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; 30th November 2012 at 23:55.