As used in these regulations, the following terms have the meanings indicated unless the context requires otherwise. Words not specifically defined that relate to aeronautical practices, processes, and equipment shall be construed according to their general usage in the aviation industry. Terms Defined. “Administration” means the Maryland Aviation Administration of the Maryland Department of Transportation, established pursuant to Transportation Article, §2-102(b)(2), Annotated Code of Maryland. Repealed. “Airport” means a public use airport licensed by the Administration or owned or operated, or both, by a public entity of Maryland and used by fixed wing aircraft. “Airport obstruction zone” means all land within a 3 nautical mile radius of the established reference point of an airport. “Established airport elevation” means the highest point of an airport's usable runways measured in feet from mean sea level. “Established reference point” means the center of the longest runway existing or planned at the time of the initial adoption of an airport obstruction program, and if changed at a later date, means the center of the longest runway existing as a result of the change. “Hazard” means any object which affects the area available for landing, take-off, and maneuvering of aircraft, thus tending to impair or destroy the utility of an airport and present a potential danger to users of the airport and residents of the area. “Imaginary surfaces” means a series of planes or curved surfaces placed at various angles or arcs in relation to an airport's runways and based on a runway's classification and most precise available or planned aircraft approach path, more fully described in Regulation .04D of this chapter. “Nautical mile” means a distance of 6,076 consecutive linear feet. “Non-conforming use” means any preexisting object or use of land which is inconsistent with the provisions of the airport's obstruction standards described in Regulation .04 of this chapter. “Non-precision instrument approach” means an instrument approach procedure using air navigation facilities with horizontal guidance only. “Object” means tangible personal property or real property, including vegetation and terrain features. “Obstruction” means an object that penetrates any imaginary surface taking precedence as defined in these regulations. “Personalty” means any personal property. “Precision instrument approach” means an instrument approach procedure using an instrument landing system or a precision approach radar system which provides horizontal and vertical guidance for landing on a runway. “Public-use airport” means any airport, whether publicly or privately owned, at which the owner or persons having a right of access and control invite, encourage, or allow flight operations by the public without the need for prior permission. “Runway” means any existing or planned hard surface or turf covered area of an airport which is specifically designated and used or planned to be used for takeoff or landing of aircraft. “Slope” means an incline from the horizontal expressed in an arithmetic ratio or horizontal distance to vertical distance. “Statute mile” means a distance of 5,280 consecutive linear feet. “Substantial alteration” means any change in an object which results in a modification of the dimensions of that object. “Utility runway” means a runway constructed for or intended to be used by propeller-driven aircraft of 12,500 pounds or less (maximum gross weight). “Visual runway” means a runway intended solely for the operation of aircraft using visual approach procedures, as indicated on an airport layout plan (ALP). For example: