Air attack How California uses dozens of aircraft to battle wildfires

Firefighting planes on Aug. 22

Air attack

How California uses dozens of aircraft to battle wildfires

Firefighters 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 firefighting 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.

Tactical aircraft

Monitor fires and direct airtankers and helicopters to critical areas

Helicopters

Can scoop and drop water but can also be used to transport firefighters and equipment

Tankers

Drop fire retardant or water

Tactical aircraft

Monitor fires and direct airtankers and helicopters to critical areas

Helicopters

Can scoop and drop water but can also be used to transport firefighters and equipment

Tankers

Drop fire retardant or water

Helicopters

Can scoop and drop water but can also be used to transport firefighters and equipment

Tactical aircraft

Monitor fires and direct airtankers and helicopters to critical areas

Tankers

Drop fire retardant or water

Tactical aircraft

Monitor fires and direct airtankers and helicopters to critical areas

Helicopters

Can drop water or transport firefighters

Tankers

Drop fire retardant or water

Helicopters

Can scoop and drop water but can also be used to transport firefighters and equipment

Tactical aircraft

Monitor fires and direct airtankers and helicopters to critical areas

Tankers

Drop fire retardant or water

According to Cal Fire’s website, the fleet’s more than 50 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.

Cal Fire said on August 23 that a total of 95 aircraft were battling the blazes.

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.

OV-10 “Bronco”

OV-10 “Bronco”

OV-10 “Bronco”

OV-10 “Bronco”

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 Cal Fire tactical flights around the LNU Lightning complex fires over the course of the day on August 22. Flight path data from FlightRadar24 shows how five OV-10s made flights over the fire, staying in the air for hours.

Active fire edges

Windsor

Circling over the

edge of the fire

Santa Rosa

Active

fire edges

Middletown

Active fire edges

Healdsburg

Circling over the

edge of the fire

Windsor

Circling over the

edge of the fire

St Helena

Santa Rosa

Active

fire edges

Middletown

Active fire edges

Healdsburg

Circling over the

edge of the fire

Windsor

Circling over the

edge of the fire

St Helena

Santa Rosa

Active fires

Circling over

edge of fire

Dozens

of flights

Santa

Rosa

Active

fire edges

Middletown

Active fire edges

Healdsburg

Circling over the

edge of the fire

Windsor

Circling over the

edge of the fire

St Helena

Santa Rosa

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.

Tanker planes

The workhorse of Cal Fire’s fleet is the Grumman S-2T tanker. The aircraft can hold about 4,500 liters (1,200 gallons) 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.

Grumman S-2T

Grumman S-2T

Grumman S-2T

Grumman S-2T

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 refueled.

Reload and return

Flight profile for S2-T tanker on August 22.

Tankers usually reduce altitude

on approach to fire before

dropping retardant

Mission to tackle fire

1,000m

Ground

Time on ground refilling

with fire retardant

7.19pm

Missions

over

5.33 pm

Takeoff

Mission to tackle fire

Tankers usually reduce altitude

on approach to fire before

dropping retardant

1,000m

Ground

5.33 pm

Takeoff

Landing

Time on ground refilling

with fire retardant

7.19pm

Missions over

Tankers usually reduce altitude

on approach to fire before

dropping retardant

Mission to tackle fire

1,000m

Ground

5.33 pm

Takeoff

Landing

Time on ground refilling

with fire retardant

7.19pm

Missions over

Mission to tackle fire

1,000m

Ground

5.33 pm

Takeoff

Time on ground refilling

with fire retardant

7.19pm

Missions

over

The short runs are evident in flight path data, again from August 22 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.

Active fire edges

Windsor

Tankers tackling

edge of the fire

Cal Fire air base

Sonoma County Airport

Dozens

of flights

Santa Rosa

Active

fire edges

Middletown

Active fire edges

Healdsburg

Tankers tackling

edge of the fire

Windsor

Tankers tackling

edge of the fire

Cal Fire air base

Sonoma County Airport

Dozens

of flights

Santa Rosa

Active

fire edges

Middletown

Active fire edges

Tankers tackling

edge of the fire

Healdsburg

Windsor

Tankers tackling

edge of the fire

Cal Fire air base

St Helena

Sonoma County Airport

Dozens

of flights

Santa Rosa

Active fires

Tankers

tackling

edge of fire

Cal Fire

air base

Dozens

of flights

Santa

Rosa

Active

fire edges

Middletown

Active fire edges

Tankers tackling

edge of the fire

Healdsburg

Windsor

Tankers tackling

edge of the fire

Cal Fire air base

Sonoma County Airport

St Helena

Dozens

of flights

Santa Rosa

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.

