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65 Documents or regulations referenced in parentheses after the definition appear in a full reference list at the end of this section. Above Ground Level (AGL): An elevation datum given in feet above ground level. Air Carriers: The commercial system of air transportation, consisting of the certificated air carriers, air taxis (including commuters), supplemental air carriers, commercial operators of large aircraft, and air travel clubs. Aircraft Accident: An occurrence incident to flight in which, as a result of the operation of an aircraft, a person (occupant or nonoccupant) receives fatal or serious injury or an aircraft receives substantial damage. Aircraft Incident: A mishap associated with the operation of an aircraft in which neither fatal nor serious injuries nor substantial damage to the aircraft occurs. Aircraft Mishap: The collective term for an aircraft accident or an incident. Aircraft Operation: The airborne movement of aircraft at an airport or about an en route fix or at other point where counts can be made. There are two types of operations: local and itinerant. An operation is counted for each landing and each departure, such that a touch-and-go flight is counted as two operations. (FAA Stats) Airport: An area of land or water used or intended to be used for the landing and taking off of aircraft that includes its buildings and facilities, if any. (FAR 1) Airport Compatibility Zone: Areas on and near an airport in which land use and devel- opment restrictions are established to protect the safety of the public. Typical zones include the Runway Protection Zone, Inner Approach/Departure Zone, Inner Turning Zone, Outer Approach/Departure Zone, Sideline Zone, and the Traffic Pattern Zone. Airport Elevation: The highest point of an airportâs usable runways, measured in feet above mean sea level. (AIM) Airport Hazard: Any structure or use of land that obstructs the airspace required for the flight of aircraft in takeoff and landing. Airport Hazard Area: An area in which an airport hazard may be established. Airport Influence Area (AIA): An AIA is the area or areas in which current or future airport- related noise, overflight, safety, and/or airspace protection factors may significantly affect land uses or necessitate restrictions on those uses. Airport Improvement Program (AIP): Federal Aviation Administration (FAA) program that provides grants to public agencies for the planning and development of public-use airports. Glossary of Terms
66 Guidebook on Effective Land Use Compatibility Planning Strategies for General Aviation Airports Through AIP grants, the FAA funds the majority of the cost of planning studies and eligible improvement projects. Airport Layout Plan (ALP): A scale drawing of existing and proposed airport facilities, their location on an airport, and the pertinent clearance and dimensional information required to demonstrate conformance with applicable standards. Airport Master Plan (AMP): A long-range plan for development of an airport, including descriptions of the data and analyses on which the plan is based. Airspace Protection: Protection of navigable airspace from hazards to flight. Allowable Land Use: Uses of land that are allowed within a designated area by zoning ordinance in place. Ambient Noise Level: The level of noise that is all encompassing within a given environment for which a single source cannot be determined. It is usually a composite of sounds from many and varied sources near to and far from the receiver. Approach Protection Easement: A form of easement that both conveys all of the rights of an avigation easement and sets specified limitations on the type of land uses allowed to be developed on the property. Aviation-Related Use: Any facility or activity directly associated with the air transportation of persons or cargo or the operation, storage, or maintenance of aircraft at an airport or heliport. Such uses specifically include runways, taxiways, and their associated protected areas defined by the FAA, together with aircraft aprons, hangars, fixed base operations, terminal buildings, etc. Avigation Easement: A type of easement that typically conveys the following rights: â¢ A right-of-way for free and unobstructed passage of aircraft through the airspace over the property at any altitude above a surface specified in the easement (usually set according to FAR Part 77 criteria). â¢ A right to subject the property to noise, vibrations, fumes, dust, and fuel particle emissions associated with normal airport activity. â¢ A right to prohibit the erection or growth of any structure, tree, or other object that would enter the acquired airspace. â¢ A right-of-entry onto the property, with proper advance notice, for the purpose of removing, marking, or lighting any structure or other object that enters the acquired airspace. â¢ A right to prohibit electrical interference, glare, misleading lights, visual impairments, and other hazards to aircraft flight from being created on the property. Based Aircraft: Aircraft stationed at an airport on a long-term basis. Buffer Area/Zone: A technique that local governments and developers use to create a neutral area between adjacent properties. Clustering: A concentration of development into a portion of a project site. Combining District: A zoning district that establishes development standards in areas of special concern over and above the standards applicable to basic underlying zoning districts. Compatible Land Use: The use of land that is compatible and consistent with activities and purposes of ongoing airport operations. Conditional Use Permit: A permit that allows the local land use jurisdiction to consider defined uses that may not be permitted as of right within the zoning district but can be evaluated according to specific criteria through a public hearing process.
