Chapter 18.25
AVIATION OVERLAY DISTRICT (AO)
Sections:
18.25.030 Administration and enforcement.
18.25.080 Permits and variances.
18.25.010 Authority.
This chapter is adopted pursuant to the authority conferred by WS, 1977, 10-5-301 and 10-5-302, and subsequent amendments thereto. It is found that an obstruction has the potential for endangering lives and property of users of Wheatland Phifer Airfield Municipal Airport; and that an obstruction may reduce the size of areas available for the landing, takeoff and maneuvering of aircraft, thus tending to destroy or impair the utility of Wheatland Phifer Airfield Municipal Airport and the public investment therein. Accordingly, it is declared that:
(a) The creation or establishment of an obstruction has the potential of being a public nuisance and may injure the region served by Wheatland Phifer Airfield Municipal Airport.
(b) It is necessary in the interest of public health, public safety, and general welfare that the creation or establishment of obstructions that are a hazard to air navigation be prevented.
(c) That the prevention of these obstructions should be accomplished, to the extent legally possible, by the exercise of the police power without compensation.
It is further declared that the prevention of the creation or establishment of hazards to air navigation or the marking and lighting of obstructions are public purposes for which a political subdivision may raise and expend public funds and acquire land or interests in land. [Ord. 834, 2022.]
18.25.020 Definitions.
For the purpose of this chapter, the following words and phrases shall have the meanings respectively ascribed to them by this section:
“Airport” means the Wheatland Phifer Airfield Municipal Airport.
“Airport advisory board” means an advisory board consisting of five members appointed by the town council.
“Airport elevation” means the highest point of an airport’s usable landing area measured in feet from sea level.
“Approach surface” means a surface longitudinally centered on the extended runway centerline, extending outward and upward from the end of the primary surface and at the same slope as the approach zone height limitation slope set forth in WMC 18.25.050. In the plan the perimeter of the approach surface coincides with the perimeter of the approach zone.
“Approach, transitional, horizontal, and conical zones” means the zones set forth in WMC 18.25.040.
“Conical surface” means a surface extending outward and upward from the periphery of the horizontal surface at a slope of 20:1 for a horizontal distance of 4,000 feet.
“Hazard to air navigation” means an obstruction determined to have a substantial adverse effect on the safe and efficient utilization of the navigable airspace.
“Height” means for the purpose of determining the height limits in all zones set forth in this chapter and shown on the zoning map, the datum shall mean sea level.
“Horizontal surface” means a horizontal plane 150 feet above the established airport elevation, the perimeter of which in plan coincides with the perimeter of the horizontal zone.
“Larger than utility runway” means a runway that is constructed for and intended to be used by propeller-driven aircraft of greater than 12,500 pounds maximum gross weight and jet-powered aircraft.
“Nonconforming use” means any preexisting structure, object of natural growth or use of land which is inconsistent with the provisions of this chapter or an amendment thereto.
“Nonprecision instrument runway” means a runway having an existing instrument approach procedure utilizing air navigation facilities with only horizontal guidance or area-type navigation equipment for which a straight-in nonprecision instrument approach procedure has been approved or planned.
“Obstruction” means any structure, growth, or other object, including a mobile object, which exceeds a limiting height set forth in WMC 18.25.050.
“Primary surface” means 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; for military runways or 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 set forth in WMC 18.25.040. The elevation of any point on the primary surface is the same as the elevation of the nearest point on the runway centerline.
“Runway” means a defined area on an airport, prepared for landing and takeoff of aircraft along its length.
“Structure” means an object, including a mobile object, constructed, or installed by man, including, but without limitation, buildings, towers, cranes, smokestacks, earth formations and overhead transmission lines.
“Transitional surfaces” means those surfaces extended outward at 90-degree angles to the runway centerline and the runway centerline extended at a slope of seven feet horizontally for each foot vertically from the sides of the primary and approach surfaces to where they intersect the horizontal and conical surfaces.
“Tree” means any object of natural growth.
“Visual runway” means a runway intended solely for the operation of aircraft using visual approach procedures. [Ord. 834, 2022.]
18.25.030 Administration and enforcement.
It shall be the duty of the airport manager to administer and enforce the regulations prescribed in this chapter. Applications for permits and variances shall be made to the planning department upon a form published for that purpose. Applications required by this chapter to be submitted to the planning and zoning commission shall be promptly considered, granted, denied, or postponed. Applications for actions by the airport advisory board shall be forthwith transmitted by the airport manager. [Ord. 834, 2022.]
