AAI -- AZIMUTH (MLS)
AAI- (See ARRIVAL AIRCRAFT INTERVAL.)
AAR- (See AIRPORT ACCEPTANCE RATE.)
ABBREVIATED IFR FLIGHT PLANS- An authorization by ATC requiring pilots to
submit only that information needed for the purpose of ATC. It includes only a
small portion of the usual IFR flight plan information. In certain instances,
this may be only aircraft identification, location, and pilot request. Other
information may be requested if needed by ATC for separation/control purposes.
It is frequently used by aircraft which are airborne and desire an instrument
approach or by aircraft which are on the ground and desire a climb to
VFR-on-top.
ABEAM- An aircraft is "abeam" a fix,
point, or object when that fix, point, or object is approximately 90 degrees to
the right or left of the aircraft track. Abeam indicates a general position
rather than a precise point.
ABORT- To terminate a preplanned aircraft maneuver; e.g., an
aborted takeoff.
ACC [ICAO]- (See AREA CONTROL CENTER.)
ACCELERATE-STOP DISTANCE AVAILABLE- The runway plus stopway length declared
available and suitable for the acceleration and deceleration of an airplane
aborting a takeoff.
ACCELERATE-STOP DISTANCE AVAILABLE [ICAO]- The length of the take-off run
available plus the length of the stopway if provided.
ACDO- (See AIR CARRIER DISTRICT OFFICE.)
ACKNOWLEDGE- Let me know that you have received my message.
(See ICAO term ACKNOWLEDGE.)
ACKNOWLEDGE [ICAO]- Let me know that
you have received and understood this message.
ACLS- (See AUTOMATIC CARRIER LANDING SYSTEM.)
ACLT- (See ACTUAL CALCULATED LANDING TIME.)
ACROBATIC FLIGHT- An intentional maneuver involving an abrupt change in an
aircraft's attitude, an abnormal attitude, or abnormal acceleration not
necessary for normal flight.
(See ICAO term ACROBATIC FLIGHT.)
ACROBATIC FLIGHT [ICAO]-
Maneuvers intentionally performed by an aircraft involving an abrupt change in
its attitude, an abnormal attitude, or an abnormal variation in speed.
ACTIVE RUNWAY- (See RUNWAY IN USE/ACTIVE RUNWAY/DUTY RUNWAY.)
ACTUAL CALCULATED LANDING TIME- ACLT is a flight's frozen calculated landing
time. An actual time determined at freeze calculated landing time (FCLT) or
meter list display interval (MLDI) for the adapted vertex for each arrival
aircraft based upon runway configuration, airport acceptance rate, airport
arrival delay period, and other metered arrival aircraft. This time is either
the vertex time of arrival (VTA) of the aircraft or the tentative calculated
landing time (TCLT)/ACLT of the previous aircraft plus the arrival aircraft
interval (AAI), whichever is later. This time will not be updated in response to
the aircraft's progress.
ADDITIONAL SERVICES- Advisory information provided by ATC which includes but
is not limited to the following:
b. Vectors, when requested by the pilot, to assist aircraft
receiving traffic advisories to avoid observed traffic.
c. Altitude deviation information of 300 feet or more from an
assigned altitude as observed on a verified (reading correctly) automatic
altitude readout (Mode C.)
d. Advisories that traffic is no longer a factor.
e. Weather and chaff information.
g. Bird activity information.
h. Holding pattern surveillance. Additional services are provided
to the extent possible contingent only upon the controller's capability to fit
them into the performance of higher priority duties and on the basis of
limitations of the radar, volume of traffic, frequency congestion, and
controller workload. The controller has complete discretion for determining if
he/she is able to provide or continue to provide a service in a particular
case. The controller's reason not to provide or continue to provide a service
in a particular case is not subject to question by the pilot and need not be
made known to him/her.
(See TRAFFIC ADVISORIES.)
ADF- (See AUTOMATIC DIRECTION FINDER.)
ADIZ- (See AIR DEFENSE IDENTIFICATION ZONE.)
