UK and Google launch £5m AI trial to redirect flights and prevent contrails

AI flight routing initiative

The UK government, Google, and aviation research partners have launched Operation Blue Skies, a 30-month initiative to curb the climate impact of aircraft condensation trails. The £5 million program brings together the UK Department for Transport, the Met Office, air traffic service provider NATS, non-profit Contrails.org, Imperial College London, and the University of Cambridge. The UK Department for Transport provides £2.65 million in funding, while Google supplies £1.4 million of in-kind technical assistance, AI research expertise, and high-performance computing capacity. Tests will focus on the Shanwick Oceanic airspace, which covers the eastern half of the North Atlantic corridor connecting Europe and North America.

The physics of contrail formation

Contrails form when water vapour from jet engine exhaust condenses and freezes around soot particles at high altitude. In cold and humid atmospheric conditions, these ice crystals persist and spread into artificial cirrus clouds that trap heat radiating from the Earth. Scientists estimate that contrails account for roughly one third of total aviation climate warming, exceeding the warming effect from direct carbon dioxide emissions alone, which represent over 2.5% of global emissions. Although aircraft contrails often dissipate rapidly, persistent formations create heat-trapping cloud cover across high-density oceanic routes.

Dr Paul Hodgson explained the scale of the challenge during the project presentation.

We think that contrail warming is responsible for something like a third of all aviation climate warming.

Testing protocol in Shanwick airspace

The trial tests whether AI models can forecast where contrails will form by combining satellite imagery, historical flight logs, and numerical weather predictions from the Met Office. Controllers at NATS will then issue minor flight altitude adjustments of approximately 2,000 feet (about 600 metres) to route aircraft away from contrail-sensitive air layers. The Shanwick Oceanic airspace accounts for approximately 5% of global contrail warming, with atmospheric conditions most prone to contrail formation occurring between November and February. Testing will span two distinct winter periods, running across 2026–2027 and 2027–2028. The trials will take place over 20 to 40 days each winter season, primarily during lower-traffic evening and night windows.

Operational deployment and airline impact

Around 10,000 flights cross the Shanwick oceanic zone during the trial hours each year, with only a small percentage requiring altitude adjustments to circumvent contrail regions. Because altitude changes of 2,000 feet are already standard practice for navigating turbulence and weather systems, passengers are unlikely to notice adjustments. Ian Jopson of NATS stated that transatlantic flight operations will follow existing air navigation protocols throughout the operational phases. The project marks the first oceanic trial targeting contrail formation across an active international flight corridor.

Paul Hodgson described the scope of the oceanic trial during the project launch.

This is the first time a program aims to tackle contrails at the scale of an entire oceanic airspace.