Purpose – Seeking sustainable alternatives to traditional fossil fuels, hydrogen emerges as a promising candidate due to its environmental impact. --- Methodology – This project reviews the technical challenges and opportunities associated with hydrogen propulsion in aviation. Existing spreadsheets are used (and extended) for the calculation. --- Findings – Hydrogen as a propellant in passenger aircraft eliminates CO2 emissions but its altitude dependent non-CO2 repercussions remain. Lowering the cruise altitude reduces greenhouse effects regardless of the fuel used. Based on the equivalent CO2 mass, an LH2 turboprop based on A320 TLAR yields the best-case scenario but has still remaining emissions: 14.6% of the NOx and 1.5% of the Aviation Induced Cloudiness (AIC) effects in terms of equivalent CO2 mass. These impressive results can be achieved with rather conventional technologies. To get started and to learn, already certified aircraft should be converted as prototype. Later a new clean sheet design can follow. --- Research Limitations – The results can only be achieved, if assumed secondary effects of water emissions and ice crystal formation on AIC turn out to be true and NOx reduction from lean H2 combustion can be achieved as assumed. --- Practical Implications – The findings of this project may be considered by aircraft manufacturers. Students may want to extend calculations based on the extended spreadsheet. --- Social Implications – The Open Access distribution of this report allows the public to participate in discussion the results.