney. That loss has reverberated through the RFS community and beyond.

"It's devastating," said Greta Rural Fire Brigade's deputy captain Trevor Kedwell. "They happen rarely, but they do impact upon us all."

Trevor Kedwell had only returned home at 3.30am on Friday after being part of a strike force fighting an arm of the massive Gospers Mountain blaze.

But he knew to keep his uniform out. Saturday's forecast is for temperatures to 45 degrees and north-westerly winds, before shifting south to south-east, had prompted a fire danger rating of 'extreme'.

Five major fires are burning in the greater Hunter region, and RFS incident controller Superintendent Martin Siemsen has expressed concern about the blazes ahead of the heatwave conditions.

"Firefighters across the Hunter will be deployed to the field or will be on standby, ready to respond to existing or new ignitions, as required," he said.

After 18 years of being a volunteer in the NSW Rural Fire Service, Trevor Kedwell said this summer was tossing up new challenges.

"Never had an equivalent like this before, not in length of time and size of fires. Never," he said. "Apart from that, I've lived in the valley all my life and I've never seen these conditions before."

The Greta brigade has 25 members. Josh Fraser is one of its newest. This is his first season in the RFS. It has been quite literally a baptism of fire.

"Getting tired," he says. "But I'm not as tired as the other guys, because they've been in it longer than me."

The fire risk came close to home for Josh Fraser in November, as the brigade's members had to battle blazes in their hometown and North Rothbury.

"It was just out the back of my place," said Josh Fraser. "That was quite scary."

Trevor Kedwell said those battles were "short and sharp", with the flames quickly conquered. The bigger battles were being waged further afield, with fires that refused to be quelled.

"These prolonged fires are the things that take more out of you because we're just doing shift after shift," he said. "In places like the Wollombi area, we're doing 12 hours on, 12 hours off. I know it's not in the headlines, but basically the firefighting effort that's been going on out there for two months now is just non-stop. That's the thing that wears you down."

Greta brigade member Lachlan Martin is used to long hours. He works 12-hour shifts in the mining industry, as well as being a volunteer firefighter for the RFS.

"Sometimes you get pretty exhausted, but normally I'm pretty good," said Mr Martin, who joined the service five years ago when he was 16.

It's been a tragic week for the firefighters, and they expect tough times ahead. But all that adversity only pulls the Greta brigade together.

"We're fairly close," Lachlan Martin said. "It's not a team, it's a family."

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