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

Bell 505 Surpasses 700 Flight Hours on Sustainable Aviation Fuel

We are witnessing a pivotal shift in the rotorcraft industry as manufacturers move from theoretical demonstrations to practical, sustained applications of green technology. On November 24, 2025, during the European Rotors 2025 trade show in Cologne, Germany, Bell Textron Inc. announced a significant achievement in this domain. A dedicated Bell 505 helicopter has successfully surpassed 700 flight hours using blended Sustainable Aviation Fuel (SAF). This milestone marks a transition from short-term testing to long-term operational validation.

The flight hours were accumulated at the Bell Training Academy in Fort Worth, Texas. By utilizing a training aircraft for this initiative, Bell has demonstrated the viability of SAF in high-volume, daily operations. This is not merely a proof of concept, it is a stress test of the fuel’s reliability under the rigorous demands of pilot training. The initiative highlights the seamless integration of alternative fuels into existing platforms without disrupting standard operating procedures.

This achievement is the result of a strategic collaboration between Bell and Safran Helicopter Engines. It underscores a shared commitment to reducing the carbon footprint of vertical lift operations. As the aviation sector faces increasing pressure to meet global sustainability targets, data-driven milestones like this provide the necessary evidence to encourage broader adoption of SAF among operators and regulatory bodies.

Operational Reliability and Technical Specifications

The aircraft at the center of this milestone is the Bell 505 Jet Ranger X, a short light single-engine helicopter known for its versatility in corporate, public safety, and training missions. Powered by the Safran Arrius 2R engine, the aircraft utilized a specific type of fuel known as “blended SAF.” This mixture typically combines 30 to 50 percent pure sustainable fuel with conventional Jet A fuel. The accumulation of over 700 flight hours confirms that the engine and airframe can operate consistently on this blend without requiring mechanical modifications.

One of the most critical aspects of this program is the demonstration of “drop-in” capability. In the context of aviation, a drop-in fuel is one that can be substituted for conventional jet fuel within existing infrastructure and engines. The Safran Arrius 2R is currently certified to operate on up to a 50 percent SAF blend. By logging substantial hours at the Bell Training Academy, we see proof that operators can integrate these fuels into their current logistics chains without the need for expensive retrofits or specialized handling equipment.

The fuel for this initiative was supplied through partnerships with key industry providers, including Neste and Avfuel. These collaborations are essential for establishing a reliable supply chain, which remains one of the primary hurdles for widespread SAF adoption. The successful completion of these flight hours serves as a signal to the market that the hardware is ready, provided the fuel supply continues to scale to meet demand.

“Bell is proud to celebrate this next step in industry carbon reduction objectives. Working alongside Safran Helicopter Engines has given us the cutting-edge advantage of exploring opportunities in greener aviation practices.”, Robin Wendling, Managing Director of Europe, Bell.

Strategic Implications and Future Roadmap

This 700-hour milestone is part of a broader timeline of sustainability efforts by Bell and its parent company, Textron. It supports Textron’s “Achieve 2025” Sustainable Footprint goal, which targets a 20 percent reduction in greenhouse gas (GHG) emissions across the enterprise. Furthermore, it aligns with the general aviation industry’s commitment to achieving net-zero carbon emissions by 2050. We recognize that incremental steps, such as validating blended fuels, are necessary precursors to achieving these ambitious long-term targets.

While the current operations utilize a blend, the technology is rapidly advancing toward higher concentrations of sustainable components. In February 2023, Bell and Safran achieved the world’s first single-engine helicopter flight using 100 percent SAF with the Bell 505. The current 700-hour achievement complements that breakthrough by focusing on endurance and daily utility rather than maximum capability. Safran has indicated that its engines will soon be capable of operating on 100 percent drop-in SAF, which would significantly maximize emission reductions.

Commercial interest in the Bell 505 remains strong alongside these sustainability developments. At the same European Rotors 2025 event, German operator Heli Transair signed a purchase agreement for three additional Bell 505 aircraft. This suggests that the market is responding positively to the platform, viewing its compatibility with sustainable practices as a value-add rather than a compromise on performance or cost-efficiency.

