The Cessna O-2 Skymaster (nicknamed "Oscar Deuce") is a military version of the Cessna 337 Super Skymaster, used for forward air control (FAC) and psychological operations (PSYOPS) by the US military between 1967 and 2010.During the Vietnam War, the O-2A was introduced as a replacement for the O-1 Bird Dog, in the forward air control (FAC) aircraft and served in that role with the 20th Tactical Air Support Squadron. The O-2B was equipped with loudspeakers and a leaflet dispenser for use in the psychological operations (PSYOPS) role.While it was intended that the Skymaster be replaced in the FAC mission by the OV-10 Bronco, the O-2A continued to be used for night missions 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 night upgrades to the OV-10.