Australia — A SYSTEM used to rate bushfire threats becomes increasingly inaccurate as weather conditions worsen, a parliamentary inquiry heard yesterday.
Country Fire Service officials told South Australian MPs investigating this year’s Cherryville blaze that its fire danger index’s “margin of error” increased the worse conditions for a fire became.
The index rating for Mt Lofty Ranges on May 9, the day the Cherryville fire started, was 33 but it needed to reach between 45 and 50 to have aerial support on standby outside the fire season, the Community Safety and Emergency Services select committee heard.
CFS chief officer Greg Nettleton told the inquiry the system was six decades old.
A national two-year review, in the form of a scientific research project, was being undertaken in the hope of developing a new system, he added.
He admitted he wanted aerial bombers on standby all year but cost prevented this.
The Cherryville blaze destroyed a Basket Range home and razed more than600ha of scrub.
It started as a burn-off on a small property that ran out of control. when the wind changed.
The rating of 33 on May 9 was lower than the 45 to 50 deemed necessary to have aerial support ready to go outside of the fire danger season.
The company that provides aerial firefighting for the CFS, Aerotech, is usually contracted to have planes on immediate standby during this season, which finished in the hills on April 30.
“There is a margin of error (with the system) as a fire starts to increase up the scale,” Mr Nettleton said.
“The index was developed in the 1950s . . . it used to go up to 100, but we now know that fires can go up to 200 or 300,” he said.
The Fire Danger Index rates bushfire threats from low/moderate (FDI zero to 11) to catastrophic (FDI 100 or more). The index takes factors such as the dryness of an area, the wind speed, temperature and humidity into consideration to calculate the risk. of bushfires.
Committee chairman Robert Brokenshire also asked Mr Nettleton, if given his time again and there was a week of hot dry weather predicted for May, following a dry six months, if he would have the Aerotech planes on standby.
“I would have them on standby 365 days a year, but that’s a fairly expensive proposition,” he said.
Official predictions have rated the overall fire danger this year as normal in most parts of SA, however the West Coast and Far North pastoral districts have been declared high risk.
The latest Bureau of Meteorology seasonal climate outlook suggests thatpredicts slightly warmer than normal maximum temperatures were more likely in the North, West, Central and South-East districts. The CFS has warned said households that they should review their bushfire survival plans.
Last month New South Wales firefighters fought dozens of bushfires on Sydney’s outskirts.
At least two properties were destroyed, several others were threatened while several firefighters were injured battling at least 60 fierce blazes that swept the state.