| Air Carrier |
A commercial airline with published schedules operating at least five round trips per week.
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| Air Taxi |
An aircraft certificated for commercial service available for hire on demand.
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| ALP - Airport Layout Plan |
The official, FAA approved map of airport facilities
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| ALS - Approach Lighting System |
Radiating light beams guiding pilots to the extended centerline of the runway on final approach and landing.
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| Ambient Noise Level |
The existing background noise level characteristic of an environment.
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| Approach Lights |
High intensity lights located along the approach path at the end of an instrument runway. Approach lights aid the pilot as he transitions from instrument flight conditions to visual conditions at the end of an instrument approach.
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| APU - Auxiliary Power Unit |
A self-contained generator in aircraft producing power for ground operation and for starting the engines.
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| Arrival |
The act of landing at an airport.
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| Arrival Procedure |
A series of directions from air traffic control, using fixes and procedures, to guide an aircraft from the enroute environment to an airport for landing.
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| Arrival Stream |
A flow of aircraft that are following similar arrival procedures.
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| ARTCC - Air Route Traffic Control Center |
A facility providing air traffic control to aircraft on an Instrument Flight Rules flight plan within controlled airspace and principally during the enroute phase of flight.
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| ATC - Air Traffic Control |
The control of aircraft traffic, in the vicinity of airports from control towers, and in the airways between airports from control centers.
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| ATCT - Airport Traffic Control Tower |
A central operations tower in the terminal air traffic control system with an associated Instrument Flight Rules room if radar equipped, using air/ground communications and/or radar, visual signaling and other devices to provide safe, expeditious movement of air traffic.
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| Avionics |
Airborne navigation, communications, and data display equipment required for operation under specific air traffic control procedures.
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| Altitude MSL |
Aircraft altitude measured in feet above mean sea level.
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| Backblast |
Low frequency noise and high velocity air generated by jet engines on takeoff.
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| Base Leg |
A flight path at right angles to the landing runway. The base leg normally extends from the downwind leg to the intersection of the extended runway centerline.
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| Center |
See ARTCC.
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| Commuter Airline |
Operator of small aircraft (maximum size of 30 seats) performing scheduled service between two or more points.
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| Decibel (dB) |
In sound, decibels measure a scale from the threshold of human hearing, 0 dB, upward towards the threshold of pain, about 120-140 dB. Because decibels are such a small measure, they are computed logarithmically and cannot be added arithmetically. An increase of ten dB is generally perceived by human ears as a doubling of noise.
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| dBA |
A-weighted decibels adjust sound pressure towards the frequency range of human hearing.
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| dBC |
C-weighted decibels adjust sound pressure towards the low frequency end of the spectrum. Although less consistent with human hearing than A-weighting, dBC can be used to consider the impacts of certain low frequency operations.
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| Decision Height |
The height at which a decision must be made during an instrument approach either to continue the approach or to execute a missed approach.
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| Departure |
The act of an aircraft taking off from an airport.
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| Departure Procedure |
A published Instrument Flight Rules departure procedure describing specific criteria for climb, routing, and communications for a specific runway at an airport.
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| Displaced Threshold |
A threshold that is located at a point on the runway other than the physical beginning. Aircraft can begin departure roll before the threshold, but cannot land before it.
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| DME - Distance Measuring Equipment |
Equipment used to measure, in nautical miles, the distance of an aircraft from the DME navigational aid located on the airport.
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| DNL - Day/night noise level |
The daily average noise metric in which that noise occurring between 10:00 p.m. and 7:00 a.m. is penalized by 10 dB. DNL is often expressed as annual average noise levels.
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| DNL Contour |
The "map" of noise exposure around an airport. A contour is computed through a FAA model called the Integrated Noise Model (INM), which calculates the annual noise exposure.
FAA defines significant noise exposure as any area within the 65dB DNL contour; that is the area within an annual average noise exposure of 65 decibels or higher.
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| Downwind Leg |
A flight path parallel to the landing runway in the direction opposite the landing direction.
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| Duration |
The length of time in seconds that a noise event lasts. Duration is usually measured in time above a specific noise threshold.
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| Enroute |
The portion of a flight between departure and arrival terminal areas.
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| FAA - Federal Aviation Administration |
The FAA is the agency responsible for aircraft safety, movement and controls.
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| FAR - Federal Aviation Regulations |
FARs are the rules and regulations which govern the operation of aircraft, airways, and airmen.
