McDonnell Douglas DC-9

DC-9
A Northwest Airlines DC-9 in 2007.
Role	Narrow-body jet airliner Type of aircraft
National origin	United States
Manufacturer	Douglas Aircraft Company McDonnell Douglas (from Aug. 1967)
First flight	February 25, 1965
Introduction	December 8, 1965, with Delta Air Lines
Status	In limited service for cargo transport and private use
Primary users	USA Jet Airlines (historical) Aeronaves TSM Everts Air Cargo Northwest Airlines (historical)
Produced	1965–1982
Number built	976
Variants	McDonnell Douglas C-9
Developed into	McDonnell Douglas MD-80 McDonnell Douglas MD-90 Boeing 717

The McDonnell Douglas DC-9 is an American five-abreast, single-aisle aircraft designed by the Douglas Aircraft Company. It was initially produced as the Douglas DC-9 prior to August 1967, after which point the company had merged with McDonnell Aircraft to become McDonnell Douglas. Following the introduction of its first jetliner, the high-capacity DC-8, in 1959, Douglas was interested in producing an aircraft suited to smaller routes. As early as 1958, design studies were conducted; approval for the DC-9, a smaller all-new jetliner, came 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 DC-9 is powered by two rear-mounted Pratt & Whitney JT8D low-bypass turbofan engines under a T-tail for a cleaner wing aerodynamic. It has a two-person flight deck and built-in airstairs to better suit smaller airports. The Series 10 aircraft are 104 ft (32 m) long for typically 90 coach seats. The Series 30, stretched by 15 ft (4.5 m) to seat 115 in economy, has a larger wing and more powerful engines for a higher maximum takeoff weight (MTOW); it first flew in August 1966 and entered service in February 1967. The Series 20 has the Series 10 fuselage, more powerful engines, and the Series 30's improved wings; it first flew in September 1968 and entered service in January 1969. The Series 40 was further lengthened by 6 ft (2 m) for 125 passengers, and the final DC-9-50 series first flew in 1974, stretched again by 8 ft (2.5 m) for 135 passengers. When deliveries ended in October 1982, 976 had been built. Smaller variants competed with the BAC One-Eleven, Fokker F28, and Sud Aviation Caravelle, and larger ones with the original Boeing 737.

The original DC-9 was followed by the second generation in 1980, the MD-80 series, a lengthened DC-9-50 with a larger wing and a higher MTOW. This was further developed into the third generation, the MD-90, in the early 1990s, as the body was stretched again, fitted with V2500 high-bypass turbofans, and an updated flight deck. The shorter and final version, the MD-95, was renamed the Boeing 717 after McDonnell Douglas's merger with Boeing in 1997; it is powered by Rolls-Royce BR715 engines. The DC-9 family was produced between 1965 and 2006 with a total delivery of 2441 units: 976 DC-9s, 1191 MD-80s, 116 MD-90s, and 155 Boeing 717s. As of August 2022, 250 aircraft remain in service: 31 DC-9s (freighter), 116 MD-80s (mainly freighter), and 103 Boeing 717s (passenger), while the MD-90 was retired without freighter conversion.