The Fanjet 500 prototype first flew on September 15, 1969 and it was certified as the Citation on September 9, 1971, upgraded in 1976 as the Citation I and a single pilot variant, production ended in 1985 after 689 deliveries. Powered by JT15D turbofans, the straight wing aircraft was developed into the Citation II/Bravo. The aircraft was powered by two Pratt & Whitney Canada JT15D-1 turbofan engines after Cessna's experience with the T-37 Tweet twinjet trainer. Turbofan rather than turbojets and straight wings rather than swept wings made it cruise slowly compared to other business jets and Learjet salesmen mocked it as the “Nearjet” vulnerable to “bird strikes from the rear”; Cessna renamed it the “Citation” after the thoroughbred but it was nicknamed as “Slowtation”. In early 1976, its wing span grew from 43.9 to 47.1 ft (13.4 to 14.4 m).[5] It also gained thrust reversers and higher gross weights. The enhanced Citation I was introduced later in 1976 with higher weights, JT15D-1A engines and an increased span wing. The 501 Citation I/SP, certificated for single pilot operations, was delivered in early 1977. Production ended in 1985, it was developed into the Citation II/Bravo and the Citation V/Ultra/Encore. Over 690 Citations, Citation Is and I/SPs were built between 1971 and 1985.
