The Douglas DC-9 entered service Dec. 8, 1965, and was produced until 1982. A total of 976 DC-9s were built — including 41 C-9 aircraft for military customers.

The C-9A Nightingale was used by the U.S. Air Force to transport sick and injured military personnel. The U.S. Navy and Marine Corps flew C-9B Skytrain IIs. Three VC-9Cs configured as VIP transports were delivered to the Air Force by the end of 1976.

The 90-passenger DC-9-10 was expanded into the 15-foot (4.6-meter) longer DC-9-30, which first flew on Aug. 1, 1966, and could carry up to 115 passengers. The DC-9-20, which first flew Sept. 18, 1968, was especially useful for short landing fields.

The DC-9-40, first flown Nov. 28, 1967, was 6 feet (1.8 meters) longer than the -30 and could hold 125 passengers, and the DC-9-50, which first flew in 1974, was 12 feet (3.6 meters) longer and had the ”new look” interior patterned after the wide-cabin DC-10. The DC-9-80, later redesignated MD-80, launched the family of commercial jet airliners with McDonnell Douglas ”MD” designation.

In 1996, more than 880 DC-9s were still flying. However, on Jan. 6, 2014, Delta Airlines officially retired its remaining DC-9 following flight 2014 departing Minneapolis/St. Paul for Atlanta. The airline said it was the last scheduled commercial flight of the DC-9 by a major U.S. airline.