TUIfly and the German Aerospace Centre (DLR) have launched an ambitious new research campaign in which a DLR research aircraft shadows regular TUIfly passenger flights to study how aircraft contrails form—and how their climate impact can be reduced.
Announced on 26 November 2025, the project is part of the EU-funded A4Climate initiative, which aims to provide practical tools and technologies to curb aviation’s environmental footprint. By flying behind TUIfly aircraft in real operating conditions, DLR scientists can directly measure the characteristics of contrails—the thin white streaks that form in cold, humid air at cruising altitude.
Contrails and the cirrus clouds they can develop into are among aviation’s largest climate-warming factors. Yet their formation depends on multiple variables, including engine type, fuel composition, altitude, and atmospheric conditions. The new campaign is designed to help untangle these influences.
Using specialised onboard instruments, the DLR research aircraft will analyse exhaust particles, ice crystals, temperature and humidity levels, and how different engine technologies behave in real time. The data will ultimately feed into models that could shape future aircraft design and airline operations.
According to TUI and DLR, the findings may support new engine concepts, alternative fuels, and climate-optimised flight routes—for example, avoiding areas of the atmosphere where contrails are most likely to persist and warm the planet.
The partners describe the project as an important step toward identifying concrete, scalable solutions for more climate-efficient flying. Further test flights and evaluations will continue over the coming months as researchers assemble what is expected to become one of the most comprehensive contrail datasets in Europe.