Britain and Google launch Operation Blue Skies, a first-of-its-kind trial to erase the vapour trails warming the planet

The British government and Google have launched an ambitious experiment to tackle one of aviation's least understood contributions to global warming. Announced on 18 August, the initiative, named Operation Blue Skies, will test whether artificial intelligence can steer aircraft away from the atmospheric conditions that produce contrails, the thin white lines that trail behind planes high in the sky.

Billed by its backers as a world first, the trial is the first state-backed attempt to manage contrail avoidance across an entire stretch of oceanic airspace. Rather than a small laboratory study, it will play out in one of the busiest air corridors on the planet, the North Atlantic, where thousands of flights cross between Europe and North America every week of the year.

The experiment focuses on the Shanwick oceanic airspace, which covers the eastern half of the North Atlantic corridor and is controlled by the UK air traffic body NATS. That single region is responsible for an estimated 5 percent of the warming caused by contrails worldwide, making it an unusually concentrated target for any effort to cut aviation's climate footprint.

What the trial actually does

At the heart of the project is a forecasting system built by Google. The company will use records of where aircraft have created contrails in the past, then combine that data with weather patterns to predict where and when new contrails are most likely to form. Those forecasts are then passed to NATS, whose air traffic controllers can act on them in something close to real time.

The intervention itself is designed to be modest. Instead of sending planes on long detours, controllers will mostly ask pilots to make small changes in altitude during the quieter periods of the night, nudging them out of the thin bands of cold, humid air where contrails take shape. The adjustments are handled through the standard air traffic control communication channels already in daily use.

Contrails form when the hot, moist exhaust from jet engines meets extremely cold and humid air at cruising height, freezing into ice crystals that can linger for hours and spread out into cirrus-like clouds. Because these conditions occur in narrow layers of the atmosphere, a relatively small vertical shift can be enough to keep an aircraft clear of the danger zone entirely.

Why contrails matter

For years, aviation's climate debate has centred almost entirely on carbon dioxide. Yet research increasingly suggests that contrails account for roughly a third of the industry's total contribution to global warming, a share comparable to the effect of the carbon released by burning jet fuel itself, and one that has so far gone largely unaddressed by regulators.

Unlike carbon emissions, the warming effect of contrails is short lived, which is precisely why scientists find them so appealing as a target. If flights can be routed around contrail-forming regions, the climate benefit is felt almost immediately, offering a rare example of an aviation measure that could deliver results without waiting decades for new fuels or cleaner aircraft designs.

The trial is timed to match the periods when the problem is at its worst. Contrail warming peaks during the colder months, roughly between November and February, so the flight tests will be concentrated in the winter seasons of 2026 to 2027 and 2027 to 2028, with somewhere between 20 and 40 nights of testing planned in each of those two winters.

Who is involved and what it costs

Operation Blue Skies brings together an unusual mix of partners. Alongside Google and NATS, the consortium includes the Met Office, the non-profit research group Contrails.org, Imperial College London and the University of Cambridge. The 30-month programme carries a total budget of 5 million pounds, of which 2.65 million comes from the UK Department for Transport.

The project has drawn support from across government and industry. Keir Mather, the UK minister for aviation, maritime and freight, said that by testing small tweaks to flight paths over the Atlantic, the country could cut the vapour trails left behind by planes. Ian Jopson, NATS director of sustainability, said the trial would test how contrail avoidance could work within the tightly coordinated world of air traffic management.

The road ahead

Whether the approach can work at scale remains the central question. Kemal Armada, a product manager at Google, framed the challenge bluntly, saying the issue is no longer whether contrails can be mitigated but whether that mitigation can be made to work at scale. With around ten thousand flights passing through the Shanwick corridor, the results of the coming winters could shape how airlines and regulators treat aviation's non carbon warming for years to come.