This demonstration conducted by United Airlines was the world's first passenger flight operated using 100% sustainable aviation fuel (SAF) in one of the Boeing 737 Max 8's two engines. Supplied with 500 gallons of World Energy's SAF, this flight from Chicago's O'Hare International Airport to Washington DC's Reagan National Airport was designed to validate the performance of SAF as a 100% drop-in substitute for conventional jet fuel. [1]