The McDonnell Douglas MD-81 is a twin-engine, single-aisle jet airliner that first entered service in 1980. It is part of the MD-80 family, which was designed for short to medium-haul flights. The aircraft can typically seat around 130 passengers and is known for its fuel efficiency and reliability. The MD-81 features a T-tail design and is powered by two Rolls-Royce engines. It has a range of approximately 2,500 miles, making it suitable for various domestic and international routes. The aircraft was widely used by many airlines during its operational years, contributing to its popularity in commercial aviation.