17.54.010 Legislative findings

The City Commission makes the following findings:

1. The runway protection zone is entirely located on the property under control of the Great Falls International Airport (GFIA).
2. Based on statistics compiled by the National Transportation Safety Board, the majority of aircraft accidents occur at airports or in the immediate area of the extended centerline of the runway.
3. Given the increased level of risk associated with landings and takeoffs, it is important to protect the approach and departure ends of each runway.
4. Some types of land uses can be located near airports because they are compatible with the proper functioning and continued operation of airports, while others are not. Examples of incompatible land uses include tall structures and buildings, residential, places of public assembly, and uses that cause electronic interference, glare, smoke emissions, or dust, or that attract birds and wildlife.
5. Some types of buildings can be designed to reduce the effects of airport-related noise on its occupants, while others cannot.
6. Inappropriate development near airports increases the perceived impact of aircraft noise.
7. Uncontrolled growth and development around airports present a clear threat to the safety of those in aircraft and those on the ground.
8. The State has authorized the City to adopt regulations regarding the height of structures and uses of land around airports.
9. In developing the regulations contained in this chapter, the following factors were considered: the character of the flying operations expected to be conducted at the airport, the nature of the terrain within the area, the character of surrounding land uses, and the uses to which the property to be zoned is put and adaptable
10. In developing the noise regulations contained in this chapter, the following factors were considered: the safety of airport users and persons and property in the vicinity of the airport; the character of the flying operations conducted or expected to be conducted at the airport; the magnitude and duration of noise produced by aircraft and the number of aircraft flybys; the nature of the terrain; the future development of the airport; and the views and mandates of the federal agency charged with fostering of civil aeronautics as to the aerial surfaces necessary for flying operations.

17.54.020 Purpose

This chapter is established to promote the public health, safety, and welfare and is intended to accomplish the following purposes:

1. minimize the conflicts between airport operations and surrounding land uses by imposing limitations on the height of structures and objects of natural growth and land use
2. ensure that people buying property near the airport are aware of the potential noise levels and risks associated with the continued operation of the airport
3. protect the significant public and private investments already made at the Great Falls International Airport and Malmstrom Air Force Base

17.54.030 Applicability

1. Generally. This chapter applies to the land within the City limits.
2. Exemptions to height restrictions. Trees less than 75 feet in vertical height above the ground surface are exempt when within the following limits, except when, because of terrain, land contour, or topographic features, such tree would extend above the height limits prescribed for such zones:
   1. in areas of the horizontal zone and conical zone
   2. in areas lying within the limits of the approach zones, but at a horizontal distance of not less than 4,200 feet from each end of the runway
   3. in areas within the limits of the transition zones beyond the perimeter of the horizontal zone

   Nothing contained in this section shall be construed as permitting or intending to permit any construction, or alteration of any structure, or growth of any tree in excess of any of the height limits established by this chapter or State or federal law.

17.54.040 Airport height districts

1. Runway classification. The runways at GFIA are classified as shown in Exhibit 54-1.
2. Imaginary surface. For each runway, imaginary surfaces are established, as generally depicted in Exhibit 54-2 based on the dimensions shown in Exhibit 54-3.
3. Airport height districts. The following four airport height districts are established:
   1. Airport height district 1 (AHD-1). This district corresponds to the projection of the approach surface onto a horizontal plane.
   2. Airport height district 2 (AHD-2). This district corresponds to the projection of the conical surface onto a horizontal plane.
   3. Airport height district 3 (AHD-3). This district corresponds to the projection of the horizontal surface onto a horizontal plane.
   4. Airport height district 4 (AHD-4). This district corresponds to the projection of the transition surface onto a horizontal plane.

4. Limitation on heights. No structure shall be erected, altered, or maintained, and no tree shall be allowed to grow in any zone created by this chapter that penetrates the imaginary surfaces associated with each district.

   Where the precision instrument runway approach zone projects beyond the conical zone, there are established height limits sloping 7 feet outward for each foot upward beginning at the sides of and at the same elevation as the approach surface, and extending a horizontal distance of 5,000 feet measured at 90 degree angles to the extended runway centerline.

Exhibit 54-3. Dimensions (in feet) for imaginary surfaces (Based on airport elevation)

Dimension (1)	Description	Visual Runway (2)		Non-Precision Instrument Runway (2)			Precision Instrument Runway
		A	B	A	B
					C	D
1	Width of primary surface and approach surface width at inner end	250	500	500	500	1,000	1,000
2	Radius of horizontal surface	5,000	5,000	5,000	10,000	10,000	10,000
3	Approach surface width at end	1,250	1,500	2,000	3,500	4,000	16,000
4	Approach surface length	5,000	5,000	5,000	10,000	10,000	50:1 for inner 10,000 feet and 40:1 for an additional 40,000
5	Approach slope	20:1	20:1	20:1	34:1	34:1
6	Width of conical surface	4,000	4,000	4,000	4,000	4,000	4,000
7	Height of horizontal surface above height of airport elevation	150	150	150	150	150	150
8	Height of outer edge of conical surface above height of airport	350	350	350	350	350	350

