New Way to Fight Fire With Fire

T U C S O N, Ariz., Aug. 13 -- Firefighters have always believed the best way to fight a fire is with fire.

Igniting a so-called burnout in front of advancing flames deprives the fire of fuel. But the process is expensive, time-consuming and dangerous.

A Hotshot team — an elite firefighting crew — of more than a dozen members outfitted with fire "drip pots" can spend an entire night setting only a few acres on fire. Sometimes, as in the case of the Los Alamos fire in New Mexico a couple of years ago, the fire gets out of hand. Sometimes there are injuries.

So, the U.S. Forest Service is increasingly relying on a much safer, more cost-effective strategy. Rangers use aerial ignition devices — which are plastic ping-pong balls filled with highly flammable potassium permanganate. Loaded into a helicopter dispenser, the little balls are injected with antifreeze just before they're dropped into the targeted area.

By the time these small missiles hit the ground, the chemicals have mixed. The ping-pong balls burst into flames and set the surrounding area on fire.

Timing Is Everything

Lewis Puckett, the exclusive distributor of the ping-pong balls, says timing is everything.

"It free-falls for up to 45 seconds, filtering down through the trees to the ground and then it ignites," said Puckett, who supplies the Forest Service and Bureau of Land Management with nearly 1 million balls a year. "When it does ignite, it doesn't explode or anything. But it does totally consume itself and it's extremely safe."

Just in case the devices erupt into flame prematurely, the dispenser is outfitted with an automatic fire extinguisher.

Typically, a string of the little balls is dropped along a line. Ultimately, a wall of fire is created, which eats up dry grasses, brush, trees and other fuel on the ground. The balls are particularly useful in narrow canyons and on steep mountains that are difficult to access on foot.

Safer, More Economical

Bill Brandau of the Forest Service conducted a recent burnout using the devices and was pleased with the results. "See that area?" he said, pointing to a broad stretch of hills and canyons north of Tucson. "We burned all of that in about two hours."