The University of Illinois is spearheading the Hy2PASS program to explore the potential of hydrogen hybrid power systems in commercial aviation. This initiative aims to revolutionize aircraft design and performance by leveraging a unique architecture that combines fuel cell technology with gas turbine engines. Unlike traditional hybrid systems, the Hy2PASS design focuses on air handling, utilizing a fuel cell-powered electric compressor to supply oxygen to the fuel cell cathode and gas turbine burner. By decoupling the compressor from the turbine, the system enables variable pressure ratios, enhancing operational flexibility and efficiency. This innovation not only reduces mission energy requirements but also offers a zero-emission solution, aligning with NASA's Strategic Objective of driving sustainable aviation advancements. Through the Hy2PASS program, researchers are working towards optimizing aircraft systems and mission trajectories to minimize environmental impacts and propel the development of ultra-efficient subsonic transports. By showcasing the feasibility and benefits of the Hy2PASS system, the project aims to usher in a new era of eco-friendly and high-performance aircraft designs in the near future.