Ministry of Defence spokesman Andres Sang told Postimees that the problem with these wind farms is the planned height of the wind turbines being built.

According to Sang, the spinning blades of a turbine create false target returns on radar images, i.e. the radar registers the moving blades as aircraft and begins to calculate their future positions, which creates an unnecessary burden on the radar itself. Also, the spinning blades creates a blind spot on the radar which would block out actual aviation activity falling within that area.

Estonian Air Force radars are the only radars in the country capable of seeing Russian military jets flying in border-region international airspace with their transponders turned off; planes flying with their transponders turned off are invisible to radars in use by civil aviation.

The air force’s air surveillance system is a part of NATO’s Integrated Air and Missile Defence System (NATINAMDS), which produces aggregate airspace imagery for NATO allies. As such, any interference in radar imagery is a problem not just for Estonia, but for all of NATO.

Sang noted that this concern regarding wind farms is by no means unique to Estonia; among other countries, Great Britain, France, Denmark and Finland are dealing with the same issue as well. The problem is mitigated somewhat by the use of matte finishes on turbine blades to reduce glare, however this does nothing to solve the issue of blind spots. Radar image blind spots can only be avoided by careful coordination of radar and wind farm locations in respect to one another.