The Boeing 720 is an American narrow-body airliner produced by Boeing Commercial Airplanes.Announced in July 1957 as a 707 derivative for shorter flights from shorter runways, the 720 first flew on November 23, 1959.Its type certificate was issued on June 30, 1960, and it entered service with United Airlines on July 5, 1960. A total of 154 Boeing 720s and 720Bs were built until 1967.As a derivative, the 720 had low development costs, allowing profitability despite few sales.