Multiple lines of retardant around a fire at Henry W. Coe State Park,

California, on August 29.

Fire retardant

To city of

Morgan Hill

500 m

Satellite image: Planet Labs

Multiple lines of retardant around a fire at Henry W. Coe State Park, California, on August 29.

Fire retardant

To city of

Morgan Hill

500 m

Satellite image: Planet Labs

Lines of retardant around a fire at

Henry W. Coe State Park, California, on Aug. 29

Retardant

To city of

Morgan Hill

500 m

Satellite image: Planet Labs

Mega Tankers

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.

McDonnell Douglas DC-10

External water tank

McDonnell Douglas MD-87

External water tank

British Aerospace 146

C-130 “Hercules”

McDonnell Douglas DC-10

External water tank

McDonnell Douglas MD-87

External water tank

British Aerospace 146

C-130 “Hercules”

McDonnell Douglas DC-10

External water tank

McDonnell Douglas MD-87

External water tank

British Aerospace 146

C-130 “Hercules”

DC-10

Water tank

MD-87

Water tank

Bae 146

C-130

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.

Aircraft capacity

In liters

UH-1H

“Super Huey”

1,200 liters

(buckets)

Grumman

S-2T

4,500

CL-415

“Super Scooper”

6,100

WATER

British

Aerospace 146

11,400

RETARDANT

McDonnell

Douglas MD-87

11,400

C-130

“Hercules”

15,100

McDonnell

Douglas DC-10

35,600

Boeing 747 Supertanker

68,100

Equivalent of over

56 helicopter buckets

Aircraft capacity

In liters

UH-1H

“Super Huey”

1,200 liters

(buckets)

McDonnell

Douglas MD-87

11,400

RETARDANT

WATER

Grumman S-2T

4,500

British

Aerospace 146

11,400

CL-415 “Super Scooper”

6,100

747 carries the

equivalent of over

56 helicopter

buckets

C-130 “Hercules”

15,100

McDonnell

Douglas DC-10

35,600

Boeing 747 Supertanker

68,100

Aircraft capacity

In liters

UH-1H “Super Huey”

helicopter

1,200 liters

(carried in buckets)

McDonnell

Douglas MD-87

11,400

RETARDANT

WATER

Grumman S-2T

4,500

British

Aerospace 146

11,400

CL-415 “Super Scooper”

6,100

747 carries the

equivalent of over

56 helicopter

buckets

C-130 “Hercules”

15,100

McDonnell

Douglas DC-10

35,600

Boeing 747 Supertanker

68,100

Aircraft capacity

In liters

UH-1H

“Super Huey”

1,200 liters

(buckets)

Grumman

S-2T

4,500

CL-415

“Super Scooper”

6,100

British

Aerospace 146

11,400

WATER

RETARDANT

McDonnell

Douglas MD-87

11,400

C-130

“Hercules”

15,100

McDonnell

Douglas DC-10

35,600

Boeing 747 Supertanker

68,100

Equivalent of over

56 helicopter buckets

Cal Fire is also using the 747 supertanker, the largest firefighting aircraft in the world, to battle the current wildfires. The converted Boeing 747, the world’s most easily recognized jetliner, with its humped fuselage and four engines, is currently the only such model in operation.

The aircraft’s pressurized system can dump about 68,000 liters (18,000 gallons) of retardant in a matter of seconds from as low as 60-90 meters (yards) above ground level.

Boeing 747 Supertanker

Retardant

tanks

Discharge

valves

Pressurized

air tanks

Boeing 747 Supertanker

Retardant

tanks

Large retardant

tanks

Discharge

valves

Pressurized

air tanks

Boeing 747 Supertanker

Retardant

tanks

Large retardant

tanks

Discharge

valves

Pressurized

air tanks

Boeing 747 Supertanker

Retardant

tanks

Discharge

valves

Pressurised

air tanks

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.

