TORA—Takeoff Runway Available
TPP—Terminal Procedures Publication
TRACAB—Terminal Radar Approach Control in Tower Cab
TSO—Technical Standard Order
TSOA—Technical Standing Order Authorization
UHF—Ultra High Frequency
UNICOM—Universal Communications
U.S.—United States
USAF—United States Air Force
USDA—United States Department of Agriculture
VCOA—Visual Climb Over Airport / Airfield
VDA—Vertical Descent Angle
VDP—Visual Descent Point
VFR—Visual Flight Rules
VGSI—Visual Glide Slope Indicator
VHF—Very High Frequency
VLJ—Very Light Jet
VMC—Visual Meteorological Conditions
VMINI—Minimum Speed–IFR
VNAV—Vertical Navigation
VNEI—Never-Exceed Speed-IFR
VSI—Vertical Speed Indicator
VOR—Very High-Frequency Omnidirectional Range
VORTAC—Very High Frequency Omnidirectional Range/Tactical Air Navigation
VOT—VOR Test Facility Signal
VPA—Vertical Path Angle
VREF—Reference Landing Speed
V/S—Vertical Speed
VSO—Stalling Speed or the Minimum Steady Flight Speed in the Landing Configuration
WAAS—Wide Area Augmentation System
WAC—World Aeronautical Chart
WAM—Wide Area Multi-lateration
WP—Waypoint
ZFW—Fort Worth Air Route Traffic Control Center
Glossary
Abeam Fix . A fix, NAVAID, point, or object positioned
approximately 90 degrees to the right or left of the aircraft
track along a route of flight. Abeam indicates a general
position rather than a precise point.
Accelerate-Stop Distance Available (ASDA) . The runway
plus stopway length declared available and suitable for
the acceleration and deceleration of an airplane aborting a
takeoff.
Advanced Surface Movement Guidance and Control
System (A-SMGCS). A system providing routing, guidance
and surveillance for the control of aircraft and vehicles,
in order to maintain the declared surface movement rate
under all weather conditions within the aerodrome visibility
operational level (AVOL) while maintaining the required
level of safety.
Aircraft Approach Category. A grouping of aircraft based
on reference landing speed (V REF), if specified, or if V REF is
not specified, 1.3 VSO (the stalling speed or minimum steady
flight speed in the landing configuration) at the maximum
certificated landing weight.
Airport Diagram. A full-page depiction of the airport that
includes the same features of the airport sketch plus
additional details, such as taxiway identifiers, airport
latitude and longitude, and building identification. Airport
diagrams are located in the U.S. Terminal Procedures
booklet following the instrument approach charts for a
particular airport.
Airport/Facility Directory (A/FD). Section within the Chart
Supplement regional booklets published by Aeronautical
Information Services that provides information about all
airports in the region. The A/FD section includes runway
length and width, runway surface, load bearing capacity,
runway slope, airport services, and hazards, such as birds
and reduced visibility.
Airport Sketch. Depicts the runways and their length, width,
and slope, the touchdown zone elevation, the lighting
system installed on the end of the runway, and taxiways.
Airport sketches are located on the lower left or right
portion of the instrument approach chart.
Airport Surface Detection Equipment-Model X
(ASDE-X). Enables air traffic controllers to detect potential
runway conflicts by providing detailed coverage of movement
on runways and taxiways. By collecting data from a variety of
sources, ASDE-X is able to track vehicles and aircraft on the
airport movement area and obtain identification information
from aircraft transponders.
Air Route Traffic Control Center (ARTCC) . A facility
established to provide air traffic control service to aircraft
operating on IFR flight plans within controlled airspace and
principally during the en route phase of flight
Air Traffic Service (ATS) . Air traffic service is an ICAO
generic term meaning variously, flight information service,
alerting service, air traffic advisory service, air traffic control
service (area control service, approach control service, or
aerodrome control service).
Approach End of Runway (AER) . The first portion of the
runway available for landing. If the runway threshold is
displaced, use the displaced threshold latitude/longitude
as the AER.
