Announced in June 2021, the HyFlyer II program continues ZeroAvia's aggressive push to prove hydrogen is the path forward in aviation. The original HyFlyer program put a six-seater in the air back in 2020, and it was the biggest hydrogen-powered plane ever to fly at the time. It has now completed more than 30 flights

In 2021, the company made headlines when a two-seat test plane lost power and made a forced landing in a field, losing its left wing in a hedge before coming to an "abrupt stop" in a ditch. Thankfully, nobody was injured, and a subsequent AAIB investigation found the hydrogen powertrain was not responsible for the incident, but it was certainly a wake-up call and a cautionary tale for other companies hoping to take a fast-paced startup mindset into the aviation world.

Now, one of the company's two 19-seaters has entered the test flight phase for the first time – albeit with a more cautious implementation of the technology. ZeroAvia has left the standard Honeywell TPE-331 combustion engine on the right wing, while fitting the left wing with a 600-kW electric motor.

For this test machine, the hydrogen tanks, fuel cell stacks and lithium-ion buffer batteries are all inside the cabin, where they can easily be monitored and accessed. ZeroAvia says it hopes to have a fully commercial-ready configuration ready to submit for certification later this year, in which the whole powertrain will be kept outside the cabin, presumably in the wing. The company hopes to have this 600-kW powertrain fully certified and running commercial flights for nine-to-19-seat aircraft by 2025.