United Airlines has announced plans to bring back supersonic travel with aircraft flying at twice the speed of today's fastest jets. The carrier hopes to start passenger services by 2029.
The US airline says it has reached a commercial agreement with American aerospace venture firm Boom Supersonic to add aircraft to its global fleet.
United says it will purchase 15 of Boom's jets once they meet the airline's safety and sustainability requirements.
The companies say the supersonic jet with 65 to 88 seats can cut current flight times by roughly half.
It would connect San Francisco to Tokyo in six hours. Transatlantic flights from Newark, near New York, to Frankfurt would be cut to four hours; and three and a half hours to London.
There have been supersonic passenger jets in the past.
Concorde, developed by Britain and France, was retired from commercial service in 2003, partly due to poor fuel efficiency and noise pollution.