Approach Fix . From a database coding standpoint, an
approach fix is considered to be an identifiable point
in space from the intermediate fix (IF) inbound. A fix
located between the initial approach fix (IAF) and the IF is
considered to be associated with the approach transition
or feeder route.
Approach Gate. An imaginary point used by ATC to vector
aircraft to the final approach course. The approach gate
is established along the final approach course 1 NM from
the final approach fix (FAF) on the side away from the
airport and is located no closer than 5 NM from the landing
threshold.
Area Navigation (RNAV) . A method of navigation that
permits aircraft operations on any desired course within
the coverage of station referenced navigation signals or
within the limits of self contained system capability.
Automated Surface Observing System (ASOS)/Automated
Weather Sensor System (AWSS) . The ASOS/AWSS is the
primary surface weather observing system of the U.S.
Automated Surface Observing System (ASOS). A weather
observing system that provides minute-by minute weather
observations, such as temperature, dew point, wind, altimeter
setting, visibility, sky condition, and precipitation. Some
ASOS stations include a precipitation discriminator that can
differentiate between liquid and frozen precipitation.
Automated Weather Observing System (AWOS) . A suite
of sensors that measure, collect, and disseminate weather
data. AWOS stations provide a minute-by-minute update
of weather parameters, such as wind speed and direction,
temperature and dew point, visibility, cloud heights and types,
precipitation, and barometric pressure. A variety of AWOS
system types are available (from AWOS 1 to AWOS 3), each
of which includes a different sensor array.
Automated Weather Sensor System (AWSS) . The AWSS
is part of the Aviation Surface Weather Observation Network
suite of programs and provides pilots and other users
with weather information through the Automated Surface
Observing System. The AWSS sensor suite automatically
collects, measures, processes, and broadcasts surface
weather data.
Automated Weather System . Any of the automated
weather sensor platforms that collect weather data at
airports and disseminate the weather information via
radio and/or landline. The systems currently consist of the
Automated Surface Observing System (ASOS), Automated
Weather Sensor System (AWSS), and Automated Weather
Observation System (AWOS).
Automatic Dependent Surveillance-Broadcast (ADS-B) .
A surveillance system that continuously broadcasts GPS
position information, aircraft identification, altitude,
velocity vector, and direction to all other aircraft and air
traffic control facilities within a specific area. Automatic
dependent surveillance-broadcast (ADS-B) information
is displayed in the flight deck via a flight deck display of
traffic information (CDTI) unit, providing the pilot with
greater situational awareness. ADS-B transmissions also
provides controllers with a more complete picture of traffic
and updates that information more frequently than other
surveillance equipment.
Automatic Terminal Information Service (ATIS) . A
recorded broadcast available at most airports with an
operating control tower that includes crucial information
about runways and instrument approaches in use, specific
outages, and current weather conditions, including visibility.
Center Radar ARTS Presentation/Processing (CENRAP) .
CENRAP was developed to provide an alternative to a
non-radar environment at terminal facilities should an ASR
fail or malfunction. CENRAP sends aircraft radar beacon
target information to the ASR terminal facility equipped
with ARTS.
Changeover Point (COP). A COP indicates the point where
a frequency change is necessary between navigation aids,
when other than the midpoint on an airway, to receive
course guidance from the facility ahead of the aircraft
instead of the one behind. These COPs divide an airway
or route segment and ensure continuous reception of
navigational signals at the prescribed minimum en route
IFR altitude.
Chart Supplement (CS or d-CS for digital Chart Supplement).
Regional booklets published by Aeronautical Information
Services that provides general information (graphic and
textual) about all airports, both VFR and IFR (in the A/FD
section), Notices, Associated Data and Airport Diagrams.
The A/FD section includes runway length and width,
runway surface, load bearing capacity, runway slope,
airport services, and hazards such as birds and reduced
visibility.
