In order to carry out the provision of this title, there are created and established certain zones which include all of the land lying within the approach zones, transitional zones, horizontal zones, and conical zones as they apply to the Bert Mooney-Silver Bow County Airport. An area located in more than one of the following zones is considered to be only in the zone with the more restrictive height limitation. The various zones are established and defined as follows:

A.

Utility Runway Visual Approach. The inner edge of this approach zone coincides with the end of the primary surface and is five hundred feet wide for runway 29 and two hundred fifty feet for runways 2 and 20. The approach zone for runways 2, 20 and 29 expands outward uniformly to a width of one thousand two hundred fifty feet at a horizontal distance of five thousand feet from the primary surface. Its centerline is the continuation of the centerline of the runway.

B.

Utility Runway Nonprecision Instrument Approach Zone. The inner edge of this approach zone coincides with the end of the primary surface and is five hundred feet wide. The approach zone for runway 11 expands outward uniformly to a width of two thousand feet from the primary surface. Its centerline is the continuation of the centerline of the runway.

C.

Runway Larger Than Utility Visual Approach Zone. The inner edge of this approach zone coincides with the end of the primary surface and is one thousand feet wide. The approach zone for runway 33 expands outward uniformly to a width of one thousand five hundred feet at a horizontal distance of five thousand feet from the primary surface. Its centerline is the continuation of the runway.

D.

Precision Instrument Runway Approach Zone. The inner edge of this approach zone coincides with the end of the primary surface and is one thousand feet wide. The approach zone for runway 15 expands outward uniformly to a width of sixteen thousand feet at a horizontal distance of fifty thousand feet from the primary surface. Its centerline is the continuation of the centerline of the runway.

E.

Transitional Zones. These zones are established as the area beneath the transitional surfaces. These surfaces extend outward and upward at ninety-degree angles to a runway centerline extended at a slope of seven feet horizontally or each foot vertically from the sides of the primary and approach surfaces to where they intersect the horizontal and conical surfaces. Transitional zones for those portions of the precision approach zones which project through and beyond the limits of the conical surface extend a distance of five thousand feet measured horizontally from the edge of the approach zones and at ninety-degree angles to the extended runway centerline.

F.

Horizontal Zone. The horizontal zone is established by swinging arcs of ten thousand feet radii from the center of each end of the primary surface of runways 15 through 33, and connecting the adjacent arcs by drawing lines tangent to those arcs. The horizontal zone does not include the approach and transitional zones.

G.

Conical Zone. The conical zone is established as the area that commences at the periphery of the horizontal zone and extends outward therefrom a horizontal distance of four thousand feet. The conical zone does not include the precision instrument approach zones and the transitional zones.

(Ord. 53 § 160-1, 1978)

Except as otherwise provided in this title, no structure or tree shall be erected, altered, allowed to grow, or be maintained in any zone created by this title to a height in excess of 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.

Utility Runway Visual Approach Zone. Slopes upward twenty feet horizontally for each foot vertically, beginning at the end of and at the same elevation as the primary surface and extending to a horizontal distance of five thousand feet along the extended runway centerline.

B.

Utility Runway Nonprecision Instrument Approach Zone. Slopes upward twenty feet horizontally for each foot vertically beginning at the end of and at the same elevation as the primary surface and extending to a horizontal distance of five thousand feet along the extended runway centerline.

C.

Runway Larger Than Utility Visual Approach Zone. Slopes upward twenty feet horizontally for each foot vertically beginning at the end of and at the same elevation as the primary surface and extending to a horizontal distance of five thousand feet along the extended runway centerline.

D.

Precision Instrument Runway Approach Zone. Slopes upward fifty feet horizontally for each foot vertically beginning at the end of and at the same elevation as the primary surface and extending to a horizontal distance of ten thousand feet along the extended centerline; thence slopes upward forty feet horizontally for each foot vertically to an additional horizontal distance of forty thousand feet along the extended runway centerline.

E.

Transitional Zones. Slopes upward and outward seven feet horizontally for each foot vertically beginning at the side of and at the same elevation as the primary surfaces and the approach zones, and extending to a height of one hundred fifty feet above the airport elevation, which airport elevation is five thousand five hundred fifty-three feet above mean sea level. In addition to the foregoing, there are established height limits sloping upward and outward seven feet horizontally for each foot vertically beginning at the sides of and at the same elevation as the approach zones, and extending to where they intersect the conical surface. Where the precision instrument runway approach zone projects beyond the conical zone, height limits sloping upward and outward seven feet horizontally for each foot vertically shall be maintained beginning at the sides of and at the same elevation as precision instrument runway approach surface, and extending to a horizontal distance of five thousand feet measured at ninety-degree angles to the extended runway centerline.