1. The numbers correspond to Exhibit 54-2.
2. The letters correspond to the following type of runways:
   1. Utility runway (Intended to be used by a propeller driven airplane with a maximum gross weight of 12,500 pounds and less.)
   2. Runway larger than utility
   3. Visibility minimum greater than ¾ mile
   4. Visibility minimum less than ¾ mile

17.54.050 Airport noise districts

1. Establishment. The following noise districts are established as described:
   1. Airport noise district 1 (AND-1). This district is located between the boundary of the airport influence area and the 65 LDN contour
   2. Airport noise district 2 (AND-2). This district is located between the 65 LDN contour and the 70 LDN contour.
   3. Airport noise district 3 (AND-3). This district is located between the 70 LDN contour and the 75 LDN contour.
   4. Airport noise district 4 (AND-4). This district is located within the 75 LDN contour.
   5. Airport noise district 5 (AND-5). This district is a rectangle 1,000 feet wide, centered on the centerline of the 03/21 runway, and extending 10,000 feet off of each end of the runway.
2. Source of noise contours. The noise contour lines referenced in this section are from the noise exposure map prepared consistent with FAR Part 150 and as adopted by the City Commission. This map is on record with the City Clerk.
3. Airport influence area. The boundary of the airport influence area is a rectangle extending 5,000 feet on either side of the runway centerline of the primary runway (Runway 03/21), and extending 10,000 feet off of each end of the runway.
4. Development limitations in AND-1 through AND-4. Land uses shall conform to the standards contained in Exhibit 54-4.
5. Development limitations in AND-5. Places of mass assembly (e.g., churches, stadiums, schools) are prohibited along with residential development greater than 3 units per acre.

Exhibit 54-4. Land use compatibility

Residential	Airport Noise District (AND)
	1	2	3	4
Single family (stick-built and factory-built units)	P(1)	-	-	-
Single family (mobile homes and manufactured homes)	P(3)	-	-	-
Duplexes	P(1)	-	-	-
Multi-family	P(1)	-	-	-
Transient lodging	P(1)	-	-	-
	-	-	-	-
Public
Schools	P	-	-	-
Hospitals and nursing homes	P	-	-	-
Churches and the like	P	-	-	-
Government services	P	P(4)	P(5)	-
Transportation	P	P	P(4)	P(5)
Parking	P	P	P(4)	P(5)
Commercial
Office and professional	P	P	P(1)	P(2)
Wholesale and retail building materials, hardware, and farm equipment	P	P	P(4)	P(5)
Retail trade – general	P	P	P(1)	P(2)
Utilities	P	P	P(4)	P(5)
Communication	P	P	P(1)	P(2)
Manufacturing and Production
Manufacturing	P	P	P(4)	P(5)
Photographic and optical	P	P	P(1)	P(2)
Agriculture (except livestock) and forestry	P	P	P	P
Livestock farming and breeding	P	P	P	-
Mining and fishing resource production and extraction	P	P	P	P
Recreational
Outdoor sports arenas and spectator sports	P	P(6)	P(6)	N
Outdoor music shells, amphitheaters	P	-	-	-
Nature exhibits and zoos	P	P	-	-
Amusement parks, parks, and resorts, and camps	P	P	P	-
Golf courses, riding stables, and water recreation	P	P	P(1)	P(2)

-   The use is not permitted in the district

P  The use is permitted in the district by right provided it is allowed in the underlying base zoning district

1. Measures to achieve NLR of 25 dB shall be incorporated into the design and construction of the building.

2. Measures to achieve NLR of 30 dB shall be incorporated into the design and construction of the building.

3. Manufactured homes are not permitted unless they are certified by the manufacturer as meeting a sound reduction of 25 dB.

4. Measures to achieve NLR of 25 dB shall be incorporated into the design and construction of portions of those buildings where the public is received, office areas, noise sensitive areas, or where the normal noise level is low.

5. Measures to achieve NLR of 30 dB shall be incorporated into the design and construction of portions of those buildings where the public is received, office areas, noise sensitive areas, or where the normal noise level is low.

6. Land use is compatible provided that special sound reinforcement systems are installed.

17.54.060 Performance standards

Notwithstanding any other provision of this chapter, no use may be made of land, structures, 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, create bird strike hazards, or otherwise endanger or interfere with the landing, takeoff, or maneuvering of aircraft intending to use GFIA. In addition, no use may be made of land structures or water within any zone established by this chapter which would result in legal action being taken against the airport or the City.

17.54.070 Fair disclosure statement

A property owner with land in the airport influence area, in the airport hazard zone, in the extended runway zone, in one of the noise impact zones, or in one of the height zones, shall notify potential buyers and their agents that such property is subject to the provisions of this chapter.

17.54.080 Hold harmless agreement

As a condition of subdivision approval or issuance of a conditional use permit for property within the airport influence area or one of the noise impact zones located outside the airport influence area, the property owner shall sign a hold harmless agreement similar to the sample provided in Appendix D ( 12k PDF).