Charted Visual Flight Procedure (CVFP) . A CVFP may be
established at some towered airports for environmental
or noise considerations, as well as when necessary for the
safety and efficiency of air traffic operations. Designed
primarily for turbojet aircraft, CVFPs depict prominent
landmarks, courses, and recommended altitudes to specific
runways.
Closely Spaced Dependent Approaches. Identifies
dependent approaches to parallel runways spaced less
than 2,500 feet apart where ATC is permitted to apply
reduced diagonal separation and special wake turbulence
procedures. turbulence procedures.
Cockpit Display of Traffic Information (CDTI). The display
and user interface for information about air traffic within
approximately 80 miles. It typically combines and shows
traffic data from TCAS, TIS-B, and ADS-B. Depending on
features, the display may also show terrain, weather, and
navigation information.
Collision Hazard . A condition, event, or circumstance
that could induce an occurrence of a collision or surface
accident or incident.
Columns. See database columns.
Contact Approach. An approach where an aircraft on an
IFR flight plan, having an air traffic control authorization,
operating clear of clouds with at least one mile flight
visibility, and a reasonable expectation of continuing to
the destination airport in those conditions, may deviate
from the instrument approach procedure and proceed to
the destination airport by visual reference to the surface.
This approach is only authorized when requested by the
pilot and the reported ground visibility at the destination
airport is at least one statute mile.
Controlled Flight Into Terrain (CFIT) . A situation where a
mechanically normally functioning aircraft is inadvertently
flown into the ground, water, or an obstacle. There are
two basic causes of CFIT accidents; both involve flight
crew situational awareness. One definition of situational
awareness is an accurate perception by pilots of the factors
and conditions currently affecting the safe operation of the
aircraft and the crew. The causes of CFIT are the flight crews’
lack of vertical position awareness or their lack of horizontal
position awareness in relation to terrain and obstacles.
Database Columns . The spaces for data entry on each
record. One column can accommodate one character.
Database Field . The collection of characters needed to
define one item of information.
Database Identifier. A specific geographic point in space
identified on an aeronautical chart and in a naviation
database, officially designated by the controlling state
authority or derived by Jeppesen. It has no ATC function
and should not be used in filing flight plans nor used when
communicating with ATC.
Database Record. A single line of computer data made up
of the fields necessary to define fully a single useful piece
of data.
Decision Altitude (DA). A specified altitude in the precision
approach at which a missed approach must be initiated
if the required visual reference to continue the approach
has not been established. The term “Decision Altitude (DA)”
is referenced to mean sea level and the term “Decision
Height (DH)” is referenced to the threshold elevation. Even
though DH is charted as an altitude above MSL, the U.S.
has adopted the term“DA” as a step toward harmonization
of the United States and international terminology. At
some point, DA will be published for all future instrument
approach procedures with vertical guidance.
Decision Height (DH). See Decision Altitude.
Departure End of Runway (DER) . The end of runway
available for the ground run of an aircraft departure. The
end of the runway that is opposite the landing threshold,
sometimes referred to as the stop end of the runway.
Altitude, velocity vector, and direction to all other aircraft
and air traffic control facilities within a specific area.
Automatic dependent surveillance-broadcast (ADS-B)
information is displayed in the flight deck via a cockpit
display of traffic information (CDTI) unit, providing the pilot
with greater situational awareness. ADS-B transmissions
also provide controllers with a more complete picture of
traffic and update that information more frequently than
other surveillance equipment.
Descend Via. A descend via clearance instructs you to follow
the altitudes published on a STAR. You are not authorized to
leave your last assigned altitude unless specifically cleared
to do so. If ATC amends the altitude or route to one that
is different from the published procedure, the rest of the
charted descent procedure is canceled. ATC will assign
you any further route, altitude, or airspeed clearances, as
necessary.
Digital ATIS (D-ATIS). An alternative method of receiving
ATIS reports by aircraft equipped with datalink services
capable of receiving information in the flight deck over
their Aircraft Communications Addressing and Reporting
System (ACARS) unit.
Digital Elevation Model (DEM). A digital representation of
ground surface topography or terrain.
