California launches drone to help battle growing Rim Fire

The 4,000 firefighters battling the giant 12-day-old Rim Fire in the Sierra Nevada that has now burned more than 192,000 acres added a California National Guard Predator drone to their arsenal Wednesday to give them almost immediate views of any portion of the flames chewing through rugged forests in and around Yosemite National Park.

Three firefighters sustained minor injuries while battling the blaze on Wednesday, bringing the total number of firefighters injured to six out of the 4,200 staff members who have been working on the fire for the past 11 days.

"This one's a beast and the beast is spreading," one firefighter told Al Jazeera.

Though the fire continues to grow and is moving at the equivalent pace of a fast walk, California officials said they expect to fully surround the blaze in three weeks, although it will burn much longer that that. Containment is now at 30 percent. 

The MQ-1 unmanned aircraft, which is being remotely piloted hundreds of miles away, quickly alerted fire bosses to a new flare-up they otherwise wouldn't have immediately seen. 

The plane, the size of a small Cessna, will remain over the burn zone for up to 22 hours at a time, allowing fire commanders to monitor fire activity, determine the fire's direction of movement, the extent of containment and confirm new fires ignited by lightning or flying embers. Previously, ground commanders relied on helicopters that needed to refuel every two hours.

While unmanned aircraft have mapped past fires, use of the Predator will be the longest sustained mission by a drone in California to broadcast information to firefighters in real time. Officials were careful to point out the images are being used only to aid in the effort to contain the fire.

The Rim Fire started Aug. 17 and quickly exploded in size, becoming one of the seven largest California wildfires on record. Its progression slowed earlier this week when it moved from parts of the forest with thick underbrush that had not burned in nearly a century to areas that had seen fire in the past two decades.

Experts now think it's possible the fire will continue until California's dry season ends this fall.

"My prediction is it will burn until we see rain," said Hugh Safford, a regional ecologist with the U.S. Forest Service.

The Rim Fire has destroyed 111 structures, including 11 homes, and posed a threat to ancient giant sequoias.

The fire also has threatened San Francisco's water supply at the Hetch Hetchy Reservoir, but Stratton said it was burning itself out as it approached and that crews were lighting back burns to push it back into the wilderness.

There are 100 workers from PGE utility company repairing fire damage to power lines and 90 working at the reservoir to get the generator back up and producing power to send back to the grid for San Francisco.

Meanwhile, U.S. authorities closed a second main road into the Yosemite Valley tourist landmark Wednesday. The decision came days before the Labor Day weekend, when a surge of visitors typically visit Yosemite, which draws millions of tourists every year.

The blaze has forced the closure of multiple campgrounds and other facilities in the area, and has also threatened a number of groves of giant sequoia trees, some of the world's biggest and oldest living organisms. 

But it remains more than 15 miles away from the majestic Yosemite Valley. The park stressed again Wednesday that most of Yosemite was not affected by the fire and is relatively smoke-free. 

Al Jazeera and wire services