The supply of critical raw materials, especially titanium, poses a significant challenge for the aviation sector. Increased circularity is often proposed as a solution by industry and policymakers. However, the effects of circular strategies remain insufficiently understood. Therefore, this paper analyses different circular strategies, namely recycling, a pure lifetime extension, and an enhanced lifetime extension that includes an engine aircraft, based on real-world data up to the year 2040. The findings indicate that recycling retired aircraft only marginally affects the required rising inflow of titanium by less than 5%. The engine upgrade strategy shows similar results. In contrast, a pure lifetime extension shows the greatest potential for mitigating supply constraints and can be further enhanced to a potential of more than 10% when combined with recycling. The results highlight the complexity of circular strategies and emphasise a stronger focus on lifetime extension for the aviation sector and other industrial sectors.

With initiatives such as the European Green Deal establishing more stringent environmental requirements, there is an increasing need to develop aircraft technologies and sustainable aviation practices with reduced climate impacts. Additionally, conventional environmental Life Cycle Assessments (LCAs) often struggle to capture the dynamic and complex nature of aircraft operations; in particular, non-CO₂ in-flight impacts, which contribute significantly to climate change, are often overlooked. In this study, we improve a discrete-event LCA approach with a climate impact evaluation model and apply it to scenario analyses comparing different aircraft designs, fuel types, and flight schedules. Our findings reveal that, contrary to previous LCA studies, the climate impact per kilometre flown increases with longer flight distances and that an efficiently planned flight schedule can reduce the overall environmental impact. The study highlights the necessity of incorporating non-CO₂ effects and operational scenarios into LCA to achieve a more accurate understanding of aviation's environmental impact.

As the aviation industry strives to minimise its environmental footprint, understanding the full life cycle impacts, including maintenance, becomes essential for sustainable development. This paper addresses the critical research gap in the environmental assessment of aircraft maintenance by conducting a comprehensive life cycle assessment based on an Airbus A320 aircraft. By combining a top-down check-level analysis and a detailed examination of the aircraft manufacturer's maintenance planning document, this study provides significant insights into the environmental implications of maintenance activities. The check-level analysis provides a general overview, while the analysis of the maintenance planning document delves into individual tasks, enabling the identification of components with the highest ecological impacts. This research emphasises the importance of including aircraft maintenance activities in life cycle assessment studies and provides valuable guidance for researchers, industry practitioners, and policy makers in prioritising sustainability measures and enhancing the environmental performance of aircraft throughout their life cycle.