LOS ANGELES — Firefighters are getting a high-tech ally in their battle against wildfires: a remote-controlled spy plane that doesn't mind smoke, can see in the dark and never sleeps.

Scientists have been testing whether such planes — similar to the spy drones the U.S. military flies over Iraq and Afghanistan — can help track the direction and behavior of fast-moving flames without putting firefighters in harm's way.

After experimental flights of three unmanned aerial vehicles this summer, the U.S. Forest Service will launch the first real-life deployment next spring. The plan calls for planes to traverse a dozen Western states, mapping real forest fires 24 hours a day.

"Unmanned aircraft have the capability to do what we call the 3-D missions — the dull, dark and dangerous missions where you don't want to put a pilot on," said Vince Ambrosia, research scientist at NASA's Ames Research Center in Moffett Field in Silicon Valley, where the experiment was done.

Pilots now fly over hot spots and fire perimeters in aircraft outfitted with special heat-sensing cameras that see through smoke and spot fires. The cameras relay images to ground personnel who plot how best to confront the blaze.

There is plenty of ground to cover — tens of thousands of fires burn millions of acres each year — but most planes can fly only during daylight hours. The Forest Service banned night flights after poor dusk visibility led to several crashes involving firefighting air tankers.

It'll be awhile before unmanned planes can be used directly to put out fires because they are not large enough to hold tanks of water.

But for patrolling and mapping blazes, such planes are becoming practical. However, the use of unmanned aerial vehicles — or UAVs, as they are called — will come with restrictions.

The Federal Aviation Administration must first approve pilotless planes in civilian airspace before they can be routinely deployed. UAV flights in the United States are permitted on a case-by-case basis if they can be flown safely alongside passenger-carrying aircraft, FAA spokesman Allen Kenitzer said.

The Department of Homeland Security uses unmanned planes to patrol the seas and the U.S.-Mexico border. When Mount St. Helens rumbled to life last year, scientists used one to monitor the volcano.

Overseas, spy drones such as the Global Hawk from Northrop Grumman Corp. and the Predator from General Atomics Aeronautical Systems Inc. are routinely used in the war against terrorism, spotting enemies from high up and in some cases firing laser-guided missiles.

Last month, the Forest Service tested three UAVs with 12-foot wingspans. The UAVs, which could fly as low as 1,000 feet, were equipped with thermal sensors and hovered over four deliberately set fires, beaming back almost instantaneous infrared updates.

In the spring, the Forest Service plans its first night flight using UAVs. Next summer, the agency will team up with NASA to test the high-flying Altair from General Atomics.

The Altair, with its 86-foot wingspan, can crisscross Western states for up to 32 hours without refueling. It can reach as high as 52,000 feet and has a maximum range of about 4,200 miles.

UAVs are by no means cheap — an Altair costs upward of $1 million, while small UAVs are priced up to $100,000 each — and they won't replace piloted aircraft. But they're another set of eyes for firefighters.

"The more tools you have available in your toolbox," said Everett Hinkley, who heads the Forest Service's Remote Sensing Applications Center in Salt Lake City, "the better job you can do."