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Punctuality: in time for a new departure

The punctuality of an aircraft depends on many factors, some of which can be controlled by air navigation management (grouped under the acronym CRSTMP - C-Capacity, R-Routing, S-Staffing, T-Equipment, M-Airspace management, P-Special events) and some - such as the weather - are beyond anyone’s control. Other factors are dependent on airport services. In all circumstances, in flight or on arrival at an airport, skeyes manages traffic in order to keep delays to a minimum and thus reduce costs for its customers, waiting times for passengers and the environmental impact.



of flights were managed in a punctual manner by skeyes in 2020

En-route delays

0.06 min / flight

= 3.6 seconds delay per flight

Average en-route ATFM delay per flight (CRSTMP causes). This figure represents the average delay per flight caused by skeyes’ en-route air navigation services. This delay occurred in the first quarter of 2020, before the impact of the health crisis on traffic volumes.

0.14 min / flight

= 8.4 seconds delay per flight

Average en-route ATFM delay per flight in FABEC airspace (CRSTMP causes). FABEC comprises six countries (Belgium, France, Germany, Luxembourg, the Netherlands and Switzerland) and manages more than 55% of European air traffic. skeyes’ performance in terms of en-route punctuality helped reduce the average en-route delay in FABEC.

Arrival delays at airports

To assess the performance of air navigation in terms of airport punctuality, only arrivals are taken into account. The timely departure of an aircraft is dependent on many other factors - such as ground services (baggage, refuelling, etc.) - which are beyond skeyes’ control, but which are coordinated with skeyes through an information exchange application based on the concept of Airport CDM (Collaborative Decision Making) and developed by skeyes. This application - the AMS (Airport Movement System) - makes it possible to effectively manage not only airport air traffic control activities but also the coordination of all ground services in order to optimise traffic flows at airports.

0.37 min /flight

= 22.2 seconds delay per flight on arrival at Brussels Airport for all causes.

90.8% of these delays are due to weather conditions.

0.03 min /flight

= 1.8 seconds delay per flight on arrival at Brussels Airport if only the CRSTMP causes that skeyes can control are taken into account.

Antwerp Airport
0 min /flight

= 0 seconds delay per flight

Brussel South Charleroi Airport
0 min /flight

= 0 seconds delay per flight

Liege Airport
0.15 min /flight

= 9 seconds delay per flight

Weather conditions are the sole cause of arrival delays at Liege Airport (100%).

0 min /flight

= 0 seconds delay per flight

if only the CRSTMP causes that skeyes can control are taken into account.

Ostend-Bruges Aiport
0 min /flight

= 0 seconds delay per flight

Procedures to limit the impact on the environment

Coordinating activities at the airport to effectively manage traffic flows also has a positive impact on fuel consumption and therefore on emissions, local air quality, noise and costs for airlines. Aircraft engines are started up at the right time and waiting times on taxiways are kept to a minimum.


of departing aircraft at Brussels Airport have received approval to start up their engines at the expected time (TSAT - Target Start-up Approval Time)


of aircraft at Brussels Airport taxied between the runway and their stand in less than the average time required (VTT - Variable Taxi Time)


Green landings (CDO - Continuous Descent Operations)

Another way to reduce aircraft consumption is to 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.

Collaborative Environmental Management

The objective of Collaborative Environmental Management (CEM) is to strengthen cooperation with airlines and airports in order to take joint initiatives that reduce the environmental impact of airport operations.

At Brussels Airport, since its launch in 2018, CEM has delivered very good results, including the improvement of green landings (CDO), the reduction of low-altitude holding, single-engine taxiing on the airport’s taxiways, etc.

In September 2020, CEM was launched at Liege Airport in partnership with SOWAER (Société Wallonne des Aéroports) and the main airlines operating at Liège Airport. First project planned: the improvement of CDOs to reduce noise pollution and fuel consumption.



of landings followed the green landing procedure at Brussels Airport in 2020



of landings followed the green landing procedure at Brussels South Charleroi Airport in 2020



of landings followed the green landing procedure at Liege Airport in 2020


Ever shorter trajectories

Airspace structure and air routes are very important elements in the optimisation of traffic flows. The shortest possible trajectories routes are advantageous in terms of fuel consumption and emissions but also often in terms of cost for airlines. skeyes supports them by conducting projects primarily on two fronts: civil-military cooperation and the reorganisation of airspace.

Civil-military cooperation

Almost half of Belgian airspace consists of military training and operations zones. These zones can be made available to civil air traffic when they are not put to military use with the benefit of it being possible to offer airlines much more direct routes. The safety of these operations requires seamless coordination in accordance with Flexible Use of Airspace (FUA) procedures. skeyes and the Belgian Defence are working ever more closely together to improve this coordination as well as in other areas such as training or Aeronautical Information Management with the publication of a joint AIP.

On 2 December 2020, skeyes and the Belgian Defence celebrated the first anniversary of the colocation of civil and military air traffic control in the CANAC 2 air traffic control centre in Steenokkerzeel. This colocation greatly facilitates coordination and work for the joint management of Belgian airspace. In June 2020, an important step was taken towards increased civil-military cooperation in air traffic control services with the commissioning of the new “supervisor suite”. This workstation is the heart of the operations of the CANAC 2 air traffic control centre and it now brings together skeyes and Defence supervisors, which is a key factor for continued cooperation between the two partners. Through direct interaction between supervisors, coordination and communication are faster and clearer, enabling the needs of both parties to be met for the even more optimal use of airspace.

As part of the flexible use of airspace in Belgium, the Airspace Management Cell (AMC) has been operational since 21 September 2020. It is a civil-military airspace management unit in which continuous consultation is crucial. CIV-MIL coordination ensures that airspace safety and capacity increases and that civilian and military air operations are more efficient and flexible.

Reorganisation of airspace

In December 2020, the Sector 3 project was finalised and put into operation. It involved making significant adjustments to the airspace referred to as “Sector 3” in the Netherlands. skeyes has worked closely with LVNL since early 2018 with the aim of optimising air navigation in the very busy airspace over the Netherlands and Belgium.

The operational objective was to reduce the high workload in the current segmentation of airspace managed by the Amsterdam control centre within Sector 3 by reconfiguring it and reorganising the corresponding traffic flows to airports such as Amsterdam, Eindhoven and Rotterdam.