The Fire Mappers

Woody Smith, at the National Infrared Operations (NIROPS) headquarters. Image Credit: Osha Gray Davidson.

Woody Smith, at the National Infrared Operations (NIROPS) headquarters. Image Credit: Osha Gray Davidson.

With the 2013 fire season ramping down in much of the arid western United States, Woody Smith is looking forward to days that are divided into more than three parts.

“At the busy part of the season,” he says, “we’re either flying, eating, or sleeping. That’s it.”

Smith, the 49-year-old supervisory electronic technician at the National Infrared Operations (NIROPS) headquarters, has been living with this kind of grueling schedule for 25 years. And he loves it. Like most people working in similar positions at NIFC (National Interagency Fire Center) Smith began his career out on the fire lines. In 1988, he was introduced to infrared (IR) mapping and was instantly hooked.

“Very long nights spent mapping wildland fires in the back of small airplanes became my chosen profession,” he says and shrugs, as if admitting

Fire density calendar map. Image Credit: U.S. Forest Service.

Fire density calendar map. Image Credit: U.S. Forest Service.

to a personality defect. It’s easy to see the allure, however. There are few other positions that allow someone to combine a passion for firefighting with hands-on daily use of some of the most sophisticated mapping tools on the planet. The most important of these are the instruments, called line scanners, capable of detecting fist-sized hot spots from an altitude of 14,000 feet.

The resulting map “is an incredibly effective tool for firefighters when planning their operations,” Jim Hyland, a spokesman for federal crews battling the massive 2011 Wallow Fire in Arizona, told a reporter for the Arizona Republic at the time.

Originally developed for the military in 1947, the early imaging devices were bulky, slow to process an image, and not very accurate, says Smith.


green figure 2

Color image of the Ft. Hamlin, Dall City, Alaska fire, Aug. 22, 2004. Red areas come from high readings on the A Channel sensor (high temperatures) and indicate fire. Green areas show readings from the B Channel sensor (lower temperatures), with lighter shades correlating with warming temperatures. Yellow areas represent regions hot enough to register on the A Channel, but too low to trigger the fire detection algorithm. Image Credit: NIROPS.

Designed to be carried by a tactical fighter going 1,000 miles per hour and spot targets like tanks, these early mechanisms would have been of little help in mapping wildfires. But, in 1962, the Forest Service began working with the military and private industry to adapt the technology for mapping forest fires in an effort dubbed Project Fire Scan.

Composite view, Ft. Hamlin, Dall City, Alaska fire, Aug. 28, 2004. Image Credit: NIRPOS.

Composite view, Ft. Hamlin, Dall City, Alaska fire, Aug. 28, 2004. Image Credit: NIRPOS.

For these early tests, an infrared optical receiver was placed in the nose of a Beechcraft AT-11, a twin engine plane used by the Air Force to train bombardiers. Pilots flew over metal buckets filled with burning charcoal placed on flat, treeless terrain outside of Missoula, Montana. As the infrared detection equipment was refined, tests were made more complicated to better simulate actual fires. Heat sources were placed under various types of forest canopies on rugged terrain with ridges and valleys. Pilots made flyovers at altitudes ranging from 2,000- 10,000 feet.

Phase 1 of Project Fire Scan was something less than an overwhelming success. According to a  1966 internal Forest Service report, “The first season’s work produced very few definitive results.” In fact, the first three years of the program proved most useful for ruling out equipment and techniques. Researchers determined that infrared flights during the day were essentially useless, given the background heat generated by sunlight. The device itself was not sensitive enough even for nighttime flights. Overall, the single greatest achievement of Project Fire Scan was the creation of a team of experts who now understood the potential for using infrared mapping technology, and the hurdles that needed to be cleared to make IR the indispensible tool it would become. What was needed was a breakthrough in technology.

That breakthrough came in 1967, with the development of the new generation Kennedy Optical Line Scanner (named for its inventor Howard V. Kennedy, a Texas Instruments engineer). While much has changed since then, the essentials of the system remain the same.

A Beechcraft AT-11, the type of aircraft used in developing early infrared fire detectors in Project Fire Scan. Image Credit: U.S. Air Force.

A Beechcraft AT-11, the type of aircraft used in developing early infrared fire detectors in Project Fire Scan. Image Credit: U.S. Air Force.

Fire scan system, 1967. Image Credit: U.S. Forest Service.

