EUROCONTROL is forecasting an increase in network traffic of 5% compared to 2024, which has seen a growth of 5,3 % vs. 2023. In its April Flash Briefing focussing on Summer 2025 preparations the regional bottlenecks were pointed out. The increase is once again very unevenly distributed. The centre of European airspace, managed by DFS Deutsche Flugsicherung, is heavily affected.
I discussed with the DFS COO, Dirk Mahns the specific challenges of DFS and its preparedness for summer 2025.
Managing the known: Staffing capacity and operational flexibility
The preparation of summer 2025 already started in autumn last year and Dirk Mahns is emphasising the good cooperation between all stakeholders: “We are prepared, and we have more staff than 2024 but we do not know exactly what traffic amount will be there, even the forecasts get every time better by the Network Manager. For example, the military activities are different in comparison to last year.”
Mahns explains the significant increase in traffic in the sector Germany South due to changes in traffic flows: “The Sector family South of Karlsruhe specifically saw a 14% increase in April and an overall 40% increase compared to 2019.” System-wide, DFS observed so far a traffic increase of 3,3% up to May 2025 vs. 2024. DFS continues to monitor and adapt to changing traffic flows and reactivity is key. The recent impacts from the Israel-Iran escalation or prior India-Pakistan crisis highlight the short-term adaption needs.
Dirk Mahns outlines that more staff is available compared to the previous year, following the annual intake of 136 new ATCOs. Greater flexibility with rostering has been achieved: “They are phased in where they are assumed to be needed most”. Significant benefits were gained by successful implementation of complexity management tools in all centres, to better adapt staffing to the expected complexity and workload, instead staffing to pure traffic numbers.
These tools are expected to make a real difference: “Familiarisation of supervisors with complexity management tools in all control centres is ongoing to unlock the direct link with ATCO numbers.”
Mahns points out that DFS is still suffering from the backlog of the Covid-2019 impacts when training was hampered due to the drop in traffic and pandemic sanity restrictions. This is still hurting the operation. In 2025, around 380 people are continuously in training and DFS is running at maximum training capacity, as with planned intakes of 136 trainees in 2025 and 144 in the next years.
It is the sum of a lot of small measures to increase capacity
Major airspace restructuring projects, such as those in Northern German airspace, in cooperation with Maastricht Upper Area Control (MUAC) were key for the North. This helped in particular to provide airspace for the increased military training needs while limiting the impact on the civil airspace users. The Northern German training zone set a benchmark in cooperation between the stakeholders and for civil-military cooperation to mutual benefit.
Mahns explains the positive impact of the implementation of Trajectory Based Operation (TBO) to increase capacity, as well the challenges encountered in the implementation phase. Issues with data quality and accuracy were detected. “You need high-quality input data to find the right approach to introduce TBO. To achieve the benefits, the fine-tuning of the software and procedures had to go hand-in-hand with change management”. Dirk Mahns emphasised that the DFS experiences of implementing TBO are in line with the feedback received from colleagues in other neighbouring countries. TBO now delivers the expected capacity effects and provides the foundation for further enhancements.
The implementation of the new ATM system iCAS two years ago in ACC Munich and the iCAS system in UAC Karlsruhe laid further groundwork for the progress in operational efficiency. Dirk Mahns summarised the challenges to finally provide the needed capacity:
“Getting the balance right between operations, training, airspace projects and technology support”. He draws the clear conclusion: “It is the sum of a lot of small measures increasing capacity and not the one big thing.”
Collaborative progress: Advancing stakeholder coordination
‘Collaboration’ is currently the most frequently used word in discussions amongst airspace stakeholders. The need for continuous collaboration improvements is pointed out by Dirk Mahns deliberately again. A lot of successful preparatory work for the summer 2025 preparation took place in the Network Manager Board (NMB) and between the stakeholder groups bilaterally. While acknowledging the huge progress made, we are not yet where we need to be: “It is difficult to establish a continuous coordination process due to staff availability and organisational differences. “
Managing the unknown: Weather, military demands, and crisis response
Adverse weather has become the second main delay cause, for 43% of all delays in 2024 in European airspace, after capacity and staffing, according to EUROCONTROL. In DFS operations, 83% more severe weather occurrences were measured in 2024 compared to 2023. The weather-related delays increased by 50% versus 2023. Mahns explains another challenge with respect to precise weather predictions: “DFS, as many other national ANSPs, is obliged to receive their weather information from the national weather provider.”
Other weather information is available, but can’t be used. The quality of weather data in the operations room will be improved if weather information from several providers is usable, especially for cross-border coordination. With the upcoming season of thunderstorms, Mahns expresses his concerns as this is an area of high stress for the operation: “Severe thunderstorms and the impact on operations is hard to predict. At the end of the day the passengers expect a safe and smooth flight. Safety first is the most important objective in these situations.”
Another impact on capacity comes from the military demand and due to the ad-hoc crises. Germany is continuing to provide key routes for supply traffic toward Ukraine and is absorbing significant traffic re-routings. Diversions due to restrictions preventing the use of Ukrainian and Russian airspace for overflights to Asia have changed the south-east flight patterns.
Acknowledging the changed geopolitical situation in the fourth year of the Russian war against Ukraine and the military escalations in the Middle East, the discussion concludes: The aim of predictability remains – but another focus is reactivity and operational flexibility. While planned military traffic and military training needs are accommodated to a maximum, aiming to minimise impact on civil airlines, any crisis and ad-hoc military demand will remain a challenge for the system and may impact the passenger with resulting delay. This is often out of the control of the ANSP.
Future roadmap: Key milestones ahead
In a brief overview Mahns laid out key milestones planned for further improving capacity and future operational efficiency: Airspace measures planned for next winter for ACC Munich and UAC Karlsruhe, afterwards within 20 months in the airspace of ACC Langen. In early 2028, the implementation of the ATM system iCAS in ACC Bremen will take place.
The preparation of CPDLC in lower airspace has started, with a target completion date in about 20 months. While the benefits of TBO will increase: “We made it and we are more and more proud of it.”
Conclusions for the summer 2025: Prepared but vigilant
DFS operations are prepared for the operations in the high peak season with a clear understanding of the strength factors but also about the uncertainties and the remaining challenges.
The next step for all stakeholders is to cross their fingers that the thunderstorm season and geopolitical crisis do not cause further detriment to summer performance. Managing the known, adhere to planning and predictability while acting as flexible as needed in the operations, is already a sufficient challenge for this summer.
Dirk Mahns summarises: “Summer 2025 will be about mastering complexity – we are prepared, but reactivity is just as vital as planning. Our mission is to increase operational performance in all areas in accordance with our commitments for the benefit of the airspace users.”
