The Boeing 767 is a mid- to large-size, long-range, wide-body twin-engine jet airliner built by Boeing Commercial Airplanes. It was launched as the 7X7 program on July 14, 1978, and the prototype first flew on September 26, 1981. The original 767-200 entered service on September 8, 1982, with United Airlines, and the extended-range 767-200ER in 1984. It was stretched into the 767-300 in October 1986, followed by the 767-300ER in 1988, the most popular variant. The 767 was designed as a smaller wide-body airliner than earlier aircraft such as the 747, with seating capacity for 181 to 375 persons and a design range of 3,850 to 6,385 nautical miles, depending on the variant. The 767 and 757 shared much of the same design and technology, which allowed pilots to obtain a common type rating to operate both aircraft. The 767 is also used as a freighter, with the 767 Freighter carrying up to 23,980 gallons of fuel and capable of ferrying more than 60 tons of revenue payload 3,765 nautical miles.