Air Tanker History

Today firefighters on the ground work with aerial firefighters to help extinguish wildfires across the world. The pilots drop a mixture of water and fire retardant onto the fires. But, having a good tool to help extinguish fires didn’t happen overnight.

As early as 1930 Forest Service firefighters were flying over fires delivering water to the crews on the ground. In 1930, a Ford Tri-Motor airplane made the first water drop using a wooden beer keg filled with water. This turned out to be more of a hazard to the firefighters on the ground than originally thought. But, the proper combination of procedures and personnel wasn’t yet discovered.

The world’s first practical fire bomber was a 1939 Boeing Stearman 75 that had been converted into a crop duster. Willows Flying Service, a California Agricultural Applicator cut a hole into the fabric belly of the plane and fitted the hopper with a hatch that opened when the pilot pulled a rope. This would release 170 gallons of water.

On August 12, 1955, the first free-flowing water airdrop from an airplane onto a fire was made during the Mendenhall Fire (Mendocino National Forest). The pilot, Vance Nolta, dropped 6 loads of water to support the firefighters. While there had been a few test drops on controlled grass fires, this was the first time a real forest fire had been at least partially quenched by free-fall water.

In 1956 six Navy surplus biplane trainers (N3Ns) were bought by Willows and turned into firebombers. With these additions, Willows had a fleet that they used throughout California to respond to local fire departments and the forest service.

However, it soon became apparent that water alone was not going to work since hotter fires evaporated the water before it could do what it needed to do. Because of this, personnel created another solution – they mixed sodium calcium borate with water. Adding the chemical made evaporation a slower process. The planes then became known as “Borate Bombers,” and even though better processes were later developed, the planes were stuck with the name for quite some time.

In January of 1954 a multi-agency brainstorming session dubbed “Operation Firestop” was started after a bad fire season in California left 14,000 acres burned and 14 firemen dead. Operation Firestop’s agenda also included discussions about techniques for dropping water or chemicals on fires.

Testing for Operation Firestop began at the Marine Corps Base in Camp Pendleton where they had thousands of acres at their disposal for tests. They made drops over the canyons in Pendleton that were laced with wires and anemometers and other testing equipment. Each of these drops was analyzed for dispersal, wind drift, effectiveness, and other criteria.

Operation Firestop ended in 1954 and is responsible for aerial firefighting tools and techniques that have evolved over the years and we still use to this day.