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| FAR Part 36 |
A Federal Aviation Regulation defining maximum noise emissions for aircraft.
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| FAR Part 150 |
A Federal Aviation Regulation governing noise and land use compatibility studies and programs.
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| FAR Part 91 |
A Federal Aviation Regulation governing the phaseout of Stage 1 and 2 aircraft as defined under FAR Part 36.
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| FAR Part 161 |
A Federal Aviation Regulation governing the ability of airports to implement restrictions based on noise.
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| Fix |
A geographical position determined by visual references to the surface, by reference to one or more Navaids, or by other navigational methods.
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| Fleet Mix |
The mix or differing aircraft types operated at a particular airport or by an airline.
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| Flight Plan |
Specific information related to the intended flight of an aircraft. A flight plan is filed with a Flight Service Station or Air Traffic Control facility.
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| GA - General Aviation |
Civil aviation excluding air carriers, commercial operators and military aircraft.
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| Glide Slope |
Generally a 3-degree angle of approach to a runway established by means of airborne instruments during instrument approaches, or visual ground aids for the visual portion of an instrument approach and landing.
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| GPS - Global Positioning System |
A satellite based radio positioning, navigation, and time-transfer system.
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| GPU - Ground Power Unit |
A source of power, generally from the terminals, for aircraft to use while their engines are off.
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| Ground Track |
Ground track is the seeming path an aircraft would follow on the ground if its airborne flight path were plotted on the terrain.
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| High Speed Exit Taxiway |
A taxiway designed and provided with lighting or marking to define the path of aircraft traveling at high speed from the runway center to a point on the center of the taxiway.
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| IFR - Instrument Flight Rules |
Instrument Flight Rules are a set of regulations and procedures for flying aircraft without the assumption that pilots will be able to see and avoid obstacles, terrain, and other air traffic; it is an alternative to visual flight rules (VFR), where the pilot is primarily or exclusively responsible for see-and-avoid. Since navigation and control of the aircraft under IFR is done by instruments, flying through clouds is allowed; under VFR it is not. Commercial traffic (a flight carrying paying passengers or cargo) operates under IFR almost exclusively.
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| ILS - Instrument Landing System |
A precision instrument approach system which normally consists of a localizer, glide slope, outer marker, middle marker, and approach lights.
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| IMC - Instrument Meteorological Conditions |
Instrument meteorological conditions describes weather conditions that require pilots to fly primarily by reference to instruments, and therefore under Instrument Flight Rules (IFR).
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| Instrument Approach |
Each instrument approach is designed to navigate to an airport, hold in the vicinity of the airport if required, then fly to a position from where sufficient runway environment visual references can be obtained for a safe landing, all without assistance from air traffic control. If visual reference with the runway environment is not made at the decision height (precision approaches) or missed approach point (non-precision approaches), a missed approach must be executed. The approach is defined and published enabling aircraft to land in case of a radio communication failure. It also allows instrument approaches to be made at airports where air traffic control does not use radar.
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| Knots |
A measure of speed used in aerial navigation. One knot is equal to one nautical mile per hour (1.15 knots = 1 mile per hour).
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| Load Factor |
The percentage of seats occupied in an aircraft.
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| Lmax |
The peak noise level reached by a single aircraft event.
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| Localizer |
A navigational aid that consists of a directional pattern of radio waves modulated by two signals which, when receding with equal intensity, are displayed by compatible airborne equipment as an on-course indication, and when received in unequal intensity are displayed as an off-course indication.
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| Middle Marker |
A beacon that defines a point along the glide slope of an Instrument Landing System, normally located at or near the point of decision height.
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| Missed Approach Procedure |
Missed Approach is an IFR procedure which is a standard (but optional) component segment of an instrument approach. Generally, if the pilot determines by the time the aircraft is at the decision height (for a precision approach) or missed approach point (for a non-precision approach), that the runway or its environment is not in sight, or that a safe landing cannot be accomplished for any reason, the landing approach must be discontinued and the missed approach procedure must be initiated immediately.
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| NAS - National Airspace System |
The common network of U.S. airspace; air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information, manpower and material.
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| Nautical Mile |
A measure of distance used in air and sea navigation. One nautical mile is equal to the length of one minute of latitude along the earth's equator. The nautical mile is officially set as 6,076.115 feet.
