Ventral airstairs are featured on most tail-engined airliners, such as the Boeing 727, the McDonnell Douglas DC-9, MD-80 and MD-90, the BAC 1-11, and the Yakovlev Yak-40/Yak-42 series, and are incorporated as ramps which lower from the fuselage. The Ilyushin Il-86 has three airstairs on the port side.