This research project investigated the potential benefits of using hybrid hydrogen fuel-cell powertrains in commuter aircraft certified under the EASA CS-23 category to reduce the aviation industry's environmental impact. The study used an in-house aircraft design synthesis software to model conventional and fuel cell aircraft, including a sensitivity analysis. The fuel cell aircraft had a higher take-off mass, but almost equal mission energy use. Fuel cell aircraft brought a 76-98% reduction in global warming potential when using green hydrogen. The energy purchase costs were higher for fuel cell aircraft but equalized when emission allowance costs for the mid-term future were factored in. Overall, fuel cell powertrains have potential in reducing aviation's environmental impact, but further research is needed.