§ 91.071 AIRPORT-REFERENCED IMAGINARY SURFACES.
   (A)   In order to carry out the purposes of this subchapter, there are hereby established six airport-referenced imaginary surfaces, as shown on the map, which consist of and are described as follows.
      (1)   Datum plane. The datum plane is a horizontal plane or surface, which includes the surface point of the airport elevation established to be at 763 feet above mean sea level.
      (2)   Approach surfaces (noninstrument runways). The approach surfaces are inclined planes located directly above the approach area, extending upward and outward from its point of beginning at the near end of the runway or landing strip, at a slope ratio of one foot vertical to 40 feet horizontal, or at an angle of 1°25'56" from the horizontal, the approach area being symmetrically located with respect to the extended runway or landing strip centerline; the dimensions of the approach area are measured horizontally as follows:
      A length of 10,000 feet beginning 200 feet from the end of the runway or 100 feet from the end of the landing strip, and extending outward, ending at a point 10,200 feet from the end of the runway or 10,100 feet from the end of the landing strip on the extended centerline of the runway or landing strip; a total width of 500 feet at the end nearest to the runway or landing strip and flared uniformly to a total width of 2,500 feet at the end of the 10,000-foot section.
      (3)   Approach surfaces (instrument landing system runway). The approach surfaces for all designated instrument landing system runways are inclined planes, located directly above the approach area, extending upward and outward from its point of beginning at the near end of the runway, at a slope ratio of one foot vertical to 50 feet horizontal, or at an angle of 1°08'45" from the horizontal, for the first 10,000 feet, and thence continuing upward and outward at a slope ratio of one foot vertical to 40 feet horizontal, or at an angle of 1°23'56", from the horizontal for the next 40,000 feet, the approach area being symmetrically located with respect to the extended runway centerline; the dimensions of the approach area are measured horizontal as follows:
      A length of 50,000 feet beginning 200 feet from the end of the runway or 100 feet from the end of the landing strip, and extending outward, ending at a point 50,200 feet from the end of the runway, or 50,100 feet from the end of the landing strip, on the extended centerline of the runway; and having a total width of 1,000 feet at the end nearest the runway or landing strip and flared uniformly to a total width of 16,000 feet at the end of the 50,000-foot section. The approach area requirements for instrument runway shall apply to all runways which may be designated and used for instrument operations and to both ends of the runways.
      (4)   Horizontal surfaces. The horizontal surfaces are horizontal planes, circular in shape, having a radius of 11,500 feet from the airport reference point, at its outer limits, but excluding the approach and transition surfaces, insofar as they are contained within the 11,500-foot radius, and which together with the conical surface, hereinafter described, form the upper boundary of the turning zone.
      (5)   Conical surfaces. The conical surfaces extend upward and outward from the outer limits of the horizontal surfaces. Measuring radially outward from the outer limits of the horizontal surfaces, the conical surfaces extend for a horizontal distance of 7,000 feet.
      (6)   Transition surfaces. The transition surfaces are inclined planes, symmetrically located about the centerline of the runway or landing strip extending from the lateral boundaries of all approach surfaces upward and outward, at a slope ratio of one foot to seven feet horizontal or at an angle of 08°07'48" from the horizontal, to the intersection with the horizontal surface or the conical surface, as the case may be; the transition surfaces also extend outward and upward at the same slope ratio and angle noted above from the edge of the landing strip, parallel with the runway or landing strip centerline, until they intersect the horizontal surface. With relation to a runway designated for instrument operation, the approach surfaces projecting through and beyond the outer limits of the conical surfaces have a transition surface extending upward and outward at a slope ratio of one foot vertical to seven feet horizontal, or at an angle of 08°07'48" from the horizontal, for a distance of 5,000 feet measured horizontally from the edges of the approach surfaces and at right angles to the extended runway centerline.
   (B)   The boundaries and areas of these airport-referenced imaginary surfaces are hereby established as shown on the map.
(1990 Code, § 5-117) (Ord. 67-924, passed 9-18-1967)