Aircraft rely exclusively on fossil jet fuel to operate, which explains why growing passenger numbers have rapidly increased emissions from the sector. Carbon pricing and a modal shift are important, but it is only when we swap fossil jet fuel for truly sustainable advanced fuels (SAFs) that emissions from flying will fall. Such a switch can address both CO2 and non-CO2 effects but to differing degrees. To date, no effective measures have been put in place at the European level to achieve such a switch. The ReFuelEU Regulation proposal changes that. The proposal introduces an obligation on jet fuel suppliers to blend a growing share of SAFs (biofuels and synthetic aviation fuels) into fuel provided at major airports in the EU.