Aviation is difficult to decarbonise due to its reliance on high energy-density fuels, making liquid hydrogen a promising option for reducing in-flight CO2 emissions. This study develops a profitdriven fleet development and network optimisation model for intra-European aviation (2035–2050). The problem is formulated as a rolling-horizon mixed-integer linear programme (MILP); scenario and sensitivity analyses and SHAP-based feature importance are used to interpret results. The model links fleet replacement and route allocation to technology readiness and a staged roll-out of hydrogenready airports with spatially differentiated LH2 prices. In the most favourable scenario, LH2 demand reaches 1.7 Mt/yr by 2050, corresponding to a 24% CO2 reduction relative to the no-hydrogen reference case; less favourable pathways yield lower demand due to delayed entry, operational penalties, and higher LH2 costs. Uptake forms north–south corridors and, as conditions worsen, shifts toward low-LH2-cost airports. Sensitivity results indicate that LH2 cost and operational performance dominate uptake: demand collapses once LH2 costs rise by 20–30% above the assumed price levels, and in a global sensitivity analysis, LH2 cost explains 40–50% of the variance in LH2 demand. Overall, meaningful hydrogen deployment by mid-century is conditional on coordinated progress in hydrogen cost competitiveness, operational efficiency, technology entry, and strategically sequenced airport infrastructure roll-out.