United Therapeutics subsidiary Unither Bioélectronique successfully achieved the first flight of a piloted hydrogen-powered helicopter, marking a significant milestone in aviation history. The modified Robinson R44 technology demonstrator, equipped with low-temperature proton exchange membrane fuel cells and an electric motor, completed a three-minute test flight at Roland-Désourdy Airport in Bromont, Québec. The project, named Proticity, involved collaboration between Unither and Robinson Helicopter Company, with a focus on sustainability and zero-emission vertical flight. Challenges during development included designing a cooling system to manage heat from the fuel cells and creating a state machine algorithm for precise power control. The successful flight demonstrated stable power output and showcased the potential for enhanced safety and redundancy features in case of partial failures. Unither also developed a custom display to inform the pilot about the status of the fuel cell, battery, and motor, enhancing the overall flying experience. The achievement was praised by industry leaders for its advancements in sustainable aviation technology and the shift towards hydrogen-powered aircraft.