In early July 1953, the first US-built production aircraft (52-1418) rolled out; it conducted its maiden flight on 20 July 1953. One month later, this initial production aircraft was accepted by the USAF, by which point a cessation of hostilities had come into effect in Korea. This was one of only eight B-57A Canberras to be manufactured; the remaining 67 aircraft from this first batch, deemed no longer to be required as bombers, were converted on the assembly line to serve as medium-altitude reconnaissance aircraft while retaining all the basic Canberra features, and were accordingly re-designated as the "RB-57A" Canberra.