Google AI cuts heat-trapping contrails by 62% in major American Airlines trial

Google rerouted over 100 flights to cut climate-warming contrails

A trial involving thousands of flights between the US and Europe has found that planes produce fewer contrails if they follow flight paths recommended by an artificial intelligence to reduce their global warming impact. The streaks of condensation triggered by soot particles produced by aircraft engines are thought to cause more warming than the carbon dioxide that planes emit. Research has also shown that some ice-rich regions of the upper atmosphere are more likely to form contrails when a plane passes through them, and that AI can predict where these regions will be using detailed weather forecasts. There have been small-scale trials showing that planes rerouted through these regions will produce fewer contrails, but the practice has yet to be applied to commercial flights at scale. Now, Dinesh Sanekommu at Google and his colleagues have used an AI contrail-forecasting tool to give routing advice in a randomised control trial of more than 2400 real American Airlines flights. The trial involved flights heading eastward from the US to Europe and ran for around 17 weeks, from January to May 2025. The direction was only one-way because these flights would take place at night, which is when contrails have been found to have a clearer warming effect. During the day, contrails can have a cooling effect because they reflect sunlight back into space. Each flight route between two cities was randomly assigned to one of two groups. For the first group, air traffic dispatchers had an option in their flight-planning software to pick an AI-optimised, low-contrail route, but for the second, no alternative was suggested. Although dispatchers in the first group always had the option of picking a low-contrail route, only 112 out of 1232 flights in this group actually ended up taking the alternative path because of operational concerns, such as cost or safety, says Sanekommu. According to an AI analysis of satellite imagery of flight paths, there was a 62 per cent lower amount of visible contrails for flights that took the contrail-optimised route suggested to air traffic dispatchers. When all flights that had the option of taking a contrail-optimised route are included, the effective overall reduction in contrail formation was 11.6 per cent compared with the control group. "It validated the thesis of, if we could figure out how to safely and correctly integrate into the flight planning process, then this is a scalable route to consider contrail avoidance across many flights," says Sanekommu. The team estimates that the flights' warming effect was reduced by 13.7 per cent in the entire group given a suggested route and 69.3 per cent in the flights that took the optimised route. There was no statistically significant difference in fuel consumption between the groups. "This is probably the best you can do, at least with the tools we have at the moment," says Edward Gryspeerdt at Imperial College London. "It does indicate that this is possible. The 62 per cent reduction in satellite-observed contrails that they see is unlikely to have happened by chance." However, it is unclear how much the 11.6 per cent figure can be improved in real-world operations, because of the intricacies of flight planning, says Gryspeerdt. "You can't necessarily just scale this up to be a 60 per cent reduction in contrails from every flight everywhere, but even a 10 per cent reduction in contrails is still a non-negligible effect."

American Airlines and Google say AI helped airplanes reduce contrails that trap heat