Fire scan system, 1967. Image Credit: U.S. Forest Service.

In a small room at the back of NIFC’s Radio Cache building, Woody Smith stands beside an irregularly-shaped black metal box resting on a work bench. “This is the ultimate fire detection tool,” he says proudly. On first glance, the device looks more like an engine block pulled from an old Datsun than a multi-million dollar machine. Inside the plain looking frame is an array of precisely machined instruments.

At one end sits a triangular arrangement of mirrors. When in operation over a fire, these mirrors spin at a rate of 67 revolutions per second, directing infrared energy from below to a pair of sensors on the opposite end. Channel A, the “fire channel,” detects heat at or above 300 degrees Celsius (572 degrees Fahrenheit). Channel B registers cooler temperatures and is used to paint the background. By comparing the two channels, the program’s software is able to filter out reflected heat from rocks, warm roads and even plumes of hot gases that rise above fires.

The twin detectors use a photovoltaic mercury cadmium telluride alloy that is extremely sensitive to infrared light, but only when it’s super-cooled. Sitting on the workbench at room temperature, the instruments couldn’t register a raging blaze a foot away. But when Smith adds liquid nitrogen, a cooling plate next to the sensors plunges the temperature to 77 degrees Kelvin, about minus 320 degrees F. Properly cooled, the fire channel sensor will trip on a heated target one-tenth the width of a human hair.

During fire season, officials in charge of battling blazes send orders for IR mapping services  to Boise via the Internet, arriving by a 3:30 p.m.

deadline. The orders arrive as boxes, their corners described by latitude and longitude coordinates. Smith and another Forest Service employee


Line Scanner. Image Credit: Osha Gray Davidson.

spend the next several hours planning each run, the  order in which they’ll be made and all the associated logistics of keeping two aircraft and their crews moving steadily across the country during the night.

The pilots who fly these missions are among the best the Forest Service has ever had, says Smith. They have to be, given the conditions they must navigate. All flying is done at night, over mountainous terrain with smoke obscuring any visual reference points. As a result, IR pilots rely almost exclusively on navigational instruments. “Sometimes my IR guys fly an entire mission without having looked out the window once,” says Smith.

The planes have to refuel periodically, stops which, though inevitable, are a bane of Smith’s work. There are so many fires, and producing accurate maps of each one, every night, is critical. In Smith’s view, every minute a plane is on the ground is a minute it’s not doing its job.



The two IR aircraft are a twin-engine Beechcraft Super King Air B-200 and a small jet, the Cessna Citation Bravo II. Both aircraft take off at between 7-9 p.m. and continuing mapping runs until 4 a.m.

Mapping flights follow a grid plotted out in advance, at an altitude of 10,000- 14,000 feet. From that height, each pass scans a swath 6.5 miles wide. For accuracy, passes overlap each other by 25-30 percent. Flying at 300 miles per hour, a map produced by the Super King is accurate by plus or minus 1 foot. The faster moving jet is only slightly less precise – providing maps accurate to plus or minus 10 feet.

The imagery is sent in real-time to interpreters on the ground while the aircraft are still making runs over a fire. Some 48 interpreters are scattered across the country and will have completed maps on the screens of firefighter command centers before the aircraft make their last landings of the night.

“One night in July, we flew four small fires in California,” Smith recalls. “We started at 21:00 and by about 21:30 we finished the last fire. The interpreters already had the other three mapped and delivered.

The number of missions flown on a given night varies. On a moderately busy night, each plane will map three or four fires, but at the height of fire season the IR aircraft will be called on to cover a dozen fires each.

“Our record is 28 fires in one aircraft,” says Smith. “The other one flew 12 fires that night – but they were 12 really big ones.” Even with that many flights, the IR team was unable to fill all orders; there were requests to map 75 wildfires that night.

In time, more IR aircraft may be needed, as climate change leads to larger fires and a longer fire season. A recent study by environmental scientists at the Harvard School of Engineering and Applied Sciences (SEAS) projected that by 2050, the average wildfire seasons will be three weeks longer and burn three to four times more land in some regions of the U.S.

Meanwhile, efforts continue to produce even more accurate maps using the existing equipment and aircraft. “As we clean up the navigation system and signal,” says Smith, “we get closer and closer every year.”

Beechcraft Super King Air B-200. Image Credit:

Beechcraft Super King Air B-200. Image Credit: