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GLOSSARY OF
TERMS
Appendix A
Glossary of Terms
A - 1
A
ABOVE GROUND LEVEL: The elevaƟ on of a point or
surface above the ground.
ACCELERATE-STOP DISTANCE AVAILABLE (ASDA):
See declared distances.
ADVISORY CIRCULAR: External publicaƟ ons issued
by the FAA consisƟ ng of nonregulatory material
providing for the recommendaƟ ons relaƟ ve to a
policy, guidance and informaƟ on relaƟ ve to a specifi c
aviaƟ on subject.
AIR CARRIER: An operator which: (1) performs at
least fi ve round trips per week between two or more
points and publishes fl ight schedules which specify
the Ɵ mes, days of the week, and places between
which such fl ights are performed; or (2) transports
mail by air pursuant to a current contract with the
U.S. Postal Service. CerƟ fi ed in accordance with
Federal AviaƟ on RegulaƟ on (FAR) Parts 121 and 127.
AIRCRAFT: A transportaƟ on vehicle that is used or
intended for use for fl ight.
AIRCRAFT APPROACH CATEGORY: A grouping of
aircraŌ based on 1.3 Ɵ mes the stall speed in their
landing confi guraƟ on at their maximum cerƟ fi cated
landing weight. The categories are as follows:
• Category A: Speed less than 91 knots.
• Category B: Speed 91 knots or more, but less
than 121 knots.
• Category C: Speed 121 knots or more, but less
than 141 knots.
• Category D: Speed 141 knots or more, but less
than 166 knots.
• Category E: Speed greater than 166 knots.
AIRCRAFT OPERATION: The landing, takeoff, or
touch-and-go procedure by an aircraft on a runway
at an airport.
AIRCRAFT OPERATIONS AREA (AOA): A restricted and
secure area on the airport property designed to protect
all aspects related to aircraŌ operaƟ ons.
AIRCRAFT OWNERS AND PILOTS ASSOCIATION: A
private organizaƟ on serving the interests and needs
of general aviaƟ on pilots and aircraŌ owners.
AIRCRAFT RESCUE AND FIRE FIGHTING: A facility
located at an airport that provides emergency vehicles,
exƟ nguishing agents, and personnel responsible
for minimizing the impacts of an aircraŌ accident or
incident.
AIRFIELD: The porƟ on of an airport which contains
the faciliƟ es necessary for the operaƟ on of aircraŌ .
AIRLINE HUB: An airport at which an airline
concentrates a significant portion of its activity
and which often has a significant amount of
connecting traffic.
AIRPLANE DESIGN GROUP (ADG): A grouping of
aircraŌ based upon wingspan. The groups are as
follows:
• Group I: Up to but not including 49 feet.
• Group II: 49 feet up to but not including 79 feet.
• Group III: 79 feet up to but not including 118 feet.
• Group IV: 118 feet up to but not including 171 feet.
• Group V: 171 feet up to but not including 214 feet.
• Group VI: 214 feet or greater.
AIRPORT AUTHORITY: A quasi-governmental public
organizaƟ on responsible for seƫ ng the policies
governing the management and operaƟ on of an
airport or system of airports under its jurisdicƟ on.
AIRPORT BEACON: A navigaƟ onal aid located at
an airport which displays a rotaƟ ng light beam to
idenƟ fy whether an airport is lighted.
AIRPORT CAPITAL IMPROVEMENT PLAN: The
planning program used by the Federal AviaƟ on
AdministraƟ on to idenƟ fy, prioriƟ ze, and distribute
funds for airport development and the needs of the
NaƟ onal Airspace System to meet specifi ed naƟ onal
goals and objecƟ ves.
AIRPORT ELEVATION: The highest point on the
runway system at an airport expressed in feet above
mean sea level (MSL).
AIRPORT IMPROVEMENT PROGRAM: A program
authorized by the Airport and Airway Improvement
Act of 1982 that provides funding for airport planning
and development.
AÖÖÄ®ø A
Glossary of Terms
A - 2
AIRPORT LAYOUT DRAWING (ALD): The drawing
of the airport showing the layout of exisƟ ng and
proposed airport faciliƟ es.
AIRPORT LAYOUT PLAN (ALP): A scaled drawing of the
exisƟ ng and planned land and faciliƟ es necessary for
the operaƟ on and development of the airport.
AIRPORT LAYOUT PLAN DRAWING SET: A set of
technical drawings depicƟ ng the current and future
airport condiƟ ons. The individual sheets comprising
the set can vary with the complexiƟ es of the
airport, but the FAA-required drawings include the
Airport Layout Plan (someƟ mes referred to as the
Airport Layout Drawing (ALD), the Airport Airspace
Drawing, and the Inner PorƟ on of the Approach
Surface Drawing, On-Airport Land Use Drawing, and
Property Map.
AIRPORT MASTER PLAN: The planner’s concept of
the long-term development of an airport.
AIRPORT MOVEMENT AREA SAFETY SYSTEM: A
system that provides automated alerts and warnings
of potenƟ al runway incursions or other hazardous
aircraŌ movement events.
AIRPORT OBSTRUCTION CHART: A scaled drawing
depicting the Federal Aviation Regulation (FAR)
Part 77 surfaces, a representation of objects that
penetrate these surfaces, runway, taxiway, and
ramp areas, navigational aids, buildings, roads and
other detail in the vicinity of an airport.
AIRPORT REFERENCE CODE (ARC): A coding
system used to relate airport design criteria to the
operaƟ onal (AircraŌ Approach Category) to the
physical characterisƟ cs (Airplane Design Group) of
the airplanes intended to operate at the airport.
AIRPORT REFERENCE POINT (ARP): The laƟ tude and
longitude of the approximate center of the airport.
AIRPORT SPONSOR: The enƟ ty that is legally
responsible for the management and operaƟ on of an
airport, including the fulfi llment of the requirements of
laws and regulaƟ ons related thereto.
AIRPORT SURFACE DETECTION EQUIPMENT: A radar
system that provides air traffi c controllers with a
visual representaƟ on of the movement of aircraŌ
and other vehicles on the ground on the airfi eld at
an airport.
AIRPORT SURVEILLANCE RADAR: The primary
radar located at an airport or in an air traffi c control
terminal area that receives a signal at an antenna
and transmits the signal to air traffi c control display
equipment defi ning the locaƟ on of aircraŌ in the air.
The signal provides only the azimuth and range of
aircraŌ from the locaƟ on of the antenna.
AIRPORT TRAFFIC CONTROL TOWER (ATCT): A
central operaƟ ons facility in the terminal air traffi c
control system, consisƟ ng of a tower, including an
associated instrument fl ight rule (IFR) room if radar
equipped, using air/ground communicaƟ ons and/or
radar, visual signaling and other devices to provide
safe and expediƟ ous movement of terminal air traffi c.
AIR ROUTE TRAFFIC CONTROL CENTER: A facility
which provides en route air traffi c control service to
aircraŌ operaƟ ng on an IFR fl ight plan within controlled
airspace over a large, mulƟ -state region.
AIRSIDE: The porƟ on of an airport that contains the
faciliƟ es necessary for the operaƟ on of aircraŌ .
AIRSPACE: The volume of space above the surface
of the ground that is provided for the operaƟ on of
aircraŌ .
