Firefighting aircraft and helicopters: The flying fire brigade
Aircraft and helicopters can help battle forest fires quickly and effectively, adopting different models depending on the geography of the area. An overview.
08.2020 | Text: Denis Dilba
Denis Dilba holds a degree in mechatronics, is a graduate of the German School of Journalism, and founded the “Substanz” digital science magazine. He writes articles about a wide variety of technical and business themes.
Firefighting aircraft over Australia, the Amazon rainforest, Indonesia, California and the Arctic—images of devastating forest fires repeatedly dominated the news last year. The online platform Global Forest Watch Fires counted more than 4.5 million fires larger than one square kilometer for 2019, an increase of 400,000 from the previous year.
Even though there were already a good 5 million fires of this magnitude in 2004, and even though that figure fluctuates, it is clear that the risk of forest fires is steadily increasing around the world: “Climate change is making extreme weather more frequent, leading to more extreme fires: increasing drought provides more and more fuel for forest fires, so they become hotter, bigger, more intense—and increasingly difficult to extinguish,” says Alexander Held, forest fire expert at the European Forest Institute in Bonn. He adds that in densely populated and built-up countries like Germany, even small forest fires can cause plenty of chaos and damage.
Overview of fires worldwide: Satellite images from NASA show where the world is currently burning. Each red dot on NASA’s world fire map represents a fire. With large parts of Central and East Africa bright red, it appears that a whole chunk of Africa is going up in flames. However, the zoom effect means the points are not to scale, but instead show many smaller fires. Nevertheless, while the fires there bring death and devastation, they are also the lifeblood of the African savannah.
Firefighting aircraft are the fastest and most effective means of initial attack
This is why, Held explains, it is important to arrive at the scene as soon as possible after a forest fire has broken out—when the fires are still small, the extinguishing measures are particularly effective. Where possible, this should be done from the ground. “However, in areas that are more difficult to access, or where there is an extreme danger of forest fires, firefighting aircraft are the only option for a truly rapid first attack.” To be able to get to the source of the fire quickly, it’s best to keep the aircraft parked on the runway ready for takeoff—better still is to have them already in the air on patrol. In regions of southern Europe with a history of forest fires, this has long been the case. Because the risk of forest fires is rising in Germany, there are calls for the country to procure its own aircraft, including from Mike Goldhahn, director of the German Aerial Firefighting Brigade (Deutsche Löschflugzeug Rettungsstaffel, DLFR). “This would be especially practical for the many areas contaminated with munitions, particularly in Brandenburg,” he says. He proposes starting with three aircraft: “With these and with three pilots, you can keep two firefighting aircraft on standby during the season.” Over the long term, Goldhahn recommends a fleet of six to eight aircraft.
Held can also envision firefighting aircraft in Germany: “I’m talking about small aircraft such as the Air Tractor 802, not the big Canadair amphibious aircraft you find in southern Europe.” The latter work most efficiently on large bodies of open water, of which Germany does not have many. Moreover, the Canadair aircraft are significantly more expensive than smaller models. Goldhahn therefore believes small firefighting aircraft are the way to go. However, all types of aircraft and helicopters in firefighting operations require experienced pilots: turbulence is to be expected above the fires, and visibility is often poor due to the smoke. In addition, the pilot must keep the aircraft flying at a stable attitude when dropping the water, which often weighs several metric tons. One particular challenge for amphibian firefighting aircraft is scooping up water while still in the air: pilots have to contend with waves, changing winds and obstacles on the water’s surface.
In addition, pilots are put under high levels of stress lasting several hours, because unlike on a scheduled flight, for example, firefighting operations are flown without an autopilot. The pilots steer by sight and, on flights with contact to the water’s surface, they have to manage without guidance from a tower. Water dropped onto a fire often contains chemicals. Special equipment is used to mix them with the water in the tanks or external containers, sometimes even while in the air. The chemicals give the water a gel-like property, allowing it to adhere better to trees and bushes and protect them more effectively from the flames. Foams for fighting forest fires, on the other hand, are usually applied from the ground. Color added to the water, usually red, helps the pilots see where they have already been.
