The United Kingdom and Google are collaborating on a 30-month trial, dubbed Operation Blue Skies, to test how minor adjustments to flight altitudes can reduce the climate impact of airplane contrails. Hundreds of commercial flights will alter their paths over the northeastern Atlantic Ocean during the next two winters to assess the effectiveness of these changes.
The trial focuses on the Shanwick Oceanic Control Area, a busy air traffic corridor between Europe and North America over the eastern North Atlantic. This region is identified as a hotspot for contrail formation. Contrails, the visible ice crystal clouds formed by engine exhaust in cold, humid air, trap heat and contribute to global warming. According to Contrails.org, contrails are responsible for 1% to 2% of Earth's warming, and the Shanwick airspace accounts for approximately 5% of this contribution.
During approximately 20 to 40 test days each winter, air traffic controllers will instruct selected flights to deviate up to 2,000 feet to avoid areas where contrails are likely to form. The British government expects hundreds of the roughly 10,000 flights transiting the Shanwick airspace during the testing periods to deviate, a figure estimated to be between 1% and 5% of the total. This level of deviation is anticipated to be sufficient to demonstrate a statistically significant reduction in contrail formation on an airspace scale.
Google is contributing its artificial intelligence-powered forecasts to identify regions where contrails are most likely to form. The UK government is funding more than half of the study, which has a total cost of approximately £5 million (about $6.76 million).
This initiative builds upon previous efforts by individual airlines, such as a collaboration between Google and American Airlines that used AI forecasting to reduce the climate impact of specific flights. Operation Blue Skies expands this approach to an entire flight corridor, aiming to show the possibility of moving multiple aircraft simultaneously to minimize contrail formation and assess potential overall reductions for a region. This could serve as a model for other airspaces globally.
The consortium involved in Operation Blue Skies includes the UK Department for Transport, Google, the Met Office, NATS (the UK's air navigation service provider), Contrails.org, Imperial College London, and the University of Cambridge. Researchers from Imperial College London previously found in a 2020 study that small adjustments to flight paths could significantly reduce the climate impact of contrails. This trial represents an opportunity to test those findings in a real-world, large-scale scenario.