It will operate in Shanwick Oceanic airspace, the eastern portion of the North Atlantic corridor managed by NATS. Atmospheric modeling attributes approximately 5% of global contrail warming to this one region, with much of it concentrated between November and February.<\/p>\n
Two trial windows: winters 2026\u201327 and 2027\u201328, each lasting approximately four months
\nActive testing: about 20 to 40 lower-traffic days during each winter
\nFlights in the airspace: approximately 10,000 during trial hours each year
\nFlights changed: roughly 1% to 5%, or hundreds of flights, depending on the weather
\nThe maneuver: an altitude change up or down of as much as 2,000 feet, delivered through normal air traffic control channels<\/p>\n
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The U.K. is spending \u00a3219 million to subsidize home-grown \u2018green\u2019 aviation fuel. They\u2019re spending \u00a32.65 million towards this, with Google putting in \u00a31.4 million of research, engineering and compute. Imperial College London and Cambridge will independently evaluate the results.<\/p>\n
A Small Number Of Flights Cause Most Contrail Warming<\/p>\n
Contrails form when water vapor in aircraft exhaust freezes around soot particles in very cold, humid air. Many disappear quickly. Others persist for hours, spread into cirrus clouds and trap heat that would otherwise escape the atmosphere.<\/p>\n
They also reflect incoming sunlight, so an individual daytime contrail can have a cooling effect. Persistent nighttime contrails can\u2019t reflect sunlight and are warming. The goal is to prevent the relatively small number of strongly warming contrails.<\/p>\n
A 2024 global analysis<\/a> found that about 14% of flights formed net-warming contrails, but only about 2% of all flights generated 80% of annual contrail energy forcing. And rerouting slightly can avoid this.<\/p>\n An Imperial College study<\/a> previously estimated that changing the altitude of 1.7% of flights by 2,000 feet could reduce contrail forcing 59%, with less than a one-tenth of one percent increase in total fuel consumption.<\/p>\n I first wrote about this in 2020<\/a>. Since then we\u2019ve learned that flying higher isn\u2019t always the solution. The aircraft may need to climb or descend to leave a particular ice-supersaturated layer, and newer aircraft flying at higher altitudes can sometimes be more likely to encounter contrail-forming conditions.<\/p>\n American Airlines And Google Already Showed That This Can Work<\/p>\n American Airlines deserves real credit for doing some of the best environmental work of any U.S. carrier here, even though it has received less attention than airlines get for subsidized fuel.<\/p>\n Peer-reviewed analysis<\/a> used 44 matched flights, 22 assigned to avoid predicted contrail regions and 22 controls. They were about to reduce the number of flights forming a detectable trail by 64%. <\/p>\n Then American, Google, Contrails.org and FlightKeys ran a much larger randomized test<\/a> during the first five months of 2025 with about 2,400 American transatlantic flights included.<\/p>\n Across all 1,232 treatment-eligible flights, observable contrail formation fell 11.6% and estimated warming fell 13.7%. The New Trial Tests Air Traffic Control<\/p>\n An individual airline can optimize its own airplane, but can\u2019t manage the aircraft around it. It also bears any extra fuel or operational cost itself without gaining the climate benefit directly.<\/p>\n NATS can coordinate multiple aircraft at once and determine whether moving one flight creates a conflict, displaces another flight or causes a new contrail somewhere else. And it can test whether contrail avoidance is safe and practical for controllers, whetherthe airspace produces measurably less warming overall, and whether the procedure can be copied by other air navigation providers.<\/p>\n If contrails account for roughly one-third of aviation\u2019s total climate impact, a global system that eliminated half to two-thirds of their warming could reduce aviation\u2019s overall climate impact by roughly one-sixth to one-fifth just by using better data in air traffic. <\/p>\n Aviation generates approximately 2.5% of annual global carbon dioxide emissions. When contrails and other non-CO\u2082 effects are included, it has contributed roughly 3.5% to 4% of historical warming. That includes both passenger flights and cargo. <\/p>\n Fashion and textiles by the way are estimated by the United Nations Environment Programme to generate up to 8% of global greenhouse gas emissions<\/a>. <\/p>\n This Is More Promising Than Sustainable Aviation Fuel<\/p>\n Sustainable aviation fuel is supposed to deliver 65% of the reductions in the airline industry\u2019s net-zero plan by 2050. Today, production is 0.8% of airline fuel demand<\/a> and costs up to three times as much. <\/p>\n Sustainable aviation fuel has been a convenient fiction to deflect criticism. It\u2019s a strategy to claim a path to net zero, while seeking subsidies and with a built-in constituency to lobby for them. Plus, politicians get to announce factories, jobs and spending.<\/p>\n Contrail avoidance doesn\u2019t produce rents for politicians to distribute. And it doesn\u2019t even benefit hte airline\u2019s bottom line like fuel subsidies can. Historically it hasn\u2019t even been included in the accounting toward an airline\u2019s net-zero carbon target.<\/p>\n This Is What Real Climate Work Looks Lke<\/p>\n Air New Zealand withdrew its 2030 emissions target and left the Science Based Targets initiative in 2024. Delta recently deleted its pledge to use SAF for 10% of its fuel by 2030 and changed net zero by 2050 from a \u201cgoal\u201d to an \u201caspiration.\u201d<\/p>\n Contrail avoidance won\u2019t put net zero back on track because it doesn\u2019t remove carbon dioxide. United separately funded some direct carbon capture work<\/a> which still has promise. <\/p>\n Delta claimed to be the world\u2019s first carbon-neutral airline while continuing to burn jet fuel and even owning an oil refinery. It spent more than $280 million on carbon credits between March 2020 and March 2022, including credits tied to projects with fabricated deforestation assumptions and double counting.<\/p>\n![](\"https:\/\/www.europesays.com\/ai\/wp-content\/uploads\/2026\/08\/contrails-inflight.jpg\"\/)
Credit: Sander van der Wel\/Wikimedia Commons (CC BY-SA 2.0)<\/p>\n
\nFor the 112 flights that actually followed the optimized plan, observable contrails fell 62% and estimated warming fell approximately 69%.
\nThe researchers found no statistically significant fuel penalty in the flights that followed the plan.<\/p>\n![](\"https:\/\/www.europesays.com\/ai\/wp-content\/uploads\/2026\/08\/fuel-track-and-plane.jpg\"\/)
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