Sustainable Aviation
DLR and TUI fly collaborate to study aviation contrail climate impact
DLR and TUI fly research how Boeing 737 MAX 8 emissions influence contrail formation to reduce aviation’s climate footprint.
Investigating Aviation’s Climate Footprint: The DLR and TUI fly Collaboration
In a significant step towards understanding and mitigating the environmental impact of air travel, the German Aerospace Center (DLR) has initiated a pioneering flight campaign in partnership with TUI fly. For the first time in several years, a dedicated research aircraft is trailing scheduled passenger flights to capture real-time data on emissions. This initiative is part of the broader European research project A4CLIMATE, which aims to shed light on the complex relationship between modern engine technology and the formation of condensation trails, commonly known as contrails.
While the aviation industry has long focused on reducing carbon dioxide (CO₂) emissions, scientific consensus increasingly points to non-CO₂ effects as a major contributor to global warming. Specifically, contrails and the resulting cirrus clouds are believed to trap heat in the Earth’s atmosphere. We observe that this collaboration represents a critical shift from theoretical modeling to real-world validation, as researchers seek to determine how modern “lean-burn” engines influence the atmosphere compared to older technologies.
The campaign involves high-precision coordination between scientific pilots and commercial flight crews. By analyzing the exhaust plumes of aircraft in regular service, the project partners aim to develop robust strategies for climate-optimized flight planning. This effort highlights a growing industry trend where operational expertise and atmospheric science converge to address the urgent challenges of Climate change.
The Mission Profile: Chasing Data at 30,000 Feet
The core of this campaign features a DLR Dassault Falcon 20E research aircraft following a TUI fly Boeing 737 MAX 8. The operation requires the research plane to maintain a distance of approximately 10 kilometers (five nautical miles) behind the passenger jet. This specific distance allows the exhaust plume to evolve sufficiently for meaningful measurement while remaining fresh enough to analyze the immediate chemical and physical properties of the emissions.
The flights are currently being conducted on regular routes between Germany and Egypt. These corridors were selected due to their high probability of contrail formation, providing researchers with ample opportunities to gather relevant data. The focus of the study is the Boeing 737 MAX 8, which is equipped with modern CFM International LEAP-1B engines. These engines are characterized by their “lean-burn” combustion technology, which is designed to be more fuel-efficient and emit significantly less soot than previous engine generations.
Instruments onboard the Falcon 20E are tasked with measuring the evolution of soot and volatile particles within the exhaust plume for periods of up to 30 minutes. The primary scientific question driving this specific phase of the research is whether the reduction in soot emissions from these modern engines translates directly to a reduction in persistent contrails. While it is known that soot particles act as nuclei for ice crystals, the exact correlation between reduced soot mass and the number of ice crystals formed remains a complex variable that requires empirical verification.
“We want to understand how much global warming can be reduced when aircraft are more modern and smarter. It is still unclear whether less soot automatically means fewer contrails.”, Christiane Voigt, Project Manager at DLR Institute of Atmospheric Physics.
The Science of Contrails and Climate Impact
To understand the significance of this study, we must look at the mechanics of contrail formation. Contrails are created when hot, humid exhaust gases from aircraft engines mix with the cold air of the upper atmosphere. If the air is sufficiently cold and humid (ice-supersaturated), the water vapor condenses and freezes around particles, primarily soot, emitted by the engines. These ice crystals can persist and spread, forming cirrus clouds that prevent heat from escaping the Earth, a phenomenon known as radiative forcing.
Current scientific estimates suggest that these non-CO₂ effects could be responsible for a substantial portion of aviation’s total climate impact. Some studies indicate that contrails and contrail-induced cirrus clouds might account for up to two-thirds of the sector’s contribution to global warming, or approximately 1% to 2% of total global warming. Unlike CO₂, which remains in the atmosphere for centuries, contrails have a lifespan measured in hours. This presents a unique opportunity: if contrail formation can be prevented, the climate benefit is immediate.
However, the interaction between engine technology and atmospheric physics is not straightforward. While modern engines emit fewer soot particles, the particles that are emitted may still be sufficient to trigger contrail formation under certain conditions. Furthermore, the size and optical properties of the ice crystals formed by lean-burn engines may differ from those formed by older engines, potentially altering their warming effect. The data collected by the Falcon 20E is essential for refining climate models and verifying the accuracy of prediction tools used for flight planning.
The A4CLIMATE Project: A European Initiative
This flight campaign is a central component of the A4CLIMATE project, a major research initiative funded by the European Union. The project brings together a consortium of 17 partners from nine countries, including leading research institutions like the Max Planck Society, ETH Zurich, and Imperial College London, as well as industry heavyweights such as Airbus, Rolls-Royce, and Lufthansa Systems. The goal is to develop practical, science-based solutions to minimize the climate impact of aviation beyond simple fuel efficiency.
