Recent weeks have seen some developers of cleaner-energy aircraft forging ahead with ambitious plans, while others have faded from the scene, underscoring the challenge of bringing to market entirely new classes of aircraft.

Meanwhile, European industry is adjusting to a new sustainable aviation fuel (SAF) mandate, while US airlines and fuel producers are waiting to see what support SAF will receive from the administration of President Donald Trump, who has vowed to roll back his predecessor’s clean-energy projects.

It adds up to lots of uncertainty.

But in the USA, electric air taxi developer Joby Aviation secured a new partnership with Virgin Atlantic Airways, and the FAA approved Archer Aviation’s pilot-training programme. Those firms are still considered frontrunners in the race to certification.

FlightGlobal also took a recent deep dive into the Australian developers aiming to lead that country’s clean-energy aviation transition, while French start-up Beyond Aero has revealed a revised design for its conceptual hydrogen-electric business jet.

Additionally, US firm JetZero has shown recent progress, landing Pratt & Whitney as a partner in its bid to bring to market a blended-wing airliner it says could be 50% more efficient than current types.

Also, numerous electric- and hydrogen-powered seaplane developers recently came together at a conference in Miami, generating momentum for projects they see as having enormous market potential.

Still, the urban air mobility segment has lost some bounce in recent months, as Eviation laid of its workforce and Lilium Aerospace closed shop. Even Airbus backed away from its plan to bring hydrogen-powered aircraft to market in the 2030s under its ZEROe programme.

Meanwhile, the world’s airlines are taking a close look at their net-zero-emission commitments as they cope with slim SAF availability and limited supply of more-efficient new aircraft.

SAF production has been incredibly slow to ramp up, and much remains uncertain about government incentives. That is especially true in the USA, where airlines, fuel companies and environmental groups are waiting for the Trump administration to define which SAF types will quality for production tax credits.

Meanwhile in Europe, SAF mandates just entered force, with fuel companies required to supply a 2% SAF blend across to airports in 2025.

At the same time, carriers have been unable to replace older jets with new, more-efficient Airbus A320neo-family jets and 737 Max as quickly as they had hoped. That is because Airbus and Boeing have struggled to hike production amid supply chain struggles and, particular to Boeing, quality shortcomings. Additionally, new-generation engines are proving less reliable than hoped, forcing airlines to ground large numbers of jets.