Airlines explore how contrails can be reduced
German airlines are participating in a program to better understand the formation of contrails.
(Image: DLR/NASA/Friz.)
Optimized flight routes can avoid contrails in individual cases. This is the result of the first evaluated test flights in the 100 Flights program. The aim of the program is to better understand how non-CO₂ effects, i.e. climate-damaging contrails, arise in air traffic. Lufthansa, TuiFly, Condor, DHL, EAT and Eurocontrol are participating in the program run by German Air Traffic Control (DFS) and the German Aerospace Center (DLR).
The 100 flights will be monitored by satellites. They will analyze how great the effect of the unavoidable contrails would have been compared to the climate impact of the additional CO₂ caused by the detour. Final results are expected next fall and will then be evaluated by the scientific institutions, according to a statement from the German Aviation Association (Branchenorganisation der deutschen Luftfahrtindustrie, BDL). It is already clear that one of the other challenges for more climate-friendly flying is to automate the flight planning process.
Findings only scalable to a limited extent
Contrails consist of water vapor and exhaust gases emitted by aircraft. Soot particles can also act as condensation nuclei at high altitudes, and the water molecules freeze to form ice crystals and long-lasting cirrus clouds. They reflect the Earth's heat radiation and contribute to the greenhouse effect. The Working Group on Climate-Neutral Aviation (Arbeitskreis klimafreundliche Luftfahrt, AKkL), which was founded by the Federal Ministry of Economics and the Federal Ministry of Transport and is also responsible for the 100-flights program, has been working on this phenomenon since 2022.
The AKkL presented a working report (PDF) on the occasion of the International Aerospace Exhibition (Internationale Luft- und Raumfahrtausstellung, ILA), which is currently taking place in Berlin. Among other things, it calls for better conditions for the production of sustainable aviation fuel (SAF). The report also states that the climate impact of aviation is twice as high as its pure CO₂ emissions due to the non-CO₂ effects. The working group also writes that the findings from the 100 flights are only scalable to a limited extent. If extensive ice-saturated areas are avoided, capacity bottlenecks could quickly occur in the airspace.
In 70 test flights in 2023, Google Research, American Airlines and Breakthrough Energy analyzed how contrails can be reduced in flight operations with the help of artificial intelligence. During the flights, the pilots avoided altitudes where contrails were more likely to occur. To achieve this, they were able to use predictions calculated by Google Research using AI and machine learning from weather data and satellite images, which were compared with models from Breakthrough Energy.
(anw)