The A4CLIMATE strategy explores three primary avenues for mitigation. First, as demonstrated by the current TUI fly campaign, is the assessment of advanced engine technologies and their combustion characteristics. Second, the project is investigating the potential of SAF, which naturally contain fewer aromatics and therefore produce less soot, potentially reducing contrail formation further. Third, the project focuses on climate-optimized routing, or “contrail avoidance.”
Climate-optimized routing involves adjusting flight paths, often by small changes in altitude, to avoid regions of the atmosphere that are supersaturated with ice. If aircraft can fly around or above these “cold and humid” pockets, contrails can be avoided entirely. TUI fly has already been active in this area; since early 2025, the Airlines has routed several hundred flights specifically to avoid long-lasting contrails, providing operational data to researchers. The current measurement campaign serves to validate the predictions that guide these routing decisions.
“As a partner to science, we are providing our flights and our operational expertise. We want to help ensure that research results are quickly incorporated into everyday aviation practice, in order to reduce the climate impact of our flights.”, Christoph Todt, Head of Environmental Sustainability at TUI Airline.
Conclusion and Future Implications
The collaboration between DLR and TUI fly under the A4CLIMATE project marks a pivotal moment in aviation Sustainability research. By directly measuring the emissions of modern aircraft in real-world conditions, the industry is moving closer to understanding the full scope of its environmental footprint. The data gathered from these flights will be instrumental in calibrating the next generation of climate models and validating the effectiveness of new engine technologies.
Looking ahead, the implications of this research extend into regulatory and operational domains. As the European Union moves toward monitoring and reporting non-CO₂ effects, accurate data becomes a prerequisite for compliance. Furthermore, if the hypothesis regarding flight path optimization is validated, we may see a fundamental shift in air traffic management, where climate impact is weighed alongside safety and efficiency in flight planning. This offers a potential “quick win” for the climate, allowing the aviation sector to reduce its warming impact significantly even before zero-emission propulsion technologies become widely available.
FAQ
What is the main goal of the DLR and TUI fly collaboration?
The primary goal is to investigate the climate impact of contrails generated by modern “lean-burn” aircraft engines and to validate flight path optimization strategies that could reduce aviation’s global warming footprint.
How is the data being collected?
A DLR Falcon 20E research aircraft follows TUI fly passenger flights (Boeing 737 MAX 8) at a distance of approximately 10 kilometers to measure the composition and evolution of the exhaust plume in real-time.
Why are contrails considered a climate problem?
Contrails can form cirrus clouds that trap heat in the Earth’s atmosphere. Scientific estimates suggest they may contribute as much or more to global warming than the CO₂ emissions from aviation.
What is the A4CLIMATE project?
A4CLIMATE is an EU-funded research initiative involving 17 partners from 9 countries. It aims to develop solutions to minimize aviation’s climate impact through advanced engines, sustainable fuels, and climate-optimized flight routing.
Sources: TUI Group
Photo Credit: TUI
Sustainable Aviation
Singapore Airlines Signs SAF Offtake Deal with Aether Fuels
Singapore Airlines commits to buying SAF from Aether Fuels’ Project Beacon facility in Singapore, due online in 2028.
Singapore Airlines (SQ) has finalized a firm purchase agreement to offtake next-generation Sustainable Aviation Fuel (SAF) from Aether Fuels, becoming the first carrier to commit to the upcoming Project Beacon production facility in Singapore.
Announced in a joint press release on 28 October 2026, the agreement transitions a previous memorandum of understanding into a binding contract. The deal secures future fuel volumes to support the airline’s target of replacing 5 percent of its total fuel consumption with SAF by 2030.
Transitioning from framework to firm commitment
The 28 October 2026 announcement builds on a Memorandum of Understanding (MoU) signed by the two companies on 4 February 2025. That initial framework outlined the airline’s intention to procure neat SAF for a five-year period, with an option to extend for an additional five years, once Aether commenced commercial production.
While the companies confirmed the transition to a firm offtake agreement, the exact fuel volumes and financial terms were not disclosed in the release.
Project Beacon and the Aurora technology
Aether Fuels, a climate technology firm incubated and funded in 2022 by Temasek-backed deep tech venture firm Xora, officially launched Project Beacon on 11 November 2025. The project is a partnership with Aster, a joint venture between Indonesian chemical and infrastructure company Chandra Asri and commodities trader Glencore.
The commercial-scale SAF facility will be located at Aster’s refining hub on Pulau Bukom in Asia-Pacific in Singapore. Aster acquired this site from Shell to develop a dedicated sustainable fuels footprint. Construction of the facility is scheduled to commence in 2026.