ADLY- (See ARRIVAL DELAY.)
ADMINISTRATOR- The Federal Aviation Administrator or any person to whom
he/she has delegated his/her authority in the matter concerned.
ADVISE INTENTIONS- Tell me what you plan to do.
ADVISORY- Advice and information provided to assist pilots in the safe
conduct of flight and aircraft movement.
ADVISORY FREQUENCY- The appropriate
frequency to be used for Airport Advisory Service.
(See LOCAL AIRPORT ADVISORY.)
(Refer to ADVISORY CIRCULAR NO. 90-42.)
ADVISORY SERVICE- Advice and information provided
by a facility to assist pilots in the safe conduct of flight and aircraft
movement.
(See LOCAL AIRPORT ADVISORY.)
(See TRAFFIC ADVISORIES.)
(See ADDITIONAL SERVICES.)
(See EN ROUTE FLIGHT ADVISORY
SERVICE.)
AERIAL REFUELING- A procedure used by the military
to transfer fuel from one aircraft to another during flight.
(Refer to VFR/IFR Wall Planning Charts.)
AERODROME- A defined area
on land or water (including any buildings, installations and equipment) intended
to be used either wholly or in part for the arrival, departure, and movement of
aircraft.
AERODROME BEACON [ICAO]- Aeronautical beacon used to indicate the location of
an aerodrome from the air.
AERODROME CONTROL SERVICE [ICAO]- Air traffic control service for aerodrome
traffic.
AERODROME CONTROL TOWER [ICAO]- A unit established to provide air traffic
control service to aerodrome traffic.
AERODROME ELEVATION [ICAO]- The elevation of the highest point of the landing
area.
AERODROME TRAFFIC CIRCUIT [ICAO]- The specified path to be flown by aircraft
operating in the vicinity of an aerodrome.
AERONAUTICAL BEACON- A visual NAVAID displaying flashes of white and/or
colored light to indicate the location of an airport, a heliport, a landmark, a
certain point of a Federal airway in mountainous terrain, or an obstruction.
(See AIRPORT ROTATING BEACON.)
AERONAUTICAL CHART- A map used in air navigation
containing all or part of the following: topographic features, hazards and
obstructions, navigation aids, navigation routes, designated airspace, and
airports. Commonly used aeronautical charts are:
a. Sectional Aeronautical Charts (1:500,000)- Designed for visual
navigation of slow or medium speed aircraft. Topographic information on these
charts features the portrayal of relief and a judicious selection of visual
check points for VFR flight. Aeronautical information includes visual and
radio aids to navigation, airports, controlled airspace, restricted areas,
obstructions, and related data.
b. VFR Terminal Area Charts (1:250,000)- Depict Class B airspace
which provides for the control or segregation of all the aircraft within Class
B airspace. The chart depicts topographic information and aeronautical
information which includes visual and radio aids to navigation, airports,
controlled airspace, restricted areas, obstructions, and related data.
c. World Aeronautical Charts (WAC) (1:1,000,000)- Provide a
standard series of aeronautical charts covering land areas of the world at a
size and scale convenient for navigation by moderate speed aircraft.
Topographic information includes cities and towns, principal roads, railroads,
distinctive landmarks, drainage, and relief. Aeronautical information includes
visual and radio aids to navigation, airports, airways, restricted areas,
obstructions, and other pertinent data.
d. En Route Low Altitude Charts- Provide aeronautical information
for en route instrument navigation (IFR) in the low altitude stratum.
Information includes the portrayal of airways, limits of controlled airspace,
position identification and frequencies of radio aids, selected airports,
minimum en route and minimum obstruction clearance altitudes, airway
distances, reporting points, restricted areas, and related data. Area charts,
which are a part of this series, furnish terminal data at a larger scale in
congested areas.
e. En Route High Altitude Charts- Provide aeronautical information
for en route instrument navigation (IFR) in the high altitude stratum.
