The document provides details on the McDonnell Douglas MD-80, which was an upgraded version of the DC-9 airliner with a longer fuselage, larger wings, and more powerful JT8D turbofan engines. Key details include that the MD-80 had a 147-foot fuselage, could carry up to 172 passengers, and was powered by new JT8D-209 engines that were quieter and more fuel efficient compared to earlier versions. The MD-80 offered airlines an upgraded twin-engine aircraft at a time when environmental regulations were restricting the use of noisier trijets.