To cut 80% of air transport's CO2 emissions by 2050, Clean Sky 3 would need reverse planning: due to the life expectancy of aircraft, required technologies would have to enter service in 2030-35 and should be demonstrated in 2025–27. The 2021-27 EU budget should be voted on by the end of 2019 and detailed allocation in 2020, with the Horizon Europe research and innovation program maybe including Clean Sky 3 starting on January 1, 2021, at best.[10]