Glossary of Terms 67 Controlled Airspace: Any of several types of airspace within which some or all aircraft may be subject to air traffic control. (FAR 1) Critical Zone for Wildlife Hazards: Areas that may possess important natural functions and community values. Areas may include wetlands, streams, fish and wildlife habitat, flood hazard areas, water detention basins, and areas with significant vegetation. Day-Night Average Sound Level (DNL): The noise metric adopted by the U.S. Environmental Protection Agency for measurement of environmental noise. It represents the average daytime noise level during a 24-hour day, measured in decibels and adjusted to account for the lower tolerance of people to noise during nighttime periods. The mathematical symbol is Ldn. Decibel (dB): A unit measuring the magnitude of a sound, equal to the logarithm of the ratio of the intensity of the sound to the intensity of an arbitrarily chosen standard sound, specifically a sound just barely audible to an unimpaired human ear. For environmental noise from aircraft and other transportation sources, an A-weighted sound level (abbreviated dBA) is normally used. The A-weighting scale adjusts the values of different sound frequencies to approximate the auditory sensitivity of the human ear. Deed Notice: A formal statement added to the legal description of a deed to a property and referenced on any subdivision map. As used in airport land use planning, a deed notice would state that the property is subject to aircraft overflights. Deed notices are used as a form of buyer notification as a means of ensuring that those who are particularly sensitive to aircraft overflights can avoid moving to the affected areas. Density and Intensity Limitations: Establishment of criteria limiting the maximum number of dwellings or people in areas close to the airport. Displaced Threshold: A landing threshold located at a point on the runway other than the designated beginning of the runway. (AIM) Dwelling Unit: Any building, structure or portion thereof which is occupied as, or designed or intended for occupancy as, a residence by one or more families, and any vacant land that is offered for sale or lease for the construction or location thereon of any such building, structure, or portion thereof. (HUD) Easement: A less-than-fee-title transfer of real property rights from the property owner to the holder of the easement. Equivalent Sound Level (Leq): The level of constant sound that, in the given situation and time period, has the same average sound energy as does a time-varying sound. Extraterritorial Jurisdiction: The legal ability of a government to exercise authority beyond its normal boundaries. Federal Aviation Regulations (FAR) Part 77: The part of Federal Aviation Regulations that deals with objects affecting navigable airspace in the vicinity of airports. Objects that exceed the Part 77 height limits constitute airspace obstructions. FAR Part 77 establishes standards for identifying obstructions to navigable airspace, sets forth requirements for notice to the FAA of certain proposed construction or alteration, and provides for aeronautical studies of obstruc- tions to determine their effect on the safe and efficient use of airspace. A copy of the regulations is available at www.ecfr.gov. FAR Part 77 Surfaces: Imaginary airspace surfaces established with relation to each runway of an airport. There are five types of surfaces: â¢ Primary: A surface longitudinally centered on a runway. When the runway has a specially prepared hard surface, the primary surface extends 200 feet beyond each end of that runway,
68 Guidebook on Effective Land Use Compatibility Planning Strategies for General Aviation Airports but when the runway has no specially prepared hard surface, the primary surface ends at each end of that runway. â¢ Approach: A surface longitudinally centered on the extended runway centerline and extending outward and upward from each end of the primary surface. â¢ Transitional: These surfaces connect the primary surfaces, the first 200 feet of the clear zone surfaces, and the approach clearance surfaces to the inner horizontal surface, conical surface, outer horizontal surface or the other transitional surfaces. â¢ Horizontal: A horizontal plane 150 feet above the established airport elevation, the perimeter of which is constructed by swinging arcs of specified radii from the center of each end of the primary surface of each runway. â¢ Conical: A surface that extends upward and outward from the outer limits of the horizontal surface for a horizontal distance of 4,000 feet. The slope of the conical surface is 20:1 (5 percent) measured in a vertical plane. Federal Aviation Administration (FAA): The U.S. government agency responsible for ensuring the safe and efficient use of the nationâs airports and airspace. Federal Aviation Regulations (FAR): Regulations formally issued by the FAA to regulate air commerce. Findings: Legally relevant subconclusions that expose a government agencyâs mode of analysis of facts, regulations, and policies, and that bridge