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Wind Farms & Aviation Safety

Old 8th Oct 2007, 16:57
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Wind Farms & Aviation Safety

Here in the UK our government ministers, and politicians of all parties, whose total knowledge of electrical power generation would probably fit on a pinhead, have decided that we are to have nation-wide eco-friendly power sources.
This means that there will be thousands of large wind turbines on land, and hundreds of ‘wind farms' with even bigger wind turbines offshore around the UK. Another favoured idea is that every building in the UK will be covered in solar panels.
I am wondering also if any of these people have given a single thought to aviation safety. A ‘Google’ through the UKs websites detailing these things shows that, although shipping safety around off-shore wind farms has been addressed, aviation safety is not even mentioned. Of course, the fact that a bird has been killed by a wind turbine did get a mention!
Just imagine you are a GA pilot heading for Britain in poor visibility. Will you fly high enough to avoid our huge wind turbines – up to 70 m (230 ft) high, with 50 m (165 ft) blades, or will you even see them through the murk? As a stranger to these shores, will you be expecting huge structures in the sea taller than the largest ship?
And where is the collision avoidance beacon installed on a wind turbine? If it is on top of the tower, that is not the highest point. Each blade will, at some point in the revolution, be higher than the tower. So, should a beacon be fitted on the end of each turbine blade?
No doubt the UK CAA and military know of the problems, and aviation charts will highlight the obstructions. But already a number of planes and helicopters entering UK airspace have come to grief approaching high ground.
So who will be the first pilot to collide with a wind turbine or wind farm? Obviously, solar panels would not be dangerous but, even then, flying over the UK will require the wearing of sunglasses (shades), because of the glare from all those solar panels!
In spite of my light-hearted post, some serious discussion on the World-wide introduction of ‘alternative energy’, and its effect on air movements, would be a good thing. Have you had a problem with wind turbines in or around your country? What do you think?
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Old 8th Oct 2007, 20:46
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We have just spent 2 years fighting the placement of a 300 foot high wind turbine on base leg of our airfield.

The wind farm people have no interest in saving the planet only in huge government grants and making a profit. The lies and deceit they indulged in to get this turbine past the planners beggers belief.

The sad truth is that yet again the CAA were nowhere to be seen. What price flight safety.
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Old 9th Oct 2007, 16:33
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Up here in the North East, Newcastle Airport regularly object to any wind farms in radar range because of the possibility of confusion. However, in Germany last year saw some massive wind turbines almost on the door step of Hahn. Is the impact on radar returns that significant?
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Old 9th Oct 2007, 21:04
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The impact on radar is indeed significant and presents the single biggest challenge to wind farm proliferation in the UK. The turbines are clearly visible to radar, as the blades move at speeds that fall within the detection thresholds. Already there have been numerous public enquiries dealing specifically with wind versus aviation. The spread is significant, Defence Estates deal with in excess of 1000 enquiries per year on behalf of MoD and I don't know of any airports who are not currently dealing with a wind application. The flip side is that generally the wind energy guys are pretty good and willing to listen to the genuine concerns of airports.

As far as obstacles are concerned, the point about lighting is a good one and something I was discussing with a developer last week. They only tend to be lit when in the vicinity of an airfield (and even then only when the airfield insist). However, they are on charts so no sympathy to any numpty who elects to fly into one (although I'd love to be there to watch)
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Old 24th Oct 2007, 19:17
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Offshore wind farms are normally lighted with high intensity beacon as per aviation regulations. Even in poor weather they are clearly visible when flying.
Unless of course the cloud base is below the nacelle - but such weather can't really be called VMC.

In regards of the radar signatures, they should be easy to filter out since the wind turbines aren'r really moving anywhere.

Personally I think it makes much more sense placing them out to sea than on land. They are more efficient and don't disturb the neighbours.

Well, just my thoughts.