Information includes the portrayal of jet routes, identification and
frequencies of radio aids, selected airports, distances, time zones, special
use airspace, and related information.
f. Instrument Approach Procedures (IAP) Charts- Portray the
aeronautical data which is required to execute an instrument approach to an
airport. These charts depict the procedures, including all related data, and
the airport diagram. Each procedure is designated for use with a specific type
of electronic navigation system including NDB, TACAN, VOR, ILS/MLS, and RNAV.
These charts are identified by the type of navigational aid(s) which provide
final approach guidance.
g. Instrument Departure Procedure (DP) Charts-
Designed to
expedite clearance delivery and to facilitate transition between takeoff and
en route operations. Each DP is presented as a separate chart and may serve a
single airport or more than one airport in a given geographical location.
h. Standard Terminal Arrival (STAR) Charts- Designed to expedite
air traffic control arrival procedures and to facilitate transition between en
route and instrument approach operations. Each STAR procedure is presented as
a separate chart and may serve a single airport or more than one airport in a
given geographical location.
i. Airport Taxi Charts- Designed to expedite the efficient and safe
flow of ground traffic at an airport. These charts are identified by the
official airport name; e.g., Washington National Airport.
(See ICAO term AERONAUTICAL CHART.)
AERONAUTICAL CHART [ICAO]- A
representation of a portion of the earth, its culture and relief, specifically
designated to meet the requirements of air navigation.
AERONAUTICAL INFORMATION MANUAL- A primary FAA publication whose purpose is
to instruct airmen about operating in the National Airspace System of the U.S.
It provides basic flight information, ATC Procedures and general instructional
information concerning health, medical facts, factors affecting flight safety,
accident and hazard reporting, and types of aeronautical charts and their use.
AERONAUTICAL INFORMATION PUBLICATION [AIP] [ICAO]- A publication issued by or
with the authority of a State and containing aeronautical information of a
lasting character essential to air navigation.
A/FD- (See AIRPORT/FACILITY DIRECTORY.)
AFFIRMATIVE- Yes.
AIM- (See AERONAUTICAL INFORMATION MANUAL.)
AIP [ICAO]- (See AERONAUTICAL INFORMATION PUBLICATION.)
AIRBORNE DELAY- Amount of delay to be encountered in airborne holding.
AIR CARRIER DISTRICT OFFICE- An FAA field office serving an assigned
geographical area, staffed with Flight Standards personnel serving the aviation
industry and the general public on matters related to the certification and
operation of scheduled air carriers and other large aircraft operations.
AIRCRAFT- Device(s) that are used or intended to be used for flight in the
air, and when used in air traffic control terminology, may include the flight
crew.
(See ICAO term AIRCRAFT.)
AIRCRAFT [ICAO]- Any machine that can
derive support in the atmosphere from the reactions of the air other than the
reactions of the air against the earth's surface.
AIRCRAFT APPROACH CATEGORY- A grouping of aircraft based on a speed of 1.3
times the stall speed in the landing configuration at maximum gross landing
weight. An aircraft shall fit in only one category. If it is necessary to
maneuver at speeds in excess of the upper limit of a speed range for a category,
the minimums for the next higher category should be used. For example, an
aircraft which falls in Category A, but is circling to land at a speed in excess
of 91 knots, should use the approach Category B minimums when circling to land.
The categories are as follows:
a. Category A- Speed less than 91 knots.
b. Category B- Speed 91 knots or more but less than 121 knots.
c. Category C- Speed 121 knots or more but less than 141 knots.
d. Category D- Speed 141 knots or more but less than 166 knots.
e. Category E- Speed 166 knots or more.
AIRCRAFT CLASSES- For the purposes of Wake
Turbulence Separation Minima, ATC classifies aircraft as Heavy, Large, and Small
as follows:
a. Heavy- Aircraft capable of takeoff weights of more than 255,000
pounds whether or not they are operating at this weight during a particular
phase of flight.
b. Large- Aircraft of more than 41,000 pounds, maximum certificated
takeoff weight, up to 255,000 pounds.
c. Small- Aircraft of 41,000 pounds or less maximum certificated
takeoff weight.
