More than 100 passengers took the flight from Chicago O’Hare International airport to Ronald Reagan Washington National airport on Wednesday (1 December).

United said the flight marked a "turning point" in the aviation industry’s efforts to address climate change.

“United continues to lead from the front when it comes to climate change action,” said chief executive Scott Kirby, who took the flight on Wednesday.

He hailed it a "significant milestone" for efforts to decarbonise aviation.

"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 added.

The flight was operated using a Boeing 737 Max 8 aircraft with 500 gallons of SAF in one engine and the same of conventional jet fuel in the other to prove there is "no operational difference" between the two.

Airlines are currently permitted to use a maximum 50% blend of SAF; United said the flight showed SAF was "drop-in ready and compatible with existing fleets".

The carrier partnered with Boeing, aircraft engine manufacturer CFM International, SAF tech firm Virent and SAF producer World Energy for the flight.