Operation Blue Skies, a £5 million UK-backed programme involving the University of Cambridge, will run operational airspace trials to test whether AI-guided, minor altitude changes can avoid persistent warming contrails on commercial flights over the North Atlantic. The trials matter because persistent contrails account for roughly one-third of aviation’s total climate impact.
Key facts
- Operation Blue Skies is a 30-month programme with two operational trials planned for winter periods in 2026–27 and 2027–28.
- The tests will take place in NATS-controlled Shanwick oceanic airspace, the eastern half of the North Atlantic corridor.
- AI models will identify locations and times where flight-path interventions may have the greatest potential to reduce contrail-related warming.
- Cambridge and Imperial College London researchers will evaluate outcomes and independently verify climate impact.
What is Operation Blue Skies testing?
Operation Blue Skies is testing the operational feasibility and environmental benefit of adjusting commercial aircraft altitudes to avoid atmospheric conditions associated with persistent contrails. It will use AI models and established air-traffic-control communications to direct small changes within standard flight operations during lower-traffic periods.
Contrails form when water vapour in jet-engine exhaust condenses and freezes around soot particles and other aerosols in cold, humid upper-atmosphere air. Persistent contrails can trap outgoing heat. The programme is focused on the winter period from November to February, when a significant share of contrail warming in Shanwick airspace is concentrated.
Atmospheric modelling cited by the programme estimates that Shanwick airspace accounts for about 5% of global contrail warming. The planned test schedule is approximately 20 to 40 days in each winter testing period.
How will the North Atlantic trials work?
The two trials are due to be conducted primarily in the winters of 2026–27 and 2027–28. Rather than introducing a separate operating system, the manoeuvres will be coordinated through standard Air Traffic Control channels and will focus on minor altitude adjustments.
The consortium will assess whether contrail avoidance can be safe, measurable and practical across oceanic airspace. Contrails.org is supporting the work by helping to connect forecasts, trial parameters and data analysis, while Cambridge and Imperial researchers will assess the results and provide independent climate-impact verification.
The programme describes the initiative as the world’s first airspace trial aimed at reducing contrails. Its central question is whether an approach identified by atmospheric and AI modelling can function at airspace-wide scale in a real-world operating environment.
Who is involved and how is it funded?
The consortium includes the University of Cambridge, Google, the Department for Transport, the Met Office, NATS, Contrails.org and Imperial College London. The programme is co-funded by industry partners and the Department for Transport through the ATI Programme, a partnership involving the Aerospace Technology Institute, the Department for Business, Innovation, Science and Trade, and Innovate UK.
The Department for Transport is providing £2.65 million of the programme’s £5 million budget. Google UK is contributing £1.4 million in-kind through AI research expertise, engineering time and high-performance computing infrastructure. The programme states that all government grant funding is allocated directly to academic, non-profit and aviation partners.
What this means for students and researchers
For students and researchers at the University of Cambridge and Imperial College London, Operation Blue Skies creates a live research setting around aviation, atmospheric science, AI and air-traffic operations. Their stated role is to evaluate trial outcomes and independently verify the climate impact of the altitude-adjustment interventions.
The project also brings academic researchers into a consortium with operational, government, technology and meteorological partners. That structure centres on testing whether an AI-informed climate intervention can work within normal commercial-flight and air-traffic-control processes.
Frequently asked questions
When will Operation Blue Skies trials take place?
The operational trials are planned primarily for winter testing windows in 2026–27 and 2027–28. Each winter is expected to include about 20 to 40 test days, with testing undertaken during periods of lower air traffic.
Why does the programme focus on Shanwick airspace in winter?
Shanwick oceanic airspace covers the eastern half of the North Atlantic corridor and is estimated to account for approximately 5% of global contrail warming. The programme says a significant part of that warming occurs between November and February, making winter the targeted period for interventions.