Diverse Vector Area (DVA) . An airport may establish a
diverse vector area if it is necessary to vector aircraft below
the minimum vectoring altitude to assist in the efficient
flow of departing traffic. DVA design requirements are
outlined in FAA Order 8260.3 and allow for the vectoring
of aircraft immediately off the departure end of the runway
below the MVA.
Dynamic Magnetic Variation . A field that is simply a
computer model calculated value instead of a measured
value contained in the record for a waypoint.
EFVS Operation. An operation in which visibility conditions
require an EFVS to be used in lieu of natural vision to
perform an approach or landing, determine enhanced
flight visibility, identify required visual references, or
conduct a rollout.
Electronic Flight Bag (EFB) . An electronic display system
intended primarily for flight deck or cabin use. EFB devices
can display a variety of aviation data or perform basic
calculations (e.g., performance data, fuel calculations, etc.).
In the past, some of these functions were traditionally
accomplished using paper references or were based on
data provided to the flight crew by an airline’s flight dispatch
function.The scope of the EFB system functionality may also
include various other hosted databases and applications.
Physical EFB displays may use various technologies,
formats, and forms of communication. These devices are
sometimes referred to as auxiliary performance computers
(APC) or laptop auxiliary performance computers (LAPC).
Ellipsoid of Revolution. The surface that results when an
ellipse is rotated about one of its axes.
En Route Obstacle Clearance Areas . Obstacle clearance
areas for en route planning are identified as primary,
secondary, and turning areas, and they are designed to
provide obstacle clearance route protection width for
airways and routes.
Enhanced Flight Vision System (EFVS). An installed aircraft
system which uses an electronic means to provide a display
of the forward external scene topography (the natural or
manmade features of a place or region especially in a way to
show their relative positions and elevation) through the use
of imaging sensors, including but not limited to forward-
looking infrared, millimeter wave radiometry, millimeter
wave radar, or low-light level image intensification. An
EFVS includes the display element, sensors, computers and
power supplies, indications, and controls.
Expanded Service Volume . When ATC or a procedures
specialist requires the use of a NAVAID beyond the
limitations specified for standard service volume, an
expanded service volume (ESV) may be established. See
standard service volume.
Feeder Route. A feeder route is a route depicted on IAP
charts to designate courses for aircraft to proceed from the
en route structure to the IAF. Feeder routes, also referred
to as approach transitions, technically are not considered
approach segments but are an integral part of many IAPs.
Field. See database field.
Final Approach and Takeoff Area (FATO) . The FATO is a
defined heliport area over which the final approach to a
hover or a departure is made. The touchdown and lift-off
area (TLOF) where the helicopter is permitted to land is
normally centered in the FATO. A safety area is provided
around the FATO.
Fix. A geographical position determined by visual reference
to the surface, by reference to one or more radio NAVAIDs,
by celestial plotting, or by another navigational device.
Note: Fix is a generic name for a geographical position
and is referred to as a fix, waypoint, intersection, reporting
point, etc.
Flight Information Region (FIR) . A FIR is an airspace of
defined dimensions within which Flight Information Service
and Alerting Service are provided. Flight Information Service
(FIS) is a service provided for the purpose of giving advice
and information useful for the safe and efficient conduct
of flights. Alerting Service is a service provided to notify
appropriate organizations regarding aircraft in need of search
and rescue aid, and assist such organizations as required.
Flight Level (FL) . A flight level is a level of constant
atmospheric pressure related to a reference datum of
29.92 "Hg. Each flight level is stated in three digits that
represents hundreds of feet. For example, FL 250 represents
an altimeter indication of 25,000 feet.
Floating Waypoints . Floating waypoints represent
airspace fixes at a point in space not directly associated
with a conventional airway. In many cases, they may be
established for such purposes as ATC metering fixes,
holding points, RNAV-direct routing, gateway waypoints,
STAR origination points leaving the en route structure,
and SID terminating points joining the en route structure.
