Michigan Compiled Laws, Chapter 259. Aviation § 259.481

(a) “Airport” means a structure or an area of land or water that is designed and set aside for the landing and taking off of aircraft, is utilized or to be utilized by and in the interest of the public for the landing and taking off of aircraft, and is licensed by the commission.

(b) “Anemometer” means an instrument for measuring and recording the speed of wind.

(c) “Approach surface” means an imaginary plane longitudinally centered on a runway's centerline extended, and extending outward and upward from each end of that runway's primary surface, which plane has the specifications described in section 2c.  1

(d) “Commission” means the Michigan aeronautics commission.

(e) “Conical surface” means an imaginary plane extending outward and upward from the perimeter of a runway's horizontal surface at 1 of the following slopes, as applicable:

(f) “FAA” means the Federal Aviation Administration or a successor agency to the Federal Aviation Administration.

(g) “Heliport approach surface” means an imaginary plane projecting outward and upward from the perimeter of a heliport primary surface at a slope of 8 to 1.

(h) “Heliport primary surface” means an imaginary plane that is at the elevation established for a heliport coinciding in size and shape with the designated takeoff and landing area of that heliport.

(i) “Horizontal surface” means an imaginary horizontal plane 150 feet above the elevation established for an airport, the perimeter of which plane is constructed as described in section 2e.  2

(j) “Meteorological tower” means a structure, including all guy wires and accessory facilities, on which an anemometer is mounted for the purposes of documenting wind resources for the operation of a wind turbine generator.

(k) “Minimum obstruction clearance altitude” means the lowest FAA published altitude that assures acceptable navigational signal coverage and that is in effect between radio fixes on a low altitude airway, on an off-airway route, or, if the altitude meets obstacle clearance requirements for the entire route segment, on a route segment.

(l) “Nonprecision approach procedure” means a straight-in instrument approach in which an electronic glide slope is not provided.

(m) “Permit” means a permit issued by the commission under this act.

(n) “Person” means an individual, firm, partnership, corporation, association, or body politic. Person includes a trustee, receiver, assignee, or other similar representative of a person.

(o) “Precision approach procedure” means a standard instrument approach in which an electronic glide slope is provided.

(p) “Primary surface” means an imaginary plane longitudinally centered on a runway, which plane has the specifications described in section 2b.  3

(q) “Runway” means the portion of an airport designated as either of the following:

(r) “Structure” means an object constructed or installed, including, but not limited to, a building, tower, antenna, smokestack, or overhead transmission line.

(s) “Transitional surface” means an imaginary plane perpendicular to a runway centerline and to that centerline extended through the runway's primary surface and approach surface, which plane extends outward and upward from each side of the runway's primary surface and approach surface at a slope of 7 to 1 for the distances described in section 2d.  4

(t) “Utility runway” means a runway that is constructed for and intended to be used by propeller-driven aircraft with a maximum gross weight of 12,500 pounds or less.

(u) “Visual approach procedure” means an approach in which an aircraft on an instrument flight rules flight plan, operating in visual flight rules conditions under the control of an air traffic control authorization, may proceed to the airport of destination in visual flight rules conditions.