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 own lead aircraft and team, or Cal Fire’s tactical OV-10s serve as lead aircraft.

An air tanker is guided by a lead plane before dropping retardant in Pope Valley, California. August 21, 2020. REUTERS

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

Flight profiles of aircraft fighting LNU Lightning Complex fires on August 22.

1.00 pm

5.00 pm

8.00 pm

Coordinating role

Flight profiles suggest these three planes

could have been circling in higher

positions to coordinate resources

Altitude

OV-10

TACTICAL

AIRCRAFT

Tactical role

Lower altitude and could have been

acting as a “lead”, guiding tankers to targets

ST2

TANKERS

Seven tankers

made short

repeated runs

between the fire

and air base

Bae 164

DC-10

LARGE

TANKERS

MD-87

DC-10

1.00 pm

5.00 pm

8.00 pm

Coordinating role

Flight profiles suggest these three planes

could have been circling in higher

positions to coordinate resources

Altitude

OV-10

TACTICAL

AIRCRAFT

Tactical role

Lower altitude and could have been

acting as a “lead”, guiding tankers to targets

ST2

TANKERS

Seven tankers

made short

repeated runs

between the fire

and air base

Bae 164

DC-10

LARGE

TANKERS

MD-87

DC-10

1.00 pm

5.00 pm

8.00 pm

Coordinating role

These three planes could have been

flying in higher positions to

coordinate resources

Altitude

OV-10

Tactical

aircraft

Tactical role

Flight profiles suggest the two planes

could have been acting as “leads”,

guiding tankers to targets

Seven tankers

made short

repeated runs

between the fire

and air base

ST2

Tankers

Tanker no. 90

made eight

consecutive

cycles

Bae 164

Large

tankers

MD-87

DC-10

DC-10

2.00 pm

5.00 pm

8.00 pm

OV-10 - TACTICAL AIRCRAFT

Coordinating role

Possibly circling in higher altitudes

to coordinate resources

Altitude

Tactical role

Lower altitude and could have been

acting as a “lead”, guiding tankers to targets

ST2

TANKERS

Seven tankers

made short

repeated runs

between the fire

and air base

Bae 164

LARGE

TANKERS

DC-10

MD-87

DC-10

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.

Bombardier CL-415

“Super Scooper”

Bombardier CL-415

“Super Scooper”

Bombardier CL-415

“Super Scooper”

Bombardier CL-415

“Super Scooper”

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 August 23.

One Super Scooper flight on August 23

Tomales Bay

Scooping water

from the bay

Drops water at

edge of fire

Woodward fire

Two flights on August 23 from the same Super Scooper plane

Tomales Bay

Tomales Bay

Scooping water

from edge of bay

Scooping water

from the bay

Drops water at

different part

of perimeter

Drops water

at edge of fire

Woodward fire

Woodward fire

One Super Scooper flight on August 23

Tomales Bay

Scooping water

from the bay

Drops water at

edge of fire

Woodward fire

Helicopters

Cal Fire owns 12 Bell UH-1H “Super Huey” helicopters, which can each carry about 1,200 liters (320 gallons) of water in buckets hanging below the aircraft. They can be used for fast initial attacks on smaller wildfires.

UH-1H “Super Huey”

UH-1H “Super Huey”

UH-1H “Super Huey”

UH-1H “Super Huey”

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

Helicopters release water to extinguish fires in Pope Valley, California. August 21, 2020. REUTERS

On the ground, over 15,600 firefighters are battling the 19 major fires and lightning complexes burning in California as of September 1, according to Cal Fire. Since the lightning strikes that started on Saturday, August 15, there have been more than 900 new wildfires, which have now burned almost 1.5 million acres.

Sources

California Department of Forestry and Fire Protection (Cal Fire); FlightRadar24; Fire Information for Resource Management System (FIRMS); GLAD (Global Land Analysis & Discovery); Shuttle Radar Topography Mission (SRTM);

By Simon Scarr, Marco Hernandez and Manas Sharma

Editing by Daniel Grebler