Once operational in 2028, Project Beacon is projected to produce 50 barrels per day, equating to approximately 2,000 tons of SAF annually. The plant will utilize Aether’s proprietary Aurora technology to produce Fischer-Tropsch Synthesized Paraffinic Kerosene (FT-SPK). According to Aether Fuels, this pathway is expected to deliver a minimum 70 percent reduction in greenhouse gas emissions compared to conventional jet fuel.
De-risking commercial scale-up
The firm offtake agreement follows a critical technical milestone for Aether Fuels. On 29 September 2026, the company announced the successful operation of a fully integrated demonstration line at RTI International in North America.
The 2.5 barrel-per-day system combined Aether’s Aurora Tri-Converter and Upgrader units with an existing Fischer-Tropsch reactor. The demonstration successfully converted renewable natural gas derived from landfill gas and captured industrial carbon dioxide into synthetic aviation fuel meeting ASTM D7566 specifications. This successful run provided the engineering data required to de-risk the design and scale-up of the Project Beacon facility ahead of its construction phase.
Singapore’s SAF ecosystem and airline targets
The aviation industry is increasingly reliant on SAF to meet decarbonization targets, but feedstock availability remains a primary bottleneck. Aether’s FT-SPK pathway addresses this by utilizing industrial waste gases and biomethane, bypassing the constrained agricultural and lipid-based feedstocks, such as used cooking oil, that dominate current SAF production.
The agreement aligns with broader regional regulatory shifts. The Civil Aviation Authority of Singapore (CAAS) has mandated a SAF levy for flights departing Singapore starting in 2026 to fund centralized SAF procurement. Singapore Airlines, which operates a fleet with an average age of under eight years, has committed to achieving net-zero carbon emissions by 2050.
AirPro News analysis
We view this firm offtake agreement as a clear indicator of the tightening future market for non-lipid SAF. The aviation sector’s reliance on Hydroprocessed Esters and Fatty Acids (HEFA) SAF is running into hard limits regarding used cooking oil and tallow availability. By committing to Aether’s FT-SPK product before the Project Beacon facility has even broken ground, Singapore Airlines is moving aggressively to lock in alternative feedstock pathways.
This early commitment is necessary for airlines aiming to meet 2030 mandates. The lead times for financing, constructing, and scaling novel waste-to-fuel facilities span several years, meaning airlines cannot wait for commercial production to begin before securing their supply lines.
Photo Credit: Aether Fuels
Sustainable Aviation
SABA Members Back Infinium eSAF Facility With Long-Term Deals
Google, McKinsey, and others sign binding SAFc agreements to support Infinium Energy’s 100,000 MT/year Texas eSAF project.
Corporate members of the Sustainable Aviation Buyers Alliance (SABA) have signed binding, multi-year agreements to purchase sustainable aviation fuel certificates (SAFc) from Infinium Energy’s planned electro-sustainable aviation fuel (eSAF) facility in Texas. The commitments, announced on September 22, 2026, are designed to provide the financial demand signals necessary for Infinium to reach a final investment decision on the project.
In a press release issued by SABA, the organization confirmed that American Airlines (AA) will serve as the physical offtaker for the fuel, managing logistics and delivery. The corporate buyers purchasing the associated certificates include AVEVA, Bain & Company, Google, and McKinsey & Company. The agreement marks the first time SABA’s procurement model has been utilized to directly drive new production capacity for scalable sustainable aviation fuel.
Project Atlas production and environmental targets
Infinium Energy was selected through a SABA procurement process earlier in 2026 to provide ultra-low carbon eSAF. The fuel is produced using waste carbon dioxide and renewable energy, distinguishing it from traditional biofuel pathways that rely on agricultural or waste feedstocks.
The planned Texas facility, designated Project Atlas, is expected to have an annual sustainable aviation fuel (SAF) production capacity of 100,000 metric tons. According to the alliance, the contracted volumes will support an expected greenhouse gas abatement of 212,000 metric tons of carbon dioxide equivalent (mtCO2e). SABA equates this emissions reduction to approximately 3,500 commercial flights between John F. Kennedy International Airport (JFK) and Los Angeles International Airport (LAX).
“We’re proud to partner with SABA members including AVEVA, Bain & Company, Google, McKinsey, and others, as well as American Airlines to bring Infinium Energy’s next world scale eSAF facility to life. Their commitment reflects a shared conviction that decarbonizing aviation requires real investment in next-generation supply,” said Robert Schuetzle, CEO of Infinium Energy.
Aggregating demand through book-and-claim
The transaction utilizes a book-and-claim model. Corporate buyers purchase the SAFc to claim the environmental benefits against their business travel emissions, while the physical fuel is delivered to partner airlines. This mechanism allows corporations to fund SAF production even when the physical fuel cannot be delivered directly to the airports their employees use.
American Airlines will manage the physical integration of the eSAF into the commercial aviation fuel supply chain. Jill Blickstein, Chief Sustainability Officer at American Airlines, stated that the corporate commitments broaden participation in the SAF market and demonstrate how customers can collaborate with airlines and fuel producers to advance decarbonization.
