DC9s

DC-9s are a family of twin-engine, single-aisle jet airliners designed by McDonnell Douglas for short- to medium-range routes. The first DC-9 flew in 1965 and entered service soon after. The line aimed to provide a compact, economical option for airlines operating high-frequency domestic routes and regional services, with an emphasis on reliability and ease of operation.

Design features include rear-mounted engines on a low-mounted swept wing and a conventional tail. The cabin generally uses a two-by-two seating layout and varies by variant. Early models included the DC-9-10, -20, and -30; later, stretched, higher-capacity versions such as the DC-9-50 were introduced. The line evolved into the MD-80 and MD-90 families, preserving the basic airframe while updating engines and systems. A derivative airframe later became the Boeing 717-200 following Boeing's merger with McDonnell Douglas in 1997.

Production spanned several decades and it was widely operated by airlines worldwide. The DC-9 family is noted for reliability and economical operation, contributing to its popularity on routes with moderate demand. In the 2000s and 2010s many DC-9-era aircraft were retired or re-engined, though some remained in service with regional operators in various regions.

Today the DC-9 lineage is carried forward by the MD-80 and MD-90 successors and the Boeing 717, which inherits design features from the DC-9 and incorporates modern avionics and engines. The DC-9 remains a notable example of mid-20th-century jet airliner design and its influence on the narrow-body market.