To observers there was nothing remarkable about the small fixed wing plane that took off from Hollister airfield, in California. However the pilot and team of engineers at ZeroAvia knew they were achieving something miraculous:
The propeller plane took off and completed a test flight without expending a single drop of plane fuel.
The Californian startup has been designing hydrogen-powered engines for aviation. Instead of expelling tons of harmful carbon dioxide, the clean-running hydrogen fuel's only waste product is water.
Having operated in virtual secrecy for years, ZeroAvia has emerged with the potentially revolutionary technology.
The aviation industry is one of the biggest polluters on the planet. Air travel accounts for nearly 900,000,000 metric tons of carbon dioxide per year. Hydrogen powered planes could potentially bring that number to "zero".
The company is one of several developing the technology. However this test flight represents a material leap forward. It lends credibility to the company's 2022 goal, to be producing 20-seater light aircraft with a range of almost 1000kilometeres.
The technology - which is unlike dirty fossil-fuel combustion engines or battery-powered electric models - uses a "hydrogen drive train". ZeroAvia thinks that this hydrogen solution may provide a breakthrough.
While most companies such as Ampaire and Eviation are exploring the potential of battery-powered electric flight, they are limited by the current battery storage technology.
"For the foreseeable future, actually getting a sizable aircraft in the air for a reasonable amount of time will be quite difficult with batteries," ZeroAvia's founder and CEO, Val Miftakhov told Fast Company.
The hydrogen fuel cell solution can produce four times the energy of the best batteries available.
Batteries also have the added disadvantage of having to be regularly replaced for greatest efficiency.
Miftakhov who has his eyes on domestic, short range air travel says the hydrogen solution would be around half the cost of conventional planes, and infinitely cleaner.
"Fundamentally, there are no physical constraints on the hydrogen power train that don't allow it to be used in a large aircraft for long distances," says Miftakhov.
The hydrogen fuel cells currently used by the aircraft are similar to ones already used on the road. Liquid hydrogen - which is more volatile – would require further safety and certification, but could unlock further range and potential for the technology.
Roughly half of the world's air traffic involves flights of under 800km, which would be well within range of the hydrogen powered technology.
"Your security lines are shorter or nonexistent in the smaller airports, and that contributes to the better experience as well. So as the industry sees this sort of benefit and momentum, then we expect a significant part of the short-haul traffic that today happens between the mega hubs will go into this model."
Travellers could be able to try out the latest generation of clean flight sooner than anticipated. ZeroAvia told Fast Company it is already in conversations with airlines around the world. Norway in particular aims to be a leader in the new technology, pledging to drop air travel emissions to zero by 2040.