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• • covered the 30-day period from February 19 through March 20, 1982. The survey identified 360 flights which met the above criteria, a daily average of 12 flights. The daily count varied from a low of zero on days involving weather conditions well below VFR minimums, to as high as 56 when weather conditions were conducive to VFR flight. Not included in this survey were the calls made to the Pilot's Automatic Telephone Weather Answering Service (PATWAS) which provides weather forecasts within a 50-mile radius of Minneapolis. During the 30-day survey period, a total of 9,451 calls (315 daily average) were received on the PATWAS. Many of these calls probably could have been appropriately identified in the survey if the caller had utilized direct contact with the survey personnel. The other survey covered the period from February 22 to March 22, 1982, and recorded the number of: 1) IFR and VFR radar -identified aircraft operating within 5 miles of the proposal at or below 4,000' AMSL; 2) unidentified radar - observed traffic within 5 miles of the proposed site. The IFR aircraft count ranged from a low of 20, to a high of 301, with a daily average of 89 aircraft; VFR radar -identified aircraft from a low of zero, to a high of 122, with a daily average of 31 aircraft; and unidentified radar -observed aircraft from a low of zero, to a high of 267, with a daily average of 92 aircraft. A 700' transition area has been designated over the proposed site. Transition areas are designated to contain IFR arrival, departure, holding and enroute operations not protected by other controlled airspace. VFR aircraft which are unable to maintain VFR flight conditions within the transition area must descend to an altitude less than 700' above the surface. The second FAA survey (discussed in the previous paragraph) disclosed a significant volume of unidentified, radar -observed aircraft in the vicinity of the proposed site on days when Crystal and Minneapolis -St. Paul International Airports were reporting weather ceilings below 1,000' above ground level. Low -cloud ceilings are often accompanied by reduced visibility making skeletal structures difficult for pilots to see and avoid. In consideration of reported weather conditions and radar -observed traffic in the vicinity of the proposed site, a significant volume of aircraft could be at altitudes which would be made hazardousto aircraft by the proposed structure during adverse weather conditions. Additional problems would be experienced by pilots not given clearance to enter the TCA. If navigating along roads and railroads, they would find it necessary to descend/remain beneath the TCA to continue that method of navigation. With the top of the proposed 990' AGL structure at 2,011' AMSL, and the floor of the TCA at 4,000' AMSL, a significant volume of air traffic would be compressed into the limited airspace near the proposal. Pilots flying through this area would be required to maintain a position below the TCA, maintain clearance from the proposal in accordance with FAR Part 91, and maintain surveillance to avoid collision with other aircraft also compressed into the airspace. The number of aircraft identified in the surveys represent a significant volume of air traffic. Page 7 of 8 Pages Aeronautical Study No. 81-AGL-1556-0E