AIR TAXI: An air carrier cerƟ fi cated in accordance
with FAR Part 121 and FAR Part 135 and authorized
to provide, on demand, public transportaƟ on of
persons and property by aircraŌ . Generally operates
small aircraŌ “for hire” for specifi c trips.
AIR TRAFFIC CONTROL: A service operated by an
appropriate organizaƟ on for the purpose of providing
for the safe, orderly, and expediƟ ous fl ow of air
traffi c.
AIR ROUTE TRAFFIC CONTROL CENTER (ARTCC):
A facility established to provide air traffi c control
service to aircraŌ operaƟ ng on an IFR fl ight plan
within controlled airspace and principally during the
en route phase of fl ight.
AIR TRAFFIC CONTROL SYSTEM COMMAND CENTER:
A facility operated by the FAA which is responsible for
the central fl ow control, the central alƟ tude reservaƟ on
system, the airport reservaƟ on posiƟ on system, and
the air traffi c service conƟ ngency command for the air
traffi c control system.
Glossary of Terms
A - 3
AIR TRAFFIC HUB: A categorizaƟ on of commercial
service airports or group of commercial service
airports in a metropolitan or urban area based upon
the proporƟ on of annual naƟ onal enplanements
exisƟ ng at the airport or airports. The categories
are large hub, medium hub, small hub, or non-
hub. It forms the basis for the apporƟ onment of
enƟ tlement funds.
AIR TRANSPORT ASSOCIATION OF AMERICA: An
organizaƟ on consisƟ ng of the principal U.S. airlines
that represents the interests of the airline industry on
major aviaƟ on issues before federal, state, and local
government bodies. It promotes air transportaƟ on
safety by coordinaƟ ng industry and governmental
safety programs and it serves as a focal point for
industry eff orts to standardize pracƟ ces and enhance
the effi ciency of the air transportaƟ on system.
ALERT AREA: See special-use airspace.
ALTITUDE: The verƟ cal distance measured in feet
above mean sea level.
ANNUAL INSTRUMENT APPROACH (AIA): An
approach to an airport with the intent to land by an
aircraŌ in accordance with an IFR fl ight plan when
visibility is less than three miles and/or when the ceiling
is at or below the minimum iniƟ al approach alƟ tude.
APPROACH LIGHTING SYSTEM (ALS): An airport
lighƟ ng facility which provides visual guidance to
landing aircraŌ by radiaƟ ng light beams by which the
pilot aligns the aircraŌ with the extended centerline
of the runway on fi nal approach and landing.
APPROACH MINIMUMS: The alƟ tude below which
an aircraŌ may not descend while on an IFR approach
unless the pilot has the runway in sight.
APPROACH SURFACE: An imaginary obstrucƟ on
limiƟ ng surface defi ned in FAR Part 77 which is
longitudinally centered on an extended runway
centerline and extends outward and upward from
the primary surface at each end of a runway at a
designated slope and distance based upon the type of
available or planned approach by aircraŌ to a runway.
APRON: A specifi ed porƟ on of the airfi eld used for
passenger, cargo or freight loading and unloading,
aircraŌ parking, and the refueling, maintenance and
servicing of aircraŌ .
AREA NAVIGATION: The air navigaƟ on procedure
that provides the capability to establish and maintain
a fl ight path on an arbitrary course that remains
within the coverage area of navigaƟ onal sources
being used.
AUTOMATED TERMINAL INFORMATION SERVICE
(ATIS): The conƟ nuous broadcast of recorded non-
control informaƟ on at towered airports. InformaƟ on
typically includes wind speed, direcƟ on, and runway
in use.
AUTOMATED SURFACE OBSERVATION SYSTEM
(ASOS): A reporƟ ng system that provides frequent
airport ground surface weather observaƟ on data
through digiƟ zed voice broadcasts and printed reports.
AUTOMATIC WEATHER OBSERVATION STATION
(AWOS): Equipment used to automaƟ cally record
weather condiƟ ons (i.e. cloud height, visibility, wind
speed and direcƟ on, temperature, dew point, etc.)
AUTOMATIC DIRECTION FINDER (ADF): An aircraŌ
radio navigaƟ on system which senses and indicates
the direcƟ on to a non-direcƟ onal radio beacon (NDB)
ground transmiƩ er.
AVIGATION EASEMENT: A contractual right or
a property interest in land over which a right of
unobstructed fl ight in the airspace is established.
AZIMUTH: Horizontal direcƟ on expressed as the
angular distance between true north and the
direcƟ on of a fi xed point (as the observer’s heading).
B
BASE LEG: A fl ight path at right angles to the landing
runway off its approach end. The base leg normally
extends from the downwind leg to the intersecƟ on
of the extended runway centerline. See “traffi c
paƩ ern.”
BASED AIRCRAFT: The general aviaƟ on aircraŌ that
use a specifi c airport as a home base.
BEARING: The horizontal direcƟ on to or from any
point, usually measured clockwise from true north
or magneƟ c north.
BLAST FENCE: A barrier used to divert or dissipate jet
blast or propeller wash.
Glossary of Terms
A - 4
BLAST PAD: A prepared surface adjacent to the
end of a runway for the purpose of eliminaƟ ng
the erosion of the ground surface by the wind
forces produced by airplanes at the iniƟ aƟ on of
takeoff operaƟ ons.
BUILDING RESTRICTION LINE (BRL): A line which
idenƟ fi es suitable building area locaƟ ons on the
airport.
C
CAPITAL IMPROVEMENT PLAN: The planning
program used by the Federal AviaƟ on AdministraƟ on
to idenƟ fy, prioriƟ ze, and distribute Airport
Improvement Program funds for airport development
and the needs of the NaƟ onal Airspace System to
meet specifi ed naƟ onal goals and objecƟ ves.
CARGO SERVICE AIRPORT: An airport served by
aircraŌ providing air transportaƟ on of property only,
including mail, with an annual aggregate landed
weight of at least 100,000,000 pounds.
CATEGORY I: An Instrument Landing System (ILS)
that provides acceptable guidance informaƟ on to
an aircraŌ from the coverage limits of the ILS to the
point at which the localizer course line intersects the
glide path at a decision height of 200 feet above the
horizontal plane containing the runway threshold.
CATEGORY II: An ILS that provides acceptable guidance
informaƟ on to an aircraŌ from the coverage limits
of the ILS to the point at which the localizer course
line intersects the glide path at a decision height of
100 feet above the horizontal plane containing the
runway threshold.
CATEGORY III: An ILS that provides acceptable
guidance informaƟ on to a pilot from the coverage
limits of the ILS with no decision height specifi ed
above the horizontal plane containing the runway
threshold.
CEILING: The height above the ground surface to
the locaƟ on of the lowest layer of clouds which is
reported as either broken or overcast.
CIRCLING APPROACH: A maneuver iniƟ ated by the
pilot to align the aircraŌ with the runway for landing
when fl ying a predetermined circling instrument
approach under IFR.
CLASS A AIRSPACE: See Controlled Airspace.
CLASS B AIRSPACE: See Controlled Airspace.
CLASS C AIRSPACE: See Controlled Airspace.
CLASS D AIRSPACE: See Controlled Airspace.
CLASS E AIRSPACE: See Controlled Airspace.
CLASS G AIRSPACE: See Controlled Airspace.
CLEAR ZONE: See Runway ProtecƟ on Zone.
COMMERCIAL SERVICE AIRPORT: A public airport
providing scheduled passenger service that enplanes
at least 2,500 annual passengers.
COMMON TRAFFIC ADVISORY FREQUENCY: A radio
frequency idenƟ fi ed in the appropriate aeronauƟ cal
chart which is designated for the purpose of transmiƫ ng
airport advisory informaƟ on and procedures while
operaƟ ng to or from an uncontrolled airport.
COMPASS LOCATOR (LOM): A low power, low/
medium
frequency
radio-beacon
installed
in
conjuncƟ on with the instrument landing system at
one or two of the marker sites.
CONICAL SURFACE: An imaginary obstrucƟ on-
limiƟ ng surface defi ned in FAR Part 77 that extends
Nontowered
Airport
14,500 MSL
Nontowered
Airport
700 AGL
1,200 AGL
18,000 MSL
FL 600
10 n.m.
40 n.m.
30 n.m.
20 n.m.
12 n.m.
20 n.m.
10 n.m.
- Above Ground Level
- Flight Level in Hundreds of Feet
- Mean Sea Level
AGL
FL
MSL
KEY
CLASS A
CLASS E
CLASS B
CLASS G
CLASS C
CLASS D
Source:
"Airspace Reclassification and Charting
Changes for VFR Products," National Oceanic
and Atmospheric Administration, National
Ocean Service. Chart adapted by Coffman
Associates from AOPA Pilot, January 1993.
Glossary of Terms
A - 5
from the edge of the horizontal surface outward and
upward at a slope of 20 to 1 for a horizontal distance
of 4,000 feet.
CONTROLLED AIRPORT: An airport that has an
operaƟ ng airport traffi c control tower.
CONTROLLED
AIRSPACE:
Airspace
of
defi ned
dimensions within which air traffi c control services
are provided to instrument fl ight rules (IFR) and
visual fl ight rules (VFR) fl ights in accordance with
the airspace classifi caƟ on. Controlled airspace in the
United States is designated as follows:
• CLASS A: Generally, the airspace from 18,000
feet mean sea level (MSL) up to but not
including fl ight level FL600. All persons must
operate their aircraŌ under IFR.
• CLASS B: Generally, the airspace from the
surface to 10,000 feet MSL surrounding the
naƟ on’s busiest airports. The confi guraƟ on of
Class B airspace is unique to each airport, but
typically consists of two or more layers of air
space and is designed to contain all published
instrument approach procedures to the airport.
An air traffi c control clearance is required for all
aircraŌ to operate in the area.
• CLASS C: Generally, the airspace from the sur-
face to 4,000 feet above the airport elevaƟ on
(charted as MSL) surrounding those airports that
have an operaƟ onal control tower and radar ap-
proach control and are served by a qualifying
number of IFR operaƟ ons or passenger enplane-
ments. Although individually tailored for each
airport, Class C airspace typically consists of a
surface area with a fi ve nauƟ cal mile (nm) radius
and an outer area with a 10 nauƟ cal mile radius
that extends from 1,200 feet to 4,000 feet above
the airport elevaƟ on. Two-way radio communi-
caƟ on is required for all aircraŌ .
• CLASS D: Generally, that airspace from the
surface to 2,500 feet above the air port eleva-
Ɵ on (charted as MSL) surrounding those air-
ports that have an operaƟ onal control tower.
Class D airspace is individually tailored and
confi gured to encompass published instru-
ment approach procedure. Unless otherwise
authorized, all persons must establish two-way
radio communicaƟ on.
• CLASS E: Generally, controlled airspace that
is not classifi ed as Class A, B, C, or D. Class E
airspace extends upward from either the sur-
face or a designated alƟ tude to the overlying
or adjacent controlled airspace. When desig-
nated as a surface area, the airspace will be
confi gured to contain all instrument proce-
dures. Class E airspace encompasses all Victor
Airways. Only aircraŌ following instrument
fl ight rules are required to establish two-way
radio communicaƟ on with air traffi c control.
• CLASS G: Generally, that airspace not classifi ed
as Class A, B, C, D, or E. Class G airspace is
uncontrolled for all aircraŌ . Class G airspace
extends from the surface to the overlying Class
E airspace.
CONTROLLED FIRING AREA: See special-use airspace.
CROSSWIND: A wind that is not parallel to a runway
centerline or to the intended fl ight path of an aircraŌ .
CROSSWIND COMPONENT: The component of wind
that is at a right angle to the runway centerline or the
intended fl ight path of an aircraŌ .
CROSSWIND LEG: A fl ight path at right angles to the
landing runway off its upwind end. See “traffi c paƩ ern.”
D
DECIBEL: A unit of noise represenƟ ng a level relaƟ ve
to a reference of a sound pressure 20 micro newtons
per square meter.
DECISION HEIGHT/DECISION ALTITUDE: The height
above the end of the runway surface at which a
decision must be made by a pilot during the ILS or
Precision Approach Radar approach to either conƟ nue
the approach or to execute a missed approach.
DECLARED DISTANCES: The distances declared
available for the airplane’s takeoff runway, takeoff
distance, accelerate-stop distance, and landing
distance requirements. The distances are:
• TAKEOFF RUNWAY AVAILABLE (TORA): The runway
length declared available and suitable for the ground
run of an airplane taking off .
Glossary of Terms
A - 6
• TAKEOFF DISTANCE AVAILABLE (TODA): The TORA
plus the length of any remaining runway and/or
clear way beyond the far end of the TORA.
• ACCELERATE-STOP DISTANCE AVAILABLE (ASDA):
The runway plus stopway length declared available
for the acceleraƟ on and deceleraƟ on of an aircraŌ
aborƟ ng a takeoff .
• LANDING DISTANCE AVAILABLE (LDA): The
runway length declared available and suitable
for landing.
DEPARTMENT OF TRANSPORTATION: The cabinet
level federal government organizaƟ on consisƟ ng
of modal operaƟ ng agencies, such as the Federal
AviaƟ on AdministraƟ on, which was established to
promote the coordinaƟ on of federal transportaƟ on
programs and to act as a focal point for research
and development eff orts in transportaƟ on.
DISCRETIONARY FUNDS: Federal grant funds that
may be appropriated to an airport based upon
designaƟ on by the Secretary of TransportaƟ on
or Congress to meet a specifi ed naƟ onal priority
such as enhancing capacity, safety, and security, or
miƟ gaƟ ng noise.
DISPLACED THRESHOLD: A threshold that is located
at a point on the runway other than the designated
beginning of the runway.
DISTANCE MEASURING
EQUIPMENT
(DME):
Equipment
(airborne
and ground) used to
measure,
in
nauƟ cal
miles,
the
slant
range distance of an
aircraŌ from the DME
navigaƟ onal aid.
DNL: The 24-hour average sound level, in decibels,
obtained aŌ er the addiƟ on of ten decibels to sound
levels for the periods between 10 p.m. and 7 a.m.
as averaged over a span of one year. It is the FAA
standard metric for determining the cumulaƟ ve
exposure of individuals to noise.
DOWNWIND LEG: A fl ight path parallel to the landing
runway in the direcƟ on opposite to landing. The
downwind leg normally extends between the crosswind
leg and the base leg. Also see “traffi c paƩ ern.”
E
EASEMENT: The legal right of one party to use a
porƟ on of the total rights in real estate owned by
another party. This may include the right of passage
over, on, or below the property; certain air rights above
the property, including view rights; and the rights to
any specifi ed form of development or acƟ vity, as well
as any other legal rights in the property that may be
specifi ed in the easement document.