American Airlines and Google said Thursday that they significantly reduced the climate impact of some of the airline's flights using an AI-based forecasting tool to help prevent contrails. When airplanes fly through cold and humid areas, ice crystals can form around the soot particles emitted from the engine, creating clouds that trap heat and warm the planet. Google is using artificial intelligence to predict where these condensation trails, or contrails, are likely to form if planes pass through. American Airlines added the forecasts to its flight planning system on a trial basis to show where pilots could safely shift altitude or use optional routes to avoid those areas. American Airlines and Google said the tool could be one of the most cost-effective, scalable climate solutions available in aviation now. The aviation industry is under growing pressure to take action on climate change. And while those thin, white lines that form behind airplanes may look wispy, they're responsible for a surprising amount of Earth's warming -- 1% to 2%, according to Contrails.org, a nonprofit research organization dedicated to reducing aviation's climate impact through contrail management, as part of the Breakthrough Energy group founded by Bill Gates. The group was among the collaborators in the trial. Switching to cleaner fuels, such as sustainable aviation fuel, can significantly reduce emissions and contrails, though that's far more expensive than slightly altering a flight route. Many contrails are short-lived, but some may persist for hours or even days if it's extremely humid. Research on the subject suggested that minor adjustments to flight altitudes or routes to avoid these regions could eliminate a significant portion of this warming using a minimal amount of additional fuel -- a theory tested through this trial. The trial involved 2,400 flights from the U.S. to Europe. In research shared in a blog post Thursday, Google said half were given a route option to avoid creating contrails and the other half were the control group. For the 112 flights that flew that option, they formed 62% fewer contrails compared to the control group, the paper said. The researchers estimated that reduced the climatological warming from those flights by about 69%. The trial started in January 2025 and ended in May. Flightkeys, the flight planning service used by American Airlines, joined the airline, Google and Contrails.org in the collaborative work. "We know that aviation is one of the hardest, most difficult sectors to decarbonize," Dinesh Sanekommu, who leads Google's work on contrails, said in an interview. "We think there's a way that AI can help make that a reality. 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." This built on earlier work by Google, American Airlines and Breakthrough Energy. They partnered in 2023 to reduce the warming effects of contrails and did a smaller test where the flights were identified manually versus integrated into the flight planning system. As for what's next, Sanekommu said they need to do a larger trial and they want to work with all the other flight planning software providers to build contrail forecasts and avoidance features into their products. One of the biggest deterrents for airlines in adjusting a route is the potential cost of extra fuel, but the trial found no statistically significant difference in fuel usage observed between the two groups. It's also a challenge to coordinate among pilots and air traffic controllers over different airspace regions internationally, said Thomas Walker, who researches aviation climate impacts at the Boston-based Clean Air Task Force. CATF has been talking with other major airlines about avoiding contrails, Walker said, and "there's been a little bit of pushback." Jill Blickstein, vice president of sustainability at American Airlines, said the trial showed it wasn't difficult for dispatchers and pilots to file and fly alternative plans to avoid contrails. The North Atlantic region is a hot spot for contrails, making attempts to avoid creating them there particularly effective, added Walker, CATF's senior transportation technology manager. Walker said there have been trials in Europe to adjust routes, and this is the largest one he has heard of in the United States, which is "a pretty big step in the right direction." He said he hoped American Airlines' positive results will encourage other airlines to participate. American Airlines said it's not yet making contrail avoidance a routine part of its regular flight planning process. The airline said it hopes to continue working with its partners on additional studies, potentially involving different flight routes and times of day, that could help answer important scientific questions. ___ The Associated Press' climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP's standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.

Our new study explores how AI can reduce the climate impact of air travel.

In 2023, Google partnered with American Airlines to show that pilots using AI-based forecasts could reduce contrails on a small set of test flights. A 54% reduction across 70 flights marked the industry's first proof point that commercial flights could verifiably reduce their contrail impact -- but identifying the right flights still required hours of manual coordination. Our new study shows what happens when contrail avoidance is built directly into the tools airlines already use. Google's AI contrail forecasts were integrated into American Airline's flight planning software and used in a trial of 2,400 transatlantic flights that were part of the airline's standard schedule. For the flights that successfully flew the contrail avoidance plans, there was a 62% reduction in contrail formation rate compared to the control group. We're excited to scale this work and continue our research and partnership with the industry to automate contrail avoidance, a solution that offers a scalable and cost-effective way to reduce the climate impact of flying. Results like these bring that reality within reach.

Google: AI tool helped prevent heat-trapping contrails

Google said on Thursday that its artificial intelligence (AI) forecasts helped prevent contrails, the white lines that often follow planes in the sky. The tech giant said in a blog post that it had decided to collaborate with American Airlines in 2023 "to show that pilots using AI-based forecasts could reduce contrails on a small set of test flights." "A 54% reduction across 70 flights marked the industry's first proof point that commercial flights could verifiably reduce their contrail impact -- but identifying the right flights still required hours of manual coordination," the blog post reads. Google said through a new study, it had found that its AI contrail forecasts, when implemented in American Airlines's flight planning software and put to use on 2,400 transatlantic flights, had reduced contrails by a significant amount "[f]or the flights that successfully flew the contrail avoidance plans." "There was a 62% reduction in contrail formation rate compared to the control group," Google added in the post. According to the Federal Aviation Administration (FAA), contrails occur "when airplanes fly in cold and humid atmospheric conditions and ice crystals form around the particles emitted from the engine." Contrails, through their expansions and mergers, can blanket thousands of square miles in the sky and cause heat to stay trapped in the atmosphere, according to Google.

