Fahrenheit 747: World’s Biggest Fire Extinguisher Douses L.A. County

The deadly fires that have blackened more than 105,000 acres around Los Angeles prompted authorities to call in the world’s largest fire extinguisher — a Boeing 747 that can drop 20,000 gallons of retardant over a swath of land three miles long.

The plane made its first-ever drop in the continental United States when fire officials summoned it to the Oak Glen fire east of Los Angeles mid day on Monday. After the successful first drop, the Supertanker was called back into action Monday evening where it made further drops on the massive Station fire north of the city which grew to more than 164 square miles and threatened 10,000 homes. Nearly 2,600 firefighters from as far away as Montana are throwing everything they have at the blaze, and on Monday they called in the biggest tool in their inventory.

Supertanker, a 747-100 modified by Evergreen Aviation of Oregon, can deliver more than 20,000 gallons of fire retardant with considerable accuracy using its unique pressurized delivery system. Although Supertanker can’t snake through canyons like smaller aircraft, nothing can touch its payload or its ability to perform multiple controlled drops during a single flight. The Grumman S-2, a dedicated workhorse of California’s airtanker fleet, carries 1,200 gallons. That’s a thimbleful compared to the Supertanker.

“This aircraft can lay down a three-mile-long, football field-wide swath of retardant if needed,” Evergreen’s Rick Campfield told Wired.com. “There’s no close second.”

Evergreen spent more than $50 million developing the Supertanker and hopes to sell it around the world as the premier aerial firefighting tool.

There has long been debate on the usefulness of firefighting air tankers. The debate peaked several years ago after the high-profile crashes of firefighting aircraft prompted several agencies to ground many of the aging aircraft that were the backbone of the fleet. Although there is still some question as to the cost-effectiveness of airborne firefighters, there are some new options on the marketplace.

In addition to the Supertanker 747, an outfit called 10 Tanker Air Carrier developed an aerial firefighter based on the McDonnell Douglas DC-10. It carries 12,000 gallons and has been flying since 2006. Supertanker saw action in North America for the first time in July when it was deployed in Alaska. Before that, it made a demonstration drop in Spain.





Besides being big, the Supertanker is persistent. The pressurized system can make several precision drops per flight. During the flight in Alaska, it dropped 17,000 gallons on its first pass over the fire, then returned to dump the rest of its payload. Most firefighting air tankers use a simple gravity drop where the doors are opened and everything is dumped at once.

“If an incident commander says he wants a thousand gallons here, a thousand there and 15 thousand over there, we can do that,” Campfield says. “It’s like an aerosol can. You have much better control with a pressurized system.”

This kind of capability means Supertanker can fight several small fires, after a lightning storm for example, or cover a three-mile swath of property to protect a community. With a top speed in excess of 600 mph, Supertanker can get from its base to the fire line quickly. Currently the 747 is based at McClellan Airfield outside Sacramento. Once it’s over the fire, Supertanker can slow down to around 160 mph while making drops 300 feet above the ground. And unlike many other firefighting aircraft that are flying at or near their maximum weight, the 747 is flying well below its maximum providing an added safety margin for the pilots.

One disadvantage of large tankers is the time it takes to reload them with retardant. Both the DC-10 and 747 require very long runways of more than 8,000 feet and turnaround times of around 30 minutes to refill the fire retardant, refuel and interestingly, let the brakes cool down. Other aerial tankers including the Martin Mars (the world’s largest flying boat) as well as large helicopters such as the Sikorsky Air Crane can refill quickly from nearby water sources such as a lake or pond. But Campfield says the Supertanker isn’t a replacement for these or other firefighting aircraft.

“It complements the fleet for those situations that make sense,” he says. The plane, he says, can make the current fleet more adaptable. Grummans and Sikorskys can be used in those areas where agility is needed, and the Supertanker is perfect for those instances that demand sheer volume.

“We can lay down the long line” of retardant, he says.

Of course this kind of capability doesn’t come cheap. While helicopters and smaller aircraft might cost a few thousand dollars per hour to fight fires, Supertanker comes in close to $30,000/hour. This does fuel the cost-effectiveness debate, but with Supertanker delivering at least eight times as much retardant as the typical tanker in the fleet, the math keeps it in the same dollar per gallon-delivered range as other aircraft.

Another capability still under development by Evergreen is the ability to fight fires at night. The pressurized delivery system allows the Supertanker to make effective drops from as high as 400 feet — about twice the altitude of most air tankers. That added altitude could allow crews to safely make drops at night.

After Monday’s drops, there was no word from California fire officials on when the 747 might be called in again according to Campfield. But after being told the first flights of Supertanker were “very effective,” expect the veteran airliner to return to service soon in its new life as a fire extinguisher.

Photos of the Evergreen Supertanker making a test drop in Arizona last spring: Evergreen Aviation

Video: myFOXla.com

