§ 50-97. Airport zones and airspace height limitations.

(a)

In order to carry out the provisions of this division, there are hereby created, and established, certain zones which include all of the land lying beneath the approach, transitional, horizontal and conical surfaces as they apply to a particular airport. Such zones are shown on the airport zoning map which is attached to this division and made a part hereof. An area located in more than one of the described zones is considered to be only in the zone with the more restrictive height limitation. The various zones are hereby established and defined as provided in this section.

(b)

Public civil airport height zones and limitations shall be as follows:

(1)

Primary zone: An area longitudinally centered on a runway extending 200 feet beyond each end of that runway with the width so specified for each runway for the most precise approach existing or planned for either end of the runway. No structure or obstruction will be permitted within the primary zone, that is not part of the landing and takeoff area, and is of a greater height than the nearest point on the runway centerline. The width of the primary zone is as follows:

Runway 05/23; 250 feet for utility runways having only visual approaches.

The width of the primary zone of a runway will be that width prescribed in this section for the most precise approach existing or planned for either end of that runway. No structure or obstruction will be permitted within the primary zone, that is not part of the landing and takeoff facilities and is of a greater height than the nearest point on the runway centerline.

(2)

Horizontal zone: The area around each civil airport with an outer boundary the perimeter of which is constructed by swinging arcs of specified radii from the center of each end of the primary zone of each airport's runway and connecting the adjacent arcs by lines tangent to those arcs. The radius of each arc is as follows:

Runway 05/23; 5,000 feet for all runways designated as utility or visual.

The radius of the arc specified for each end of a runway will have the same arithmetical value. That value will be the highest composite value determined for either end of the runway. When a 5,000-foot arc is encompassed by tangents connecting two adjacent 10,000-foot arcs, the 5,000-foot arc shall be disregarded on the construction of the perimeter of the horizontal zone. No structure or obstruction will be permitted in the horizontal zone that has a height greater than 150 feet above the airport height.

(3)

Conical zone: The area extending outward from the periphery of the horizontal zone for a distance of 4,000 feet. Height limitations for structures in the conical zone are 150 feet above airport height at the inner boundary with permitted height increasing one foot vertically for every 20 feet of horizontal distance measured outward from the inner boundary to a height of 350 feet above airport height at the outer boundary.

(4)

Approach zone: An area longitudinally centered on the extended runway centerline and extending outward from each end of the primary surface. An approach zone is designated for each runway based upon the type of approach available or planned for that runway end.

a.

The inner edge of the approach zone is the same width as the primary zone and it expands uniformly to a width of:

Runway 05/23; 1,250 feet for that end of a utility runway with only visual approaches.

b.

The approach surface extends for a horizontal distance of:

Runway 05/23; 5,000 feet for all utility and visual runways.

c.

The outer width of an approach zone to an end of a runway will be that width prescribed in this subsection for the most precise approach existing or planned for that runway end.

d.

Permitted height limitation within the approach zones is the same as the runway end height at the inner edge and increases with horizontal distance outward from the inner edge as follows:

Runway 05/23; permitted height increases one foot vertically for every 20 feet horizontal distance for all utility and visual runways.

(5)

Transitional zone: The area extending outward from the sides of the primary zones and approach zones connecting then to the horizontal zone. Height limits within the transitional zone are the same as the primary zone or approach zone at the boundary line where it adjoins and increases at a rate of one foot vertically for every seven feet horizontally, with the horizontal distance measured at right angles to the runway centerline and extended centerline, until the height matches the height of the horizontal zone or conical zone or for a horizontal distance of 5,000 feet from the side of the part of the precision approach zone that extends beyond the conical zone.

(6)

Other areas: In addition to the height limitations imposed in subsections (b)(1)—(5) of this section, no structure or obstruction will be permitted within the county or the City of Williston, that would cause a minimum obstruction clearance altitude, a minimum descent altitude or a decision height to be raised.

(Ord. No. 77-3, § IV, 9-29-1977)