ELEVATION: The verƟ cal distance measured in feet
above mean sea level.
ENPLANED PASSENGERS: The total number of
revenue passengers boarding aircraŌ , including
originaƟ ng, stop-over, and transfer passengers, in
scheduled and nonscheduled services.
ENPLANEMENT: The boarding of a passenger,
cargo, freight, or mail on an aircraŌ at an airport.
ENTITLEMENT:
Federal
funds
for
which
a
commercial service airport may be eligible based
upon its annual passenger enplanements.
ENVIRONMENTAL
ASSESSMENT
(EA):
An
environmental analysis performed pursuant to the
NaƟ onal Environmental Policy Act to determine
whether an acƟ on would signifi cantly aff ect the
environment and thus require a more detailed
environmental impact statement.
ENVIRONMENTAL AUDIT: An assessment of
the current status of a party’s compliance with
applicable environmental requirements of a party’s
environmental compliance policies, pracƟ ces, and
controls.
ENVIRONMENTAL IMPACT STATEMENT (EIS): A
document required of federal agencies by the
NaƟ onal Environmental Policy Act for major projects
are legislaƟ ve proposals aff ecƟ ng the environment.
It is a tool for decision-making describing the
posiƟ ve and negaƟ ve eff ects of a proposed acƟ on
and ciƟ ng alternaƟ ve acƟ ons.
ESSENTIAL AIR SERVICE: A federal program which
guarantees air carrier service to selected small ciƟ es
by providing subsidies as needed to prevent these
ciƟ es from such service.
10NM
10NM
30 NM
20 NM
20 NM
Glossary of Terms
A - 7
F
FEDERAL AVIATION REGULATIONS: The general
and permanent rules established by the execuƟ ve
departments
and
agencies
of
the
Federal
Government for aviaƟ on, which are published in the
Federal Register. These are the aviaƟ on subset of the
Code of Federal RegulaƟ ons.
FEDERAL INSPECTION SERVICES: The provision of
customs and immigraƟ on services including passport
inspecƟ on, inspecƟ on of baggage, the collecƟ on of
duƟ es on certain imported items, and the inspecƟ ons
for agricultural products, illegal drugs, or other
restricted items.
FINAL APPROACH: A fl ight path in the direcƟ on of
landing along the extended runway centerline. The
fi nal approach normally extends from the base leg to
the runway. See “traffi c paƩ ern.”
FINAL APPROACH AND TAKEOFF AREA (FATO).
A defi ned area over which the fi nal phase of the
helicopter approach to a hover, or a landing is
completed and from which the takeoff is iniƟ ated.
FINAL APPROACH FIX: The designated point at which
the fi nal approach segment for an aircraŌ landing on a
runway begins for a non-precision approach.
FINDING OF NO SIGNIFICANT IMPACT (FONSI): A
public document prepared by a Federal agency that
presents the raƟ onale why a proposed acƟ on will not
have a signifi cant eff ect on the environment and for
which an environmental impact statement will not
be prepared.
FIXED BASE OPERATOR (FBO): A provider of services
to users of an airport. Such services include, but are
not limited to, hangaring, fueling, fl ight training,
repair, and maintenance.
FLIGHT LEVEL: A measure of alƟ tude used by aircraŌ fl ying
above 18,000 feet. Flight levels are indicated by three digits
represenƟ ng the pressure alƟ tude in hundreds of feet.
An airplane fl ying at fl ight level 360 is fl ying at a pressure
alƟ tude of 36,000 feet. This is expressed as FL 360.
FLIGHT SERVICE STATION: An operaƟ ons facility in
the naƟ onal fl ight advisory system which uƟ lizes
data interchange faciliƟ es for the collecƟ on and
disseminaƟ on of NoƟ ces to Airmen, weather, and
administraƟ ve data and which provides pre-fl ight
and in-fl ight advisory services to pilots through air
and ground based communicaƟ on faciliƟ es.
FRANGIBLE NAVAID: A navigaƟ onal aid which retains
its structural integrity and sƟ ff ness up to a designated
maximum load, but on impact from a greater load,
breaks, distorts, or yields in such a manner as to
present the minimum hazard to aircraŌ .
G
GENERAL AVIATION: That porƟ on of civil aviaƟ on
which encompasses all facets of aviaƟ on except air
carriers holding a cerƟ fi cate of convenience and
necessity, and large aircraŌ commercial operators.
GENERAL AVIATION AIRPORT: An airport that
provides air service to only general aviaƟ on.
GLIDESLOPE (GS): Provides verƟ cal guidance for
aircraŌ during approach and landing. The glideslope
consists of the following:
1. Electronic
components
emiƫ ng
signals
which provide verƟ cal guidance by reference
to airborne instruments during instrument
approaches such as ILS; or
2. Visual ground aids, such as VASI, which provide
verƟ cal guidance for VFR approach or for the
visual porƟ on of an instrument approach and
landing.
GLOBAL POSITIONING SYSTEM (GPS): A system
of 48 satellites used as reference points to enable
navigators equipped with GPS receivers to determine
their laƟ tude, longitude, and alƟ tude.
GROUND ACCESS: The transportaƟ on system on and
around the airport that provides access to and from
the airport by ground transportaƟ on vehicles for
passengers, employees, cargo, freight, and airport
services.
H
HELIPAD: A designated area for the takeoff , landing,
and parking of helicopters.
HIGH INTENSITY RUNWAY LIGHTS: The highest
classifi caƟ on in terms of intensity or brightness for
lights designated for use in delineaƟ ng the sides of
a runway.
Glossary of Terms
A - 8
HIGH-SPEED EXIT TAXIWAY: A long radius taxiway
designed to expedite aircraŌ turning off the runway
aŌ er landing (at speeds to 60 knots), thus reducing
runway occupancy Ɵ me.
HORIZONTAL SURFACE: An imaginary obstrucƟ on-
limiƟ ng surface defi ned in FAR Part 77 that is specifi ed
as a porƟ on of a horizontal plane surrounding a
runway located 150 feet above the established airport
elevaƟ on. The specifi c horizontal dimensions of this
surface are a funcƟ on of the types of approaches
exisƟ ng or planned for the runway.
I
INITIAL APPROACH FIX: The designated point at
which the iniƟ al approach segment begins for an
instrument approach to a runway.
INSTRUMENT APPROACH PROCEDURE: A series of
predetermined maneuvers for the orderly transfer
of an aircraŌ under instrument fl ight condiƟ ons from
the beginning of the iniƟ al approach to a landing, or
to a point from which a landing may be made visually.
INSTRUMENT FLIGHT RULES (IFR): Procedures for
the conduct of fl ight in weather condiƟ ons below
Visual Flight Rules weather minimums. The term
IFR is oŌ en also used to defi ne weather condiƟ ons
and the type of fl ight plan under which an aircraŌ is
operaƟ ng.
INSTRUMENT LANDING SYSTEM (ILS): A precision
instrument approach system which normally
consists of the following electronic components
and visual aids:
1. Localizer.
2. Glide Slope.
3. Outer Marker.
4. Middle Marker.
5. Approach Lights.
INSTRUMENT
METEOROLOGICAL
CONDITIONS:
Meteorological condiƟ ons expressed in terms
of specifi c visibility and ceiling condiƟ ons that
are less than the minimums specifi ed for visual
meteorological condiƟ ons.
