The possibility of using aircraft for fighting wildland fires in California was first proposed in 1931 and again in the late 1940s after World War II. In 1953, the Nolta brothers of Willows, California proposed using their agriculture spray planes for fighting brush and grass fires. During the four fire seasons from 1954–1957, CAL FIRE used several small airtankers on a call-when-needed basis. These were primarily spray airplanes converted for use as firefighters. Also during this period, several enterprising aviation companies had been converting World War II Grumman TBM Avengers for air tanker use. Thus, in 1958 CAL FIRE first contracted for air tanker services with private aviation companies. That year contracts were let for three Naval Aircraft Factory N3N Canary, four Stearman and four TBM Avenger air tankers. The N3Ns and Stearmans were World War II biplanes used for pilot training and converted for use as agricultural spray planes. They were capable of carrying up to 200 gallons of fire retardant chemicals. The TBM, a World War II torpedo bomber, could deliver 600 gallons.