'Green' landings at Brussels Airport

March 21, 2012

Belgocontrol, Brussels Airlines and Brussels Airport have jointly developed a new environmentally friendly landing technique. This technique, consisting of a more streamlined approach, results in less fuel consumption, less emissions and even in less aircraft noise. This was confirmed by numerous tests conducted last year by the three partners with the support of the EU in the framework of the international AIRE programme and SESAR.

The airspace above Belgium is generally considered to be the most complex and busiest of Europe. Air traffic to and from various civil airports (Brussels Airport, Charleroi, Liège, Ostend, Antwerp, Schiphol, Paris CDG, London, Frankfurt, Cologne, Dusseldorf) crosses the Belgian airspace. Moreover, the military aeronautical activities around four military bases claim their routes in the airspace. In this context it is not easy to conduct optimal landings. That is why airplanes need to approach the airport in steps.  In  such a stair-step approach, pilots constantly need to increase and decrease the thrust of the aircraft engines. Therefore, airplanes consume more kerosene and emit more CO2 than in a continuous descent. Moreover, the frequent changes in thrust result in extra noise and are experienced as uncomfortable by the passengers.

Continuous Descent Operations

In the autumn of 2010, Belgocontrol, Brussels Airlines and Brussels Airport formed a consortium (‘B3’) that was faced with the challenge of developing and testing a procedure that increases the number of green approaches. A green approach, called a ‘Continuous Descent Operation’ (CDO) in aviation jargon, means that an approaching aircraft descends according to a continuous vertical profile. In doing so, the airplane operates with reduced engine power.
The tested procedure implies that, when the air traffic situation permits a CDO, the air traffic controllers provide the pilots with adapted information for this operation. More specifically, air traffic control provides the distance to be flown and, from a certain height onwards (3,500 metres on average), authorizes the pilot to determine the optimal point to commence the descent in a continuous way.

The B3 partners requested and obtained support for this ambitious test project. In the framework of the AIRE programme (Atlantic Interoperability Initiative to Reduce Emissions),  SESAR (Single European Sky ATM Research) decided to liberate funds to develop the CDO concept, execute test flights, make air traffic controllers and pilots aware and measure the results of the green landings.

The B3 test phase took place between 1 January and 30 October 2011. Besides Brussels Airlines, four other airlines participated in the tests: Thomas Cook Airlines, Jetairfly, DHL and Singapore Airlines Cargo.

Air traffic around Brussels Airport is extremely dense, which made the challenge particularly tough. For example, the Continuous Descent Operations procedure, demanding a high level of co-ordination between all participants, can for the time being only be performed at a distance of 70 to 15 kilometres from the runway. Because of the required standard separations between airplanes, the procedure could not be applied at all times. During the test phase the new procedure could be applied to 9% of participating flights. In total over 3,000 flights were concerned.

Significant green results

A thorough analysis of these tests have shown that the impact of these green landings on fuel consumption and CO2  emissions of aircraft that participated in the test is significant.
On average, one medium haul aircraft (Airbus A319/A320) consumed 50 kg less fuel and emitted 160 kg less C02 . For long haul aircraft these environmentally friendly economies even ran up to 100 kg of kerosene and 315 kg of CO2. By way of comparison: this decrease in CO2 at the approach of a long haul aircraft equals the CO2 emission of a trip by car of over 2,000 kilometres.

If today 9% of all aircraft approaches on Brussels Airport would be performed using a Continuous Descent Operation pattern, this would lead to a CO2 decrease of at least 1,700 tons and a fuel economy of 550 tons.

Noise abatement

To measure the full effect of the Continuous Descent Operations on the environment, the engine noise of these flights was studied by the University of Leuven. In the area beyond 15 kilometres from the airport, they calculated a noise reduction of 2 dB(A) for medium haul aircraft and 3 dB(A) for long haul aircraft.

Next step

Now that the test phase of the B3 Continuous Descent Operations project has been successfully completed, the next step is to incorporate this green landing technique in the official procedures so that all airline companies landing at Brussels Airport will be able to apply this working method. Of course, these procedures will only be followed at times when air traffic permits for it.

“We realise that we, major representatives of the Belgian aeronautical sector, have an important  role to play in the environmental debate”, the B3 promoters state (Belgocontrol, Brussels Airlines, Brussels Airport). “With this project, we have taken full responsibility to progress towards safer and greener air transportation, and we are fully committed to continue to do so.”  

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