United Airlines became the first U.S. airline to publicly commit to reducing its own greenhouse gas emissions by 50 percent by 2050, on September 13, 2018.

United's pledge to reduce its greenhouse gas emissions by 50 percent relative to 2005 represents the equivalent of removing 4.5 million vehicles from the road each year, or the total number of cars in Los Angeles and New York City combined. The airline will continue to invest in the company's ongoing environmental initiatives to support this commitment, including expanding the use of more sustainable aviation biofuels, welcoming newer, more fuel-efficient aircraft into its fleet and implementing further operational changes to better conserve fuel.

Sustainable aviation biofuel flight from San Francisco to Zurich

United operated flight 44 on September 14, 2018, from its hub in San Francisco to Zurich with a Boeing 787 using a blend of sustainable aviation fuel supplied by World Energy's California-based AltAir Fuels. The airline used 16,000 gallons of biofuel at a 30/70 blend with conventional jet fuel for the flight to Zurich, representing the longest transatlantic flight to date - and longest by a U.S. airline - powered by a biofuel volume of this size. United has sourced more than 2 million gallons of sustainable aviation biofuel since 2016 and is responsible for more than 50 percent of the airline industry's commitments to biofuel.