UK and Google test AI-assisted altitude changes to avoid contrails

A flight crossing the northeastern Atlantic may soon receive a small instruction from air traffic control: climb or descend, not to dodge a storm, but to avoid a strip of air where its exhaust could become a warming cloud. Hundreds of commercial flights are expected to take part in the UK's Operation Blue Skies, a 30-month trial with Google and aviation researchers.

The test focuses on the Shanwick Oceanic Control Area, the eastern half of the North Atlantic route between Europe and North America. In cold, humid air, water vapor from a jet engine can freeze around soot particles and form a contrail — a cloud made by the aircraft. Some vanish quickly. Others last for hours and trap heat. Google says the warming type accounts for about one-third of aviation's overall climate impact; Contrails.org puts contrails at 1% to 2% of Earth's warming, a difference that reflects different ways of measuring the effect.

Google's artificial intelligence will combine weather, atmospheric and flight data to forecast the altitude bands and corridors where persistent contrails are likely. Controllers could then direct selected flights to shift by up to 2,000 feet (610 meters), using established air-traffic procedures. Afterward, AI systems will examine satellite images of the Atlantic to assess whether the expected contrails formed.

The trial will run during 20 to 40 test days per winter in the winters of 2026/2027 and 2027/2028, when traffic is lighter. Around 10,000 flights are expected to pass through the test airspace, and 1% to 5% may be asked to deviate — enough, Google technical lead Paul Hodgson said, to measure an airspace-scale reduction. NATS says safety comes first: any maneuver will be dropped if it raises operational concerns.

And so what, concretely? The experiment tests whether airlines and controllers can reduce a climate effect without sending aircraft on long detours: only flights entering the most sensitive air may need a modest altitude change. The Shanwick area is estimated to represent about 5% of contrail warming worldwide, especially in winter, so a result there could offer a template for other busy air corridors. But the outcome is not established yet; the consortium still has to show that the forecasts, coordinated instructions and satellite measurements reduce contrails in regular operations.