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Effect of Wind farms on radar?

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Effect of Wind farms on radar?

Old 29th Nov 2012, 16:18
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Effect of Wind farms on radar?

Hi,

I have previously posted on PPRuNe regarding my dissertation: the effect of wind farms on aviation. I'm looking for some more responses from ATC on their view of them. Various papers and websites have announced the growing fears for aviation safety from increased wind farm development due to clutter, shadows etc. on radar. However, I'm interested in your view and if you have ever experience problems of clutter. Or maybe you think they aid pilots as navigational sources for G/A? I would appreciate any ATCO, or pilot who could let me know their personal view:

https://docs.google.com/spreadsheet/...JhUUE6MQ#gid=0

Thanks in advance!

Mike91
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Old 29th Nov 2012, 16:46
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From an SSR point of view, you won't have an issue, but primary is where it begins to have issues. It will appear as a primary contact which under DS rules, need to take 5 miles laterally. Having small collective groups of windfarms will appear as large contacts, smaller ones may look as clutter. With more turning up over the country, it will be more strain on ATCO's and Aircrew to get them to avoid (or achieve best effort) on these contacts.
As for VMC conditions, yes they're probably a good tool for navigation, but I'd think the negatives would begin to out weight the positives in terms of Air Traffic

D.
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Old 29th Nov 2012, 16:58
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Dagowly,

Thanks for that!
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Old 30th Nov 2012, 18:41
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It will appear as a primary contact which under DS rules, need to take 5 miles laterally
Well, not quite. MATS Part 1 advises:
In the event of clutter being present on the situational display controllers should consider the nature and extent of the clutter and if necessary take the following actions:
a) For aircraft in receipt of a Deconfliction Service, controllers should inform the pilot of the extent of the clutter and where practicable offer a reroute. However, this may not be possible due to traffic density, airspace availability and/or the requirement to follow specific arrival or departure tracks. The extent of such a reroute should where possible aim to achieve the planned lateral deconfliction minima from the observed clutter. However, it may still be necessary to reduce traffic information/deconfliction advice from the direction of the clutter as detailed at Section 1 Chapter 11.
Note the "if necessary", "where practicable" and "where possible".
NS
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Old 30th Nov 2012, 22:10
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<<It will appear as a primary contact >>

MTI? (Or modern version of?)
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Old 30th Nov 2012, 23:20
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HD.....If the blades are rotating there is a potential for false plots or tracks.
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Old 1st Dec 2012, 00:43
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the main issues can be:

primary plots
due to the massive size of the rotors and their movement, these can cause radar reflections which then pass through the low speed filters (>50kn), high speed filters (<500kn) and moving target filters.

track initiation
a big issue for us is cumulative impact where 1 or 2 turbines may be allowed, but no more as a third one or more could lead to circumstances where 3 or more adequately spaced plots are created, and a track may be generated.

track seduction
similar to the above issue, but where the tracker may have a real a/c track which then ends up using turbine plot/s in its tracking giving rise to losing the aircraft and tracking the turbines for a few sweeps, or potentially split tracks

Radar Processor loading issues
the number of plots the radar can deal with are defined by design but you can imagine how many plots you may get from 200 x 125m turbines visible to radar.

Impact on the Probability of detection of aircraft behind the turbines as some of the outbound energy is reflected/lost due to the turbines effectively placing the aircraft to be detected in its shadow.

These are all Primary radar issues.
When this all gets a bit confusing, just remember that a radar is designed to pick up a C152 at 150nm by bouncing some radar energy off it and figuring out if it's speed is sensible.

Now replace that C152 with something on the top of a hill, staring at the radar, that's maybe 125m tall and a 40-50m blade that's spinning at reasonable speeds. If in doubt, place another 50 nearby.

It's funny but if you wanted to trick a radar into seeing an airplane, you'd probably design something big, flat, that moves and why not place it somewhere high up where it can be seen 100km away.

Historically radar was here first, which is why the issue is now with the wind industry who have to address ATC issues...had it been the other way round, I doubt we'd be using PSR today!

With SSR we have azimuth error due to the radar pulse being deflected and the aircraft responding from where it really is.

With VOR and Comms we have straightforward interference which can cause bearing errors in VORs.

It can cause loss of comms/interference in AGA comms, especially where the turbine is between the TX/RX and the aircraft. This is a lot worse in scenarios where you have low flying aircraft (e.g. MIL or Oil rig helicopters) at a range (100km).

Basically, they have a pretty negative impact if their position is not considered. To this effect, the UK Safeguarding Direction requires NATS and MOD to be consulted on all wind turbines irrespective of size and location anywhere in the UK. BAA and all other airport operators define the areas for which they are to be consulted as their radar range varies.

CTG

Last edited by cleartouchandgo; 1st Dec 2012 at 00:55.
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Old 1st Dec 2012, 00:58
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Yet another example of a so-called “scientific study” using the name of an educational establishment to give it credibility.

Safety and aesthetics are completely different subjects and yet the questionnaire combines both. As with all surveys, it’s the question not the answer and this one is heavily weighted to produce an anti-windfarm response.

There is no question to determine the difference between ground clutter of nuke and coal fired power stations compared to wind farms and pilots & ATCO’s opinions of commercial & visual impacts (with answers provided) has nothing to do with aviation safety.

