McDonnell Douglas MD-80

MD-80 series
An Iberia MD-88 in 2002
Role	Narrow-body jet airliner
Manufacturer	McDonnell Douglas Boeing Commercial Airplanes (from Aug. 1997)
First flight	October 18, 1979
Introduction	1980 with Swissair and Austrian Airlines
Status	In service
Primary users	Delta Air Lines American Airlines Allegiant Air
Produced	1979–1999
Number built	1,191
Unit cost	US$41.5–48.5 million
Developed from	McDonnell Douglas DC-9
Variants	McDonnell Douglas MD-90
Developed into	Boeing 717

The McDonnell Douglas MD-80 is a series of twin-engine, short- to medium-range, single-aisle commercial jet airliners. It was lengthened and updated from the DC-9. This series can seat from 130 to 172 passengers depending on variant and seating configuration.

The MD-80 series was introduced into commercial service on October 10, 1980 by Swissair. The series includes the MD-81, MD-82, MD-83, MD-87, and MD-88. These all have the same fuselage length except the shortened MD-87. The series was followed into service in modified form by the MD-90 in 1995 and the Boeing 717 (originally MD-95) in 1999.

Douglas Aircraft developed the DC-9 in the 1960s as a short-range companion to their larger DC-8. The DC-9 was an all-new design, using two rear fuselage-mounted turbofan engines, and a T-tail. The DC-9 has a narrow-body fuselage design with five-abreast seating, and holds 80 to 135 passengers depending on seating arrangement and aircraft version. The DC-9 family is one of the most successful jet airliners with a total of over 2,400 units produced; it ranks third behind the second-place Airbus A320 family with over 6,600 produced, and the first place Boeing 737 with over 8,600 produced.

The development of MD-80 series began in the 1970s as a lengthened, growth version of the DC-9-50, with a higher maximum take-off weight (MTOW) and a higher fuel capacity. Availability of newer versions of the Pratt & Whitney JT8D engine with higher bypass ratios drove early studies including designs known as Series 55, Series 50 (refanned Super Stretch), and Series 60. The design effort focused on the Series 55 in August 1977. With the projected entry into service in 1980, the design was marketed as the "DC-9 Series 80". Swissair launched the Series 80 in October 1977 with an order for 15 plus an option for five.