Fly-by (FB) Waypoint. A waypoint that requires the use of
turn anticipation to avoid overshooting the next flight
segment.
Fly-over (FO) Waypoint. A waypoint that precludes any turn
until the waypoint is overflown, and is followed by either
an intercept maneuver of the next flight segment or direct
flight to the next waypoint.
Four Corner Post Configuration . An arrangement of air
traffic pathways in a terminal area that brings incoming
flights over fixes at four corners of the traffic area, while
outbound flights depart between the fixes, thus minimizing
conflicts between arriving and departing traffic.
Gateway Fix . A navigational aid or fix where an aircraft
transitions between the domestic route structure and the
oceanic route airspace.
Geodetic Datum. The reference plane from which geodetic
calculations are made. Or, according to ICAO Annex 15, the
numerical or geometrical quantity or set of such quantities
(mathematical model) that serves as a reference for
computing other quantities in a specific geographic region,
such as the latitude and longitude of a point.
Glidepath Angle (GPA). The angular displacement of the
vertical guidance path from a horizontal plane that passes
through the reference datum point (RDP). This angle is
published on approach charts (e.g., 3.00°, 3.20°, etc.). GPA
is sometimes referred to as vertical path angle (VPA).
Global Navigation Satellite System (GNSS). An umbrella term
adopted by the International Civil Aviation Organization
(ICAO) to encompass any independent satellite navigation
system used by a pilot to perform onboard position
determinations from the satellite data.
Gross Navigation Error (GNE). In the North Atlantic area of
operations, a gross navigation error is a lateral separation
of more than 25 NM from the centerline of an aircraft’s
cleared route, which generates an Oceanic Navigation Error
Report. This report is also generated by a vertical separation
if you are more than 300 feet off your assigned flight level.
Ground Communication Outlet (GCO) . An unstaffed,
remotely controlled ground/ground communications
facility. Pilots at uncontrolled airports may contact ATC and
AFSS via very high frequency (VHF) radio to a telephone
connection. This lets pilots obtain an instrument clearance
or close a VFR/IFR flight plan.
Head-Up Display (HUD) . See head-up guidance system
(HGS).
Head-up Guidance System (HGS) . A system that projects
critical flight data on a display positioned between the pilot
and the windscreen. In addition to showing primary flight
information, the HUD computes an extremely accurate
instrument approach and landing guidance solution, and
displays the result as a guidance cue for head-up viewing
by the pilot.
Height Above Touchdown (HAT) . The height of the DA
above touchdown zone elevation (TDZE).
Highway in the Sky (HITS) . A graphically intuitive pilot
interface system that provides an aircraft operator with all
of the attitude and guidance inputs required to safely fly
an aircraft in close conformance to air traffic procedures.
Initial Climb Area (ICA). An area beginning at the departure
end of runway (DER) to provide unrestricted climb to at
least 400 feet above DER elevation.
Instrument Approach Waypoint . Fixes used in defining
RNAV IAPs, including the feeder waypoint (FWP), the initial
approach waypoint (IAWP), the intermediate waypoint
(IWP), the final approach waypoint (FAWP), the RWY WP ,
and the APT WP , when required.
Instrument Landing System (ILS) . A precision instrument
approach system that normally consists of the following
electronic components and visual aids: localizer, glide
slope, outer marker, middle marker, and approach lights.
Instrument Procedure with Vertical Guidance (IPV). Satellite
or flight management system (FMS) lateral navigation
(LNAV) with computed positive vertical guidance based
on barometric or satellite elevation. This term has been
renamed APV.
International Civil Aviation Organization (ICAO) .
ICAO is a specialized agency of the United Nations whose
objective is to develop standard principles and techniques
of international air navigation and to promote development
of civil aviation.
Intersection. Typically, the point at which two VOR radial
position lines cross on a route, usually intersecting at a good
angle for positive indication of position, resulting in a VOR/
VOR fix.
Landing Distance Available (LDA). ICAO defines LDA as the
length of runway, that is declared available and suitable for
the ground run of an aeroplane landing.