the analytical gap between raw data and ultimate decision. Usually required to be documented in a resolution approving a develop- ment or variance application. Flight Hazard: Any object or use of land that has the potential to lead to, cause, or contribute to the severity of an aircraft accident. General Aviation: That portion of civil aviation that encompasses all facets of aviation except air carriers. (FAA Stats) Geographical Information Systems (GIS): A system (or tool) used for gathering, analyzing, and presenting spatial or geographic data. Global Positioning System (GPS): A navigational system that utilizes a network of satellites to determine a positional fix almost anywhere on or above the earth. Developed and operated by the U.S. Department of Defense, GPS has been made available to the civilian sector for surface, marine, and aerial navigational use. For aviation purposes, the current form of GPS guidance provides en route aerial navigation and selected types of nonprecision instrument approaches. Eventual application of GPS as the principal system of navigational guidance throughout the world is anticipated. Helipad: A small, designated area, usually with a prepared surface, on a heliport, airport, landing/takeoff area, apron/ramp, or movement area used for takeoff, landing, or parking of helicopters. (AIM) Heliport: A facility used for operating, basing, housing, and maintaining helicopters. (HAI) Highly Risk-Sensitive Use: A critical type of land use that should be avoided near the ends of runways regardless of the number of people involved. Incompatible Land Use: A use of land that conflicts with airport operations and activities. Infill: Development that takes place on vacant property largely surrounded by existing development, especially development that is similar in character. Instrument Approach Procedure: A series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial
Glossary of Terms 69 approach to a landing or to a point from which a landing may be made visually. It is prescribed and approved for a specific airport by competent authority. (AIM) Instrument Flight Rules (IFR): Rules governing the procedures for conducting instrument flight. Generally, IFR applies when meteorological conditions with a ceiling below 1,000 feet and visibility less than 3 miles prevail. (AIM) Instrument Operation: An aircraft operation in accordance with an IFR flight plan or an operation where IFR separation between aircraft is provided by a terminal control facility. (FAA ATA) Instrument Runway: A runway equipped with electronic and visual navigation aids for which a precision or nonprecision approach procedure having straight-in landing minimums has been approved. (AIM) Inverse Condemnation: An action brought by a property owner seeking just compensation for land taken for a public use against a government or private entity having the power of eminent domain. It is a remedy peculiar to the property owner and is exercisable by that party where it appears that the taker of the property does not intend to bring eminent domain proceedings. Land Use Compatibility/Compatible Land Use: The coexistence of land uses surrounding the airport with airport-related activities. Land Use Controls: Measures established by local governments to implement land use planning. Land Use Density: A measure of the concentration of land use development in an area. Mostly the term is used with respect to residential development and refers to the number of dwelling units per acre. Land Use Intensity: A measure of the concentration of nonresidential land use development in an area. For the purposes of airport land use planning, the term indicates the number of people per acre attracted by the land use. Master Plan/Comprehensive Plan: A document and graphics prepared by a community or land use jurisdiction setting out goals, objectives and desired patterns for future land use, transportation and other development factors. The Master Plan is the basis for enactment of zoning ordinances to effect the Planâs objectives. Mean Sea Level (MSL): An elevation datum given in feet from mean sea level. Minimum Descent Altitude (MDA): The lowest altitude, expressed in feet above mean sea level, to which descent is authorized on final approach or during circle-to-land maneuvering in execution of a standard instrument approach procedure where no electronic glide slope is provided. (FAR 1) Mixed-Use Development: A mix of residential and nonresidential development on a single property or site. National Transportation Safety Board (NTSB): The U.S. government agency responsible for investigating transportation accidents and incidents. Navigational Aid (NAVAID): Any visual or electronic device airborne or on the surface that provides point-to-point guidance information or position data to aircraft in flight. (AIM) Noise Contours: Continuous lines drawn on a map and representing equal noise levels around a noise source, such as an airport or highway. The lines are generally drawn in 5-decibel increments so that they resemble elevation contours in topographic maps.
