How California uses dozens of aircraft to battle wildfires
Fire fighters have been battling some of the largest fires in California’s history in recent weeks. In total, about 2,2 million acres have been blackened, according to the California Department of Forestry and Fire Protection (Cal Fire). A fleet of specially equipped fire fighting aircraft that can steer or contain a fire’s perimeter help fire crews on the ground. We show here the types of aircraft, from specially converted passenger jets to aircraft that can scoop water from a lake, in action and their specific roles. Cal Fire has its own fleet of aircraft operating from 12 airfields and 10 helicopter bases across the state that can reach most fires within about 20 minutes. The three main components of the fleet are tactical planes, airtankers and helicopters. All have specific roles but work together as a unit to combat fires. According to Cal Fire’s website, the fleet’s more than 50 planes and helicopters make it the largest department-owned fleet of aerial fire fighting equipment in the world. But if extra resources are needed, the department hires additional planes on a contract basis and in extreme conditions, it can request help from the military. Cal Fire said on 23 August 2020 that a total of 95 aircraft were battling the blazes.
These aircraft are used in aerial command and control roles in fighting wildfires, providing tactical coordination with commanders on the ground and other aircraft in the sky. Most of Cal Fire’s tactical planes are North American Rockwell OV-10 aircraft. The OV-10 Bronco is a twin-turboprop, multi-mission aircraft that served with the US Navy, Marine Corps and Air Force until the 1990s. Cal Fire obtained 15 of the retired planes from the Department of Defence in 1993 and converted them for fire fighting.
The map shows Cal Fire tactical flights around the LNU Lightning complex fires over the course of the day on 22 August 2020. Flight path data from FlightRadar24 shows how five OV-10s made flights over the fire, staying in the air for hours. The planes circled repeatedly around two active edges of the fires for long periods of time, managing resources and directing crews in the air and on the ground. Unlike air tankers, which need to make repeated short runs to refill with water or fire retardant after a drop, the OV-10s can stay airborne for hours and can also act as lead planes when necessary to guide large tankers into drop zones.
The workhorse of Cal Fire’s fleet is the Grumman S-2T tanker. The aircraft can hold about 4 500 litres of fire retardant that it can drop in the path of fires. The planes are smaller than many air tankers and can be used in fast initial attacks on fires. The ex-military aircraft were used to track submarines until the 1970s. The Grumman S-2T has a fill spout in the tail, allowing it to be ‘hot loaded’ with retardant without having to shut off its engines. This means it can be back in the air within minutes. One S-2T can cycle through multiple times this way before it needs to be shut down and refuelled. The short runs are evident in flight path data, again from 22 August 2020 around the LNU Lightning Complex fires. The map shows how the planes repeatedly loop around to the edge of the fire before returning to land at the air base. Tankers don’t usually drop retardant directly on the fire itself. Instead, they let it go in front of a fire, directing its course or slowing its advance, and giving ground crews a chance to control or extinguish it. Retardant can also be released to protect homes or important sites and to keep access roads open.
Cal Fire can also employ contractors to bring in Large Air Tankers (LATs) and Very Large Air Tankers (VLATs) to help suppress major fires. The aircraft are usually passenger jets that have been converted to tankers. Here are some of the tankers that have helped fight the fires in California recently. The large air tankers can carry a much larger load than the smaller Cal Fire tankers. The diagram below shows how much retardant or water can be dropped by each type of aircraft.
Cal Fire is also using the 747 supertanker, the largest fire fighting aircraft in the world, to battle the current wildfires. The converted Boeing 747, the world’s most easily recognised jetliner, with its humped fuselage and four engines, is currently the only such model in operation. The aircraft’s pressurised system can dump about 68 000 litres of retardant in a matter of seconds from as low as 60 to 90 metres above ground level. The 747 Supertanker takes around 30 minutes to fill on the ground, longer than some other tankers and much more than the few minutes needed for the S2-T Cal Fire tankers. But the line of retardant that can be delivered to the ground in one run is significantly more effective than that of other tankers.
Some tankers require a ‘lead’ aircraft to guide them in and show exactly where to drop retardant. Some large tankers come with their own lead aircraft and team or Cal Fire’s tactical OV-10s serve as lead aircraft. All of the aircraft work in unison to fight the fires, many of them making multiple flights through the day, coordinated by Cal Fire OV-10 Broncos flying above for hours on end.
Fire fighting “Super Scooper” planes refill by descending to the placid waters of bays and lakes and skimming the water’s surface to load their tanks. They then release the water to douse a blaze and repeat the process until they need to refuel. According to flight tracking data from FlightRadar24, for example, aircraft number N386AC made two flights and dozens of repeated water scoops to tackle the Woodward fire on 23 August 2020.
Cal Fire owns 12 Bell UH-1H ‘Super Huey’ helicopters, which can each carry about 1 200 litres of water in buckets hanging below the aircraft. They can be used for fast initial attacks on smaller wildfires. The helicopters have also proven valuable when moving or evacuating fire fighters and civilians. Cal Fire’s helicopter crews are trained to carry out ‘short-haul’ rescues, which often involve a crew-member being lowered from a hovering helicopter. Once hooked to a harness or basket, the target and crew-member are carried a short distance to safety.
On the ground, over 15 600 fire fighters are battling the 19 major fires and lightning complexes burning in California as of 1September 2020, according to Cal Fire. Since the lightning strikes that started on Saturday, 15 August 2020, there have been more than 900 new wildfires, which have now burned almost 1,5 million acres.