Anyone who has looked up at the sky has probably seen the thin white lines trailing behind aircraft. These are called contrails, and scientists say they play a role in warming the planet.
Contrails form when hot exhaust from jet engines meets cold air at high altitude. This creates ice crystals that can spread into thin clouds.
Many of these clouds disappear within minutes. Others can linger and trap heat that would otherwise escape into space.
A new trial in the UK will test whether artificial intelligence can help solve the problem. The £5 million project is called Operation Blue Skies.
It will focus on the Shanwick Oceanic airspace over the eastern North Atlantic. This corridor is responsible for around 5% of contrail warming worldwide.
The project brings together Google, the UK government, the Met Office, air traffic provider NATS, and researchers from Cambridge and Imperial College London.
How the Technology Works
Google will use satellite images and flight data to figure out where planes have created contrails in the past.
That information gets combined with weather forecasts. Together, they can predict where new contrails are likely to form.
The forecasts are then sent to NATS, where air traffic controllers can guide pilots away from those zones.
Rather than rerouting flights entirely, most changes will involve adjusting altitude by about 2,000 feet. This is similar to how planes already shift height to dodge turbulence or storms.
Passengers likely won't notice any difference during the trial.
Testing Timeline and Costs
Testing will happen on select evenings and nights during the winters of 2026-27 and 2027-28, when air traffic is quieter.
Roughly 10,000 flights are expected to cross the test airspace over that period. Only a small portion will actually need to change altitude to avoid a contrail.
The Department for Transport is funding £2.65 million of the project. Google is contributing £1.4 million through research, engineering, and computing support.
Aviation Minister Keir Mather said the trial would test small changes to flight paths that could help make flying cleaner.
One question raised by the project is whether flying higher or lower burns more fuel, and if that could offset any climate benefit.
Google's technical lead, Dr Paul Hodgson, said earlier trials found the extra fuel use was much smaller than the warming caused by a contrail left unchecked.
He said the added carbon cost was under 1%, while contrail warming can match a large share of aviation's total emissions.
Modelling for the project suggests a full route change through the Shanwick corridor would use about 100kg of extra fuel per flight.
Earlier airline trials found contrail formation could be cut by 60% to 70% using similar methods.
Results from Operation Blue Skies are expected to be published for outside scientific review once the trial periods are complete.