70 Guidebook on Effective Land Use Compatibility Planning Strategies for General Aviation Airports Noise Level Reduction (NLR): A measure used to describe the reduction in sound level from environmental noise sources occurring between the outside and the inside of a structure. Noise-Sensitive Receptor: Land uses in which occupants are especially susceptible to the effects of exposure to unwanted sound. These uses include residences, schools, hospitals, parks, auditoriums, churches, nursing homes, libraries, and guest lodges. Nonconforming Use: An existing land use that does not conform to subsequently adopted or amended zoning or other land use development standards. Obstruction: Any object of natural growth, terrain, or permanent or temporary construction or alteration, including equipment or materials used therein, the height of which exceed the standards established in Subpart C of FAR Part 77, Objects Affecting Navigable Airspace. Open Land: Land that is relatively level and free of large obstacles and can be used for emergency landing of aircraft near an airport. Overflight: Any distinctly visible and/or audible passage of an aircraft in flight, not necessarily directly overhead. Overflight Easement: An easement that describes the right to overfly the property above a specified surface and includes the right to subject the property to noise, vibrations, fumes, and emissions. An overflight easement is used primarily as a form of buyer notification. Overflight Zone: The area(s) where aircraft maneuver to enter or leave the traffic pattern, typically defined by the FAR Part 77 horizontal surface. Overlay Zone/Overlay District: See Combining District. Permitted Height: The height that a structure can have without penetrating the airportâs airspace protection surfaces. Prohibited Uses: Facilities and uses that are often not permitted within an airportâs influ- ence area. Recorded Deed of Notice: A form of buyer awareness measure whose objective is to ensure that prospective buyers of airport area property are informed about the airportâs impact on the property. Redevelopment: The acquisition and renovation of a previously developed area or land. Runway Protection Zone (RPZ): An area (formerly called a clear zone) off the end of a runway used to enhance the protection of people and property on the ground. (Airport Design AC) Runway Vicinity: Areas immediately adjoining the runway surface. Rezoning: To assign land or an area to a different zone. Safety Zone: For the purpose of airport land use planning, an area near an airport in which land use restrictions are established to protect the safety of the public from potential aircraft accidents. Single-Event Noise: As used herein, the noise from an individual aircraft operation or overflight. Single-Event Noise Exposure Level (SENEL): A measure, in decibels, of the noise exposure level of a single event, such as an aircraft flyby, measured over the time interval between the initial and final times for which the noise level of the event exceeds a threshold noise level and normalized to a reference duration of one second. SENEL is a noise metric established for use
Glossary of Terms 71 in California by the state Airport Noise Standards and is essentially identical to Sound Exposure Level (SEL). Sound Exposure Level (SEL): A time-integrated metric (i.e., continuously summed over a time period) that quantifies the total energy in the A-weighted sound level measured during a transient noise event. The time period for this measurement is generally taken to be that between the moments when the A-weighted sound level is 10 dB below the maximum. Statutes: State-level laws and regulations that provide guidance to airport land use compatibility. Structure: Something that is constructed or erected. Taking: Government appropriation of private land for which compensation must be paid as required by the Fifth Amendment of the U.S. Constitution. It is not essential that there be physical seizure or appropriation for a taking to occur, only that the government action directly interferes with or substantially disturbs the ownerâs right to use and enjoyment of the property, or significantly diminishes its economic value. Touch-and-Go: An operation by an aircraft that lands and departs on a runway without stopping or exiting the runway. (AIM) Traffic Pattern: The traffic flow prescribed for aircraft landing at, taxiing on, or taking off from an airport. The components of a typical traffic pattern are upwind leg, crosswind leg, downwind leg, base leg, and final approach. (AIM) Traffic Pattern Zone: An elliptical area that includes the majority of other portions of regular air traffic patterns and pattern entry routes. Urban Encroachment (Sprawl): Expansion of populations away from the concentrated urban areas to low-density areas. Variance: Permission to deviate from the specific use, bulk or other requirements of a zoning ordinance, granted by a Board of Adjustment or other authorized land use board or commission. Visual Approach: An approach where the pilot must use visual reference to the runway for landing under VFR conditions. Visual Flight Rules (VFR): Rules that govern the procedures for conducting flight under visual conditions. VFR applies when meteorological conditions are equal to or greater than the specified minimumâgenerally, a 1,000-foot ceiling and 3-mile visibility. Visual Runway: A runway intended solely for the operation of aircraft using visual approach procedures, with no straight-in instrument approach procedure and no instrument designation indicated on an FAA-approved ALP. (Airport Design AC) Wildlife Hazards: Facilities or structures that create wildlife attractants that pose a threat to aircraft operations. Zoning: A police power measure, enacted primarily by units of local government, in which the community is divided into districts or zones within which permitted and special uses are established, as are regulations governing lot size, building bulk, placement, and other develop- ment standards. Requirements vary from district to district, but they must be uniform within districts. A zoning ordinance consists of two parts: the text and a map. Zoning Ordinance: A legal document that allows a local government effective and legal regulation of uses of property while protecting and promoting the public interest.
72 Guidebook on Effective Land Use Compatibility Planning Strategies for General Aviation Airports Glossary Sources FAR 1: Federal Aviation Regulations Part 1, Definitions and Abbreviations AIM: FAA, Aeronautical Information Manual Airport Design AC: Federal Aviation Administration Advisory Circular 150/5300-13, Airport Design FAA ATA: Federal Aviation Administration, Air Traffic Activity FAA Stats: Federal Aviation Administration, Statistical Handbook of Aviation HAI: Helicopter Association International HUD: U.S. Department of Housing and Urban Development