It certainly is possible. In fact it is a matter of serious concern in some areas of the United Kingdom at least, and I think some other countries as well, because over-the-horizon radar picks up the movement of the blades strongly enough to cause military authorities a great deal of worry. I do not know offhand whether commercial aircraft radar is affected.Remember that the blades are very large and have flat surfaces; they are also moving at varying speeds depending on their activity and the strength of the wind. These things make it very difficult to allow for in dealing with radar clutter.Obviously, given my lack of hands on experience with operational radar, I cannot give you any definitive answer, but in the light of such considerations, it seems entirely reasonable.Fortunately, though it would increase the costs to move wind turbines far enough offshore to avoid radar problems, there really is a lot of sea out there where no one should be too fussed by a turbine in a gale.