The sound bite from Leck Chet Lam, managing director of the events business Experia, was a precursor to three days packed with green-focused panels and announcements, often accompanied by the tagline "sustainable aerospace together".

Despite the public-facing united front, the air show has exposed deep divides over how the industry can achieve its goal of "net zero" carbon emissions by 2050.

Airline bosses, green fuel producers and manufacturers contradicted each other and pointed fingers over the thorniest issue: who is responsible for the slow take up of so-called sustainable aviation fuel (SAF).

SAF, a biofuel made from plant or animal materials, such as used cooking oil or agricultural waste, can reduce carbon emissions by up to 80% compared with traditional jet fuel.

But it is up to five times more expensive and there is a huge shortage of feedstock needed to make it. SAF is similar in chemistry and performance to fossil jet fuel.

Two decades after airlines began pledging to use biofuels, SAF makes up just 0.2% of the global jet fuel market. The aviation industry says that number will rise to 65% by 2050, although environmental groups say there is no credible roadmap to achieve the goal.

Willie Walsh, the director general of the International Air Transport Association, said at an event on Monday that the only way to achieve "net zero" was the widespread use of SAF.

"Demand is not an issue," Walsh said, adding that airlines use "every drop" of SAF that is produced.

BLAME GAME

The companies that produce SAF tell a different story.

Hours before Walsh's comments, Ong Shwu Hoon, vice president of Asia-Pacific fuels at ExxonMobil (XOM.N), said SAF demand was "very low", discouraging producers.

Walsh, head of the biggest airline trade group, later hit back: "they would say that, because they don't want to produce any (SAF)".

Exxon has said it is ramping up SAF production and is committed to supporting the aviation industry's net-zero goal.

Environmental groups say the blame game over why SAF is struggling exemplifies an industry that sets arbitrary targets with no agreed upon plan to get there.

"This chicken-and-egg debate is getting old and counterproductive," said Jo Dardenne, aviation director at Transport and Environment, a Brussels-based non-governmental organisation.

"How can the industry put on a straight face when announcing net zero by 2050, when SAF uptake is less than 1% today and over 40,000 new planes will take to the skies in the next 20 years," Dardenne said.

Dardenne called for regulators to take control and put strict mandates in place for SAF production and use.

Some airline bosses speaking at the air show similarly sceptical of the industry's SAF plan.

Riyadh Air Chief Operating Officer Peter Bellew said at a panel discussion on Tuesday that there wasn't enough feedstock to hit the industry's SAF targets. Bellew suggested that making air traffic control more efficient would be a quicker way to cut emissions.

On the same panel, Yasuhiro Fukada, co-founder of the Japanese low-cost airline Zipair, said he was focusing on cutting plastic packaging on planes because that was more important than green fuel to the younger "Gen-Z" consumers his airline targets.

Many environmentalists contend that the concept of a "sustainable" air show is evidence that the industry is tone deaf about tackling a looming climate emergency.

Shows around the world were cancelled during the COVID pandemic, but they are now back in full force.

As airline CEOs talked about paving a sustainable future inside a vast, air-conditioned aircraft hangar in Singapore, outside fighter jets and military helicopters performed mind-bending aerial tricks, spewing exhaust into the sky.

On the ground, delegates who were flown in from around the world sat in snaking traffic queues trying to enter and exit the show.

"Days of events like this must surely be numbered if we're serious about climate," said Robin Hicks, deputy editor of Eco-Business, a Singapore-based environmental group.