A genuine scientific study wouldn’t ask for opinions. It would carefully evaluate results from radar technicians and properly conducted tests.

Next Daily Fail headline; “Air traffic controllers report windfarms are a danger to aviation safety”

You’ll have to do better than that, son.
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Old 1st Dec 2012, 03:42
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I understand the radar(s) at Glasgow airport are affected by reflections from local windfarms, but what form this interference takes I don't know.
Manston ATC have instigated the establishment of a Transponder Mandatory Zone off North Foreland/Isle of Thanet due to clutter caused by the vast offshore windfarm.
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Old 1st Dec 2012, 08:51
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difference between ground clutter of nuke and coal fired power stations compared to wind farms
that's the issue....nuke and coal fire stations will not generate clutter, they will be like other fixed obstacles such as buildings, bridges, hills etc. It all gets filtered out as any reflections will always be in the same place and will not have any varying frequency component due to the movement.

Wind turbines are moving and that's the key issue, if they didn't they'd be filtered out like any other fixed obstacle....effectively they are the same as an aircraft, only much much bigger and often closer, and more of them.

“Air traffic controllers report windfarms are a danger to aviation safety”
well...not quite but it's only about
serious safety risks for air traffic
(Air traffic objection to proposed wind farm near East Heslerton (From Gazette & Herald))
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Old 1st Dec 2012, 08:57
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about Offshore etc, this can be less of a problem if the airspace is not used by GA and MOD. With the Greater Wash wind farm, a TMZ consultation was held and the CAA has gone ahead with it.

http://www.caa.co.uk/docs/2111/20120...etterGWTMZ.pdf

This means that the whole windfarm can now be filtered out in Primary radar. This obviously means that anything flying over the top of it will not be seen, and that's why you mandate a transponder.

Try to do that in the South East and it would be different! GA wouldn't agree and ATC wouldn't be happy without being able to see infringers etc.

Again, the effect of Windfarms on radar is a single plot, a few plots moving/twinkling around, or at worst a whole area of radar picture blighted with dozens of false plots. If air traffic flies towards another plot, what should the controller do?

Even if they know it's a wind farm?...just go ahead? or maybe assume it could be something else? What if that plot appears near final approach to a RWY where you are vectoring 2-3 aircraft? Just ignore it? or vector around it and break up all your careful planning, extend miles, create a more complex situation or even worse conflict?

that's exactly the point....

here are some FAQs from the Scottish Govt.
Aviation and radar - Department of Energy and Climate Change


CTG
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Old 1st Dec 2012, 10:04
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Safety and aesthetics are completely different subjects and yet the questionnaire combines both.
The guy's doing an Environmental Geography degree, both areas seem perfectly legitimate to me.

As with all surveys, it’s the question not the answer and this one is heavily weighted to produce an anti-windfarm response.
All of his questions asking for an opinion offer the same range of equally weighted agree/disagree responses. Why would you consider that to be skewed ?
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Old 2nd Dec 2012, 19:04
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North South - Problem is, on our radar screen they appear as a group of solid primary contacts which are quite large, if it appeared as clutter, you're right, then it would be a different situation.
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Old 2nd Dec 2012, 19:06
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HD.....If the blades are rotating there is a potential for false plots or tracks.
Correct, where most computers will remove a contact that doesn't move - anything large enough that moves will appear.
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Old 2nd Dec 2012, 19:29
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When the 23cm radar was installed at Heathrow, every time it swept past the tower we heard loud bleeps in our headsets. Tels rapidly arranged for the signal to be surpressed as it swept past the tower and the problem was solved. Surely it must be possible to remove a known stationary target even if it does have a propellor on it?
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Old 2nd Dec 2012, 19:53
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I remember driving out of the LHR tunnel either with AM radio on or a VHF scanner and you could hear the "zap".

Yes, you can disable the radar in a certain azimuth, it is routinely done if a radar is close to a residential area. Unfortunately if you look at the situation in Aberdeenshire for example, you´d see that the radar tower would be useful as a nice flower pot stand or water tank but little else.

NATS/MOD receive more than 3000 consultations each year, ok, they are quite geographically sensitive with the north significantly "worse" than the south but these things are flourishing.

Here's a snapshot.... but may not include single farm type turbines, we're quite lucky down south, but you'd be scared at how many of these things are around in other areas.

Every windfarm mapped - and the MPs who hate them | News | guardian.co.uk

CTG
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Old 8th Dec 2012, 17:33
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Wind Farms and Radar

Wind Farms do cause returns on primary radar because whilst the turbines themselves are stationary the blade tips have speeds of over 100 knots meaning that radar returns have enough doppler shift to pass through MTI filters.

These effects can be readily observed on a variety of radar screens in the UK on a regular basis. For some radar wind turbines can be in radar line of sight but may not appear on radar screens if they have been removed with blanking or some other form of filtering.

Whilst wind turbines can theoretically affect SSR, VORs and AGA radio as far as I know there are no records or experience of this happening in practice.

The best single publication on this subject is the CAA's CAP764 "CAA Policy and Guidelines on Wind Turbines". Just put CAP 764 in a search engine of your choice and you should be able to find it. There are many others.

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