The UK Civil Aviation Authority opened the third round of applications for its Hydrogen Sandbox on 2 June 2026, extending a research programme designed to prepare aviation regulation and industry for hydrogen use. The initiative is being run as a regulatory sandbox to improve understanding of hydrogen fuel in aircraft and airport operations.
The CAA said the programme is intended to identify safety risks, close regulatory gaps and support collaboration with industry and academia. Its scope includes flight trials, safety assessments, hydrogen propulsion testing, airport infrastructure work and research by aeronautical institutes. The regulator has linked the effort to the UK’s wider Jet Zero policy framework.
The Hydrogen Challenge, launched in November 2023, was expanded in February 2025 and funded through the Regulators’ Pioneer Fund, with later support from the Department for Transport. The CAA said the sandbox was enlarged from three to thirteen projects, and that trials under the expanded model will last three years. Interested parties can contact hydrogenchallenge@caa.co.uk.