Originally Posted by Basil
I'd doubt that the rotation speed of a wind turbine would cause a radar
problem.
Wrong. Fortissimo is absolutely correct. Stationary obstructions (masts, towers, etc) can be masked from a primary radar picture through digital processing. But wind speed and direction both affect the radar return from wind turbine blades, and this means that they cannot be mapped out of a radar picture. Allied to that, modern primary radars typically include some doppler signal processing logic with which the blades play merry havoc. Take it from me, they are a significant issue near airfields; I've been denied a deconfliction service on several occasions because the number of returns from windfarms meant that the controller couldn't provide the level of service required (there being no way to guarantee that the mass of ever-shifting returns don't include a non-squawking light aircraft).