Contrail Prevention Studies/Trials

[TEEJ]

I noted the following during a search. Please feel free to update the thread.

July 2025

EUROCONTROL Maastricht Upper Area Control Centre, responsible for managing the upper airspace in one of Europe's busiest airspace areas, is harnessing Google's contrail prediction tools and satellite image recognition as part of an operational trial to further advance research into contrail prevention.


Source: https://www.youtube.com/watch?v=R8WrCA5w2ZM


March 2025

From the Copenhagen Contrails Conference: Airlines and tech companies are testing contrail avoidance in simulations and real-life trials. This session will give you a quick idea of the results, challenges, and learnings from these experiences.


Source: https://www.youtube.com/watch?v=7QavgYP1f5I

 

[yoshy]

I previously assumed contrails would have a net cooling effect by reflecting sunlight, but my assumption was wrong (though it's small compared to other sources):

The researchers found that contrails have an overall warming effect, acting like a light blanket. "The contrails are trapping more heat in the atmosphere compared to cooling from reflected sunlight," Spangenberg said. However, Bedka and Spangenberg said that the effect is still quite small. "When you consider all of the man-made radiative forcing and all the changes we're making that can affect climate, contrails are one of the smaller effects, compared to carbon dioxide and other emissions," Spangenberg said. "Globally, you would have to increase the contrail effect by roughly 100 times to get the same effect as all of the anthropogenic carbon dioxide in the atmosphere."

https://www.earthdata.nasa.gov/news/feature-articles/trail-contrails

 

[Trailspotter]

An open access article in the tomorrow issue of Nature, published online today, April 1st.

Substantial aircraft contrail formation at low soot emission levels

Abstract

Contrail cirrus clouds are a main contributor to the climate forcing from aviation1​. Yet, the number of contrail ice crystals forming behind aircraft with modern lean-burn engines is unknown. Theory spans a four orders of magnitude range in ice crystal numbers2,3​—rendering related climate effects unpredictable. Here we show that lean-burn combustion reduces soot particle number emissions by three orders of magnitude compared with conventional rich–quench–lean engines4,5​—but does not significantly decrease volatile particles or contrail ice crystal numbers—both can exceed 1015​ particles per kg of burned fuel. Our findings arise from in-flight observations behind an A321neo aircraft with lean-burn engines, thus providing real-world confirmation of some laboratory work6​ and narrowing the range of theoretical expectations. Our results indicate that the tested lean-burn engine configurations alone are unlikely to reduce the warming effect of contrails, suggesting that modifications of fuel composition and lubrication oil venting architecture may be required. We show that contrail ice particle numbers in the low-soot regime can be reduced by using low-sulfur fuels and that organic fuel constituents and lubrication oil vapours can increase contrail ice particle numbers. Future research should explore how reductions in volatile particles, apart from soot, affect contrail ice formation.

https://www.nature.com/articles/s41586-026-10286-0