F.

Horizontal Zone. One hundred and fifty feet above the airport elevations or a height of five thousand seven hundred three feet above mean sea level.

G.

Conical Zone. Slopes upward and outward twenty feet horizontally for each foot vertically beginning at the periphery of the horizontal zone and at one hundred and fifty feet above the airport elevation and extending to a height of three hundred and fifty feet above the airport elevation.

H.

Excepted Height Limitations. Nothing in this title shall be construed as prohibiting the growth, construction, or maintenance of any tree or structure to a height of up to fifty feet above the surface of the land, except in approach zones within two thousand five hundred feet of the ends of the primary surfaces.

Where an area is covered by more than one height limitation, the more restrictive limitation shall prevail.

(Ord. 53 § 160-2, 1978)

Notwithstanding any other provisions of this title, no use may be made of land or water within any zone established by this title 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 or otherwise in any way create a hazard or endanger the landing, takeoff, or maneuvering of aircraft intending to use the airport.

(Ord. 53 § 160-3, 1978)

A.

Regulations Not Retroactive. The regulations prescribed in 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 the effective date of the ordinance codified in this title, or otherwise interfere with the continuance of a nonconforming use. Nothing contained herein shall require any change in the construction, alteration, or intended use of any structure, the construction or alteration of which has begun prior to the effective date of the ordinance codified in this title, and is diligently prosecuted.

B.

Marking and Lighting. Notwithstanding the preceding provision 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 manager to indicate to the operators of aircraft in the vicinity of the airport, the presence of such airport hazards. Such markers and lights shall be installed, operated and maintained at the expense of Butte-Silver Bow, state of Montana.

(Ord. 53 § 160-4, 1978)

A.

Application for Permit. Each application for a permit shall be submitted to the zoning officer, and shall indicate the purpose for which the permit is desired, with sufficient particulars to determine whether the resulting use, structure or tree would conform to the regulations herein prescribed. If such determination is in the affirmative, the permit shall be granted, but the permit shall not be granted for any use, structure or tree which would violate any airport zone.

B.

Future Uses. No material change shall be made in the use of land and no structure or tree, exceeding twenty-five feet in height above the surface of the land in approach zones within twenty-five hundred feet of the ends of the primary surfaces, or exceeding fifty feet in height above the surface of the land in other areas, shall be erected, altered, planted, or otherwise established or allowed to exist in any zone created by this chapter unless a permit therefor has been applied for and granted.

C.

Existing Uses. No permit shall be granted that would allow the establishment or creation of an airport hazard or permit a nonconforming use, structure, or tree to become a greater hazard to air navigation than it was on the effective date of the ordinance codified in this title, or any amendments thereto, or than it is when the application for a permit is made.

D.

Nonconforming Uses Abandoned or Destroyed. Whenever the zoning officer determines that a nonconforming tree or structure has been abandoned or more than eighty percent torn down, physically deteriorated, or decayed, no permit shall be granted that would allow such structure or tree to exceed the applicable height limits or otherwise deviate from the zoning regulations.

E.

Variances. Any person desiring to erect or increase the height of any structure, or permit the growth of any tree, or use his property not in accordance with the regulations prescribed in this title, may apply to the board of adjustment for a variance from such regulations. Such variances shall be allowed where it is duly found that a literal application or enforcement of the regulations would result in practical difficulty or unnecessary hardship, and relief granted would not be contrary to the public interest but will do substantial justice and be in accordance with the spirit of this title.

F.

Hazard Marking and Lighting. Any permit or variance granted may, if such action is deemed advisable to effectuate the purpose of this title and be reasonable in the circumstances, be so conditioned as to require the owner of the structure or tree in question to permit Butte-Silver Bow, state of Montana, at its own expense, to install, operate, and maintain thereon such markers and lights as may be necessary to indicate to pilots the presence of an airport hazard.

(Ord. 53 § 160-5, 1978)

It shall be the duty of the zoning officer to administer and enforce the regulations prescribed in this chapter. Applications for permits or variances shall be made to the zoning officer upon forms to be furnished by him. Applications for permits shall be acted upon within a reasonable time. Applications for action by the zoning commission or board of adjustment shall be forthwith transmitted to the zoning commission or board of adjustment by the zoning officer. The zoning officer shall not be or include any member of the zoning commission or board of adjustment.

(Ord. 53 § 160-6, 1978)