skeyes is very committed to reducing the environmental impact of aviation. Although the potential contribution of air traffic management to this reduction is only estimated at 6%, each action reinforces the overall efforts. To achieve the objectives of the European Green Deal, skeyes continues to implement its Environmental Action Plan, develops projects, applies new procedures and collaborates with its partners. All phases of a flight – ground movements, take-offs, en-route, approaches and landings – are optimised to reduce consumption or noise. The granting of the GreenATM level 4 accreditation of skeyes in 2025 – a world premiere - demonstrates its strong and permanent ecological commitment.
En-route: as close as possible to the ideal trajectory
Reducing the environmental impact of aviation is one of the objectives of the Single European Sky legislation (SES). The FABEC performance plan therefore includes a performance indicator which consists of measuring the horizontal en- route flight efficiency (KEA – Key Performance Environment Indicator based on Actual trajectory). This indicator applies only to FABEC as a whole and compares the actual trajectory followed by an aircraft, the trajectory planned in the flight plan and the shortest route provided by the Network Manager (EUROCONTROL). This results in a score that corresponds to the horizontal flight-inefficiency, i.e. a percentage of deviation from the most environmentally friendly ‘ideal’ route.
actual horizontal flight inefficiency score in FABEC in 2025. Despite an improvement compared to 2024, FABEC barely misses its objective, which remains very ambitious, given the density of traffic to be managed and the complexity of its airspace.
3.06%
This is the horizontal flight inefficiency threshold that FABEC must not exceed under its performance plan. This threshold has been lowered compared to the previous reference period and the level of requirement has therefore been strengthened.
2.89%
96,94%
of horizontal flight efficiency in FABEC. Most flights in FABEC follow the most environmentally friendly path.
96,65%
In Belgian airspace, the vast majority of flights take the most efficient route.
+3,74%
compared with 2024.
horizontal flight inefficiency target not to be exceeded in the Belgian airspace jointly managed by skeyes (for the lower airspace below 24,500 feet) and MUAC (for the upper airspace). After a reassessment taking into account the overall FABEC network and local constraints such as the complexity and density of airspace, the level of requirement was lowered for Belgian airspace for this 4th reference period.
3.50%
inefficiency score in 2025 in Belgian airspace jointly managed by skeyes and MUAC.
3.35%
For skeyes, the room for ‘en-route’ manoeuvre is reduced due to the structure of the airspace it manages. It is small, limited to an altitude of 7,500 metres and crossed by numerous (training) areas reserved for military staff with whom skeyes coordinates the sharing of airspace by applying the Flexible Use of Airspace principle. skeyes meets regularly with its FABEC partners in the FABEC Standing Committee Environment permanent working group to develop operational solutions for environmental optimisation.
For the first time this horizontal flight efficiency target has been achieved in Belgian airspace.
The horizontal flight efficiency score has improved by 8% in FABEC since 2019, highlighting the effectiveness of cooperation and environmental measures. The comparison is made with 2019 because the years that followed were marked by disruptions related to the global health crisis.
8%
This improvement since 2019 has reached 13% in Belgian airspace.
13%
Green Landings (CDO - Continuous Descent Operations)
The approach phase is very fuel intensive. In a conventional approach, the aircraft descends in stages. To avoid stages and reduce aircraft consumption, air traffic controllers can manage air traffic so that aircraft can be landed using the Continuous Descent Operation (CDO) procedure. The CDO - also known as green landing - is an operation in which the aircraft descends continuously, employing minimum engine thrust to the greatest possible extent, depending on the characteristics of the flight and the air traffic situation. This enables a reduction in noise pollution, fuel consumption and greenhouse gas emissions.
80%
of landings followed the green landing procedure at Brussels Airport in 2025 (-1 percentage point compared to 2024).
75%
of landings followed the green landing procedure at Brussels South Charleroi Airport in 2025 (+2 percentage points compared to 2024).
68%
of landings followed the green landing procedure at Liege Airport in 2025 (-1 percentage point compared to 2024).
Number of CDOs in absolute terms relative to the number of landings in 2025
Working closely with partners in Collaborative Environmental Management (CEM), skeyes developed new environmental indicators for CDOs in 2023. Thus, the average levelling-off time below an altitude of 10,000, 6,000 and 3,000 feet is recorded in order to study targeted improvement actions.
towards sustainable aviation