Firefighting aircraft have been unleashing tens of thousands of gallons of water and bright-pink fire retardant on the wildfires ripping through Los Angeles over the past week.

These aircraft have long been vital against wildfires. They help contain the perimeters of blazes and can attack rugged terrain inaccessible to firefighters on the ground. With more than 60 planes and helicopters, California’s Department of Forestry and Fire Protection, known as Cal Fire, says it has the largest fleet of aerial firefighting equipment of any civilian agency in the world.

Two planes important to aerial firefighting missions are air tankers, which carry and drop the fire retardant, and the lead plane, a smaller, more nimble aircraft that flies ahead.

The lead plane maps out the route and instructs the air tanker where to make the drop, said Jordan Mattiacci, a pilot who flies aircraft that play a similar role in Australia. In the past few weeks, he has been out battling a monstrous blaze in the mountain ranges in the state of Victoria that local officials said burned over 187,800 acres of national park and farmland. Areas that could be targeted include along the fire’s edge to help stop its spread, or on homes farther away to protect them, he said.

Depending on the situation, Mr. Mattiaci said, he might do a demonstration flight to show the tanker the route to take. The lead plane is also responsible for making sure the air tanker has a safe path out, he said.

“When we’re certain they’ve got the picture of where we want it, they will drop,” he said, adding that the air tanker pilot is in charge of calculating how winds will affect how the retardant falls.