United Airlines announced an agreement with aerospace company Boom Supersonic to purchase supersonic, net zero carbon aircraft. The planes are expected to enter into operation with passenger flights in 2029.

Optimized to run on 100% sustainable aviation fuel (SAF), Boom’s ‘Overture’ aircraft are expected to be the first large commercial aircraft to be net-zero carbon from day one.

Under the terms of the agreement, United will purchase 15 of Boom’s ‘Overture’ airliners, once the aircraft meet the airline’s safety, operating and sustainability requirements, with an option for an additional 35 aircraft. The companies have also pledged to work together to accelerate production of greater supplies of SAF.

Sustainable aviation fuel is seen as one of the key tools for the aviation industry, which accounts for roughly 2% of global greenhouse gas emissions, to address its impact, as it generates 80% less lifecycle carbon emissions than conventional jet fuel. SAF is generally produced from sustainable resources, like waste oils and agricultural residues, or even from carbon captured from the air, rather than from fossil fuels.

United has emerged as one of the key players in the industry working to help develop the SAF market. In April, United launched the Eco-Skies Alliance, a program aimed at enabling corporate customers the opportunity to reduce the environmental impact of travel by paying the additional cost of sustainable aviation fuel (SAF).

The new aircraft will also help United meet its own sustainability goals, including a commitment to reduce greenhouse gas emissions by 100% by 2050, focused on direct emission reduction measures rather than indirect measures such as carbon offsetting, and through continued investment in the development and use of SAF.

United CEO Scott Kirby said:

“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. 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 travelers 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.”

Blake Scholl, Boom Supersonic founder and CEO, added:

“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. 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.”