Leading US carrier United Airlines announced on Thursday that it had signed a commercial agreement with US startup aerospace company Boom Supersonic to both purchase aircraft and implement a cooperative initiative to increase commercial aviation’s sustainability by accelerating and increasing the production of sustainable aviation fuels. The aircraft order is for 15 of Boom Supersonic’s Overture supersonic airliners, currently under development, with options for another 35.

In terms of fleet size and the number of routes it serves (one of which is between New York/Newark and Johannesburg), United is the world’s third largest airline. Implementation of the Boom Supersonic aircraft order depends on the Overture airliner meeting United’s strict safety, operating and sustainability standards (as well as gaining the necessary regulator approvals and certifications).

“United continues on its trajectory to build a more innovative, sustainable airline and today’s advancements in technology are making it more viable for that to include supersonic planes,” highlighted United CEO Scott Kirby. “Boom’s vision for the future of commercial aviation, combined with the industry’s most robust route network in the world, will give business and leisure travellers access to a stellar flight experience. Our mission has always been about connecting people and now working with Boom, we’ll be able to do that on an even greater scale.”

The Boom Overture will most probably be the first large commercial aircraft that will be net-zero carbon emission from the very beginning. It will be optimised to operate using 100% SAF. It will have a maximum speed of Mach 1.7 (Mach 1.0 being the speed of sound), which would make it twice as fast as the fastest airliners currently in service. It would carry from 65 to 88 passengers, with a range of 4 250 nautical miles. Boom is cooperating with renowned UK aeroengine manufacturer Rolls-Royce on the development of the powerplants for the Overture.

“The world’s first purchase agreement for net-zero carbon supersonic aircraft marks a significant step toward our mission to create a more accessible world,” affirmed Boom Supersonic founder and CEO Blake Scholl. “United and Boom share a common purpose – to unite the world safely and sustainably. At speeds twice as fast, United passengers will experience all the advantages of life lived in person, from deeper, more productive business relationships to longer, more relaxing vacations to far-off destinations.”

Currently, it is planned that the first Overture will be rolled out of the factory in 2025 and make its maiden flight in 2026. Commercial operations should start by 2029. Boom Supersonic rolled out its subscale crewed technology demonstrator aircraft, the XB-1, last year. It is currently undergoing ground tests and should make its first flight this year.