“We are particularly pleased with these SAF flights in partnership with Bell. SAF is key towards more sustainable helicopter use… Very soon, our engines will be capable of 100% drop-in SAF, paving the way for wider use of this type of fuel.”, Jean-François Sauer, EVP Programs, Safran Helicopter Engines.

Conclusion

The accumulation of over 700 flight hours on blended SAF by the Bell 505 represents a tangible step forward for sustainable rotorcraft operations. It moves the industry discussion from theoretical possibilities to proven realities, demonstrating that eco-friendly fuels can support the rigorous demands of pilot training and daily flight operations. By validating the performance of the Safran Arrius 2R engine with drop-in fuels, Bell has reduced the perceived risk for operators looking to transition to greener alternatives.

Looking ahead, the focus will likely shift toward increasing the availability of SAF and certifying engines for 100 percent sustainable fuel use. As manufacturers like Bell and Safran continue to refine the technology, and as supply chains mature, we anticipate that SAF will become a standard component of aviation logistics, driving the sector closer to its net-zero aspirations.

FAQ

What is the significance of the 700-hour milestone?
This milestone proves that the Bell 505 can operate reliably on blended Sustainable Aviation Fuel (SAF) over a long period in a high-volume training environment, validating the fuel for daily use.

Does using SAF require changes to the helicopter engine?
No. The blended SAF used is considered a “drop-in” fuel, meaning it requires no modifications to the Safran Arrius 2R engine or the airframe.

What is the difference between this milestone and the 2023 SAF flight?
The February 2023 flight demonstrated the capability to fly on 100% SAF. The current milestone focuses on the endurance and operational reliability of using blended SAF over 700 accumulated flight hours.

Sources

Textron Investor Relations

Emirates and ENOC Group Partner to Explore Sustainable Aviation Fuel Supply in Dubai

In a significant development for the aviation sector within the Middle East, Emirates and the ENOC Group have formalized a strategic partnership aimed at establishing a robust supply chain for Sustainable Aviation Fuel (SAF). Signed during the Dubai Airshow 2025, this Memorandum of Understanding (MoU) represents a critical step toward integrating low-carbon fuel solutions directly into the operations of Dubai International Airport (DXB), the world’s busiest international hub. We view this collaboration as a pivotal moment that aligns the operational needs of a major global carrier with the logistical capabilities of a leading integrated energy player.

The agreement brings together two of the United Arab Emirates’ most influential entities: Emirates, the world’s largest international airline, and ENOC Group, a global energy provider. The primary objective of this collaboration is to conduct comprehensive feasibility studies. These studies will focus on the infrastructure, supply chains, and local production capabilities required to make SAF a commercially viable reality for the airline. By focusing on local supply, the partnership aims to reduce reliance on imported biofuels and secure a dedicated energy stream for the region’s aviation sector.

This initiative is not merely a corporate agreement but a direct response to the UAE’s broader environmental strategies. The partnership supports the national goal of supplying 1% of fuel to national airlines from locally produced SAF by 2031. As the industry faces increasing pressure to decarbonize, we see this move as a necessary transition from voluntary demonstration flights to establishing the permanent infrastructure required for consistent daily operations.

Strategic Framework and National Goals

The core of this MoU involves the establishment of a joint steering committee. This body will be responsible for guiding the assessments and navigating the complex logistics of introducing a new fuel type into an established ecosystem. The scope of the agreement covers the entire value chain, from assessing potential local production facilities to determining how the fuel will be blended, stored, and delivered to aircraft. This structured approach ensures that every technical and commercial aspect is evaluated before physical implementation begins.

Contextually, this partnership is anchored in the UAE’s General Policy for Sustainable Aviation Fuel. The government has set ambitious targets, including a goal to produce 700 million liters of SAF annually by 2030. Furthermore, the region is actively developing a Power-to-Liquid (PtL) roadmap. This strategy seeks to leverage the UAE’s abundant solar energy resources to produce synthetic fuels, positioning the nation as a potential leader in the next generation of clean energy production. The collaboration between Emirates and ENOC is a practical application of these high-level government policies.

