In the mid 1970s, the California Department of Forestry and Fire Protection, or CAL FIRE, found that the contractor-owned air attack aircraft, mostly single-engine Cessna 182s and Cessna 210s, did not provide the airspeed and safety needed for the department's new air tanker program. In 1974, Senior Air Operations Officer, Cotton Mason, inspected 40 USAF O-2s at Davis-Monthan Air Force Base. The best 20 were selected and shipped to Fresno, California. These aircraft had been FAC aircraft in Vietnam and were shipped back to the United States in containers, and were disassembled and on pallets when they arrived at Fresno. A crew of California Conservation Corps (CCC) members under the supervision of a CDF Battalion Chief who was an FAA Certificated Mechanic with Inspection Authorization (IA), reassembled the aircraft. They were placed in service in 1976, and successfully served CALFIRE for more than 20 years, until replaced by a fleet of OV-10 Broncos.