The McDonnell Douglas MD-11 was aviation’s last major three-engine aircraft, and it was a late Cold War-era design that entered service just as airline economics began shifting decisively toward long-range twin-engine aircraft. Ultimately built as a modernized evolution of the DC-10, the MD-11 brought a stretched fuselage, winglets, updated avionics, and a two-pilot cockpit to a platform that carriers already understood operationally. On paper, it promised more range and better fuel burn than earlier widebodies while preserving the cargo volume and runway performance airlines prized for long-haul missions. In practice, the MD-11 became a transitional aircraft. Several major passenger airlines adopted it in the early 1990s to bridge growth and fleet-renewal cycles.