NATS Objection Evalution - Blackstone Edge Wind Farm Case Study
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Blackstone Edge Wind Farm


The Blackstone Edge wind farm comprises 3 turbines and has an installed capacity of 7.5MW. During the planning stages of the development, concerns were raised due to the potential impact on a primary surveillance radar (PSR) installation operated by UK air traffic service provider NATS.

Developer E.ON UK selected Pager Power to investigate the extent of operational effects and determine the likelihood of a planning objection.


Planning objections to wind turbines have the potential to delay projects, significantly increasing the cost and the risk of a project. Operators of PSR radar can object to wind developments up to 100km away or even further in some cases.  A common issue is the potential for clutter. This is caused by turbines being in line of sight to radar.

The Blackstone Edge wind farm received concerns from NATS about the potential impact of the turbines on the Claxby PSR. Pager Power evaluated the radar coverage and wind turbine detectability for PSR sites contained within a specified range (250km), with additional use of the NATS online self-assessment tool. The results confirmed that the Blackstone Edge development would be visible to the Claxby PSR, causing possible clutter.

The Challenge

The main challenge associated with this project was finding a solution to mitigate any possible effects on the Claxby PSR. This solution would also need to be accepted by all parties.

The Process

After completing the initial radar analysis, it was followed up with cumulative impact analysis of operational and consented wind farms in the area. This assessment identified Royd Moor; a larger existing wind farm thought to be detectable by Claxby PSR.

The cumulative assessment was then used to put forward the case that Royd Moor would generate more significant radar screen clutter than the smaller, adjacent Blackstone Edge proposal.

An assessment of the airspace in the vicinity of the site was also conducted, in order to identify any likely concerns of NATS En-Route Limited (NERL).

The Solution

Pager Power proposed that any mitigation technique applied at Royd Moor could be applied at Blackstone Edge. However, if this were not the case we proposed that an alternative mitigation strategy could be blanking an area of the radar display that had potential to be affected by the clutter – often just called ‘blanking’.

The Result

Blackstone Edge was granted consent in April 2009, and became fully operational almost 4 years on in March 2013.

Figure 1: Blackstone Edge Wind Farm location

Figure 2: Claxby PSR

Figure 3: Claxby PSR

Figure 4: Royd Moor Wind Farm


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