American Airlines and Google said they reduced the climate impact of some flights using an AI-based contrail forecasting tool that identifies where condensation trails are likely to form. The companies said the effort is intended to help prevent contrails from forming in cold, humid areas by allowing pilots to shift altitude or use optional routes during flight planning.
The companies’ description centers on how contrails form: when aircraft fly through cold, humid regions, ice crystals can gather around engine soot particles and create clouds that trap heat. In their trial, Google used artificial intelligence to predict where contrails are likely to form if planes pass through those areas, and American Airlines said it added the forecasts to its flight planning system on a trial basis.
Google and American Airlines said the trial involved 2,400 flights from the U.S. to Europe. Google said half of the flights were given a route option designed to avoid creating contrails while the other half served as a control group.
In research shared by Google in a blog post, the companies said 112 flights took the option. Google said those flights formed 62% fewer contrails than the control group, and it estimated that the reduced climatological warming from those flights was about 69%.
Dinesh Sanekommu, who leads Google’s work on contrails, said the companies see the project as evidence-building rather than a one-off demonstration. In an interview, he said, “We know that aviation is one of the hardest, most difficult sectors to decarbonize,” and added that they “think there’s a way that AI can help make that a reality.” He said, “And the hope is, whether it’s these AI-based forecasts, whether it is doing these operational scientific demonstrations together, they all add a little bit of evidence and generate a bit of data that helps make the right decisions in the long run.”
The companies said the trial ran from January 2025 to May and that Flightkeys, a flight planning service used by American Airlines, joined the airline, Google and Contrails.org in the collaborative work. The AP report described Contrails.org as a nonprofit research organization focused on reducing aviation’s climate impact through contrail management and as part of the Breakthrough Energy group founded by Bill Gates.
The trial’s proponents said route adjustments can be a more operationally feasible lever than switching to cleaner fuels. The companies said switching to sustainable aviation fuel can significantly reduce emissions and contrails but is more expensive than slightly altering flight routes, and they said research tested in the trial suggests minor changes to flight altitudes or routes to avoid contrail-prone regions could reduce a significant portion of the warming with minimal additional fuel.
Thomas Walker, who researches aviation climate impacts at the Boston-based Clean Air Task Force, said the North Atlantic region is a contrail hotspot and that avoiding contrails there could be particularly effective. Walker said CATF has been talking with other major airlines about avoiding contrails and that “there’s been a little bit of pushback,” including on how to coordinate actions across international airspace.
Walker said there have been trials in Europe adjusting routes, but that the American Airlines-Google effort is the largest one he has heard of in the United States, calling it “a pretty big step in the right direction.” He said he hoped the results would encourage other airlines to participate.
Jill Blickstein, vice president of sustainability at American Airlines, said the trial showed it was not difficult for dispatchers and pilots to file and fly alternative plans to avoid contrails. American Airlines said the airline is not yet making contrail avoidance routine in its regular flight planning process, and it said it hopes to continue working with partners on additional studies that could involve different flight routes and times of day to help answer scientific questions.
Sources said the trial also looked at fuel impacts, with the companies reporting no statistically significant difference in fuel usage observed between the control group and the flights offered the contrail-avoidance option.