A. Airport Approach Safety Zone. A surface longitudinally centered on the extended runway centerline and extending outward and upward from each end of the Primary Surface. The inner edge of the approach surface is the same width as the Primary Surface and extends to a width of: 1,250 feet for a Utility Runway having only visual approaches; 2,500 feet for a runway other than a Utility Runway having only visual approaches; 2,000 feet for a Utility Runway having a non-precision instrument approach; and 3,500 feet for a non-precision instrument runway other than utility, having visibility minimums greater than three-fourths of a statute mile. The Airport Approach Surface extends for a horizontal distance of 5,000 feet at a slope of 20 feet for each foot upward (20:1) for all utility and visual runways and 10,000 feet at a slope of 34 feet for each one foot upward (34:1) for all non-precision instrument runways other than utility.

B. Airport Hazard. Any structure, tree or use of land which exceeds height limits established by the Airport Imaginary Surfaces.

C. Airport Imaginary Surfaces. Those imaginary areas in space which are defined by the Airport Approach Safety Zone, Transitional Zones, Horizontal Zone, Clear Zone and Conical Surface and in which any object extending above these imaginary surfaces is an obstruction.

D. Clear Zone. Extends from the primary surface to a point where the approach surface is 50 feet above the runway and elevation.

E. Conical Surface. Extends one foot upward for each 20 feet outward (20:1) for 4,000 feet beginning at the edge of the horizontal surface (5,000 feet from the center of each end of the Primary Surface of each visual and utility runway or 10,000 feet for all non-precision instrument runways other than utility at 150 feet above the airport elevation) and upward extending to a height of 350 feet above the airport elevation.

F. Horizontal Surface. A horizontal plane 150 feet above the established airport elevation, the perimeter of which is constructed by swinging arcs of 5,000 feet from the center of each end of the Primary Surface of each visual or utility runway and 10,000 feet from the center of each end of the Primary Surface of all other runways and connecting the adjacent arcs by lines tangent to those arcs.

G. Noise Impact. Noise levels exceeding 55 Ldn.

H. Place of Public Assembly. A structure or place which the public may enter for such purposes as deliberation, education, worship, shopping, entertainment, amusement, awaiting transportation or similar activity.

I. Primary Surface. A surface longitudinally centered on a runway. When the runway has a specially prepared hard surface, the Primary Surface extends 200 feet beyond each end of that runway. When the runway has no specially prepared hard surface, or planned hard surface, the Primary Surface ends at each end of that runway. The width of the Primary Surface is 250 feet for Utility Runways having only visual approaches, 500 feet for Utility Runways having non-precision instrument approaches and 500 feet for other than Utility Runways.

J. Transitional Zones. Extend one foot upward for each seven feet outward (7:1) beginning on each side of the Primary Surface which point is the same elevation as the runway surface, and from the sides of the approach surfaces thence extending upward to a height of 150 feet above the airport elevation (Horizontal Surface).

K. Utility Runway. A runway is constructed and intended to be used by propeller driven aircraft of 12,500 pounds maximum gross weight or less.