Fact sheet: Wind power facilities and their impact on Swiss air traffic control

Ever since the Swiss Federal Council resolved in mid-2011 to switch in the medium term to alternative energy sources for the country’s power supplies, skyguide has seen a marked increase in the number of requests it receives to conduct impact assessments for wind power projects. Skyguide performs such studies because the wind turbines required can interfere with the company’s air navigation services (ANS) installations such as radars, navigation aids and other ground equipment. So in the interests of maintaining the safety of all flight operations, and before their construction is approved, skyguide must carefully analyse the potential impact of any such wind power facility on its ground installations.

Interference with technical installations

Skyguide maintains various ground installations throughout Switzerland that are essential to performing its mandate of managing and monitoring the traffic in its airspace to ensure safe flight operations. Its radars constantly track the positions and movements of all the flights concerned, its transmitters and receivers ensure effective communications with their pilots, its navigation aids guide the pilots through the airspace, and its instrument landing systems enable them to approach and land in total safety whatever the weather conditions. Needless to say, if optimum safety is to be maintained in all such flight operations, every effort must be made to ensure that nothing interferes with the full and proper functioning of all these ANS facilities. A wind turbine, for instance, can reflect, distort or block the electromagnetic signals emitted by an ANS installation. As a result of Switzerland’s topography, such facilities can also affect technical installations and their signals even from far away. This is why it is vital to determine in advance whether a projected wind power facility will be compatible with the existing ANS installations.

Individual impact assessments

For every concrete wind power project that is proposed, skyguide will conduct a separate impact assessment. This will look at two key issues: whether the facility projected is likely to interfere with skyguide’s technical installations, and whether the structure planned will exceed the legal maximum height of any object in the relevant airspace safety zone (this is particularly important in the areas around airports, to prevent any risk to aircraft that are climbing or descending and are thus close to the ground). This detailed analysis must be conducted in compliance with Articles 2 and 63 of the Swiss Ordinance on Air Transport Infrastructure (in French, in German). If the only problem found is that the wind power facility planned is too tall for the site proposed, skyguide will suggest that this can be solved by resizing or relocating the facility. Skyguide may also propose further ways of mitigating any problems posed if these seem to be viable.

In the interests of flight safety

Skyguide is mandated by the Swiss government to ensure the safety of the traffic using Switzerland’s airspace and the adjacent airspace areas of neighbouring countries that have been delegated to its control. To fulfil this mission, skyguide must ensure that its technical installations are not compromised in any way by any external influences, and that due regard is paid to all the building restrictions relating to the relevant airspace safety zones. If this is not the case with a particular wind power facility planned, skyguide will recommend that the project be rejected.


Skyguide conducts its impact assessments on behalf of the commissioning party, and submits them to the Swiss Federal Office of Civil Aviation. It is the FOCA that takes the final decision on whether the project proposed should be given the green light to proceed.

Future technical solutions

There are various ways and means of reducing the interference caused by wind turbine facilities. Some of these address the way the turbine is built, such as the materials used. Others focus on the ANS installations affected: newer-generation radars, for instance, are easier to calibrate that their older counterparts. Above all, however, each and every case has to be carefully analysed individually.


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