18.25.040 Zones.
To carry out the provisions of this chapter, there are created and established certain zones, which include all of the land lying beneath the approach surfaces, transitional surfaces, horizontal surfaces and conical surfaces as they apply to Wheatland Phifer Airfield Municipal Airport. An area located in more than one of the following zones is only in the zone with the more restrictive height limitation. Such areas and zones are shown on Phifer Airfield Zoning Map, dated November 2006, which may be found in the planning office. The various zones are established and defined as follows:
(a) Runway Larger Than Utility Visual Approach Zone. The inner edge of this approach zone coincides with the width of the primary surface and is 500 feet wide. The approach zone expands outward uniformly to a width of 1,500 feet at a horizontal distance of 5,000 feet from the primary surface. Its centerline is the continuation of the centerline of the runway.
(b) Runway Larger Than Utility With a Visibility Minimum Greater Than Three-Fourths Mile Nonprecision Instrument Approach Zone. The inner edge of this approach zone coincides with the width of the primary surface and is 500 feet wide. The approach zone expands outward uniformly to a width of 3,500 feet at a horizontal distance of 10,000 feet from the primary surface. Its centerline is the continuation of the centerline of the runway.
(c) Transitional Zone. The transitional zones are the areas beneath the transitional surfaces.
(d) Horizontal Zone. The horizontal zone is established by swinging arcs of 5,000 feet radii for all runways designated utility or visual and 10,000 feet for all others from the center of each end of the primary surface of each runway and connecting the adjacent arcs by drawing lines tangent to those arcs. The horizontal zone does not include the approach and transitional zones.
(e) Conical Zone. The conical zone is established by the area that commences at the periphery of the horizontal zone and extends outward therefrom a horizontal distance of 4,000 feet. [Ord. 834, 2022.]
18.25.050 Height limits.
Except as otherwise provided in this chapter, no structure shall be erected, altered, or maintained and no tree shall be allowed to grow in any zone created by this chapter to a height more than the applicable height limit established in this section for such zone. Such applicable height limitations are established for each of the zones in question as follows:
(a) Runway Larger Than Utility Visual Approach Zone. Slopes 20 feet outward for each foot upward, beginning at the end of and at the same elevation as the primary surface and extending to a horizontal distance of 5,000 feet along the extended runway centerline.
(b) Runway Larger Than Utility With a Visibility Minimum Greater Than Three-Fourths Mile Nonprecision Instrument Approach Zone. Slopes 34 feet outward for each foot upward, beginning at the end of and at the same elevation as the primary surface and extending to a horizontal distance of 10,000 feet along the extended runway centerline.
(c) Transitional Zones. Slopes seven feet outward for each foot upward, beginning at the sides of and at the same elevation as the primary surface and the approach surface and extending to a height of 150 feet above the airport elevation, which is 6,987 feet above mean sea level. In addition to the foregoing, there are established height limits sloping seven feet outward for each foot upward, beginning at the sides of and at the same elevation as the approach surface and extending to where they intersect the conical surface.
(d) Horizontal Zone. The horizontal zone is established at 150 feet above the airport elevation or a height of 4,930 feet above mean sea level.
(e) Conical Surface. The conical surface slopes 20 feet outward for each foot upward, beginning at the periphery of the horizontal zone and at 150 feet above the airport elevation and extending to a height of 350 feet above the airport elevation.
(f) Exception. Nothing in this chapter shall be construed as prohibiting the construction or maintenance of any structure or growth of any tree to a height up to 50 feet above the surface of the land. [Ord. 834, 2022.]
18.25.060 Use restrictions.
Notwithstanding any other provisions of this chapter, no use may be made of land or water within any zone established by this chapter in such a manner as to create electrical interference with navigational signals or radio communication between the airport and aircraft, make it difficult for pilots to distinguish between airport lights and others, result in glare in the eyes of pilots using the airport, impair visibility in the vicinity of the airport, create bird strike hazards or otherwise in any way endanger or interfere with the landing, takeoff or maneuvering of aircraft intending to use the airport. [Ord. 834, 2022.]