American Airlines and Google Say AI Helped Airplanes Reduce Contrails That Trap Heat

American Airlines and Google said Thursday that they significantly reduced the climate impact of some of the airline's flights using an AI-based forecasting tool to help prevent contrails. When airplanes fly through cold and humid areas, ice crystals can form around the soot particles emitted from the engine, creating clouds that trap heat and warm the planet. Google is using artificial intelligence to predict where these condensation trails, or contrails, are likely to form if planes pass through. American Airlines added the forecasts to its flight planning system on a trial basis to show where pilots could safely shift altitude or use optional routes to avoid those areas. American Airlines and Google said the tool could be one of the most cost-effective, scalable climate solutions available in aviation now. The aviation industry is under growing pressure to take action on climate change. And while those thin, white lines that form behind airplanes may look wispy, they're responsible for a surprising amount of Earth's warming -- 1% to 2%, according to Contrails.org, a nonprofit research organization dedicated to reducing aviation's climate impact through contrail management, as part of the Breakthrough Energy group founded by Bill Gates. The group was among the collaborators in the trial. Switching to cleaner fuels, such as sustainable aviation fuel, can significantly reduce emissions and contrails, though that's far more expensive than slightly altering a flight route. Many contrails are short-lived, but some may persist for hours or even days if it's extremely humid. Research on the subject suggested that minor adjustments to flight altitudes or routes to avoid these regions could eliminate a significant portion of this warming using a minimal amount of additional fuel -- a theory tested through this trial. Testing on flights from the U.S. to Europe The trial involved 2,400 flights from the U.S. to Europe. In research shared in a blog post Thursday, Google said half were given a route option to avoid creating contrails and the other half were the control group. For the 112 flights that flew that option, they formed 62% fewer contrails compared to the control group, the paper said. The researchers estimated that reduced the climatological warming from those flights by about 69%. The trial started in January 2025 and ended in May. Flightkeys, the flight planning service used by American Airlines, joined the airline, Google and Contrails.org in the collaborative work. "We know that aviation is one of the hardest, most difficult sectors to decarbonize," Dinesh Sanekommu, who leads Google's work on contrails, said in an interview. "We think there's a way that AI can help make that a reality. 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." This built on earlier work by Google, American Airlines and Breakthrough Energy. They partnered in 2023 to reduce the warming effects of contrails and did a smaller test where the flights were identified manually versus integrated into the flight planning system. As for what's next, Sanekommu said they need to do a larger trial and they want to work with all the other flight planning software providers to build contrail forecasts and avoidance features into their products. Showing the way for other airlines One of the biggest deterrents for airlines in adjusting a route is the potential cost of extra fuel, but the trial found no statistically significant difference in fuel usage observed between the two groups. It's also a challenge to coordinate among pilots and air traffic controllers over different airspace regions internationally, said Thomas Walker, who researches aviation climate impacts at the Boston-based Clean Air Task Force. CATF has been talking with other major airlines about avoiding contrails, Walker said, and "there's been a little bit of pushback." Jill Blickstein, vice president of sustainability at American Airlines, said the trial showed it wasn't difficult for dispatchers and pilots to file and fly alternative plans to avoid contrails. The North Atlantic region is a hot spot for contrails, making attempts to avoid creating them there particularly effective, added Walker, CATF's senior transportation technology manager. Walker said there have been trials in Europe to adjust routes, and this is the largest one he has heard of in the United States, which is "a pretty big step in the right direction." He said he hoped American Airlines' positive results will encourage other airlines to participate. American Airlines said it's not yet making contrail avoidance a routine part of its regular flight planning process. The airline said it hopes to continue working with its partners on additional studies, potentially involving different flight routes and times of day, that could help answer important scientific questions. ___ The Associated Press' climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP's standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.

