Federal Aviation Administration Aeronautical Study No.
Air Traffic Airspace Branch, ASW-520 2005-AGL-6526-OE
2601 Meacham Blvd.
Fort Worth, TX 76137-0520

Issued Date: 03/16/2006

Utopia Hill
Forward Energy Center
One South Wacker Drive, Suite 2020
Chicago, IL 60606** NOTICE OF PRESUMED HAZARD **

The Federal Aviation Administration has conducted an aeronautical study under the provisions of 49 U.S.C., Section 44718 and if applicable Title 14 of the Code of Federal Regulations, part 77, concerning:

Structure Type: Wind Turbine
Location: BROWNSVILLE, WI
Latitude: 43-40-12.74 NAD 83
Longitude: 88-28-12.91
Heights: 389 feet above ground level (AGL)
1442 feet above mean sea level (AMSL)

Initial findings of this study indicated that the structure as described exceeds obstruction standards and/or would have an adverse physical or electromagnetic interference effect upon navigable airspace or air navigation facilities.

Pending resolution of the issues described below, the structure is presumed to be a hazard to air navigation.

Further study has been initiated by the FAA.

See attachment for additional information.

NOTE: PENDING RESOLUTION OF THE ISSUE(S) DESCRIBED ABOVE, THE STRUCTURE IS PRESUMED TO BE A HAZARD TO AIR NAVIGATION. THIS LETTER DOES NOT AUTHORIZE CONSTRUCTION OF THE STRUCTURE EVEN AT A REDUCED HEIGHT. ANY RESOLUTION OF THE ISSUE(S) DESCRIBED ABOVE MUST BE COMMUNICATED TO THE FAA SO THAT A FAVORABLE DETERMINATION CAN SUBSEQUENTLY BE ISSUED.

If we can be of further assistance, please contact our office at (847)294-7458. On any future correspondence concerning this matter, please refer to Aeronautical Study Number 2005-AGL-6526-OE.

Signature Control No: 441481-446457 (NPH)
Fred Souchet
Specialist

Attachment(s)
Additional Information

Additional Information for ASN 2005-AGL-6526-OE

The aeronautical study indicates that the structure exceeds the Obstruction Standards of Federal Aviation Regulations (FAR) Part 77, as follows:.
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Section 77.23(a)(2) by 478 feet, a height that is 200 feet above ground Level or above the established airport elevation, whichever is higher, within 3 nautical miles of the established reference point of an airport, excluding heliports, with its longest runway more than 3,200 feet in actual length, and that height increases in proportion of 100 feet for each additional nautical mile of distance from the airport up to a maximum of 500 feet..
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OTHER AERONAUTICAL EFFECTS:.
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As shown in previous products, the proposed wind turbines are within radar line- of-sight of the Horicon radar. 84 RADES modeling and analysis tools have limited capability with respect to wind turbines. Therefore, the operational impact on the Air Force mission of the proposed wind farm development can't be fully assessed at this time. ..

Although the wind farm proposal is smaller in number than the wind farm near Tyler (MN), the proposed wind farm near Horicon will create a similar environment for the radar. To control the false targets generated from the wind turbines at Tyler, a strong run length constraint was implemented and is required on a daily basis. This constraint severely reduces target detection and degrades the operational user's ability to perform the surveillance mission.
Given the similarity between the two sites, we would expect the same degradation in performance at Horicon..

The Office of the Deputy Under Secretary of Defense for Space & Sensor Technology (ODUSD(S&T)) has been mandated by Congress to generate a report on the effects of wind turbines and their impact of military readiness. By May 2006, ODUSD(A&T) will lead a test effort to help characterize the impact of wind turbines on Air Force radars, and then provide policy to ensure the Air Force mission. Until this analysis is complete, we don't concur with the development of wind farm within the radar line-of-sight of the Horicon radar and should be delayed until a comprehensive analysis can be completed..

The Northeast Air Defense Sector (NEADS) is one of the primary users of the Horicon radar and has the responsibility of the Air Force's surveillance mission in the Horicon area. I have provided information concerning the proposed wind farm development near the Horicon radar to NEADS personnel. Until NEADS personnel have fully reviewed this information, they will not concur with the proposed wind farm development. .

Therefore, it is the best interest of the Air Force mission to delay the wind farm development until a comprehensive analysis can be completed.