USA — When large wildfires blaze, the public counts on airplanes to put them out. Pilots fly air tankers over mountainous terrain and drop fire retardant up to nearly 12,000 gallons per trip onto the dense forests below. The bursts of red slurry bring hope to those whose homes are imperiled. Politicians and the media thrill at the sight and clamor for more. But is it safe? And is it effective enough to justify the high costs?
The U.S. Forest Service, which saw its large air tanker fleet shrink to just nine planes in 2012, has 20 air tankers on exclusive-use and call-when-needed contracts for the 2015 season, plus one under Forest Service operation. Spokeswoman Jennifer Jones said the agency is working to bring up to 28 air tankers into service. Last May, Colorado Gov. John Hickenlooper approved a $21 million budget for the state to develop its own aerial firefighting fleet of helicopters, spotter planes and small retardant-dropping air tankers. California, currently the only state to have its own firefighting fleet, has 22 air tankers, 12 helicopters and 14 air tactical planes.
But unpredictable atmospheric conditions make flying over wildfires difficult and dangerous. Thirty-seven firefighters have died in aerial firefighting accidents in the last decade. If similar casualty rates prevailed on the ground, the Forest Service found, more than 200 ground firefighters would die every year. And the slurry, which is rich in nitrogen, can harm fish, wildlife and watersheds, despite agency guidelines to prevent drops onto vulnerable areas.
Aerial firefighting is expensive. Tankers cost upwards of $6,000 per hour to operate. The slurry itself averages about $2 per gallon, and the Forest Service used almost 9 million gallons of it last year. Forest Service Chief Tom Tidwell recently predicted that high fire-suppression costs for the 2015 season will divert funds from other important agency programs.
Andy Stahl, director of Forest Service Employees for Environmental Ethics, has criticized aerial firefighting. They must have a lot of money to spend to waste, he says of Colorados air corps budget. Stahl claims that fighting fire from the air is not only expensive, dangerous and environmentally harmful, but that it has yet to be proven to work.
Forest Service experiments have demonstrated that retardants can reduce fire intensity and spread up to twice as effectively as water. But in 2011, Stahls group did a correlational study using Forest Service data that found retardant use had no effect on wildfire size or initial attack success rates. (Jones said a new study hopes to address the data deficit, but data collection will need to continue for several more years.)
Once a big fire is burning, theres no time to pause and debate issues of effectiveness or cost, however. If a house burns down and you failed to use a 747 that could dump dollar-a-gallon fancy fertilizer water because you didnt think it would make any difference, you shouldnt be fighting fires, Stahl says. You will get clobbered politically when that house burns.