ITINERANT OPERATIONS: OperaƟ ons by aircraŌ that
are not based at a specifi ed airport.
K
KNOTS: A unit of speed length used in navigaƟ on
that is equivalent to the number of nauƟ cal miles
traveled in one hour.
L
LOCAL-AREA AUGMENTATION SYSTEM: (LAAS) is an
all-weather aircraŌ landing system based on real-Ɵ me
diff erenƟ al correcƟ on of the GPS signal.
LANDSIDE: The porƟ on of an airport that provides the
faciliƟ es necessary for the processing of passengers,
cargo, freight, and ground transportaƟ on vehicles.
LANDING DISTANCE AVAILABLE (LDA): See declared
distances.
LARGE AIRPLANE: An airplane that has a maximum
cerƟ fi ed takeoff weight in excess of 12,500 pounds.
LOCAL AREA AUGMENTATION SYSTEM: A diff erenƟ al
GPS system that provides localized measurement
correcƟ on signals to the basic GPS signals to improve
navigaƟ onal accuracy integrity, conƟ nuity, and
availability.
LOCAL OPERATIONS: AircraŌ operaƟ ons performed
by aircraŌ that are based at the airport and that
operate in the local traffi c paƩ ern or within sight of
the airport, that are known to be deparƟ ng for or
arriving from fl ights in local pracƟ ce areas within a
prescribed distance from the airport, or that execute
simulated instrument approaches at the airport.
LOCAL TRAFFIC: AircraŌ operaƟ ng in the traffi c
paƩ ern or within sight of the tower, or aircraŌ known
to be deparƟ ng or arriving from the local pracƟ ce
areas, or aircraŌ execuƟ ng pracƟ ce instrument
approach procedures. Typically, this includes touch
and-go training operaƟ ons.
LOCALIZER: The component of an ILS which provides
course guidance to the runway.
LOCALIZER TYPE DIRECTIONAL AID (LDA): A facility
of comparable uƟ lity and accuracy to a localizer, but
is not part of a complete ILS and is not aligned with
the runway.
LONG RANGE NAVIGATION SYSTEM (LORAN): Long
range navigaƟ on is an electronic navigaƟ onal aid
Glossary of Terms
A - 9
which determines aircraŌ posiƟ on and speed by
measuring the diff erence in the Ɵ me of recepƟ on of
synchronized pulse signals from two fi xed transmiƩ ers.
Loran is used for en route navigaƟ on.
LOW INTENSITY RUNWAY LIGHTS: The lowest
classifi caƟ on in terms of intensity or brightness for lights
designated for use in delineaƟ ng the sides of a runway.
M
MEDIUM INTENSITY RUNWAY LIGHTS: The middle
classifi caƟ on in terms of intensity or brightness for lights
designated for use in delineaƟ ng the sides of a runway.
MICROWAVE
LANDING
SYSTEM
(MLS):
An
instrument approach and landing system that
provides precision guidance in azimuth, elevaƟ on,
and distance measurement.
MILITARY OPERATIONS: AircraŌ operaƟ ons that are
performed in military aircraŌ .
MILITARY OPERATIONS AREA (MOA): See special-
use airspace
MILITARY TRAINING ROUTE: An air route depicted
on aeronauƟ cal charts for the conduct of military
fl ight training at speeds above 250 knots.
MISSED APPROACH COURSE (MAC): The fl ight route
to be followed if, aŌ er an instrument approach, a
landing is not aff ected, and occurring normally:
1. When the aircraŌ has descended to the decision
height and has not established visual contact; or
2. When directed by air traffi c control to pull up or to
go around again.
MOVEMENT AREA: The runways, taxiways, and other
areas of an airport which are uƟ lized for taxiing/hover
taxiing, air taxiing, takeoff , and landing of aircraŌ ,
exclusive of loading ramps and parking areas. At those
airports with a tower, air traffi c control clearance is
required for entry onto the movement area.
N
NATIONAL AIRSPACE SYSTEM: The network of air
traffi c control faciliƟ es, air traffi c control areas, and
navigaƟ onal faciliƟ es through the U.S.
NATIONAL PLAN OF INTEGRATED AIRPORT SYSTEMS:
The naƟ onal airport system plan developed by the
Secretary of TransportaƟ on on a biannual basis for
the development of public use airports to meet
naƟ onal air transportaƟ on needs.
NATIONAL TRANSPORTATION SAFETY BOARD: A
federal government organizaƟ on established to
invesƟ gate and determine the probable cause of
transportaƟ on accidents, to recommend equipment
and procedures to enhance transportaƟ on safety,
and to review on appeal the suspension or revocaƟ on
of any cerƟ fi cates or licenses issued by the Secretary
of TransportaƟ on.
NAUTICAL MILE: A unit of length used in navigaƟ on
which is equivalent to the distance spanned by one
minute of arc in laƟ tude, that is, 1,852 meters or
6,076 feet. It is equivalent to approximately 1.15
statute mile.
NAVAID: A term used to describe any electrical or
visual air navigaƟ onal aids, lights, signs, and associated
supporƟ ng equipment (i.e. PAPI, VASI, ILS, etc.)
NAVIGATIONAL AID: A facility used as, available for
use as, or designed for use as an aid to air navigaƟ on.
NOISE CONTOUR: A conƟ nuous line on a map of
the airport vicinity connecƟ ng all points of the same
noise exposure level.
NON-DIRECTIONAL BEACON (NDB): A beacon
transmiƫ ng nondirecƟ onal signals whereby the
pilot of an aircraŌ equipped with direcƟ on fi nding
equipment can determine their bearing to and
from the radio beacon and home on, or track to,
the staƟ on. When the radio beacon is installed in
conjuncƟ on with the Instrument Landing System
marker, it is normally called a Compass Locator.
NON-PRECISION
APPROACH
PROCEDURE:
A
standard instrument approach procedure in which
no electronic glide slope is provided, such as VOR,
TACAN, NDB, or LOC.
NOTICE TO AIRMEN: A noƟ ce containing informaƟ on
concerning the establishment, condiƟ on, or change
in any component of or hazard in the NaƟ onal
Airspace System, the Ɵ mely knowledge of which is
considered essenƟ al to personnel concerned with
fl ight operaƟ ons.
Glossary of Terms
A - 10
O
OBJECT FREE AREA (OFA): An area on the ground
centered on a runway, taxiway, or taxilane centerline
provided to enhance the safety of aircraŌ operaƟ ons
by having the area free of objects, except for objects
that need to be located in the OFA for air navigaƟ on
or aircraŌ ground maneuvering purposes.
OBSTACLE FREE ZONE (OFZ): The airspace below
150 feet above the established airport elevaƟ on and
along the runway and extended runway centerline
that is required to be kept clear of all objects, except
for frangible visual NAVAIDs that need to be located
in the OFZ because of their funcƟ on, in order to
provide clearance for aircraŌ landing or taking off
from the runway, and for missed approaches.
ONEͳENGINE INOPERABLE SURFACE: A surface
emanaƟ ng from the runway end at a slope raƟ o of
62.5:1. Air carrier airports are required to maintain a
technical drawing of this surface depicƟ ng any object
penetraƟ ons by January 1, 2010.
OPERATION: The take-off , landing, or touch-and-go
procedure by an aircraŌ on a runway at an airport.