SABA, a joint initiative of the Environmental Defense Fund (EDF), the Center for Green Market Activation (GMA), and RMI, has aggregated $500 million in SAFc demand from 35 companies to date. Aviation currently accounts for approximately 2 to 3 percent of global greenhouse gas emissions.
“Novel technologies are critical to meeting future demand for sustainable aviation fuel, but they will not be operational in time without investments made today. This procurement demonstrates how aggregated, long-term demand can help take promising eSAF projects from idea to reality,” said Jon Creyts, CEO of RMI.
AirPro News analysis
We view this agreement as a critical structural step for the eSAF market. Power-to-Liquid (PtL) fuels like those planned for Project Atlas face a steep commercialization barrier. They are highly capital-intensive to build and currently produce fuel at a significant cost premium compared to both conventional Jet A and HEFA-based SAF derived from waste fats and oils.
Airlines operate on thin margins and generally cannot absorb the full green premium of eSAF alone. By unbundling the environmental attributes from the physical fuel, the SABA model allows highly capitalized corporate entities like Google and McKinsey & Company to absorb that premium. More importantly, signing binding, multi-year offtake agreements provides the revenue certainty that infrastructure lenders require before financing first-of-a-kind industrial facilities. If Project Atlas reaches a positive final investment decision based on these contracts, it will validate the book-and-claim model as a viable financing mechanism for next-generation aerospace infrastructure.
Sources: Sustainable Aviation Buyers Alliance via PR Newswire
Photo Credit: Sustainable Aviation Buyers Alliance
Sustainable Aviation
EU Exceeds 2025 SAF Mandate at 2.79 Percent Blend Rate
EASA reports EU airports hit 2.79% SAF blend in 2025, surpassing the 2% ReFuelEU mandate with 1.1M tonnes supplied.
The European Union surpassed its initial Sustainable Aviation Fuel (SAF) mandate in 2025, with SAF accounting for 2.79 percent of all jet fuel supplied to EU airports during the first mandatory reporting year.
According to the 2026 ReFuelEU Aviation Annual Technical Report published by the European Union Aviation Safety Agency (EASA) on September 17, 2026, fuel suppliers delivered 1.1 million tonnes of SAF against a total aviation fuel supply of 39.3 million tonnes. The 2.79 percent blend rate comfortably exceeded the 2 percent minimum required by the ReFuelEU regulation for 2025. This uptake resulted in an estimated reduction of 3.77 million tonnes of CO2 equivalent greenhouse gas emissions.
“We are pleased to confirm that the SAF mandate under ReFuelEU Aviation was not only met but exceeded,” EASA Executive Director Florian Guillermet stated in the agency’s press release.
Compliance and distribution across European hubs
The EASA report indicates high compliance rates across the sector. Ninety-three percent of aircraft operators and 90 percent of fuel suppliers fulfilled their reporting obligations in 2025. EASA noted that noncompliance among aircraft operators was primarily limited to small business jet operators, nonscheduled carriers, and third-country operators that failed to respond to competent authorities.
SAF distribution reached 121 Airports across all 27 Member States, representing 79 percent of all Union airports. Uptake was heavily concentrated at major European hubs. Amsterdam Airport Schiphol (AMS) accounted for 29 percent of the tracked SAF supply, followed by Frankfurt Airport (FRA) at 8 percent and Paris Charles de Gaulle Airport (CDG) at 7 percent.
Supply chain dynamics and feedstock dependencies
While the headline blending figures demonstrate regulatory success, the technical report reveals a structural reliance on imported raw materials. Although 86 percent of the SAF supplied at EU airports was refined domestically within the European Union, 85 percent of the underlying feedstocks originated from outside the bloc.
The primary feedstock utilized was Used Cooking Oil (UCO) processed via the Hydroprocessed Esters and Fatty Acids (HEFA) pathway. Of the imported feedstocks, 61 percent originated from China, with additional volumes sourced from Malaysia and Indonesia. On the refining side, Neste’s Rotterdam facility alone produced 33 percent of all European SAF in 2025.
AirPro News analysis
The successful implementation of the 2 percent mandate in 2025 proves that the logistical framework for SAF distribution at major European hubs is functional. However, the heavy reliance on Asian Used Cooking Oil presents a long-term vulnerability for European aviation. As the ReFuelEU mandate scales to 6 percent in 2030, the Regulations will also introduce sub-mandates for synthetic aviation fuels (e-fuels). With approximately 50 synthetic fuel projects awaiting final investment decisions and no large-scale e-fuel facilities currently operational in Europe, we anticipate significant capital mobilization will be required over the next 36 months to prevent future supply bottlenecks and reduce dependency on imported biomass.
Photo Credit: European Union Aviation Safety Agency
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