SECTION:
11-35-1: Definitions
11-35-2: Zones
11-35-3: Height Limitations And Exceptions
11-35-4: Use Restrictions
11-35-5: Nonconforming Uses
11-35-6: Permits
11-35-7: Variances
11-35-8: Issuance Subject To Conditions
11-35-9: Enforcement
11-35-10: Airport Board Of Adjustment
11-35-11: Appeals
11-35-12: Judicial Review
11-35-13: Conflicting Regulations
For the purposes of this chapter, the following definitions are applicable:
AIRPORT: The Helena airport.
AIRPORT BOARD OF ADJUSTMENT: The board consisting of five (5) members appointed by the Helena city commission and Lewis and Clark County commissioners as provided in section 1-718 and 11-2707, Revised Codes of Montana, 1947.
AIRPORT ELEVATION: The established elevation of the highest point on the usable landing area.
AIRPORT HAZARD: Any structure, tree or use of land which obstructs the air space required for, or is otherwise hazardous to, the flight of aircraft in landing or taking off at the airport.
AIRPORT REFERENCE POINT: The point established as the approximate geographic center of the airport landing area and so designated.
HEIGHT: For the purpose of determining the height limitations in all zones established by this chapter and shown on the Helena airport zoning map, the datum shall be mean sea level elevation unless otherwise specified.
LANDING AREA: The area of the airport used for the landing, taking off, or taxiing of aircraft.
NONCONFORMING USE: Any preexisting structure, tree, natural growth or use of land which is inconsistent with the provisions of this chapter or amendment thereto.
NONPRECISION INSTRUMENT RUNWAY: A runway having or planned an instrument approach procedure utilizing area type navigation equipment for a straight in, nonprecision instrument approach.
PRECISION INSTRUMENT RUNWAY: A runway equipped or to be equipped with a precision electronic navigation aid or landing aid or other air navigation facilities, suitable to permit the landing of aircraft by an instrument approach under restricted visibility conditions.
RUNWAY: The paved surface of an airport landing strip.
STRUCTURE: An object or structure constructed or installed by man, including, but not limited to, buildings, towers, smoke stacks, and overhead transmission lines.
TREE: Any vegetation or other naturally growing object.
UTILITY RUNWAY: A runway that is constructed for and intended to be used by propeller driven aircraft of twelve thousand five hundred (12,500) pounds maximum gross weight or less. (Ord. 2359, 5-20-1985)
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)
A. Except as otherwise provided in this chapter, no structure or tree shall be erected, altered, allowed to grow, or maintained in any zone created by this chapter to a height in excess of the height limitation established for such zone. Such height limitations are established for each of the zones as follows:
1. Precision Instrument Approach Zone: One foot (1') in height for each fifty feet (50') in horizontal distance beginning at a point two hundred feet (200') from and at the centerline elevation of the planned end of the precision instrument runway and extending to a distance of ten thousand two hundred feet (10,200') from the end of the runway; thence one foot (1') in height for each forty feet (40') in horizontal distance to a point fifty thousand two hundred feet (50,200') from the planned end of the runway.
2. Utility Approach Zones: One foot (1') in height for each twenty feet (20') in horizontal distance beginning at a point two hundred feet (200') from and at the centerline elevation of the planned end of the utility runway and extending to a point five thousand two hundred feet (5,200') from the planned end of the runway.
3. Transition Zones: One foot (1') in height for each seven feet (7') in horizontal distance beginning at any point one hundred twenty five feet (125') normal to and at the elevation of the centerline of utility runways, extending two hundred feet (200') beyond each end thereof, and five hundred feet (500') normal to and at the elevation of the centerline of the precision instrument runway, extending two hundred feet (200') beyond each end thereof, extending to a height of one hundred fifty feet (150') above the airport elevation which is three thousand eight hundred seventy three feet (3,873') above mean sea level. In addition to the foregoing there are established height limits of one foot (1') vertical height for each seven feet (7') horizontal distance measured from the edges of all approach zones for the entire length of the approach zones and extending upward and outward to the points where they intersect the horizontal or conical surfaces. Further where the precision instrument approach zone projects through and beyond the conical zone, a height limit of one foot (1') for each seven feet (7') of horizontal distance shall be maintained beginning at the edge of the instrument approach zone measured normal to the centerline of the runway extended.
4. Horizontal Zone: One hundred fifty feet (150') above the airport elevation or a height of four thousand twenty three feet (4,023') above mean sea level.
5. Conical Zone: One foot (1') in height for each twenty feet (20') of horizontal distance beginning at the periphery of the horizontal zone, extending to a height of three hundred fifty feet (350') above the airport elevation.
B. Nothing in this chapter shall be construed as prohibiting the growth, construction or maintenance of any tree or structure to a height up to fifty feet (50') above the surface of the land. (Ord. 2359, 5-20-1985)
Notwithstanding any other provision of this chapter, no use may be made of land within any zone established by this chapter in such manner as to create electrical interference with radio communication between the airport and aircraft, make it difficult for operators or aircraft to distinguish between airport lights and others, result in glare in the eyes of operators of aircraft using the airport, impair visibility in the vicinity of the airport or otherwise endanger the landing, taking off, maneuvering, or operating of aircraft. (Ord. 2359, 5-20-1985)
A. 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 February 5, 1973, or otherwise interfere with the continuance of any use which was nonconforming as of such date. Nothing herein contained shall require any change in the construction or alteration of which was begun prior to February 5, 1973, and was diligently prosecuted, except as hereinafter provided in regard to hazard marking and lighting.
B. Notwithstanding the preceding provision of this section, the owner of any nonconforming structure or tree shall permit the installation, operation, and maintenance thereon of such markers and lights as shall be deemed necessary by the joint city-county airport board 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 the joint city- county airport board.
C. Whenever a nonconforming structure or tree has been abandoned, or has been torn down, physically deteriorated, decayed, damaged or otherwise destroyed, to an extent of more than fifty percent (50%) of its replacement cost at the time of such occurrence, such structure or tree shall not be reconstructed, repaired or replaced in a manner exceeding any applicable height limitation or otherwise deviating from the provisions of this chapter, and no permit allowing the same shall be issued hereunder without the prior granting of a variance. (Ord. 2359, 5-20-1985)
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