By Simon Scarr, Vijdan Mohammad Kawoosa and Sudev Kiyada
Firefighters have been battling some of the most destructive fires in Los Angeles' history in recent days. The massive wildfires menacing the city from the east and west have turned entire neighbourhoods to ash. Numerous firefighting air tankers from throughout California are flying fire suppression missions as conditions allow, according to the California Department of Forestry and Fire Protection (Cal Fire).
The specially equipped aircraft can steer or contain a fire’s perimeter, helping fire crews on the ground. We show here the types of aircraft available, from specially converted passenger jets to aircraft that can scoop water from a lake, and their specific roles.
Cal Fire has its own fleet of aircraft operating from 14 airfields and 11 helicopter bases across the state that can reach most fires within about 20 minutes. The three main components of the fleet are tactical planes, air tankers 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 60 planes and helicopters make it the largest department-owned fleet of aerial firefighting 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.
Dozens of helicopters and multiple air tankers were involved in fighting the current fires, according to a Jan. 8 press release from Governor Gavin Newsom’s office.
Tactical planes
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 U.S. Navy, Marine Corps and Air Force until the 1990s. Cal Fire obtained 15 of the retired planes from the Department of Defense in 1993 and converted them for fire-fighting.
The map below shows some of the tactical flights around the Palisades Fire on Jan. 9. Flight path data from Flightradar24 shows how a Cal Fire OV-10 and a Pilatus PC-12 from Colorado’s Division of Fire Prevention and Control flew over the area.
The planes circled repeatedly around the fires for long periods. 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.
Tanker planes
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.
Reload and return
Flight profile for one S-2T tanker through the course of the day on Jan 9.
Chart plotting the repeated take-off and landing of an S-2T tanker over the course of one day.
The short runs are evident in flight path data, again from Jan 9. The map shows how the plane repeatedly loops around to the edge of the fire before returning to 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. Retardants can also be released to protect homes or important sites and to keep access roads open.
Mega Tankers
Cal Fire operates large C-130 “Hercules” tankers and 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 in recent years.
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.
Before its retirement in 2021, a converted Boeing 747, the world’s most easily recognized jetliner, with its humped fuselage and four engines, was the largest firefighting aircraft but has now ceased operations.
The aircraft’s pressurized system could dump about 68,000 litres of retardant in a matter of seconds from as low as 60-90 meters (yards) above ground level. The 747 supertanker took around 30 minutes to fill on the ground, longer than some other tankers and much more than the few minutes needed for the S-2T Cal Fire tankers. But the line of retardant that could be delivered to the ground in one run is significantly more effective than that of other tankers.
Guided drops
Some tankers require a “lead” aircraft to guide them in and show exactly where to drop retardant. Some large tankers come with their lead aircraft and team, or Cal Fire’s tactical OV-10s can 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.
Aerial collaboration
An example of how multiple aircraft worked together to fight the LNU Lightning Complex fire, which devastated large parts of northern California in 2020. The chart shows flight profiles on August 22, 2020.
Super Scoopers
Firefighting “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, two Canadian super scoopers made flights and dozens of repeated water scoops to tackle the Palisades Fire.
Helicopters
Cal Fire owns a fleet of helicopters including a number of Bell UH-1H “Super Hueys”, 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.
Their Sikorsky S70i Black Hawk helicopters are also able to drop water or fire retardant, as well as conduct night operations.
Flight tracking data from Jan. 9 shows a number of helicopters operating around the Palisades Fire, including Leonardo AW139 and Sikorsky S-76 aircraft.
The helicopters have also proven valuable when moving or evacuating firefighters 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.
Winds dropped on Thursday from the 160-kph gusts seen earlier in the week, permitting crucial aerial support for crews on the ground. But officials said winds intensified again overnight, and red flag conditions were expected until Friday afternoon.
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