OUTER MARKER (OM): An ILS navigaƟ on facility in
the terminal area navigaƟ on system located four to
seven miles from the runway edge on the extended
centerline, indicaƟ ng to the pilot that he/she is passing
over the facility and can begin fi nal approach.
P
PILOT CONTROLLED LIGHTING: Runway lighƟ ng
systems at an airport that are controlled by acƟ vaƟ ng
the microphone of a pilot on a specifi ed radio
frequency.
PRECISION APPROACH: A standard instrument
approach
procedure
which
provides
runway
alignment and glide slope (descent) informaƟ on. It is
categorized as follows:
• CATEGORY I (CAT I): A precision approach which
provides for approaches with a decision height
of not less than 200 feet and visibility not less
than 1/2 mile or Runway Visual Range (RVR)
2400 (RVR 1800) with operaƟ ve touchdown
zone and runway centerline lights.
• CATEGORY II (CAT II): A precision approach
which provides for approaches with a decision
height of not less than 100 feet and visibility
not less than 1200 feet RVR.
• CATEGORY III (CAT III): A precision approach
which provides for approaches with minima
less than Category II.
PRECISION APPROACH PATH INDICATOR (PAPI):
A lighƟ ng system providing visual approach
slope guidance to aircraŌ during a landing
approach. It is similar to a VASI but provides
a
sharper
transiƟ on
between
the
colored
indicator lights.
PRECISION APPROACH RADAR: A radar facility in the
terminal air traffi c control system used to detect and
display with a high degree of accuracy the direcƟ on,
range, and elevaƟ on of an aircraŌ on the fi nal
approach to a runway.
PRECISION OBJECT FREE AREA (POFA): An area
centered on the extended runway centerline,
beginning at the runway threshold and extending
behind the runway threshold that is 200 feet long
by 800 feet wide. The POFA is a clearing standard
which requires the POFA to be kept clear of above
ground objects protruding above the runway safety
area edge elevaƟ on (except for frangible NAVAIDS).
The POFA applies to all new authorized instrument
approach procedures with less than 3/4 mile visibility.
PRIMARY AIRPORT: A commercial service airport
that enplanes at least 10,000 annual passengers.
PRIMARY SURFACE: An imaginary obstrucƟ on limiƟ ng
surface defi ned in FAR Part 77 that is specifi ed as a
rectangular surface longitudinally centered about a
runway. The specifi c dimensions of this surface are
a funcƟ on of the types of approaches exisƟ ng or
planned for the runway.
PROHIBITED AREA: See special-use airspace.
PVC: Poor visibility and ceiling. Used in determining
Annual Service Volume. PVC condiƟ ons exist when
the cloud ceiling is less than 500 feet and visibility is
less than one mile.
Glossary of Terms
A - 11
on the extended centerline of the runway usually in
conjuncƟ on with an approach lighƟ ng system.
RUNWAY DESIGN CODE: A code signifi ying the
design standards to which the runway is to be built.
RUNWAY END IDENTIFICATION LIGHTING (REIL):
Two synchronized fl ashing lights, one on each side
of the runway threshold, which provide rapid and
posiƟ ve idenƟ fi caƟ on of the approach end of a
parƟ cular runway.
RUNWAY GRADIENT: The average slope, measured in
percent, between the two ends of a runway.
RUNWAY PROTECTION ZONE (RPZ): An area off the
runway end to enhance the protecƟ on of people
and property on the ground. The RPZ is trapezoidal
in shape. Its dimensions are determined by the
aircraŌ approach speed and runway approach type
and minima.
RUNWAY REFERENCE CODE: A code signifying the
current operaƟ onal capabiliƟ es of a runway and
associated taxiway.
RUNWAY SAFETY AREA (RSA): A defi ned surface
surrounding the runway prepared or suitable for
reducing the risk of damage to airplanes in the event
of an undershoot, overshoot, or excursion from the
runway.
RUNWAY VISIBILITY ZONE (RVZ): An area on the
airport to be kept clear of permanent objects so that
there is an unobstructed line of- site from any point
fi ve feet above the runway centerline to any point
fi ve feet above an intersecƟ ng runway centerline.
RUNWAY VISUAL RANGE (RVR): An instrumentally
derived value, in feet, represenƟ ng the horizontal
distance a pilot can see down the runway from the
runway end.
S
SCOPE: The document that idenƟ fi es and defi nes
the tasks, emphasis, and level of eff ort associated
with a project or study.
SEGMENTED CIRCLE: A system of visual indicators
designed to provide traffi c paƩ ern informaƟ on at
airports without operaƟ ng control towers.
R
RADIAL: A navigaƟ onal signal generated by a Very
High Frequency Omni-direcƟ onal Range or VORTAC
staƟ on that is measured as an azimuth from the
staƟ on.
REGRESSION ANALYSIS: A staƟ sƟ cal technique that
seeks to idenƟ fy and quanƟ fy the relaƟ onships
between factors associated with a forecast.
REMOTE COMMUNICATIONS OUTLET (RCO): An
unstaff ed transmiƩ er receiver/facility remotely
controlled by air traffi c personnel. RCOs serve fl ight
service staƟ ons (FSSs). RCOs were established to
provide ground-to-ground communicaƟ ons between
air traffi c control specialists and pilots at satellite
airports for delivering en route clearances, issuing
departure
authorizaƟ ons,
and
acknowledging
instrument fl ight rules cancellaƟ ons or departure/
landing Ɵ mes.
REMOTE
TRANSMITTER/RECEIVER
(RTR):
See
remote communicaƟ ons outlet. RTRs serve ARTCCs.
RELIEVER AIRPORT: An airport to serve general
aviaƟ on aircraŌ which might otherwise use a congested
air-carrier served airport.
RESTRICTED AREA: See special-use airspace.
RNAV: Area navigaƟ on - airborne equipment which
permits fl ights over determined tracks within
prescribed accuracy tolerances without the need to
overfl y ground-based navigaƟ on faciliƟ es. Used en
route and for approaches to an airport.
RUNWAY: A defi ned rectangular area on an airport
prepared for aircraŌ landing and takeoff . Runways
are normally numbered in relaƟ on to their magneƟ c
direcƟ on, rounded off to the nearest 10 degrees.
For example, a runway with a magneƟ c heading of
180 would be designated Runway 18. The runway
heading on the opposite end of the runway is 180
degrees from that runway end. For example, the
opposite runway heading for Runway 18 would
be Runway 36 (magneƟ c heading of 360). AircraŌ
can takeoff or land from either end of a runway,
depending upon wind direcƟ on.
RUNWAY ALIGNMENT INDICATOR LIGHT: A series of
high intensity sequenƟ ally fl ashing lights installed
Glossary of Terms
A - 12
SHOULDER: An area adjacent to the edge of paved
runways, taxiways, or aprons providing a transiƟ on
between the pavement and the adjacent surface;
support for aircraŌ running off the pavement;
enhanced drainage; and blast protecƟ on. The
shoulder does not necessarily need to be paved.
SLANT-RANGE DISTANCE: The straight line distance
between an aircraŌ and a point on the ground.
SMALL AIRCRAFT: An aircraŌ that has a maximum
cerƟ fi ed takeoff weight of up to 12,500 pounds.