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Old 24th Oct 2007, 19:58
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Old 24th Oct 2007, 20:27
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One group of windfarms seem to result in concerns....

and a reason why :
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Old 24th Oct 2007, 20:42
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Has anyone considered the effects of turbulence created by turbines on aircraft taking off/landing at airfields downwind of them? As a microlight pilot I'm acutely aware of the effect even the odd tree can have, never mind one (or several) 300+ft tall!! I suppose since aviation is one of the prime destroyers of the environment, so we are told, then there is little chance of any sympathy here.
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Old 25th Oct 2007, 07:38
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An obstruction can create turbulence for a considerable distance. Measurements of windbreaks showed reductions in windspeeds (where H is the height of the obstruction): at 10H range 66% reduction; 20H - 14% reduction; 25H - 10% reduction.
Effects were measurable up to 30H downwind (4%)
With a wind turbine it is not just the height that is important - the actual obstruction size is the rotor diameter (D)
Turbulence is usually regarded as significant 2D in front of the rotor, 2D above the rotor and 10D downwind.
Turbines are rarely placed less than 6D apart. This more due to the loss of turbines through turbulence than loss of power on the occasions when they are directly downwind. The blades are wings - in severe turbulence they flex - and in a number of cases they have hit the pylon! - Hence 6D seperation!
The East Midlands turbines are going to be interesting.... but it must be remembered that they are rather small (only 27m diameter) compared to the latest turbines being constructed. I believe they are 3-400m to the side of the runway so unlikely to have a major turbulence problem (for aviation!)
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Old 26th Oct 2007, 11:54
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Building Wind Turbines on an Airport such as the ones at East Midlands are stupidity in the extreme, If they were so "Green" then they could just as easily be built out at sea where they pose no potential hazard to any aircraft..... The use of them to ofset the energy bill for the airport means they could be built anywhere and the revenue earned in the production of energy onto the national grid would be ofset against the airports energy bill....... fair enough they are to be placed near the headquarters building, but the still could pose a hazard in any unusual aircraft emergency, you just cannot rule that out........ I am afraid it is just commecially driven, putting them on the Airfield is just East Midlands Airports way of saying "look at what we are doing...we are green" when indeed they could be placed away from the airport, but of course would not generate the same publicity......

East Midlands used to or possibly still do make use on their own website that they have the rare and endangered Bee Orchids growing on the airfield........ what they don't mention is for the last 5 years just as they were starting to flower the Airport mowed them down.......... perhaps this is why the claim they are endangered and rare, as less and less have appeared this year. Even pointing this out to them over the years they appear to be suffering from the shrugged shoulder syndrome..

The latest venture appears to be placing "picnic Tables" on the sound protection berm at the racetrack end of the Airport, you now can sit up on this lightly wooded banking, (or it was till they chopped most of them down to put the path in) and look down on glorious views of the Airport Car parks, the Main Road Junction and the entrance road into the race track......whoever thought that one up must be on crack cocaine.........

Last edited by NutLoose; 26th Oct 2007 at 23:12.
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Old 28th Oct 2007, 17:22
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Recent MOD objection in Norfolk
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Old 28th Oct 2007, 21:46
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Strange that this should pose a threat to the MOD site at Trimingham 21nm away, yet not affect Norwich Airport a mere 8nm distant. Do turbines have a greater influence on Secondary returns, rather than Primary?
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Old 30th Oct 2007, 11:07
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Having analysed radar recordings from a Windfarm 'vs' Radar trial some years back, my personal views are that windfarms just do NOT mix with aviation.
On the trial, a number of differing aircraft types were flown in pre-determined patterns on the lee side of a windfarm...
The effects on primary only radar are significant, it became impossible to effectively 'track' the aircraft due to the number of false plots/tracks (clutter) created.

Secondary radar was much more resilient and the aircraft could be tracked (about 90% of the time) - however I have seen some 'strange' effects elsewhere in the UK whereby aircraft at a range of 50nm from the radar (the windfarm being about 15nm from the radar) at around FL300 would simply hyperspace/dissapear at random.

Using primary AND secondary does reduce the impact of windfarms but still intoduces false plots/tracks - not particularly usefull if you are trying to control aircraft

A number of companys have attempted to address the windfarm issues by developing advanced tracking techniques.. but they are far from perfect.

