H2FLY; HY4 Hydrogen-Hybrid Aircraft Sets Record Something has been buzzing in the new hydrogen aviation sector recently. H2FLY is a company working on a hydrogen-based aircraft and it recently set what appears to be a record for flying a hydrogen-based aircraft. To be specific the aircraft is hydrogen-electric and is called the HY4. It recently flew just above the 7,000 foot altitude mark being flown by an actual pilot. The demonstrator aircraft is likely the first hydrogen-electric based plane to fly above 7,000 with a pilot flying it. In fact, recently the aircraft flew between Stuttgart and Friedrichshafen on April 12th, marking the first time a hydrogen-electric passenger aircraft has been piloted, between two major airports.