FAA testimony before the House Armed Services Committee on the impact of wind farms on military readiness

Excerpt:

The number of wind turbine cases handled by the FAA has increased from 3,030 in 2004 to 25,618 last year. To date in 2010, we have 18,685 wind turbine cases. One concern that the wind turbines raise is that the blade tips rotate above the radar, thus affecting the capability of the target to be received on the radar equipment. Additionally, they reflect radio waves, and exceed the line of sight protection criteria. To give you an idea of the impact of wind turbines on long range radar, there is a radar cross section spectrum that identifies how clearly a range of objects are picked up on the radar. Insects and birds are at the low end. Conventional cruise missiles are in the mid range. Most aircraft are a little higher in the spectrum, with large aircraft (e.g., a Boeing 747) and the space shuttle at the highest end of the spectrum. Wind turbine blades spinning, in some instances, at more than 200 miles per hour are picked up by radars with a signal strength greater than a Boeing 747. Because the radar repeatedly sees this large return, the radar will not pick up actual aircraft in the same area.

The clutter that is created by wind turbines can result in a complete loss of primary radar detection above a wind farm. When that clutter occurs, it appears at all altitudes, so simply directing the aircraft to a different altitude does not solve the problem. Similarly, on the Next Generation Weather Radar (NEXRAD), wind farm activity looks remarkably like storm activity, thus complicating the communication of precise weather information by controllers to pilots. (Wind turbine impacts on NEXRAD, which are owned and operated by the National Oceanic and Atomospheric Administration, are not currently considered in FAA's evaluation process.) Existing FAA radars have limited capability to filter out clutter. The radar can be modified by increasing the sensitivity to reduce clutter from the wind turbines, but in doing so, what the radar can see is also reduced, to the point where actual aircraft targets can drop off. Consequently, there are real and significant issues that must be evaluated by the government prior to the approval of wind turbines.

Although not an issue of consideration in the evaluation process, another issue of some concern is that there is competition for the land which both the radars and the wind turbines need to occupy. Lease holders who currently have primary radars are now being offered substantial financial incentives not to renew their leases with the FAA and instead, lease to companies that want to install wind turbines. This puts the FAA in the undesirable position of having to condemn property at fair market value to avoid losing the use of the navigational aid. The call for the FAA to simply move its radars to accommodate requests to install wind turbines fails to take into account that this is not a realistic option for a number of reasons. The FAA cannot take down a radar without an unacceptable loss of coverage. Even assuming an acceptable, alternate site could be identified, the radar could not simply be moved. Rather, a new radar would have to be installed at the new location. The reality is that the FAA does not have extra radars available for replacement and there are no spare long range radars. Even if a new radar were available, moving the radar site would require changes to the national airspace system. Airways, reporting points, and airspace fixes are parts of the airspace system that could be impacted. Depending on the situation, such changes could require regulatory action. The bottom line is that moving radars around the country is a costly, disruptive, unacceptable, and unworkable proposition. It may sound simple, but in fact, it is not something the FAA can accommodate or the taxpayers can afford.