The McDonnell Douglas DC-9 was an American-built single-aisle jet aircraft produced from 1965 to 1982. A total of 976 units were manufactured over its 30-year production history, of which Delta Air Lines operated 305 of the type both from its own original fleet and also from Northwest Airlines, which merged with Delta in 2009. Although no US passenger carriers operate the type anymore, a few cargo airlines still use the aircraft.
History and development
In the 1950s, Douglas Aircraft, a prominent American aircraft manufacturer, wanted to create a short- and medium-range airliner to compete with Boeing’s 727 trijet. In 1962 design of the aircraft began and Douglas approved production of the type in 1963 after extensive research.
The first DC-9 prototype flew in February 1965 and the type received its certificate of airworthiness in November of the same year. The first commercial airline to operate the type was Delta Air Lines, which received delivery of the aircraft on December 8. A year later, Douglas began to offer other variants of the type, notably the -30 series, which featured a slightly larger capacity. .
In August 1967, Douglas merged with fellow American planner McDonnell Aircraft, creating the McDonnell Douglas Corporation. The DC-9 continued to be produced, but under its new name, the MD-80, which was effectively the “second generation” of the original DC-9. In the early 1990s, the MD-80 was developed into the MD-90, which later inspired the Boeing 717.
The Douglas DC-9 had many variants. The “original” aircraft was developed as the 10 series (i.e. the DC-9-10), which was the smallest variant and was about the same size as the BAC One-Eleven . A total of 137 examples of this type were built, and they had a maximum weight of 37,000 kg. The 10 series had two other variants, which include the 14 and 15 series.
The 30 series was produced to compete with the popular Boeing 737. This variant was the best-selling type of the Douglas DC-9, with 662 built (about 60% of the total DC-9s built). It was a substantial improvement over the original DC-9-10, with a 50,000 kg higher maximum takeoff weight, longer wingspan and full-span leading edge slats to aid in take-off and landing performance. The Douglas DC-9-30 entered service in February 1967 with Eastern Airlines, an American airline based in Miami.
The Series 50 was the largest variant of the Douglas DC-9 and was also the last to enter revenue service in 1975 with Eastern Airlines. The fuselage was stretched by 2.49 m and could accommodate up to 139 passengers, roughly equivalent to the capacity of the Airbus A220 family. In addition to an increase in aircraft size, the DC-9 also featured a modified thrust reverser, originally developed by Air Canada.
Besides the aforementioned commercial variants, the Douglas DC-9 also had a military variant, the McDonnell Douglas C-9, which was produced for all branches of the US military, including the C-9A Nightingale for the US Air Force, and the C-9B Skytrain II for the US Navy and Marines.