Designed by Bill Lear in the 1970s, the Challenger 600 series was originally produced by Canadair. The jet's appearance is reminiscent of a Learjet design, but has a much wider body, allowing for more movement within the cabin. When Bombardier purchased Canadair in 1986 it continued development and production of the Challenger series. Most recently, the 604 and 605 models have introduced greater fuel supply and more powerful engines, while maintaining the family's luxuriously large cabins. Civilian operators throughout the world operate Challenger 600s, and many of the world’s air forces, including China, the United States and Australia, also fly them.