Wouldn't it be nice if there were an easy way to slash global carbon emissions by more than 40m tonnes each year? That's a serious saving – about as much as the entire Danish economy.

What if the total impact on combatting climate change was twice as much as that figure suggests, because all that carbon would have been emitted – along with a cocktail of other pollutants – at high altitude? And what if the plan would also save huge amounts of time and money? If that sounds too good to be true, then you probably have't met David Parkinson, the inventor and engineer on a one-man mission to drag air-traffic control (ATC) into the digital era. Parkinson believes that using computers to calculate perfectly smooth trajectories for planes could painlessly cut 8% of aviation emissions. "We've already done it on the railways," Parkinson says. "Many people assume that train signals are still controlled manually by signalmen, but in truth the system was automated years ago." Parkinson opens his laptop to reveal a radar-style map with flashing little dots representing planes moving towards their destination. This, he explains, is a working prototype of his system – a model of airspace above the south-east UK. It looks like the screens used by the existing air-control teams, but there's a crucial difference: the computer calculates the most efficient trajectories for each plane, which saves time and fuel compared with sticking to sub-optimal routes flown at the moment. The problem, according to Parkinson, is that the current system is hugely out of date. "The operational concept is 50 or 60 years old. The guys do a good job. They're very skilful people. But the tools at their disposal include scribbling on paper strips. Planes have enormous navigational capability that has evolved over time, but for largely historical reasons controllers are still chained to manual systems." If he's correct, Parkinson's proposals could save huge amounts of fuel, emissions, time and money. Automation could also improve safety, as it has done on the railways (though admittedly that might be a hard sell to the public). Yet despite Parkinson's impeccable CV – which includes developing the ATC system used over the North Atlantic for almost 20 years (with computerisation built-in) – he has found it almost impossible to get anyone in the air-traffic establishment to even look at his proposals. I asked NATS (National Air Traffic Services), which dominates ATC in the UK, what they thought of his proposals. When I described his prototype, the spokeswoman quickly suggested he must be a crank. When I described his CV, she warmed a little but still sounded very defensive. She promised to speak to colleagues and come back to me, but I haven't heard anything since.

That response – or lack thereof – chimes with Parkison's claim that the status quo recognises the potential of automation while being reluctant to seriously engage with it. There is work being done on efficiency more broadly, as evidenced recently when the Civil Aviation Authority announced new targets for NATS to make significant fuel and carbon savings using better flight trajectories. But there appears to be a reluctance to consider more ambitious plans such as those developed by Parkinson.

It's impossible for non-specialists to gauge the viability or desirability of Parkinson's proposals. But his arguments about air-traffic systems completely failing to keep up with the available technology are compelling. And his detailed plan for safely transitioning from where we are now to a more efficient system sounds sensible. So here's my challenge to NATS and other relevant bodies: why not assess Parkinson's proposals properly? Surely at a time of financial and environmental crisis, any technology that could safely cut both costs and emissions must be worth at least seriously considering?