Aviation decarbonization depends on cooperation among competitors, yet competition law considerations can affect such efforts. Airlines increasingly pursue collaborative sustainability initiatives, including joint offtake of sustainable aviation fuel (SAF), interoperable bookand-claim registries, and shared monitoring and verification frameworks. This article argues that competition law frameworks in the EU and United Kingdom (UK) are evolving – albeit unevenly – to accommodate such sustainability collaboration, while the US remains more uncertain. It shows that regulatory fragmentation across SAF definitions, carbon-pricing regimes, and compliance rules both increases the need for private coordination and complicates its legal design. After mapping this fragmented landscape, including Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), EU Emissions Trading System, ReFuelEU, and the UK SAF Mandate, the article analyses recent EU, UK, and US competition law developments. It proposes a safe-harbour-plus blueprint for airline sustainability collaboration, based on open standard-setting, joint SAF procurement with safeguards, and interoperable registries. Properly structured, such cooperation can satisfy competition law requirements while enabling aviation decarbonization. The analysis demonstrates that competition law can facilitate – not merely constrain – collective climate action in fragmented regulatory environments.
Air and Space Law