SPECIAL-USE
AIRSPACE:
Airspace
of
defi ned
dimensions idenƟ fi ed by a surface area wherein
acƟ viƟ es must be confi ned because of their nature
and/or wherein limitaƟ ons may be imposed upon
aircraŌ operaƟ ons that are not a part of those
acƟ viƟ es. Special-use airspace classifi caƟ ons include:
• ALERT AREA: Airspace which may contain a
high volume of pilot training acƟ viƟ es or an
unusual type of aerial acƟ vity, neither of which
is hazardous to aircraŌ .
• CONTROLLED FIRING AREA: Airspace
wherein
acƟ viƟ es are conducted under
condiƟ ons so controlled as to eliminate hazards
to nonparƟ cipaƟ ng aircraŌ and to ensure the
safety of persons or property on the ground.
• MILITARY OPERATIONS AREA (MOA): Designated
airspace with defi ned verƟ cal and lateral
dimensions established outside Class A airspace
to separate/segregate certain military acƟ viƟ es
from instrument fl ight rule (IFR) traffi c and to
idenƟ fy for visual fl ight rule (VFR) traffi c where
these acƟ viƟ es are conducted.
• PROHIBITED AREA: Designated airspace within
which the fl ight of aircraŌ is prohibited.
• RESTRICTED AREA: Airspace designated under
Federal AviaƟ on RegulaƟ on (FAR) 73, within which
the fl ight of aircraŌ , while not wholly prohibited,
is subject to restricƟ on. Most restricted areas are
designated joint use. When not in use by the using
agency, IFR/VFR operaƟ ons can be authorized by
the controlling air traffi c control facility.
• WARNING AREA: Airspace which may contain
hazards to nonparƟ cipaƟ ng aircraŌ .
STANDARD INSTRUMENT DEPARTURE (SID): A
preplanned coded air traffi c control IFR departure
rouƟ ng, preprinted for pilot use in graphic and
textual form only.
STANDARD INSTRUMENT DEPARTURE PROCEDURES:
A published standard fl ight procedure to be uƟ lized
following takeoff to provide a transiƟ on between the
airport and the terminal area or en route airspace.
STANDARD TERMINAL ARRIVAL ROUTE (STAR):
A preplanned coded air traffi c control IFR arrival
rouƟ ng, preprinted for pilot use in graphic and
textual or textual form only.
STOP-AND-GO: A procedure wherein an aircraŌ will
land, make a complete stop on the runway, and then
commence a takeoff from that point. A stop-and-go
is recorded as two operaƟ ons: one operaƟ on for the
landing and one operaƟ on for the takeoff .
STOPWAY: An area beyond the end of a takeoff
runway that is designed to support an aircraŌ
during an aborted takeoff without causing structural
damage to the aircraŌ . It is not to be used for takeoff ,
landing, or taxiing by aircraŌ .
STRAIGHT-IN
LANDING/APPROACH:
A
landing
made on a runway aligned within 30 degrees of the
fi nal approach course following compleƟ on of an
instrument approach.
T
TACTICAL AIR NAVIGATION (TACAN): An ultrahigh
frequency electronic air navigaƟ on system which
provides suitably-equipped aircraŌ a conƟ nuous
indicaƟ on of bearing and distance to the TACAN
staƟ on.
TAKEOFF RUNWAY AVAILABLE (TORA):
See declared distances.
TAKEOFF DISTANCE AVAILABLE (TODA):
See declared distances.
TAXILANE: The porƟ on of the aircraŌ parking area
used for access between taxiways and aircraŌ
parking posiƟ ons.
TAXIWAY: A defi ned path established for the taxiing
of aircraŌ from one part of an airport to another.
Glossary of Terms
A - 13
TRAFFIC PATTERN: The traffi c fl ow that is prescribed
for aircraŌ landing at or taking off from an airport.
The components of a typical traffi c paƩ ern are the
upwind leg, crosswind leg, downwind leg, base leg,
and fi nal approach.
U
UNCONTROLLED AIRPORT: An airport without an air
traffi c control tower at which the control of Visual
Flight Rules traffi c is not exercised.
UNCONTROLLED AIRSPACE: Airspace within which
aircraŌ are not subject to air traffi c control.
UNIVERSAL COMMUNICATION (UNICOM):
A nongovernment communicaƟ on facility which
may provide airport informaƟ on at certain airports.
LocaƟ ons and frequencies of UNICOM’s are shown
on aeronauƟ cal charts and publicaƟ ons.
UPWIND LEG: A fl ight path parallel to the landing
runway in the direcƟ on of landing. See “traffi c
paƩ ern.”
V
VECTOR: A heading issued to an aircraŌ to provide
navigaƟ onal guidance by radar.
VERY HIGH FREQUENCY/ OMNIDIRECTIONAL RANGE
(VOR): A ground-based electronic navigaƟ on aid
transmiƫ ng very high frequency navigaƟ on signals,
360 degrees in azimuth, oriented from magneƟ c
north. Used as the basis for navigaƟ on in the naƟ onal
airspace system. The VOR periodically idenƟ fi es itself
by Morse Code and may have an addiƟ onal voice
idenƟ fi caƟ on feature.
RUNWAY
ENTRY
DOWNWIND LEG
CROSS-
WIND
LEG
BASE
LEG
FINAL APPROACH
UPWIND LEG
DEPARTURE LEG
TAXIWAY DESIGN GROUP: A classifi caƟ on of
airplanes based on outer to outer Main Gear Width
(MGW) and Cockpit to Main Gear (CMG) distance.
TAXIWAY SAFETY AREA (TSA): A defi ned surface
alongside
the
taxiway
prepared
or
suitable
for reducing the risk of damage to an airplane
unintenƟ onally deparƟ ng the taxiway.
TERMINAL INSTRUMENT PROCEDURES: Published
fl ight
procedures
for
conducƟ ng
instrument
approaches
to
runways
under
instrument
meteorological condiƟ ons.
TERMINAL RADAR APPROACH CONTROL: An
element of the air traffi c control system responsible
for monitoring the en-route and terminal segment of
air traffi c in the airspace surrounding airports with
moderate to high levels of air traffi c.
TETRAHEDRON: A device used as a landing direcƟ on
indicator. The small end of the tetrahedron points in
the direcƟ on of landing.
THRESHOLD: The beginning of that porƟ on of the
runway available for landing. In some instances the
landing threshold may be displaced.
TOUCH-AND-GO: An operaƟ on by an aircraŌ that
lands and departs on a runway without stopping or
exiƟ ng the runway. A touch-and go is recorded as
two operaƟ ons: one operaƟ on for the landing and
one operaƟ on for the takeoff .
TOUCHDOWN: The point at which a landing aircraŌ
makes contact with the runway surface.
TOUCHDOWN AND LIFT-OFF AREA (TLOF): A load
bearing, generally paved area, normally centered in
the FATO, on which the helicopter lands or takes off .
TOUCHDOWN ZONE (TDZ): The fi rst 3,000 feet of the
runway beginning at the threshold.
TOUCHDOWN ZONE ELEVATION (TDZE): The highest
elevaƟ on in the touchdown zone.
TOUCHDOWN ZONE (TDZ) LIGHTING: Two rows of
transverse light bars located symmetrically about the
runway centerline normally at 100- foot intervals. The
basic system extends 3,000 feet along the runway.
