§ 151.091 PURPOSE AND GENERALLY.
   (A)   The purpose of this division is to require that new or redeveloped buildings within the Height Restriction Area, Airport Overlay (AO-3) District, be constructed to prevent interference with safe aircraft operation and to maintain a visually permeable and physically secure buffer that lowers the vulnerability of personnel on the base to outside attacks.
   (B)   The AO-3 District designates the areas that primarily include standards for controlling height. Except as otherwise provided herein for this district, no structure shall be erected, altered, or maintained in the AO-3 District to a height in excess of the applicable height limitations established in this Division 7 or those established and enforced by the FAA, DoD, or IDOT Division of Aeronautics.
   (C)   Establishment of height restriction areas. Buildings, structures, or land shall be occupied or used only in conformity with all of the regulations set forth herein for the district in which they are located. The boundaries of the AO-3 installation buffer and height hazard restriction areas are shown on the map in § 151.078. There are two height restriction areas within the AO-3 District:
      (1)   Height hazard area. A height hazard area as shown on the map depicted in Figure 3.3 encompassing all of the AO-3 District and defined by the airport imaginary surfaces described in §§ 16.50 through 16.110 of the State Airport Hazard Zoning Regulations, Title 92, Part 16 of the Illinois Administrative Code; and
      (2)   Installation buffer. A subarea of the AO-3 District being a buffer extending 1,500 feet from the boundaries of Scott Air Force Base, as shown on map depicted in Figure 3.3 and establishing supplemental height restrictions in the AO-3 District.