HP-137 Jetstream Contour model. The Jetstream was originally a project of the very old British aviation company Handley Page. But when production costs (originally projected to be 3 million pounds) exceeded 13 million pounds, the company went into voluntary liquidation, this coming just one year after the company celebrated its diamond jubilee on June 17, 1969. It was finally Scottish Aviation Ltd. which continued manufacture of the aircraft. Even this company was to lose its identity as the Scottish Division of British Aerospace Aircraft Group on January 1, 1978. The later Jetstream 31, flown for the first time on March 28, 1980, was intended to highlight its superior cabin height by comparison with its direct competitors. The Jetstream 31 has an estimated maximum cruising speed of 303 mph, service ceiling of 31,600 feet, and a range of 484 miles.