Laserfiche WebLink
wind cone, or another approved indicator, which must be operable and <br />clearly visible from the pattern altitude when within one mile of the <br />airport during daylight hours. If the airport is lighted for night <br />operations, the wind indicator must also be lighted in an approved <br />manner. A bulletin board, a telephone, and a sanitary public toilet <br />facility shall also be provided at all public airports. <br />C. Imaginery Surfaces <br />Obstructions are a necessary consideration in the design, layout and <br />operations of an airport. An object is considered an obstruction to <br />a public airport if it is of greater height than any of the following <br />airport imaginery surfaces (illustrated in Figure 1): <br />1. The rimar surface extends 200' beyond each end of the hard surfaced <br />runway, making it 3700' long x 500' wide in this case, with the ele- <br />' vation of any point on that surface being the same as the. elevation <br />~ of the nearest point on the runway centerline; <br />2. The horizontal surface, at a height of 150 feet above the established <br />airport elevation, the perimeter of which is established by swinging <br />arcs of 6,000 feet radii from the center of each end of the primary <br />surface of each runway and connecting the adjacent arcs by lines <br />tangent to those arcs; <br />3. The conical surface extends upward and outward from the periphery <br />of the horizontal surface at a slope of 20:1 for a horizontal dis- <br />5 <br />