The aviation industry has revised its climate targets in 2021; the aim is now to achieve net carbon neutrality by 2050. Hydrogen, synthetic fuels from solar and wind energy, as well as advanced biofuels from residues and wastes are important options for a successful transition from conventional jet fuels to renewable energy carriers within just 30 years. Given the significant uncertainties along the respective process chains, it is important to develop a set of robust alternatives such that sound technological solutions are available in case key enabling technologies do not materialise their assumed potentials.