United Airlines has become a global leader in reducing the aviation industry's carbon footprint. In 2016, the carrier became the world's first airline to continuously use sustainable aviation fuel in its regular operation, mixing it with conventional jet fuel in the same engine. 

The flight flew from Chicago O'Hare to Washington D. The flight operated with one of United's new Boeing 737 MAX 8 jets with 500 gallons of The SAF in one engine and 500 gallons of traditional jet fuel in the other. "Today's SAF flight is not only a significant milestone for efforts to decarbonize our industry, but when combined with the surge in commitments to produce and purchase alternative fuels, we're demonstrating the scalable and impactful way companies can join together and play a role in addressing the biggest challenge of our lifetimes," Kirby said.

"When we fly, we connect, and our demand for the connections aviation makes possible are only going to grow," World Energy CEO Gene Gebolys said. In 2018, United became the first US carrier to commit to reducing its greenhouse gas emissions by 50% by 2050, though it has upped the goal to 100%. Then, in 2019, it operated "Flight for the Planet", which was the "most-eco-friendly commercial flight of its kind in the history of commercial aviation". In February 2021, United announced it would partner with Archer Aviation to help develop the latter's electric aircraft, which has the potential to operate as an air taxi to shuttle United customers.

In June 2021, the airline announced its investment in Boom's "Overture" airliner, a zero-emission supersonic jet that would use 100% SAF.

United's efforts will decrease its carbon footprint and help it meet its goal of reducing its greenhouse gas emissions by 100% by 2050 without the need for carbon offsets.