Wind Power in the UK (PDF). - Sustainable Development Commission

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Wind Power in the UK (PDF). - Sustainable Development Commission

10 Aviation and radarsevere as those caused by existing road traffic,chimneys, and buildings around the airport. Inrelation to the primary radar clutter, the trackprocessing applied in the airport's radarsuccessfully mitigated the effects, while the SSRfalse plots were dealt with using a proprietaryEurocontrol software tool.The Dutch and Danish experience illustrates thepotential for regulatory policy and air trafficcontrol experience to accommodate windturbines in proximity to radars. However, thedifferent experience from the UK is explained inpart by differences in the structure of airspaceand the way in which it is managed. Thesedifferences include:• The UK has more extensive uncontrolledairspace within which wind turbines have agreater potential impact• The Danish and Dutch ATC authorities routinelycontrol en route traffic using SSR only• Due to uncertainties about its ability to displaynon co-operating aircraft, the UK CAA does notpermit reliance on the type of track processingsoftware used in Denmark and theNetherlands.There is also growing experience of co-existenceof wind turbines and radar in the USA. At PalmSprings in California, clutter problems on anolder generation primary radar which hasaround one thousand wind turbines within itscoverage were addressed by the installation of anew solid-state radar in 2001. The new radarhas been able to provide a full radar service toaircraft crossing the wind farm area. Howeversubsequent investigation found that, in practice,the service over the wind farm area was beingprovided using SSR only. This would not beacceptable to the regulatory authorities in theUK due to the policy that in normalcircumstances an aircraft's radar identity mustbe confirmed and maintained using at leastprimary, and, where available, primary andsecondary radar. Routine controlling using SSRonly is only permitted in certain less busy partsof the upper airspace where proceduralseparation between aircraft can be applied inthe event of radar failure.10.7 Mitigation measuresA number of mitigation measures are availablethat could reduce the conflicts between winddevelopments and aviation/radar concerns:Operational measures• Increasing controlled airspace• Avoiding areas of significant air traffic controlinterest• Introduction of Mode S secondary surveillanceradar• Limiting radar service in uncontrolled airspaceTechnical measures• Range-azimuth gate mapping (RAG mapping)• Temporal threshold processing• Clutter maps• Track processing• Placing antennae at an elevation that raisesthe radar beam above the wind farm• A number of technical design improvements,such as radar absorption by turbine bladesFurther details on some of these measures canbe found in Annex C. The DTI-funded AMSFeasibility Study (due to be published in June2005) aims to specifically identify and evaluatetechnical software and hardware mitigationtechniques which will then be assessed by theMOD.104 Wind Power in the UK sustainable development commission