INAIR 2025 – Air Transport Research in Dialogue

The DLR Institute of Air Transport contributed seven scientific papers addressing key questions for the future – from sustainable energy carriers and economic impact analyses to quantum-based optimisation approaches for flight operations.

Sustainable Energy Carriers and Climate Protection in Air Transport

With several papers, the institute addressed the transformation towards a climate-compatible air transport system.

Hydrogen leakage at airports

One study examined the technical and climate-relevant challenges along the liquid hydrogen supply chain at airports – from liquefaction and storage to refuelling¹. The use of LH₂ can significantly reduce greenhouse gas emissions; however, released hydrogen contributes indirectly to warming. The analysis quantified potential leakages across five supply stages, distinguishing between atmospheric and recoverable losses. The results show that most losses can be recovered, enabling almost emission-free routine processes; only a small, technically unavoidable fraction escapes into the atmosphere.

Supply chains for alternative aviation fuels

Another contribution examined the infrastructural and logistical prerequisites for the future energy supply of air transport with hydrogen and sustainable aviation fuels (SAF)². The findings highlight the need for detailed assessments to ensure the energy efficiency and security of supply chains. Such assessments should consider not only ecological and economic criteria but also aspects of risk diversification and resilience in order to identify strategies that are beneficial to the overall economy. The study particularly emphasises the role of seaports and terminals in the future import of alternative energy carriers.

Costs and strategies for emission reduction

Another analysis explored the economic aspects of climate mitigation measures in aviation using so-called marginal abatement costs³. The results indicate that many technological solutions – such as hydrogen or synthetic fuels – currently entail higher costs compared to emission reduction measures in other sectors. The research team therefore recommends combining market-based instruments such as emissions trading with targeted funding schemes to make the transition to low-carbon aviation economically viable in the long term.

Economic Analyses and Demand Behaviour in Global Air Transport

Several studies by the institute addressed the economic dimensions of air transport and the interactions between supply, demand, and regulation.

Methodological foundations for assessing economic impacts

In one study, 96 international papers were reviewed to identify established and emerging methodological approaches for quantifying the economic significance of air transport⁴. The analysis recommends that macroeconomic models – such as input–output and equilibrium models – be more closely linked with regional data and empirical impact analyses to more accurately capture the diverse feedback effects of air transport on employment, value creation, and investment.

Price elasticities and market behaviour

Another study provided new empirical insights into the price elasticity of global air transport demand⁵. Based on an extensive global dataset of passenger flows from 2010 to 2019 and using a novel two-stage instrumental variables approach combined with a fixed-effects model to avoid biased influences, the study found that demand is less elastic than suggested by older research. It also showed that passengers in Europe are significantly more price-sensitive than in other regions, and that elasticity varies by route length: medium-haul passengers exhibit the strongest response to price changes. These results are relevant for both policymakers – for example, when assessing ticket taxes or carbon pricing – and for airline pricing strategies.

Passenger flows between Europe and the Gulf region

Another analysis examined traffic flows between Europe and the United Arab Emirates (UAE) and Qatar – two of the Gulf’s most significant aviation markets⁶. The study found that the UAE is increasingly gaining importance not only as a transfer hub but also as an independent travel destination, whereas Qatar still mainly serves as a transit point. Despite numerous direct connections, there remains potential for new routes, especially between some medium-sized European cities and Dubai. Such insights can support airlines and airports in strategic network planning.

Optimisation Methods and Emerging Technologies

In addition to economic and environmental research questions, the institute also explored technological innovations in operational planning. One study compared the properties of various mathematical models for crew scheduling to assess their suitability for future quantum computers⁷. By analysing both classical and quantum properties of these models, the researchers identified which types are particularly suitable for implementation on quantum hardware. The study thus represents an important step towards harnessing quantum computing for operational optimisation in air transport.

¹ _{T. Schunkert, M. Engel “Hydrogen Leakage Across an Airport Liquid Hydrogen - Supply Chain”, 14th International Conference on Air Transport (INAIR 2025), Paola, Malta.}

² _{W. Grimme, S. Kumar “The green energy transition in air transport – an analysis of supply chains for hydrogen and sustainable aviation fuels”, 14th International Conference on Air Transport (INAIR 2025), Paola, Malta.}

³ _{L. Müller, D. Plesch, J. Scheelhaase “Climate Mitigation Strategies for Aviation - A Marginal Abatement Cost Perspective”, 14th International Conference on Air Transport (INAIR 2025), Paola, Malta.}

⁴ _{S. Kumar, D. Plesch “A Literature Review and Methodological Recommendations to Measure the Economic Impact of Air Transport”, 14th International Conference on Air Transport (INAIR 2025), Paola, Malta.}

⁵ _{K. Oesingmann, K. Kölker “Price Elasticities in Aviation: Novel Estimates from Structural Gravity Modelling and Instrumental Variables Approach”, 14th International Conference on Air Transport (INAIR 2025), Paola, Malta.}

⁶ _{S. Maertens, W. Grimme “Segment and OD demand from Europe to the UAE and Qatar: Trends and potentially underserved markets”, 14th International Conference on Air Transport (INAIR 2025), Paola, Malta.}