18.25.070 Nonconforming uses.
(a) Regulations Not Retroactive. The regulations prescribed by this chapter shall not be construed to require the removal, lowering or other change or alteration of any structure or tree not conforming to the regulations as of July 2, 1979, or otherwise interfere with the continuance of a nonconforming use. Nothing contained in this chapter shall require any change in the construction, alteration or intended use of any structure, the construction or alteration of which was begun prior to July 2, 1979, and which is diligently prosecuted.
(b) Marking and Lighting. Notwithstanding subsection (a) of this section, the owner of any existing nonconforming structure or tree is required to permit the installation, operation, and maintenance thereon of such markers and lights as shall be deemed necessary by the airport advisory board to indicate to the operators of aircraft in the vicinity of the airport the presence of such airport obstruction. Such markers and lights shall be installed, operated, and maintained at the expense of the owner. [Ord. 834, 2022.]
18.25.080 Permits and variances.
(a) Permits – Future Uses. Except as specifically provided in subsections (a)(1) through (3) of this section, no material change shall be made in the use of land, no structure shall be erected or otherwise established, and no tree shall be planted in any zone created by this chapter unless a permit therefor has been applied for and granted. Each application for a permit shall indicate the purpose for which the permit is desired, with sufficient particularity to permit it to be determined whether the resulting use, structure or tree would conform to the regulations prescribed in this chapter. If such determination is in the affirmative, the permit shall be granted. No permit for a use inconsistent with the provisions of this chapter shall be granted unless a variance has been approved in accordance with subsection (d) of this section.
(1) In the area lying within the limits of the horizontal zone and conical zone, no permit shall be required for any tree or structure less than 75 feet of vertical height above ground, except when, because of terrain, land contour or topographic features, such tree or structure would extend above the height limits prescribed for such zones.
(2) In areas lying within the limits of the approach zones but at a horizontal distance of no less than 4,200 feet from each end of the runway, no permit shall be required for any tree or structure less than 75 feet of vertical height above the ground, except when such tree or structure would extend above the height limit prescribed for such approach zones.
(3) In the areas lying within the limits of the transition zones beyond the perimeter of the horizontal area, no permit shall be required for any tree or structure less than 75 feet of vertical height above the ground, except when such tree or structure, because of the terrain, land contour or topographic features, would extend above the height limit prescribed for such transition zones.
(b) Nothing contained in any of the foregoing exceptions shall be construed as permitting or intending to permit any construction or alteration of any structure or growth of any tree more than any of the height limits established by this chapter, except as set forth in WMC 18.25.050(f).
(c) Permit – Existing Uses. No permit shall be granted that would allow the establishment or creation of an obstruction or permit a nonconforming use, structure, or tree to become a greater hazard to air navigation than it was on January 1, 2022, or on the effective date of any applicable amendment to this chapter, or than it is when the application for a permit is made. Except as indicated, all applications for a permit shall be granted.
(d) Permit – Nonconforming Uses Abandoned or Destroyed. Whenever the airport manager determines that a nonconforming tree or structure has been abandoned or more than 80 percent torn down or is physically deteriorated or decayed, no permit shall be granted that would allow such structure or tree to exceed the applicable height limit or otherwise deviate from the zoning regulation.
(e) Variances. Any person desiring to erect or increase the height of any structure, permit the growth of any tree, or use property, not in accordance with the regulations prescribed in this chapter, may apply to the board of adjustment for a variance from such regulations. The application for a variance shall be accompanied by a determination from the Federal Aviation Administration as to the effect of the proposal on the operation of air navigation facilities and the safe, efficient use of navigable airspace. Such variances shall be allowed where it is duly found that a literal application or enforcement of this chapter will result in unnecessary hardship and the relief granted will not be contrary to the public interest, will not create a hazard to air navigation, will do substantial justice and will be in accordance with the spirit of this chapter. Additionally, no application for a variance from the requirements of this chapter may be considered by the board of adjustment unless a copy of the application has been furnished to the airport advisory board for advice as to the aeronautical effects of the variance.
(f) Obstruction Marking and Lighting. Any permit or variance granted may, if such action is deemed advisable to effectuate the purpose of this chapter and be reasonable in the circumstances, be so conditioned as to require the owner of the structure or tree in question to install, operate and maintain, at the owner’s expense, such marking and lights as may be necessary. If deemed proper by the airport advisory board, this condition may be modified to require the owner to permit the airport advisory board, at its own expense, to install, operate and maintain the necessary markings and lights. [Ord. 834, 2022.]