There are hereby created and established certain zones which include all of the land lying within the precision instrument approach zones, utility approach zones, transition zones, horizontal zone and conical zone. Such areas and zones are shown on Helena airport zoning map consisting of one sheet prepared by the joint city-county airport board, a copy of which is made a part hereof by reference. The various zones are defined and described as follows:
A. Precision Instrument Approach Zone: A precision instrument approach zone is established at each end of the precision instrument runway for precision instrument landings and takeoffs. Each precision instrument approach zone shall have a width of one thousand feet (1,000') at a distance of two hundred feet (200') beyond each end of the runway, widening thereafter uniformly to a width of sixteen thousand feet (16,000') at a distance of fifty thousand two hundred feet (50,200') beyond each end of the runway, with its centerline being the continuation of the centerline of the runway.
B. Utility Approach Zone: A utility approach zone is established at each end of all utility runways for visual landings and takeoffs. Each utility approach zone shall have a width of two hundred fifty feet (250') at a distance of two hundred feet (200') beyond each end of the runway, widening thereafter uniformly to a width of one thousand two hundred fifty feet (1,250') at a distance of five thousand two hundred feet (5,200') beyond each end of the runway with its centerline being the continuation of the centerline of the runway.
C. Transition Zones: Transition zones are hereby established adjacent to each precision instrument and utility runway and approach zones as indicated on the zoning map. Transition zones symmetrically located on either side of runways have variable widths as shown on the zoning map. Transition zones extend outward from a line one hundred twenty five feet (125') on either side of the centerline of the utility runway, for the length of such runway plus two hundred feet (200') on each end, and five hundred feet (500') on either side of the centerline of the precision instrument runway, for the length of such runway plus two hundred feet (200') on each end, and are parallel and level with such runway centerlines. The transition zones along such runways slope upward and outward one foot (1') vertically for each seven feet (7') horizontally to the point where they intersect the surface of the horizontal zone. Further, transition zones are established adjacent to both precision instrument and utility approach zones for the entire length of the approach zones. These transition zones have variable widths, as shown on the zoning map. Such transition zones flare symmetrically with either side of the runway approach zones from the base of such zones and slope upward and outward at the rate of one foot (1') vertically for each seven feet (7') horizontally to the points where they intersect the surfaces of the horizontal and conical zones. Additionally, transition zones are established adjacent to the precision instrument approach zone where it projects through and beyond the limits of the conical zone, extending a distance of five thousand feet (5,000') measured horizontally from the edge of the precision instrument approach zones at right angles to the continuation of the centerline of the runway.
D. Horizontal Zone: A horizontal zone is hereby established as the area within a perimeter established by swinging arcs of ten thousand feet (10,000') radius from a point two hundred feet (200') beyond the planned ends of the precision instrument runway on the continuation of the runway centerline and connecting the adjacent arcs by lines tangent to those arcs. The horizontal zone does not include the precision instrument and utility approach zones and the transition zones.
E. Conical Zone: A conical zone is hereby established as the area that commences at the periphery of the horizontal zone and extends outward there from a distance of four thousand feet (4,000'). The conical zone does not include the precision instrument approach zones and transition zones. (Ord. 2359, 5-20-1985)