AIRCRAFT SITUATION DISPLAY- ASD is a computer
system that receives radar track data from all 20 CONUS ARTCC's, organizes this
data into a mosaic display, and presents it on a computer screen. The display
allows the traffic management coordinator multiple methods of selection and
highlighting of individual aircraft or groups of aircraft. The user has the
option of superimposing these aircraft positions over any number of background
displays. These background options include ARTCC boundaries, any stratum of en
route sector boundaries, fixes, airways, military and other special use
airspace, airports, and geopolitical boundaries. By using the ASD, a coordinator
can monitor any number of traffic situations or the entire systemwide traffic
flows.
AIRCRAFT SURGE LAUNCH AND RECOVERY- Procedures used at USAF bases to provide
increased launch and recovery rates in instrument flight rules conditions. ASLAR
is based on:
a. Reduced separation between aircraft which is based on time or
distance. Standard arrival separation applies between participants including
multiple flights until the DRAG point. The DRAG point is a published location
on an ASLAR approach where aircraft landing second in a formation slows to a
predetermined airspeed. The DRAG point is the reference point at which MARSA
applies as expanding elements effect separation within a flight or between
subsequent participating flights.
b. ASLAR procedures shall be covered in a Letter of Agreement
between the responsible USAF military ATC facility and the concerned Federal
Aviation Administration facility. Initial Approach Fix spacing requirements
are normally addressed as a minimum.
AIR DEFENSE EMERGENCY- A military
emergency condition declared by a designated authority. This condition exists
when an attack upon the continental U.S., Alaska, Canada, or U.S. installations
in Greenland by hostile aircraft or missiles is considered probable, is
imminent, or is taking place.
AIR DEFENSE IDENTIFICATION ZONE- The area of
airspace over land or water, extending upward from the surface, within which the
ready identification, the location, and the control of aircraft are required in
the interest of national security.
a. Domestic Air Defense Identification Zone. An ADIZ within the
United States along an international boundary of the United States.
b. Coastal Air Defense Identification Zone. An ADIZ over the
coastal waters of the United States.
c. Distant Early Warning Identification Zone (DEWIZ.) An ADIZ over
the coastal waters of the State of Alaska.
ADIZ locations and operating and
flight plan requirements for civil aircraft operations are specified in FAR Part
99.
AIRMAN'S METEOROLOGICAL INFORMATION- (See AIRMET.)
AIRMET- In-flight weather advisories issued only to amend the
area forecast concerning weather phenomena which are of operational interest to
all aircraft and potentially hazardous to aircraft having limited capability
because of lack of equipment, instrumentation, or pilot qualifications. AIRMET's
concern weather of less severity than that covered by SIGMET's or Convective
SIGMET's. AIRMET's cover moderate icing, moderate turbulence, sustained winds of
30 knots or more at the surface, widespread areas of ceilings less than 1,000
feet and/or visibility less than 3 miles, and extensive mountain obscurement.
AIR NAVIGATION FACILITY- Any facility used in,
available for use in, or designed for use in, aid of air navigation, including
landing areas, lights, any apparatus or equipment for disseminating weather
information, for signaling, for radio-directional finding, or for radio or other
electrical communication, and any other structure or mechanism having a similar
purpose for guiding or controlling flight in the air or the landing and take-off
of aircraft.
AIRPORT- An area on land or water that is
used or intended to be used for the landing and takeoff of aircraft and includes
its buildings and facilities, if any.
AIRPORT ACCEPTANCE RATE- A dynamic input parameter specifying the number of
arriving aircraft which an airport or airspace can accept from the ARTCC per
hour. The AAR is used to calculate the desired interval between successive
arrival aircraft.
AIRPORT ADVISORY AREA- The area within ten miles of an airport without a
control tower or where the tower is not in operation, and on which a Flight
Service Station is located.
(See LOCAL AIRPORT ADVISORY.)
AIRPORT ELEVATION- The highest point of an
airport's usable runways measured in feet from mean sea level.
