Cessna O-1 Bird Dog
The Cessna Bird Dog was the most popular light aircraft used by the US Army for liaison and observation in the post-war period. More than 3,500 machines left the assembly lines from the end of 1950 and remained in service until the late 1970s, taking part in the Korean War and Vietnamese War (see also History of the O-1 Bird Dog). The Bird Dog was derived directly from the Cessna 170, a commercial model in production in 1950. From the first order for fourteen planes in June 1950, the numbers increased dramatically, until by October 1954 the total production of L-19As (as they were originally designated) was 2,486. Two years later another 310 TL-19D training planes were ordered, while in 1957 the final version appeared, namely the improved and more powerful L-19E, which brought the total production to 3,431 machines. In 1962 the different versions were renamed, in sequence, O-1A, O-1B, TO-1D and O-1E.
Few aircraft were as important for the efficient conduct of war operations in Vietnam as the small, unarmed Cessna O-1B, previously known as the L-19. Spearhead of the FAC (Forward Air Control), it formed part of the US Army organization until 1965, when all fixed-wing observation aircraft were turned over to the USAF. Flying at low level and reduced speed, their duty was to discover objectives, for the most part concealed in the jungle, such as groups of guerrillas, convoys travelling along the Ho Chi Minh Trail, or enemy units lying in ambush for unsuspecting government troops. Having spotted the enemy, they would immediately radio the DASC (Direct Air Support Centre) which, as a rule, would be able to get attack aircraft to the spot within half an hour (see also Fire Support Coordination - Tactical Air Support). The latter were again guided by the Bird Dog pilots who, in addition to pinpointing the objective with smoke or magnesium flares, would check the effectiveness of the strikes, if necessary correcting the aim. However, the O-1s were an easy target for the enemy, who could often hit them with ordinary rifle fire, without recourse to heavy anti-aircraft fire. Many Bird Dog pilots lost their lives while carrying out their duty; they were usually officers with years of experience, veterans of many battles. Among the finest fighters, they succeeded in converting their little unarmed planes into formidable offensive weapons.