Germany, February 2026 — The completion of the D-KULT research project at the end of 2025 has delivered, for the first time, practical results on how aviation can reduce the formation of climate-impacting contrails. The research indicates that optimised flight planning may offer climate benefits, although further research is required before operational implementation.

Research Programme and Project Scope

The D-KULT project ran from June 2022 to August 2025 under funding from the German Federal Ministry for Economic Affairs and Energy (BMWE) as part of the LuFo VI-2 aviation research programme. Project partners included the German Aerospace Centre (DLR), DFS Deutsche Flugsicherung, the German Meteorological Service (DWD) and German airlines.

The project name derives from the German term for a demonstrator for climate and environmentally friendly air transport. The primary objective was to develop procedures to reduce the climate impact of aviation by avoiding areas where persistent contrails are likely to form.

Persistent contrails occur when aircraft fly through ice-saturated air layers, known as potential persistent contrail (PPC) regions. These contrails can contribute significantly to global warming.

Tactical Versus Strategic Avoidance Approaches

Researchers examined two main operational approaches.

The first, tactical avoidance, involves air traffic control guiding aircraft around PPC areas in real time. Simulation results indicated this method is not currently practical, with potential airspace capacity losses of between 20 and 60 per cent, alongside increased workload for air traffic controllers.

The second, strategic avoidance, is considered more promising. This approach would require airlines to integrate climate optimisation functions into flight planning systems, allowing PPC avoidance routes to be selected before departure.

In one test involving 100 flights, PPC areas were successfully avoided through targeted planning. However, the process was highly time-intensive and manually driven, meaning it cannot yet be applied to routine operations.

Further Research Required Before Operational Use

Further research is required before PPC avoidance procedures can be introduced into daily flight operations. DLR researchers are currently assessing the impact of rerouting on fuel consumption and overall carbon footprint.

Preliminary analysis suggests that climate benefits will only be achieved if the reduction in contrail climate impact exceeds any additional carbon dioxide emissions resulting from route deviations. Early modelling shows potential but also raises new technical and operational questions.

Researchers also found that weather and climate datasets used to predict PPC formation were less robust than expected. DFS has increased scientific collaboration with DLR and DWD to develop improved predictive methods. The DLR coordinated the D-KULT programme and contributed through five participating institutes.

Industry and Network Coordination Required

DFS Chief Executive Officer Arndt Schoenemann said the project has established an important research foundation but emphasised the need for continued work both nationally and internationally.

The long-term objective is a coordinated operational approach involving airlines, air navigation service providers and European air traffic network management to support the effective avoidance of climate-relevant contrails.

About DFS Deutsche Flugsicherung

DFS is Germany’s state-owned air navigation service provider operating under private law, employing approximately 5,800 staff as of December 2025. Around 2,200 air traffic controllers manage more than three million flights annually in peak years across German airspace.

DFS operates area control centres in Bremen, Karlsruhe, Langen and Munich, as well as control towers at 15 designated international airports. Through subsidiaries and joint ventures, DFS also provides aviation services, air traffic training, drone integration solutions and flight inspection services.