American Airlines and Google say AI helped airplanes reduce trap heat

American Airlines and Google said Thursday that they significantly reduced the climate impact of some of the airline's flights using an AI-based forecasting tool to help prevent contrails. When airplanes fly through cold and humid areas, ice crystals can form around the soot particles emitted from the engine, creating clouds that trap heat and warm the planet. Google is using artificial intelligence to predict where these condensation trails, or contrails, are likely to form if planes pass through. American Airlines added the forecasts to its flight planning system on a trial basis to show where pilots could safely shift altitude or use optional routes to avoid those areas. American Airlines and Google said the tool could be one of the most cost-effective, scalable climate solutions available in aviation now. The aviation industry is under growing pressure to take action on climate change. And while those thin, white lines that form behind airplanes may look wispy, they're responsible for a surprising amount of Earth's warming -- 1% to 2%, according to Contrails.org, a nonprofit research organization dedicated to reducing aviation's climate impact through contrail management, as part of the Breakthrough Energy group founded by Bill Gates. The group was among the collaborators in the trial. Switching to cleaner fuels, such as sustainable aviation fuel, can significantly reduce emissions and contrails, though that's far more expensive than slightly altering a flight route. Many contrails are short-lived, but some may persist for hours or even days if it's extremely humid. Research on the subject suggested that minor adjustments to flight altitudes or routes to avoid these regions could eliminate a significant portion of this warming using a minimal amount of additional fuel -- a theory tested through this trial. The trial involved 2,400 flights from the U.S. to Europe. In research shared in a blog post Thursday, Google said half were given a route option to avoid creating contrails and the other half were the control group. For the 112 flights that flew that option, they formed 62% fewer contrails compared to the control group, the paper said. The researchers estimated that reduced the climatological warming from those flights by about 69%. The trial started in January 2025 and ended in May. Flightkeys, the flight planning service used by American Airlines, joined the airline, Google and Contrails.org in the collaborative work. "We know that aviation is one of the hardest, most difficult sectors to decarbonize," Dinesh Sanekommu, who leads Google's work on contrails, said in an interview. "We think there's a way that AI can help make that a reality. 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." This built on earlier work by Google, American Airlines and Breakthrough Energy. They partnered in 2023 to reduce the warming effects of contrails and did a smaller test where the flights were identified manually versus integrated into the flight planning system. As for what's next, Sanekommu said they need to do a larger trial and they want to work with all the other flight planning software providers to build contrail forecasts and avoidance features into their products One of the biggest deterrents for airlines in adjusting a route is the potential cost of extra fuel, but the trial found no statistically significant difference in fuel usage observed between the two groups. It's also a challenge to coordinate among pilots and air traffic controllers over different airspace regions internationally, said Thomas Walker, who researches aviation climate impacts at the Boston-based Clean Air Task Force. CATF has been talking with other major airlines about avoiding contrails, Walker said, and "there's been a little bit of pushback." Jill Blickstein, vice president of sustainability at American Airlines, said the trial showed it wasn't difficult for dispatchers and pilots to file and fly alternative plans to avoid contrails. The North Atlantic region is a hot spot for contrails, making attempts to avoid creating them there particularly effective, added Walker, CATF's senior transportation technology manager. Walker said there have been trials in Europe to adjust routes, and this is the largest one he has heard of in the United States, which is "a pretty big step in the right direction." He said he hoped American Airlines' positive results will encourage other airlines to participate. American Airlines said it's not yet making contrail avoidance a routine part of its regular flight planning process. The airline said it hopes to continue working with its partners on additional studies, potentially involving different flight routes and times of day, that could help answer important scientific questions.