Supply Chain Management

Reducing Flight Emissions, Delays, and Reroutings

Cross-border collaboration on air traffic management is the key to cleaner and more efficient flying

Despite costing billions of euros a year, capacity for steering air traffic in Europe still falls short of demand seven percent of the time. This in turn creates the need for long on-ground flight delays or detours to avoid congested airspace. Researchers at WHU modelled the concept of cross-border capacity sharing in European airspace and found in a large-scale case study that it can substantially reduce delays and reroutings at low cost.

The work of air traffic controllers is to ensure a safe passage of planes through airspace. This service comes at a high cost: in Europe alone, cost for provision of air traffic management (ATM) services amounted to eight billion euros in 2017. In the same year, however, the number of air traffic controllers was still too low to handle demand for ATM services in seven percent of cases. This resulted in delay costs of around 550 million euros in 2017. One reason for the observed imbalance of capacity and demand is that, in Europe, air traffic is still managed to a large extent individually by country. An air traffic controller in one country is only eligible to coordinate flights within the jurisdiction of that country – sometimes even just a specified region within a country. Germany alone is divided into four so-called airspace control centres (ACCs), and controllers are employed in only one of the four ACCs.

Over the past several years, researchers and practitioners alike have brought forward the idea of cross-border collaboration of air traffic controllers in Europe. Such collaboration would allow to assign capacity more flexibly to high-demand ACCs, instead of steering demand (i.e., flights) to high-capacity ACCs, thereby reducing the number of required reroutings. In its extreme, the entire European network would be managed as a Single European Sky, namely the SES initiative. A new study has analyzed what benefits such a collaboration could bring, and how such a cross-border collaboration scheme should look. For that purpose, an algorithm was developed that decides dynamically on the number of controllers required for each ACC based on several scenarios of upcoming traffic and weather conditions. The model was tested in a large-scale case study on 2,800 actual flights across eight countries in Europe.

The results showed that introducing cross-border collaboration can reduce delay and rerouting costs in Europe by 40 to 50 percent with additional capacity costs of less than one percent. Perhaps surprisingly, a regional cross-border collaboration where capacities are shared between only two to three neighbouring ACCs is sufficient to reap these benefits; a network-wide sharing does not add further value because the higher costs of such a setting outweigh its benefits. Additional side effects of the cross-border sharing of capacities would be a more stable network performance as well as lower flight emissions by reducing the rerouting of flights. With regards to political discussions on this topic, these findings may fuel further engagement in favour of cross-border collaboration in European ATM.

Tips for practitioners
  • Resolving imbalances of demand and capacity is theoretically quite simple: improve capacity decisions in anticipation of demand or steer demand in line with decided capacities.
  • Since capacity decisions are usually long-term oriented, they are difficult (or very costly) to adjust in the short-term. As such, consider making capacities more flexible.
  • There is a wide range of options for flexibilization including flexible contracts (for either physical goods or services), the renting of further capacities (e.g., cloud services for digital products), or the sharing of capacities with partners (as with the case of air traffic services).
  • If you opt for capacity sharing, make sure that the resulting scheme does not lead to unintended consequences, such as a sustained shift of capacity provision from one partner to another.
Literature references and methodology

The study is part of a wider research project called CADENZA funded by the European Commission (Horizon 2020). The project is a joint endeavour with various partner universities, Eurocontrol, and industry advisors.

  • Künnen, J.-R./Strauss, A./Starita, S./Fichert, F./Ivanov, N./Jovanovic, J. (2021): Cross-border capacity planning in air traffic management under uncertainty, not published yet.

Jan-Rasmus Künnen

Jan-Rasmus Künnen is a research assistant at the Chair of Demand Management & Sustainable Transport at WHU. His research interests lie in applying quantitative methods (optimization, game theory, modeling) to transportation and logistics problems. With his PhD, he focuses on developing mathematical models to balance demand with capacity in European air traffic management. He worked previously as a consultant with McKinsey & Company, specializing in supply chain and operations transformations.

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Prof. Dr. Arne K. Strauss

Prof. Dr. Arne K. Strauss holds the Chair of Demand Management & Sustainable Transport at WHU – Otto Beisheim School of Management. He specializes in the application of mathematical models to business problems, with a particular focus on the area of demand management and transport. Previously, he held positions as Associate Professor of Operational Research in the Operations Group at Warwick Business School and as Turing Fellow at the Alan Turing Institute in London. He has won several awards for his research, and he currently serves on the Strategic Advisory Team (Mathematical Sciences) of the British Engineering and Physical Sciences Research Council.

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