Google & American Airlines’ AI Aviation Contrail Reduction

Those white streaks that follow planes through the sky might be pretty, but they’re having a significant impact on the climate. 

Contrails form when aircraft fly through layers of humidity at a high altitude. 

Droplets of ice form around soot from engine exhaust which can remain in the sky for hours. 

Many clouds, including contrails, can trap heat and warm the planet and research from Imperial College London suggests they may have a more significant impact than emissions from jet fuel.

In fact, an IPCC report says contrails account for around 35% of aviation’s global warming impact.

Google Research has worked with American Airlines, Bill Gates’ Breakthrough Energy and Eurocontrol (the European Organisation for the Safety of Air Navigation) to create an AI solution for contrails. 

When American Airlines pilots tested the system, it reduced contrail generation by more than half.

Adam Elman, Director of Sustainability EMEA at Google, says: “This is just one way AI is helping to create a more sustainable future for aviation.”

How the contrail AI tool was created

Google’s Climate AI team worked with Bill Gates’ Breakthrough Energy to analyse satellite imagery, weather and flight path data.

Breakthrough Energy has a dedicated Contrails Team to address these man-made clouds.

Google Research then developed an algorithm to identify where contrail formation is likely and integrated this into aviation planning systems.

The addition of this algorithm means flight paths can be optimised to reduce contrail generation by adjusting flight paths just a few thousand feet. 

Marc Shapiro, Director of Breakthrough Energy Contrails, says: "Avoiding contrails might be one of the best ways to limit aviation's climate impact and now we have the first real-world demonstration that it's possible to do so. 

“This study is a great example of what happens when creative, ambitious organisations work together to better understand and solve a tough problem and we're grateful for American Airlines and Google's partnership."

Implementing AI for contrail reduction

American Airlines pilots did 70 test flights at a slightly lower altitude than normal over two months using predictions from the tool.

The results show this AI technology reduced contrail generation 54% and used 2% more fuel. 

Eurocontrol’s Maastricht Upper Area Control Centre (MUAC) manages the upper airspace, from 24,500 to 66,000 feet, over the Netherlands, Belgium, north-west Germany and Luxembourg.

Each day MUAC controls an average of more than 4,000 flights across its 260,000 km² of airspace. 

It was the first to conduct an operational contrail prevention trial in 2021 and has been working with Google since 2022 by sharing information. 

Ilona Sitova, Senior Aviation Sustainability Expert at Eurocontrol MUAC, told Google: “Contrail prevention is so important as it is one of the few tools that the aviation industry has to mitigate its impact on the climate in the short to medium term.”

MUAC can plan its capacity up to a year in advance, but contrail predictions are less accurate this far in advance. 

Google’s AI-generated suggestions can provide contrail information to alter trajectories for individual aeroplanes in real-time.

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