The federal government has a new high-tech weapon, but this one battles wildfires. It is a remote-controlled spy plane that does not mind smoke and can see in the dark.

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 planes 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 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, a 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 and helicopters 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.

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, which drop a retardant or water on wildfires.

The unmanned planes will not 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. Forest officials have long considered using them, but only in the past decade have heat-detecting sensors gotten small enough to fit on small robotic planes.

Unmanned aerial vehicles -- or UAVs -- are controlled by a pilot on the ground. They look like test-kit airplanes and act like flying fire towers, relaying data via antenna or satellite. But the use of UAVs will come with restrictions.

The Federal Aviation Administration must first approve pilotless planes in civilian airspace before such planes 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.

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

Using UAVs to combat wildfires made sense. Last month, the Forest Service tested three UAVs with 12-foot wingspans -- about twice that of a bald eagle -- over Moffett Field. 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 to monitor fires near Fort Hunter Liggett, 250 miles northwest of Los Angeles. Next summer, the agency will team up with NASA to test the high-flying Altair from General Atomics. It is an extended-wing commercial version of the Air Force Predator B.

The Altair, with its 86-foot wingspan, can crisscross western states for as long as 32 hours without refueling. It can reach as high as 52,000 feet and has a maximum range of about 4,200 miles. Manned planes have to take breaks and their range is more limited.

An Altair, which will not replace piloted aircraft, costs more than $1 million, while small UAVs are priced at about $100,000 each.

An unmanned plane that can track forest fires is ready to take off near Mountain View, Calif.