A CARAVAN erupted into flames at the roadside in Western Australia ... after a dramatic 2km chase to warn the owner his rig was on fire.

Travellers who were following the burning caravan graphically described to Caravanning News how they was unable to alert the owner over his UHF radio and how they desperately attempted to flag them down by flashing their headlights and sounding the horn on the winding narrow road.

But the caravanner remained unaware of the potentially lethal drama unfolding behind him.

"The whole thing was over in 30 minutes from first sighting the smoke to an inferno," Busselton grey nomads Adrian and Fay Johns, who were not towing at the time, said.

The couple was driving towards Bremer Bay on the south coast of WA when they came up behind the Jayco caravan and noticed a tiny wisp of white smoke drifting down the left hand side.

"It became a little more and we were able to see that it was coming from the air conditioning unit," they explained.

Fay tried unsuccessfully to raise the rig's driver by UHF radio.

"My husband tooted the horn and flashed the lights as it was not safe to drive alongside the vehicle because of road conditions and oncoming traffic," Fay said.

"After about 2km we were able to pull alongside and signal for the driver to pull over.

All that remained of the caravan after the roadside inferno

"When he stopped we told him there was smoke coming from the caravan. We saw a brown patch on the aluminium cladding above the dual axles. It was hot and there was a road spring hanging on the road."

The Johns said the smoke was thick and becoming blacker as the caravanners reached for their fire extinguisher mounted just inside the caravan door.

"But they were unable to get it because of the smoke and fumes," Fay explained.

"Because 000 operators do not have a full handle on the geography of Australia and did not know where Bremer Bay was, or that the fire brigade is local and manned by volunteers, it was difficult to get any satisfaction there."

Fay told of how they attempted to remove the caravan's gas cylinders.

"They were secured well, including chains and padlocks for which the keys had to be found in the ute," she said.

"By then several other vehicles had pulled up, including one from the vineyard over the road. Luckily the driver was a member of the local fire brigade and he drove to town and got the truck and other team members, but it all took time.

"I then noticed through a side window that there were flames inside the 'van so it was decided to leave the gas cylinders and get the ute unhitched and driven away."

By the time a fire truck arrived the caravan was already well ablaze and almost burnt to the chassis. Roadside vegetation was scorched by the fierce heat. Luckily a strong wind kept flames from the front-mounted gas bottles preventing them from exploding.

"I strongly believe that nothing would have saved this 'van from being gutted as the fire was obviously well established inside by the time we noticed the smoke," Fay said.

She believed there were lessons to be learnt from drama.

"Carry a fire extinguisher inside the towing vehicle as well as in the 'van and do not have everything chained and padlocked when in motion," she said.

"Have a UHF radio and turned on, preferably scanning or have your listening channel and details, ie your 'handle', on the back of the towed vehicle.

"Ensure the contents of your caravan/motorhome/fifth wheeler/camper trailer are insured, ie do they have their own policy or are they covered on your home contents when travelling?"