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| Navaid |
Navigational Aid.
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| NDB - Non-Directional Beacon |
Signal that can be read by pilots of aircraft with direction finding equipment. Used to determine bearing and can home in or track to or from the desired point.
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| NEM - Noise Exposure Map |
A FAR Part 150 requirement prepared by airports to depict noise contours. NEMs also take into account potential land use changes around airports.
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| Noise Contour |
See DNL Contour.
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| Non-Precision Approach Procedure |
Approaches are classified as either precision or nonprecision, depending on the accuracy and capabilities of the navigational aids (navaids) used. Precision approaches utilize both lateral (course) and vertical (glideslope) information. Nonprecision approaches provide course information only.
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| Operation |
A take-off, departure or overflight of an aircraft. Every flight requires at least two operations, a take-off and landing.
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| Outer Marker |
An Instrument Landing System navigation facility in the terminal area navigation system located four to seven miles from the runways edge on the extended centerline indicating the beginning of final approach.
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| Overflight |
Aircraft whose flights originate or terminate outside the metropolitan area that transit the airspace without landing.
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| Preferential Runways |
The most desirable runways from a noise abatement perspective to be assigned whenever possible.
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| Precision Approach Procedure |
Approaches are classified as either precision or nonprecision, depending on the accuracy and capabilities of the navigational aids (navaids) used. Precision approaches utilize both lateral (course) and vertical (glideslope) information. Nonprecision approaches provide course information only.
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| Radar Vectoring |
Navigational guidance where the air traffic controller issues a compass heading to a pilot.
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| Run-up |
A procedure used to test aircraft engines after maintenance to ensure safe operation prior to returning the aircraft to service. The power settings tested range from idle to full power and may vary in duration.
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| Run-up Locations |
Specified areas on the airfield where scheduled run-ups may occur. These locations are published, so as to produce minimum noise impact in surrounding neighborhoods.
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| Runway |
A long strip of land or water used by aircraft to land on or to take off from.
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| Sequencing Process |
Procedure in which air traffic is merged into a single flow, and/or in which adequate separation is maintained between aircraft.
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| SID - Standard Instrument Departure |
An aeronautical chart designed to expedite clearance delivery and to facilitate transition between takeoff and enroute operations.
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| Single Event |
Noise generated by a single aircraft operation.
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| STAR - Standard Terminal Arrival Route |
STAR is a published Instrument Flight Rules arrival procedure describing specific criteria for descent, routing, and communications for a specific runway at an airport.
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| Taxiway |
A paved strip that connects runways and terminals providing the ability to move aircraft so they will not interfere with takeoffs or landings.
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| Terminal Airspace |
The airspace that is controlled by a Terminal Radar Approach Control (see TRACON).
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| Terminal Area |
A general term used to describe airspace in which approach control service or airport traffic control service is provided.
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| TRACON - Terminal Radar Approach Control |
TRACON is an FAA air traffic control service to aircraft arriving and departing or transiting airspace controlled by the facility. TRACONs control Instrument Flight Rules and participating Visual Flight Rules flights.
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| Vector |
A heading issued to a pilot to provide navigational guidance by radar. Vectors are assigned verbally by FAA air traffic controllers.
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| VFR - Visual Flight Rules |
VFR are rules governing procedures for conducting flight under visual meteorological conditions, or weather conditions with a ceiling of 1,000 feet above ground level and visibility of three miles or greater. It is the pilot's responsibility to maintain visual separation, not the air traffic controllers.
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| VMC - Visual Meteorological Conditions |
VMC are conditions in which visual flight rules (VFR) flight is permitted�that is, conditions in which pilots have sufficient visibility to fly the aircraft without reference to instruments and can maintain visual separation from terrain and other aircraft.
Since the pilot is primarily or exclusively responsible for see-and-avoid flying through clouds is not allowed
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| Visual Approach |
A visual approach is an ATC authorization for an aircraft on an IFR flight plan to proceed visually to the airport of intended landing. It is not an instrument approach procedure. Also, there is no missed approach segment. An aircraft unable to complete a visual approach shall be handled as any go-around and appropriate separation must be provided.
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| VASI - Visual Approach Slope Indicator |
A VASI is a system of lights on the side of a runway that provides visual descent guidance information during the approach to a runway. These lights may be visible from up to eight kilometers (five miles) during the day and up to 32 kilometers (20 miles) or more at night.
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