The 500 Citation and 501 Citation I were the first entries into the light business jet market. They soon spawned the world's largest family of corporate jets. The Citation I was introduced to the world in 1976, and is a Citation 500 with a longer wingspan. This wing provides better performance at altitude and 135 pounds more fuel capacity.
The Citation I/SP, which is certificated for single-pilot operation, was introduced in early 1977. The prototype for the Citation I first flew on September 15, 1969.