McDonnell-Douglas DC-9

DC-9
A Northwest Airlines DC-9-41, 2006
Role	Narrow-body jet airliner
Manufacturer	Douglas Aircraft Company McDonnell Douglas
First flight	February 25, 1965
Introduction	December 8, 1965 with Delta Air Lines
Status	In limited service
Primary users	USA Jet Airlines Aeronaves TSM Northwest Airlines (historical) Delta Air Lines (historical)
Produced	1965–1982
Number built	976
Unit cost	US$41.5 to $48.5 million
Variants	McDonnell Douglas C-9
Developed into	McDonnell Douglas MD-80 McDonnell Douglas MD-90 Boeing 717

The McDonnell Douglas DC-9 (initially known as Douglas DC-9) is a twin-engine, single-aisle jet airliner. It was first manufactured in 1965 with its maiden flight later that year. The DC-9 was designed for frequent, short flights. The final DC-9 was delivered in October 1982.

The DC-9-based airliners, MD-80, MD-90 and Boeing 717 later followed in production. With the final deliveries of the 717 in 2006, production of the DC-9/MD-80/90/717 aircraft family ceased after 41 years and over 2,400 units built.

During the 1950s Douglas Aircraft studied a short- to medium-range airliner to complement their higher capacity, long range DC-8. (DC stands for Douglas Commercial.) A medium-range four-engine Model 2067 was studied but it did not receive enough interest from airlines and it was abandoned. In 1960, Douglas signed a two-year contract with Sud Aviation for technical cooperation. Douglas would market and support the Sud Aviation Caravelle and produce a licensed version if airlines ordered large numbers. None were ordered and Douglas returned to its design studies after the cooperation deal expired.

In 1962, design studies were underway. The first version seated 63 passengers and had a gross weight of 69,000 lb (31,300 kg). This design was changed into what would be initial DC-9 variant. Douglas gave approval to produce the DC-9 on April 8, 1963. Unlike the competing but larger Boeing 727 trijet, which used as many 707 components as possible, the DC-9 was an all-new design. The DC-9 has two rear-mounted Pratt & Whitney JT8D turbofan engines, relatively small, efficient wings, and a T-tail. The DC-9's takeoff weight was limited to 80,000 lb (36,300 kg) for a two-person flight crew by Federal Aviation Agency regulations at the time. DC-9 aircraft have five seats across for economy seating. The airplane seats 80 to 135 passengers depending on version and seating arrangement.