(See TOUCHDOWN ZONE ELEVATION.)
(See ICAO term AERODROME ELEVATION.)
AIRPORT/FACILITY DIRECTORY- A
publication designed primarily as a pilot's operational manual containing all
airports, seaplane bases, and heliports open to the public including
communications data, navigational facilities, and certain special notices and
procedures. This publication is issued in seven volumes according to
geographical area.
AIRPORT INFORMATION AID- (See AIRPORT INFORMATION DESK.)
AIRPORT INFORMATION DESK- An airport unmanned facility designed for pilot
self-service briefing, flight planning, and filing of flight plans.
AIRPORT LIGHTING- Various lighting aids that may be
installed on an airport. Types of airport lighting include:
a. Approach Light System (ALS)- An airport lighting facility which
provides visual guidance to landing aircraft by radiating light beams in a
directional pattern by which the pilot aligns the aircraft with the extended
centerline of the runway on his final approach for landing.
Condenser-Discharge Sequential Flashing Lights/Sequenced Flashing Lights may
be installed in conjunction with the ALS at some airports. Types of Approach
Light Systems are:
1. ALSF-1- Approach Light System with Sequenced Flashing Lights
in ILS Cat-I configuration.
2. ALSF-2- Approach Light System with Sequenced Flashing Lights
in ILS Cat-II configuration. The ALSF-2 may operate as an SSALR when weather
conditions permit.
3. SSALF- Simplified Short Approach Light System with Sequenced
Flashing Lights.
4. SSALR- Simplified Short Approach Light System with Runway
Alignment Indicator Lights.
5. MALSF- Medium Intensity Approach Light System with Sequenced
Flashing Lights.
6. MALSR- Medium Intensity Approach Light System with Runway
Alignment Indicator Lights.
7. LDIN- Lead-in-light system- Consists of one or more series of
flashing lights installed at or near ground level that provides positive
visual guidance along an approach path, either curving or straight, where
special problems exist with hazardous terrain, obstructions, or noise
abatement procedures.
8. RAIL- Runway Alignment Indicator Lights-
Sequenced
Flashing Lights which are installed only in combination with other light
systems.
9. ODALS- Omnidirectional Approach Lighting System consists of
seven omnidirectional flashing lights located in the approach area of a
nonprecision runway. Five lights are located on the runway centerline
extended with the first light located 300 feet from the threshold and
extending at equal intervals up to 1,500 feet from the threshold. The other
two lights are located, one on each side of the runway threshold, at a
lateral distance of 40 feet from the runway edge, or 75 feet from the runway
edge when installed on a runway equipped with a VASI.
(Refer to FAA Order 6850.2, VISUAL GUIDANCE LIGHTING SYSTEMS.)
b. Runway Lights/Runway Edge Lights- Lights having a prescribed
angle of emission used to define the lateral limits of a runway. Runway lights
are uniformly spaced at intervals of approximately 200 feet, and the intensity
may be controlled or preset.
c. Touchdown Zone 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.
d. Runway Centerline Lighting- Flush centerline lights spaced at
50-foot intervals beginning 75 feet from the landing threshold and extending
to within 75 feet of the opposite end of the runway.
e. Threshold Lights- Fixed green lights arranged symmetrically left
and right of the runway centerline, identifying the runway threshold.
f. Runway End Identifier Lights (REIL)- Two synchronized flashing
lights, one on each side of the runway threshold, which provide rapid and
positive identification of the approach end of a particular runway.
g. Visual Approach Slope Indicator (VASI)- An airport lighting
facility providing vertical visual approach slope guidance to aircraft during
approach to landing by radiating a directional pattern 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 aircraft have three-bar VASI's which
provide two visual glide paths to the same runway.
h. Boundary Lights- Lights defining the perimeter of an airport or
landing area.
AIRPORT MARKING AIDS- Markings used on runway and
taxiway surfaces to identify a specific runway, a runway threshold, a
centerline, a hold line, etc. A runway should be marked in accordance with its
present usage such as:
b. Nonprecision instrument.