Aerial missions are of little use without fire management on the ground
“In Germany, you need ‘spray authorization’ to conduct firefighting operations from the air,” Goldhahn explains. The license is valid for aircraft and firefighting helicopters. The latter also offer the flexibility to collect water from smaller lakes not used for other purposes with a specialized bucket and then discharge it at precisely the right point in areas inaccessible to aircraft, such as a slope in a narrow valley. For this purpose, the helicopters must be equipped with special external cargo hooks and, ideally, their own weight should also be reduced. Because the heavier the helicopter is, the less water it can pick up—in some cases, none at all. Firefighting experts are therefore constantly advising the authorities to keep more large helicopters, such as the military’s Sikorsky CH-53 transport aircraft, ready for action during the forest fire season. A small police helicopter can hold 5,000 liters, but larger models can pick up ten times that amount.
However, firefighting helicopters and even aircraft alone are usually not enough to extinguish a forest fire. “The crucial thing is that, before anything else, we do our homework in fire management on the ground,” Held says. “Fighting forest fires from the air doesn’t help much if we don’t have trained and well-equipped crew for forest firefighting and if we neglect preventive fire protection in the forests.”
Overview of the different models:
Various firefighting aircraft are in service around the world. The largest one, the Global Supertanker, is a converted Boeing 747-400. Stationed in the U.S., the aircraft is called to major fires, such as the one in the Amazon rainforest in 2019. The firefighting jumbo jettisons its 72,680 liters of water from heights of 60 to 90 meters above the forest fire at a speed of 278 km/h. During these missions, the pilot can choose whether to drop the water onto the fire continuously or in a series of intervals. The Supertanker requires airports with runways at least two kilometers long.
Canadair CL-215 and CL-415
Probably the most famous firefighting aircraft in the world are the Canadair CL-215 and CL-415. The former was developed by Canadian manufacturer Canadair, which was acquired by Bombardier Aerospace in 1986. In 2016, the aerial firefighting business was sold to Canadian company Viking Air. Powered by two Pratt & Whitney turboprop engines, the firefighting aircraft can refill their tanks while flying over a body of water. To scoop up 6,137 liters, the CL-415 needs twelve seconds and a distance of around 400 meters. The typically yellow aircraft are particularly popular in countries with large open bodies of water and coastal areas at risk of forest fires.
Global Supertanker: Pilots of this aircraft, which is called in for major fires, can choose whether to drop the 72,680 liters of water onto the fire continuously or in a series of intervals.
Air Tractor AT-802F: The most efficient and versatile firefighting aircraft holds up to 3,100 liters of water and can take off and land on gravel and grass runways.
Canadair CL 215 and CL 415: Powered by two Pratt & Whitney turboprop engines, the amphibious aircraft can scoop up 6,137 liters of water while flying over a body of water.
Airbus Super Puma: Operated by the German Federal Police, this helicopter can hold 2,000 liters of water.
Sikorsky CH-53: The large Sikorsky helicopter operated by the German Armed Forces is able to drop water (up to 5,000 liters) with pinpoint accuracy and can transport equipment and crew to any terrain.
Drones: The aerial images and temperature data make it easier for the emergency services on the ground to decide where to position which crew and equipment.
Air Tractor AT-802F
The small Air Tractor AT-802F from the U.S. manufacturer of the same name is considered the most efficient and versatile firefighting aircraft on the market. It can scoop up 3,100 liters of water—a staggeringly large amount considering its size. The robust single-propeller aircraft can also take off and land on gravel and grass runways. Thanks to its smaller dimensions and therefore better maneuverability, the AT-802F can also operate in narrow valleys. The PZL M18 Dromader from Polish manufacturer PZL has similar qualities: a monoplane with comparable dimensions and capacity for 2,200 liters of water.
Germany currently uses only helicopters for fighting forest fires. For this purpose, they are equipped with external water tanks of various sizes. Smaller helicopters, such as the Airbus Helicopters H135, carry around 500 liters; larger models, such as the Airbus Super Puma operated by the German Federal Police, or the very large Sikorsky CH-53 operated by the German Armed Forces, carry 2,000 and 5,000 liters, respectively. Helicopters can be used for precise water drops and transporting equipment and crew in any terrain. Since German fire departments don’t have their own aircraft, they have to contact the police or the military in the event of forest fires.
Drones to fight forest fires
Equipped with thermal imaging sensors, drones are increasingly used for early detection of forest fires. This technology is already being tested in Brandenburg, Germany. The aerial images and temperature data make it easier for the emergency services on the ground to decide where to position which crew and equipment. British start-up Faradair Aerospace reports that it is even working on a large firefighting drone: the Beha M1-AT has a span of eleven meters and a payload of ten metric tons, and is intended to fight forest fires completely autonomously. The company is already conducting test flights.