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The McDonnell Douglas DC-9 is an American five-abreast single-aisle aircraft designed by the Douglas Aircraft Company. It was initially produced by the developer company as the Douglas DC-9 until August 1967 and then by McDonnell Douglas.After introducing its heavy DC-8 in 1959, Douglas approved the smaller, all-new DC-9 for shorter flights on April 8, 1963.The DC-9-10 first flew on February 25, 1965, and gained its type certificate on November 23, to enter service with Delta Air Lines on December 8.The aircraft has two rear-mounted Pratt & Whitney JT8D low-bypass turbofans under a T-tail for a cleaner wing aerodynamic, a two-person flight deck and built-in airstairs.