Glossary of Terms
A - 14
VERY
HIGH
FREQUENCY
OMNI-DIRECTIONAL RANGE/
TACTICAL AIR NAVIGATION
(VORTAC): A navigaƟ on aid
providing VOR azimuth, TACAN
azimuth, and TACAN distance-
measuring equipment (DME)
at one site.
VICTOR AIRWAY: A control area or porƟ on thereof
established in the form of a corridor, the centerline
of which is defi ned by radio navigaƟ onal aids.
VISUAL APPROACH: An approach wherein an aircraŌ
on an IFR fl ight plan, operaƟ ng in VFR condiƟ ons under
the control of an air traffi c control facility and having
an air traffi c control authorizaƟ on, may proceed to the
airport of desƟ naƟ on in VFR condiƟ ons.
VISUAL APPROACH SLOPE INDICATOR (VASI): An
airport lighƟ ng facility providing verƟ cal visual
approach slope guidance to aircraŌ during approach
to landing by radiaƟ ng a direcƟ onal paƩ ern of high
intensity red and white focused light beams which
indicate to the pilot that he is on path if he sees red/
white, above path if white/white, and below path
if red/red. Some airports serving large aircraŌ have
three-bar VASI’s which provide two visual guide
paths to the same runway.
VISUAL FLIGHT RULES (VFR): Rules that govern
the procedures for conducƟ ng fl ight under visual
condiƟ ons. The term VFR is also used in the United
States to indicate weather condiƟ ons that are equal
to or greater than minimum VFR requirements.
In addiƟ on, it is used by pilots and controllers to
indicate type of fl ight plan.
VISUAL METEOROLOGICAL CONDITIONS:
Meteorological condiƟ ons expressed in terms of
specifi c visibility and ceiling condiƟ ons which are
equal to or greater than the threshold values for
instrument meteorological condiƟ ons.
VOR: See “Very High Frequency OmnidirecƟ onal Range
StaƟ on.”
VORTAC: See “Very High Frequency OmnidirecƟ onal
Range StaƟ on/TacƟ cal Air NavigaƟ on.”
W
WARNING AREA: See special-use airspace.
WIDE
AREA
AUGMENTATION
SYSTEM:
An
enhancement of the Global PosiƟ oning System that
includes integrity broadcasts, diff erenƟ al correcƟ ons,
and addiƟ onal ranging signals for the purpose of
providing the accuracy, integrity, availability, and
conƟ nuity required to support all phases of fl ight.
Abbreviations
AC: advisory circular
ACIP: airport capital improvement program
ADF: automaƟ c direcƟ on fi nder
ADG: airplane design group
AFSS: automated fl ight service staƟ on
AGL: above ground level
AIA: annual instrument approach
AIP: Airport Improvement Program
AIR-21: Wendell H. Ford AviaƟ on Investment and
Reform Act for the 21st Century
ALS: approach lighƟ ng system
ALSF-1: standard 2,400-foot high intensity approach
lighƟ ng system with sequenced fl ashers
(CAT I confi guraƟ on)
ALSF-2: standard 2,400-foot high intensity approach
lighƟ ng system with sequenced fl ashers
(CAT II confi guraƟ on)
AOA: AircraŌ OperaƟ on Area
APV: instrument approach procedure with verƟ cal
guidance
360°
120°
60°
180°
240°
300°
Abbreviations
A - 15
ARC: airport reference code
ARFF: aircraŌ rescue and fi re fi ghƟ ng
ARP: airport reference point
ARTCC: air route traffi c control center
ASDA: accelerate-stop distance available
ASR: airport surveillance radar
ASOS: automated surface observaƟ on staƟ on
ATC(T): airport traffi c control tower
ATIS: automated terminal informaƟ on service
AVGAS: aviaƟ on gasoline - typically 100 low lead (100LL)
AWOS: automaƟ c weather observaƟ on staƟ on
BRL: building restricƟ on line
CFR: Code of Federal RegulaƟ on
CIP: capital improvement program
DME: distance measuring equipment
DNL: day-night noise level
DWL: runway weight bearing capacity of aircraŌ
with dual-wheel type landing gear
DTWL: runway weight bearing capacity of aircraŌ
with dual-tandem type landing gear
FAA: Federal AviaƟ on AdministraƟ on
FAR: Federal AviaƟ on RegulaƟ on
FBO: fi xed base operator
FY: fi scal year
GA: general aviaƟ on
GPS: global posiƟ oning system
GS: glide slope
HIRL: high intensity runway edge lighƟ ng
IFR: instrument fl ight rules (FAR Part 91)
ILS: instrument landing system
IM: inner marker
LAAS: local area augmented system
LDA: localizer type direcƟ onal aid
LDA: landing distance available
LIRL: low intensity runway edge lighƟ ng
LMM: compass locator at middle marker
LOM: compass locator at outer marker
LORAN: long range navigaƟ on
MALS: medium intensity approach lighƟ ng system
with indicator lights
MIRL: medium intensity runway edge lighƟ ng
MITL: medium intensity taxiway edge lighƟ ng
MLS: microwave landing system
MM: middle marker
MOA: military operaƟ ons area
MSL: mean sea level
NAVAID: navigaƟ onal aid
NDB: nondirecƟ onal radio beacon
NM: nauƟ cal mile (6,076.1 feet)
NPDES: NaƟ onal Pollutant Discharge EliminaƟ on
System
NPIAS: NaƟ onal Plan of Integrated Airport Systems
NPRM: noƟ ce of proposed rule making
ODALS: omnidirecƟ onal approach lighƟ ng system
Abbreviations
A - 16
OFA: object free area
OFZ: obstacle free zone
OM: outer marker
PAC: planning advisory commiƩ ee
PAPI: precision approach path indicator
PFC: porous fricƟ on course
PFC: passenger facility charge
PCL: pilot-controlled lighƟ ng
PIW public informaƟ on workshop
PLASI: pulsaƟ ng visual approach slope indicator
POFA: precision object free area
PVASI: pulsaƟ ng/steady visual approach slope indicator
PVC: poor visibility and ceiling
RCO: remote communicaƟ ons outlet
RRC: Runway Reference Code
RDC: Runway Design Code
REIL: runway end idenƟ fi caƟ on lighƟ ng
RNAV: area navigaƟ on
RPZ: runway protecƟ on zone
RSA: runway safety area
RTR: remote transmiƩ er/receiver
RVR: runway visibility range
RVZ: runway visibility zone
SALS: short approach lighƟ ng system
SASP: state aviaƟ on system plan
SEL: sound exposure level
SID: standard instrument departure
SM: statute mile (5,280 feet)
SRE: snow removal equipment
SSALF: simplifi ed short approach lighƟ ng system
with runway alignment indicator lights
STAR: standard terminal arrival route
SWL: runway weight bearing capacity for aircraŌ
with single-wheel tandem type landing gear
TACAN: tacƟ cal air navigaƟ onal aid
TAF: Federal AviaƟ on AdministraƟ on (FAA)
Terminal Area Forecast
TDG: Taxiway Design Group
TLOF: Touchdown and liŌ -off
TDZ: touchdown zone
TDZE: touchdown zone elevaƟ on
TODA: takeoff distance available
TORA: takeoff runway available
TRACON: terminal radar approach control
VASI: visual approach slope indicator
VFR: visual fl ight rules (FAR Part 91)
VHF: very high frequency
VOR: very high frequency omni-direcƟ onal range
VORTAC: VOR and TACAN collocated
WAAS: wide area augmentaƟ on system