CDF Aviation Management Program - History - Air Tankers

Air Tankers

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, CDF 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 TMB Avengers for air tanker use. Thus, in 1958 CDF first contracted for air tanker services with private aviation companies. That year contracts were let for three N3N, 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.

During the ensuing years other aircraft were converted to air tankers and used by CDF. Among these were Twin Beech, Boeing B-17, Consolidated PBY, and Grumman F7F. The air tanker program continued to expand until finally in the early 1970s, a total of 14 TBMs, five F7Fs, one PBY and one B-17 comprised the CDF fleet.

By 1970, concerns with maintainability and accidents occurring in the TBM fleet led to an evaluation of the Grumman S-2 Tracker as a new generation air tanker. Although they were still active in the Navy, four were loaned to CDF for the evaluation. The Army Aviation Test Facility at Edwards Air Force Base completed a test program that showed the S-2 was a suitable replacement for the TBM. Two S-2 prototype air tankers were placed in service in 1973 with the prototype tank being built at the CDF Mobile Equipment Facility in Davis and the S-2 modification being completed by Hemet Valley Flying Service. These conversions were accomplished using plans developed by Ontario Lands and Forests in Ontario, Canada.

Three TBM accidents in 1973 and three F7F accidents in 1974 accelerated the CDF S-2 modification program. As a result, contracts were entered into with four California contractors, Aero Union Corp., Sis-Q Flying Service, TBM Inc. and Hemet Valley Flying Service to modify and tank ten S-2 air tankers during the 1973/1974 winter period. As a result, 12 S-2As were placed in service in 1974 and five more were built by Bay Aviation Services and put into the fleet for the 1975 fire season.

Three separate leases with the U.S. Navy brought a total of 55 S-2s and 60 engines for the program. This allowed CDF to keep the fleet going until the mid-1990s when it was decided to upgrade from S-2A to S-2T air tankers. In 1987, CDF entered into an agreement with Marsh Aviation of Mesa, Arizona to build a prototype S-2T. This prototype was placed in service and used at several bases. The success of the prototype led to acquisition of 26 S-2E/G aircraft in 1996. The E/G series S-2 was larger and newer. It could haul 1200 gallons of retardant with two TPE-331 GR turboprop engines at speeds in excess of 200 kn (370.4 km/h). A contract for building 23 of the new S-2T airtankers was entered into, with 13 delivered by the end of 2002, seven additional aircraft delivered and placed in service by the end of 2004 and the final three in 2005. As the new air tankers were delivered and placed in service, the original S-2As are retired.

In 2007, CDF contracted with 10 Tanker Air Carrier for three years' of exclusive use of their DC-10 "super tanker" known as Tanker 910, at a cost of $5 million per year.