In order to carry out the provisions of this chapter, there are hereby created and established certain zones which are described herein and depicted on the Mason City Airport Zoning Map, which is hereby made a part of this chapter. Any structure or tree located in more than one (1) zone is considered to be only in the zone with the more restrictive height and use limitation. The various zones hereby established and defined are as follows:
A. Approach Overlay Zone (AO):
1. Defined: The airspace above a sloping plane extending outward from each end of each runway, rising uniformly at a fixed ratio, and of fixed size, through which aircraft commonly operate when arriving at, and departing from, the airport. AO Zones vary in size and slope based upon the present or future use that can be expected for each airport runway. The AO Zones at the airport are as follows:
a. Runway 36 (AO36): Beginning two hundred feet (200') beyond the paved portion at the end of the runway and centered on the extended centerline of the runway, the inner edge of the zone is one thousand feet (1,000') wide, expanding uniformly to an outer edge width of sixteen thousand feet (16,000'). The altitude of the inner edge is the same as the altitude of the runway threshold at the centerline. For each fifty feet (50') of horizontal distance the floor of the zone rises from the inner edge one foot (1') (50:1) for a distance of ten thousand feet (10,000'), and for an additional forty thousand feet (40,000'), for each forty feet (40') of horizontal distance, rising at a rate of one foot (1') (40:1).
b. Runway 18 (AO18): Beginning two hundred feet (200') beyond the paved portion at the end of the runway and centered on the extended centerline of the runway, the inner edge of the zone is one thousand feet (1,000') wide, expanding uniformly to an outer edge width of sixteen thousand feet (16,000'). The altitude of the inner edge is the same as the altitude of the runway threshold at the centerline. For each fifty feet (50') of horizontal distance the floor of the zone rises from the inner edge one foot (1') (50:1) for a distance of ten thousand feet (10,000'), and for an additional forty thousand feet (40,000'), for each forty feet (40') of horizontal distance, rising at a rate of one foot (1') (40:1).
c. Runway 30 (AO30): Beginning two hundred feet (200') beyond the paved portion at each end of the runway and centered on the extended centerline of the runway, the inner edge of each zone is five hundred feet (500') wide, expanding uniformly to an outer edge width of three thousand five hundred feet (3,500'). The altitude of the inner edge is the same as the altitude of the runway threshold at the centerline. The floor of the zone rises from the inner edge one foot (1') for each thirty four feet (34') of horizontal distance (34:1), for a distance of ten thousand feet (10,000').
d. Runway 12 (AO12): Beginning two hundred feet (200') beyond the paved portion at each end of the runway and centered on the extended centerline of the runway, the inner edge of each zone is five hundred feet (500') wide, expanding uniformly to an outer edge width of three thousand five hundred feet (3,500'). The altitude of the inner edge is the same as the altitude of the runway threshold at the centerline. The floor of the zone rises from the inner edge one foot (1') for each thirty four feet (34') of horizontal distance (34:1), for a distance of ten thousand feet (10,000').
2. Height Limitations:
a. Except as otherwise provided herein, no person shall construct or alter any structure, nor plant or grow any tree, so as to penetrate any Approach Overlay Zone created herein.
b. No person shall establish or maintain any private roadway in any location that would result in penetration of any AO Zone by any portion of any vehicle that shall be permitted to operate upon such roadway.
B. Controlled Activity Zone (CA):
1. Defined: An area of fixed size, underlying the innermost portion (closest to the runway end) of the AO Zone for that runway, descending from the floor of the AO Zone to the ground. The width and length of CA Zones may vary, and may be different on each runway end. The CA Zones for the airport are as follows:
a. Runway 36 (CA36): Underlying the innermost two thousand five hundred feet (2,500') of the AO Zone at the south end of the runway, the width of the CA Zone is one thousand feet (1,000') at the inner edge and expands uniformly to a width of one thousand seven hundred fifty feet (1,750').
b. Runway 18 (CA18): Underlying the innermost two thousand five hundred feet (2,500') of the AO Zone at the south end of the runway, the width of the CA Zone is one thousand feet (1,000') at the inner edge and expands uniformly to a width of one thousand seven hundred fifty feet (1,750').
c. Runway 30/12 (CA30, CA12): Underlying the innermost one thousand seven hundred feet (1,700') of the AO Zone at each end of the runway, the width of each CA Zone is one thousand feet (1,000') at the inner edge, expanding uniformly to a width of one thousand five hundred ten feet (1,510').
2. Use Limitation: No person shall establish or maintain any noncompatible use in any Controlled Activity Zone.
C. Horizontal Overlay Zone (HO):
1. Defined: The airspace above a horizontal plane, the perimeter of which is established by swinging arcs of ten thousand foot (10,000') radii from the center of the inner edge of the AO Zones of Runways 36, 18, and 30, and an arc of five thousand foot (5,000') radius from the center of the inner edge of the AO Zone of Runway 12, and connecting the adjacent arcs by lines tangent to those arcs. The floor of the HO Zone is one hundred fifty feet (150') above the airport elevation, or one thousand three hundred sixty three feet (1,363') above mean sea level.
2. Height Limitation: Except as otherwise provided herein, no person shall construct or alter any structure, or plant or grow any tree, so as to penetrate the Horizontal Overlay Zone created herein.
D. Transitional Overlay Zone (TO):
1. Defined: The airspace above a sloping plane rising from the sides of each runway and from the sides of each AO Zone at the rate of one foot (1') of elevation for each seven feet (7') horizontally (7:1). The TO Zones for the airport are as follows:
a. Runway 36 (TO36): Along each side of the runway, beginning at a point five hundred feet (500') from the centerline of the runway and at right angles to the runway centerline, and from each side of the AO Zone at the south end of the runway, at right angles to the extended runway centerline. The TO Zone is interrupted at the point where it intersects the HO Zone, and resumes at the outer edge of the CO Zone (see subsection E of this section) and continues outward for a distance of five thousand feet (5,000') from the edge of the AO Zone.
b. Runway 18 (TO18): Along each side of the runway, beginning at a point five hundred feet (500') from the centerline of the runway and at right angles to the runway centerline, and from each side of the AO Zone at the north end of the runway at right angles to the extended runway centerline. The TO Zone ends at the point where it intersects the HO Zone.
c. Runway 30/12 (TO30/12): Along each side of the runway, beginning at a point five hundred feet (500') from the centerline of the runway and at right angles to the runway centerline, and from each side of the AO Zone at each end of the runway at right angles to the extended runway centerline. The TO Zone ends at the point where it intersects the HO Zone.
2. Height Limitations:
a. Except as otherwise provided herein, no person shall construct or alter any structure, or plant or grow any tree, so as to penetrate any Transitional Overlay Zone created herein.
b. No person shall establish or maintain any private roadway in any location that would result in penetration of any Transitional Overlay Zone by any portion of any vehicle that shall be permitted to operate upon such roadway.
E. Conical Overlay Zone (CO):
1. Defined: The airspace above a sloped horizontal plane beginning at the periphery of the HO Zone and rising one foot (1') in height for each twenty feet (20') horizontally (20:1) for a horizontal distance of four thousand feet (4,000').
2. Height Limitations: Except as otherwise provided herein, no person shall construct or alter any structure, or plant or grow any tree, so as to penetrate the Conical Overlay Zone created herein. (Ord. 09-01, 1-6-2009)