More than 80 test flights followed AI forecasts and made small route changes. Google estimates a 40% cut in contrail warming during those flights, but a larger trial is still needed.
New to this? Read it in simple words
- Cathay Pacific and Google are expanding an AI trial to avoid warming contrails. AI forecasts help pilots consider small changes in height or route.
- In the first trial, more than 80 flights followed routes planned to avoid contrails. Google estimates these flights cut their contrail warming by about 40 percent.
- Some contrails spread into thin clouds that keep heat in the atmosphere. Avoiding them may help, but it cannot replace cleaner fuel or better aircraft.
- The 40 percent is not a cut in fuel use or total emissions. A larger trial is still needed.
- Contrail
- A white line of cloud that sometimes forms behind a plane.
- Emissions
- Gases released into the air, such as carbon dioxide from burning fuel.
How the flight trial works
Contrails are the white lines that sometimes form behind an aircraft. They can appear in very cold and wet air. Some disappear quickly, while others spread into thin clouds that keep heat in the atmosphere.
Google combines weather data, AI forecasts, and satellite tools to find areas where a warming contrail may form. Cathay puts the forecast into its digital flight system. Dispatchers and pilots can then consider a small change in height or route.
Pilots already make route changes for weather and traffic. A contrail change must also fit airspace rules, fuel needs, aircraft weight, and safety. The first trial could not change every planned flight because some flights had operating limits.
Google estimates about 40% less contrail warming across more than 80 trial flights. This is not a 40% cut in total emissions.
What the 40% number means
The first trial began in late 2025 and planned more than 100 flights. More than 80 flights followed contrail-avoidance routes. Google estimates that these flights reduced the warming effect of their contrails by about 40%.
This is not a 40% cut in fuel use or carbon dioxide. An aircraft may use a little more fuel when it changes height or route. The trial is studying whether the lower contrail warming is larger than any extra warming from fuel.
The Hong Kong to Singapore route produced more than half of the measured climate benefit in the first trial. That result shows why local weather and route conditions matter. It does not mean every route will have the same benefit.
The next phase needs broader evidence
Cathay and Google now plan more tests across routes within Asia, across the Pacific, and near the poles. Cathay is the first Google airline partner in Asia-Pacific and the first to test this method on very long flights.
A larger test can show how often pilots can use the forecast, how much extra fuel is needed, and whether the result stays strong in different seasons. It can also help air-traffic teams decide how several airlines should share the same airspace.
Avoiding contrails cannot replace lower carbon dioxide emissions, cleaner fuel, or better aircraft. It may become one faster tool that works with those changes. The early result is hopeful, but the larger trial must show the full cost and climate effect.
Sources
Every fact in this story comes from the sources below. Open them to check our work.
- 1Primary source · September 8, 2026Cathay Pacific and Google partner to research and trial AI-powered contrail avoidance Cathay Pacific
- 2Research · September 7, 2026Cathay Pacific, Google expand AI trials to cut climate-warming aircraft contrails Reuters via MarketScreener
- 3Primary source · August 18, 2026Operation Blue Skies: Reducing aviation climate impact with AI Google
We used the Cathay announcement for the flight count, routes, and early estimate. We checked the main facts with Reuters and used Google's separate project page to understand the forecast method. We do not turn contrail warming into a claim about total emissions.