I'd be interested if any ATCOs have had any 'experiences' or views on windfarms.
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Old 30th Oct 2007, 15:36
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RichieD: the effects you mention on SSR are no different from the effects of chimneys, masts and tall buildings. Ask NATS!
NutLoose: do you really think EMA would build wind turbines on the airport without doing a full safety assessment and getting it signed off by the CAA?
Flying Pram: I'm sure if anyone proposed putting turbines close enough to an airfield to cause turbulence to aircraft taking off/landing there'd be plenty scope for objecting. Away from airfields normal 500ft rule applies and you just use common sense as you would in the lee of other objects which might generate turbulence.
ericferret: were you successful in stopping the turbine being built? The CAA are more willing to help these days but it depends which bit you speak to. DAP takes the lead. If you were only speaking to Aerodrome Standards you may not have had much response.
who will be the first pilot to collide with a wind turbine or wind farm
Ban hills, they really get in the way, especially if you never look at your chart or your altimeter or out of the window.
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Old 30th Oct 2007, 19:10
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If the effects on primary radar are so significant, would this be a main concern for air defence - transponders could be switched off......
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Old 30th Oct 2007, 21:38
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Yes, but of course there's a generic problem for air defence of primary-only tracks. There are thousands of them, mostly Bloggs in his microlight, gliders etc. You can't track every one, or indeed any of them, on the assumption that they're TNT-packed and heading for Canary Wharf. In the good old days it was simply a question of spotting something coming from the east at 500 knots with no flight plan.
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Old 31st Oct 2007, 06:33
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Denmark has more wind turbines and is the leading producer of turbines and yet they have not closed down one Power Station in the 25 years of growing wind power generation. In fact when the wind drops they have to buy electricity from Norway, Germany and Sweden! The amount of WTE [Wind turbine Energy] claimed by the Greenies and reality are miles apart.

On a yearly basis the efficiency when feeding the UK National Grid [many problems with variable output and AC stability] means that the Wind Farm Production figure is between 8% and 4%! Steam/Gas/Oil turbines run at around 94/96% by comparison.

WTE kills migrating birds in their thousands, are a noise issue to anyone living nearby and are a blot on remote landscapes.
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Old 31st Oct 2007, 07:45
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In Denmark nearly 20% of the electric power comes from wind turbines.
It may not have caused entire power stations to have been closed. But I believe that several are partially shut down. In that way they can be brought online should an emergency need arise.

Denmark is not forced to by electric power from our neighbours. It is done that way for economical and enviromental reasons. Electric power from swedish and norwegian water driven power plants is more enviromentally friendly than starting up one of the conventional power plants.

Offshore wind turbines do not cause many bird deaths.
Birds are more clever than most people tend to believe. They sense the turbines long before reaching them.
Just think about it, on a dark vinter night they can circumnavigate the moving branches of a tree. Surely they will be aware of a 270 feet turbine with 40 meter wings.
Besides the visual clue the birds can hear them aswell.

In Denmark we already have several offshore wind farms. Yet I have not heard anything about them causing problems for either civil or military radar.
Out of Esbjerg most of the offshore oil traffic passes one of the biggest wind farms.
I will try to investigate a little to find out whether they experience similar problems.

And personally I would rather be looking on a wind turbine than on a power plant.

"In 2004, wind-power production accounted for 18.5% of domestic electricity supply"
Danish Energy Authority

Water birds do not fly near windmills offshore
Eider and geese do in fact discover the whirling blades at sea. At the world's largest offshore wind farm, Nysted in Denmark. Danish researchers have used radar to study the reaction of migratory water birds approaching af wind farm.

Last edited by RotorDompteur; 31st Oct 2007 at 07:48. Reason: fixing link
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Old 31st Oct 2007, 08:10
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avaite1138: Wind power in Denmark & UK are not comparable. Denmark was the first European country to develop wind power but the vast majority of its turbines in the early years were small single turbine developments by individual farmers. They are not efficient on a national scale. Denmark is only just beginning to develop offshore wind which is what makes the big difference at national level, with larger machines and a much more reliable and less turbulent wind resource. Wind was never envisaged as a replacement for conventional power. But it's vital if we are to carry on with our ever-growing high energy consumption economies.

As RotorDompteur says, the attitude of some parts of the UK aviation industry to wind turbines is at odds with what has been happening for years on the continent.
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Old 31st Oct 2007, 08:24
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Up to 300 feet in height. Wow. But many control towers are 100m. [higher than 300'] and they are right in the middle of the airport!

Radar interference? Wow. How about some stealth technology applications, like radar absorbing paint!

Long live wind turbines and cheap energy!
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