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Which fighter was the only one South Vietnamese pilots could master quickly?
Short answer
The Northrop F-5 Freedom Fighter: the only fighter VNAF pilots could master quickly. Its air-to-air capability was limited to a squadron of twenty-five F-5s, reinforced after 1973 with the more modern F-5Es. Following the US withdrawal in early 1973, it received 126 F-5As.

The F-5 passes into South Vietnamese hands
In October 1966 the 10th Fighter (Commando) Squadron began training South Vietnamese pilots on the F-5 and later handed over its own aircraft to them, in June 1967. On 19 June 1967 the South Vietnamese took over all F-5 operations in Southeast Asia and the VNAF's 522nd Fighter Squadron became owner of the 10th FCS's F-5s. In June 1967 the surviving aircraft of that squadron were transferred to the Republic of Vietnam Air Force. In the Vietnam War, jets of this type flew more than 2,600 combat sorties, from the 3rd Tactical Fighter Wing at Bien Hoa Air Base, over South Vietnam, and from Da Nang Air Base.
A fighter within the VNAF's reach
The only fighter that VNAF pilots could master quickly was the F-5. The remaining F-5As were sent to the VNAF, which became one of the largest users of the model, with 189 F-5As. The VNAF's limited air-to-air capability rested on a squadron of twenty-five F-5 Freedom Fighters, reinforced after 1973 with the more modern F-5Es.
The aircraft that arrived in 1973
After the American withdrawal in early 1973, the VNAF received 126 F-5As, most of them from stocks that had previously belonged to South Korea, Iran and Taiwan.
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