For Emirates, securing a supply of SAF at its home base is a strategic priority. While the airline has previously uplifted SAF at various international outstations, including Amsterdam, London Heathrow, Paris, Lyon, and Oslo, establishing a supply line in Dubai is essential for scaling its sustainability efforts. This agreement signals a shift from sporadic international procurement to developing a self-sufficient domestic ecosystem.

“Establishing reliable SAF supply in our Dubai hub is a key priority, and this collaboration allows us to assess the most viable pathways for integration. We recognize there’s significant work ahead to address supply constraints and infrastructure requirements, but partnerships like this are essential to identifying practical solutions.”, Adel Al Redha, Deputy President and COO, Emirates

Technical Pathways and Infrastructure Challenges

A major component of the feasibility studies will be the technical integration of SAF into existing airport infrastructure. SAF is known as a “drop-in” fuel, meaning it can be blended with conventional Jet A-1 fuel, currently up to a limit of 50%, without requiring modifications to aircraft engines or airport fueling systems. However, the logistics of blending and transporting this fuel to the hydrant systems at Dubai International Airport require meticulous planning to ensure safety and efficiency.

The partnership is expected to explore multiple production pathways. In the short term, the focus is likely to be on HEFA (Hydroprocessed Esters and Fatty Acids) technology, which utilizes cooking oil and animal fats. This is currently the most mature and commercially available method for producing biofuels. ENOC Group has already demonstrated activity in this space, having signed agreements to establish SAF production plants in Fujairah and supplying SAF to private aviation sectors during the Airshow.

Looking toward the longer term, the feasibility studies may also encompass Power-to-Liquid (PtL) technologies. PtL involves using renewable electricity and captured carbon dioxide to create synthetic kerosene. While this technology is still in developmental stages compared to HEFA, it is viewed by industry experts as the “holy grail” for aviation in arid regions where biomass for traditional biofuels is scarce. We anticipate that the joint steering committee will evaluate the commercial viability of these advanced technologies as part of their roadmap.

“This MoU with Emirates reflects our shared commitment to developing local SAF production and the infrastructure needed to make low-carbon aviation a reality. As the UAE works toward supplying 1% of jet fuel to national airlines from locally produced SAF by 2031, we believe this collaboration brings us a step closer to that goal.”, Hussain Sultan Lootah, Acting CEO, ENOC Group

Concluding Section

The collaboration between Emirates and ENOC Group marks a definitive step toward maturing the sustainable aviation fuel market in the Middle East. By moving beyond simple procurement and focusing on the development of local infrastructure and production, the partnership addresses the core challenges of availability and scalability that have historically hindered the widespread adoption of SAF. The success of this initiative will depend on the findings of the feasibility studies and the subsequent speed at which physical infrastructure can be deployed.

As the 2031 deadline for the UAE’s national SAF targets approaches, the industry will be watching the outcomes of this MoU closely. If successful, this partnership could serve as a blueprint for how national carriers and energy providers can collaborate to de-risk investment in low-carbon technologies. We expect that the results of these studies will likely influence future regulatory frameworks and investment strategies across the region’s aviation and energy sectors.

FAQ

What is the main goal of the partnership between Emirates and ENOC Group?
The primary goal is to conduct feasibility studies to establish a framework for the supply of Sustainable Aviation Fuel (SAF) at Emirates’ hub in Dubai, focusing on infrastructure, blending, and local production.

What is the UAE’s target for Sustainable Aviation Fuel by 2031?
The UAE government has set a voluntary target to supply 1% of fuel to national airlines at UAE airports using locally produced SAF by 2031.

What is Sustainable Aviation Fuel (SAF)?
SAF is a “drop-in” fuel produced from sustainable resources such as waste oils or synthetic processes. It can be blended with conventional jet fuel without requiring modifications to aircraft or engines.

Sources

• Emirates Media Centre