Commercial supersonic flight return edges closer: 10 top stories of the week 04 Jun 2021 United Airlines plans supersonic flights with Boom United Airlines has agreed to buy 15 Overture supersonic airliners from Boom, with an option to buy 35 more. The aircraft, which is expected to fly from 2025, will hold up to 88 passengers and fly at up to Mach 1.7 (2,100km/h). TfL to consider driverless trains Transport for London (TfL) will develop a business case for driverless trains after reaching a deal for a £1.08bn funding package from the government. The operator will work towards fully automating at least one entire Underground line, with on-board attendants on each train.