Cessna O - 2 Skymaster The O - 2 Skymaster ( also known as the " Oscar Deuce " or " The Duck " ) is a military version of the Cessna 337 Super Skymaster utilized as an observation and forward air control ( FAC ) aircraft . The United States Air Force commissioned Cessna to build a military variant to replace the O - 1 Bird Dog in 1966 . Design and development . As with the civilian version , the Skymaster was a low - cost twin - engine piston - powered aircraft , with one engine in the nose of the aircraft and a second engine in the rear of the fuselage . The push - pull configuration meant a simpler single - engine operating procedure due to centerline thrust compared to the common low - wing mounting of most twin engine light planes , and also allowed for a high wing , providing clear observation below and behind the aircraft . During the Vietnam War , the Skymaster was intended to be replaced in the forward air control ( FAC ) mission by the OV - 10 Bronco , but the O - 2A maintained a night mission role after the OV - 10 ' s introduction due to the OV - 10 ' s high level of cockpit illumination , rendering night reconnaissance impractical . The O - 2 was phased out completely after additional OV - 10 night upgrades . The first O - 2 flew in January 1967 and the plane went into production shortly thereafter , with the USAF taking delivery in March 1967 . A total of 532 O - 2s were built in two variants for the USAF by 1970 . The O - 2A served as a FAC aircraft with the 20th Tactical Air Support Squadron , while the O - 2B was equipped with loudspeakers and a leaflet dispenser for use in the psychological operations ( PSYOPS ) role . Several USAF O - 2 aircraft were later transferred to and operated by the former VNAF South Vietnamese Air Force . Following the Vietnam War , the O - 2 continued to operate with both U . S . Air Force and Air National Guard units well into the late 1980s . Six former USAF O - 2A airframes were also transferred to the U . S . Navy in 1983 for use as " range controllers " with Attack Squadron 122 ( VA - 122 ) , the Pacific Fleet Replacement Squadron for the A - 7 Corsair II at Naval Air Station Lemoore , California . These same aircraft were later transferred to Strike Fighter Squadron 125 ( VFA - 125 ) , the F / A - 18 Hornet FRS at NAS Lemoore , in 1986 for use in the same range control role . The six Navy O - 2As remained in this role until September 1990 , when they were replaced by T - 34C Turbo Mentor aircraft transferred from the Naval Air Training Command . Four of the Navy O - 2A aircraft were retired and two of these became civil registered in October 1991 . These two aircraft were flown in U . S . airshows performing a " Viet Nam Warbird COIN / FAC " routine during the 1990s . The routine debuted at the " Wings Over Houston " ( Texas ) airshow in October 1991 . Of the six USN aircraft mentioned above , two were transferred to the U . S . Army in late 1990 . O - 2As had originally entered the U . S . Army ' s inventory in 1967 from USAF stocks and were augmented by the 1990 aircraft transfer from the U . S . Navy . Several disassembled USAF O - 2s remain in storage at Davis - Monthan AFB , Arizona . Two O - 2As were used at Laguna Army Airfield , Arizona as part of testing programs carried out by the Yuma Proving Ground . These were retired in October 2010 and sent to a museum . Operational history . A total of 178 USAF O - 2 Skymasters were lost in the Vietnam War , to all causes . El Salvador . During the Salvadoran Civil War the Salvadoran Air Force received a total of 23 O - 2As and 2 O - 2Bs from the United States , the first arriving in 1981 . The O - 2s were employed to observe the movements of FMLN formations and direct air strikes against them , playing a major role in forcing the rebel movement to abandon large - scale operations . Near the end of the war in 1990 , the rebel ' s acquisition of SA - 7 missiles resulted in the loss of two O - 2As , while another was destroyed by mortar fire , and two more were lost in crashes . Civilian use . CAL FIRE . 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 182 s and Cessna 210 s , 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 Bronco s .