The article discusses Pratt & Whitney's significant breakthrough in advancing hydrogen-burn engines for air transport, particularly focusing on its HySIITE project. The project aimed to enhance the hydrogen burn process for gas turbines, with a key focus on reducing NOx emissions and improving energy efficiency. Pratt & Whitney's experience with hydrogen-burn engines dates back to the 1950s, with past projects like the LH2-burning engine for the Lockheed CL-400. The HySIITE project, which received funding from the US Department of Energy's ARPA-E, focused on steam-injected, intercooled turbine engines, showcasing impressive results. Rig tests demonstrated a remarkable 99.3% reduction in NOx emissions compared to current benchmarks, along with a 35% improvement in energy efficiency. These outcomes position hydrogen-burn engines as a leading alternative for emission-free aircraft with over 100 seats. Pratt & Whitney's breakthrough not only addresses environmental concerns by virtually eliminating NOx emissions but also highlights the potential for enhanced energy efficiency in the aviation sector. The article concludes by hinting at a potential shift in the power equation between Liquid Hydrogen and Sustainable Aviation Fuel, setting the stage for a more sustainable future in air transport.