Lateral Navigation (LNAV) . Azimuth navigation without
positive vertical guidance. This type of navigation is
associated with nonprecision approach procedures or en
route.
Local Area Augmentation System (LAAS) . LAAS further
increases the accuracy of GPS and improves signal integrity
warnings.
Localizer Performance with Vertical Guidance (LPV). LPV is
one of the four lines of approach minimums found on an
RNAV (GPS) approach chart. Lateral guidance accuracy is
equivalent to a localizer. The HAT is published as a DA since
it uses an electronic glide path that is not dependent on
any ground equipment or barometric aiding and may be
as low as 200 feet and 1⁄2 SM visibility depending on the
airport terrain and infrastructure. WAAS avionics approved
for LPV is required. Baro-VNAV is not authorized to fly the
LPV line of minimums on a RNAV (GPS) procedure since it
uses an internally generated descent path that is subject to
cold temperature effects and incorrect altimeter settings.
Loss of Separation. An occurrence or operation that results
in less than prescribed separation between aircraft, or
between an aircraft and a vehicle, pedestrian, or object.
LPV. See Localizer Performance with Vertical Guidance.
Magnetic Variation . The difference in degrees between
the measured values of true north and magnetic north at
that location.
Maximum Authorized Altitude (MAA) . An MAA is a
published altitude representing the maximum usable
altitude or flight level for an airspace structure or route
segment. It is the highest altitude on a Federal airway, jet
route, RNAV low or high route, or other direct route for
which an MEA is designated at which adequate reception
of navigation signals is assured.
Metering Fix. A fix along an established route over which
aircraft are metered prior to entering terminal airspace.
Normally, this fix should be established at a distance from
the airport which facilitates a profile descent 10,000 feet
above airport elevation (AAE) or above.
Mid-RVR. The RVR readout values obtained from sensors
located midfield of the runway.
Mileage Break. A point on a route where the leg segment
mileage ends, and a new leg segment mileage begins, often
at a route turning point.
Military Airspace Management System (MAMS) . A
Department of Defense system to collect and disseminate
information on the current status of special use airspace.
This information is provided to the Special Use Airspace
Management System (SAMS). The electronic interface
also provides SUA schedules and historical activation and
utilization data.
Minimum Crossing Altitude (MCA). An MCA is the lowest
altitude at certain fixes at which the aircraft must cross
when proceeding in the direction of a higher minimum en
route IFR altitude. MCAs are established in all cases where
obstacles intervene to prevent pilots from maintaining
obstacle clearance during a normal climb to a higher MEA
after passing a point beyond which the higher MEA applies.
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.
Minimum En Route Altitude (MEA). The MEA is the lowest
published altitude between radio fixes that assures
acceptable navigational signal coverage and meets
obstacle clearance requirements between those fixes. The
MEA prescribed for a Federal Airway or segment, RNAV low
or high route, or other direct route applies to the entire
width of the airway, segment, or route between the radio
fixes defining the airway, segment, or route.
Minimum IFR Altitude (MIA) . Minimum altitudes for IFR
operations are prescribed in 14 CFR Part 91. These MIAs are
published on IFR charts and prescribed in 14 CFR Part 95
for airways and routes, and in 14 CFR Part 97 for standard
instrument approach procedures.
Minimum Navigation Performance Specifications (MNPS).
A set of standards that require aircraft to have a minimum
navigation performance capability in order to operate in
MNPS designated airspace. In addition, aircraft must be
certified by their State of Registry for MNPS operation.
Under certain conditions, non-MNPS aircraft can operate
in MNPS airspace, however, standard oceanic separation
minima is provided between the non-MNPS aircraft and
other traffic.
Minimum Obstruction Clearance Altitude (MOCA) . The
MOCA is the lowest published altitude in effect between
radio fixes on VOR airways, off-airway routes, or route
segments that meets obstacle clearance requirements
for the entire route segment. This altitude also assures
acceptable navigational signal coverage only within 22
NM of a VOR.