Controlled Shutdown Radar Interference Mitigation
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Mitigating the effects of wind turbines on radar interference with Controlled Shutdowns

Mitigating the effects of wind turbines on radar interference with Controlled Shutdowns
November 30, 2016 Mike Watson


Wind turbines affect aeronautical radar which means that airport and defence authorities often oppose wind farm developments resulting in wind development being prevented. Pager Power has been helping wind farm developers manage and resolve these issues throughout the world since 2002.

Aerial view of a wind farm - wind turbine radar mitigationFigure 1: Wind Farm


Radar mitigation reduces or eliminates the impact of wind turbines on radar systems which can then enable previously opposed wind farm developments to be approved and built. There are many possible radar mitigation solutions including fitting radar filters, optimizing the wind farm layout and changing air traffic operations.

Controlled Shutdowns

Controlled Shutdown Mitigation involves stopping the wind turbines rotating so that they do not affect the radar when aircraft are being controlled nearby. This mitigation can be effective when the wind turbines’ effects can be tolerated most of the time with the wind turbines being shut down occasionally for short periods.

Implementation Issues

This form of mitigation has often been explored but not subsequently implemented. This is due to the issue of who has control of the wind farm’s operation. Should it be the radar operator or the wind farm owner?

Radar operators are naturally concerned they cannot stop the turbines quickly, frequently or for sufficient time. Similarly wind turbine operators are concerned about the loss of generation and the consequent inability to predict income. In practice this can make it impossible to finance and develop wind farms subject to Controlled Shutdown Mitigation.

Practical Solutions

Nevertheless, these issues have been resolved effectively in the United Kingdom and Germany. For wind farms affecting civil radar in the United Kingdom contractual arrangements have been used whilst for wind farms affecting military radar in Germany technical arrangements have been successful. The two approaches are compared in the table below:

Control United Kingdom Civil Germany Military
Wind turbine shutdown mechanism Controlled Stop
Wind turbine shutdown initiation Wind Turbine Operator Radar Operator
Wind turbine start-up mechanism Controlled Start
Wind turbine start-up initiation Wind Turbine Operator Automatic after fixed programmable time delay

Operational Experience

Experience in Germany is that the total wind turbine shut-down time has been less than expected. The German system gives the radar operator greater control and results in a reduced overall wind turbine shutdown time. The UK system ensures that wind turbine projects can be financed more readily because there is an absolute cap on annual shut-down hours.

Further Information

If you think we may be able to help you with radar interference or aeronautical objections please call Mike Watson for a confidential no obligation discussion on 00 44 1787 319001 or email

More information regarding the automated shutdown systems can be found (in German) at the websites below:

Image accreditation: “Windmills along the Columbia River Gorge” by Sam Beebe via Flickr / CC BY 2.0 / Image cropped and resized from original.


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