AIRPORT REFERENCE POINT (ARP) - The approximate
geometric center of all usable runway surfaces.
AIRPORT RESERVATION OFFICE- Office responsible for monitoring the operation
of the high density rule. Receives and processes requests for IFR operations at
high density traffic airports.
AIRPORT ROTATING BEACON- A visual NAVAID operated at many airports. At civil
airports, alternating white and green flashes indicate the location of the
airport. At military airports, the beacons flash alternately white and green,
but are differentiated from civil beacons by dualpeaked (two quick) white
flashes between the green flashes.
(See SPECIAL VFR OPERATIONS.)
(See INSTRUMENT FLIGHT RULES.)
(See ICAO term AERODROME BEACON.)
AIRPORT SURFACE DETECTION
EQUIPMENT- Radar equipment specifically designed to detect all principal
features on the surface of an airport, including aircraft and vehicular traffic,
and to present the entire image on a radar indicator console in the control
tower. Used to augment visual observation by tower personnel of aircraft and/or
vehicular movements on runways and taxiways.
AIRPORT SURVEILLANCE RADAR- Approach control radar used to detect and display
an aircraft's position in the terminal area. ASR provides range and azimuth
information but does not provide elevation data. Coverage of the ASR can extend
up to 60 miles.
AIRPORT TAXI CHARTS- (See AERONAUTICAL CHART.)
AIRPORT TRAFFIC CONTROL SERVICE- A service provided by a control tower for
aircraft operating on the movement area and in the vicinity of an airport.
(See ICAO term AERODROME CONTROL SERVICE.)
AIRPORT TRAFFIC CONTROL
TOWER- (See TOWER.)
AIR ROUTE SURVEILLANCE RADAR- Air route traffic control center (ARTCC) radar
used primarily to detect and display an aircraft's position while en route
between terminal areas. The ARSR enables controllers to provide radar air
traffic control service when aircraft are within the ARSR coverage. In some
instances, ARSR may enable an ARTCC to provide terminal radar services similar
to but usually more limited than those provided by a radar approach control.
AIR ROUTE TRAFFIC CONTROL CENTER- 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. When
equipment capabilities and controller workload permit, certain
advisory/assistance services may be provided to VFR aircraft.
(See EN ROUTE AIR TRAFFIC CONTROL SERVICES.)
AIRSPACE HIERARCHY- Within the airspace classes,
there is a hierarchy and, in the event of an overlap of airspace: Class A
preempts Class B, Class B preempts Class C, Class C preempts Class D, Class D
preempts Class E, and Class E preempts Class G.
AIRSPEED- The speed of an aircraft relative to its surrounding air mass. The
unqualified term "airspeed" means one of the following:
a. Indicated Airspeed- The speed shown on the aircraft airspeed
indicator. This is the speed used in pilot/controller communications under the
general term "airspeed."
b. True Airspeed- The airspeed of an aircraft relative to
undisturbed air. Used primarily in flight planning and en route portion of
flight. When used in pilot/controller communications, it is referred to as
"true airspeed" and not shortened to "airspeed."
AIRSTART- The starting of
an aircraft engine while the aircraft is airborne, preceded by engine shutdown
during training flights or by actual engine failure.
AIR TAXI- Used to describe a helicopter/VTOL aircraft movement conducted
above the surface but normally not above 100 feet AGL. The aircraft may proceed
either via hover taxi or flight at speeds more than 20 knots. The pilot is
solely responsible for selecting a safe airspeed/altitude for the operation
being conducted.
AIR TRAFFIC- Aircraft operating in the air or on an
airport surface, exclusive of loading ramps and parking areas.
(See ICAO term AIR TRAFFIC.)
AIR TRAFFIC [ICAO]- All aircraft in
flight or operating on the manoeuvring area of an aerodrome.
AIR TRAFFIC CLEARANCE- An authorization by air traffic control for the
purpose of preventing collision between known aircraft, for an aircraft to
proceed under specified traffic conditions within controlled airspace. The
pilot-in-command of an aircraft may not deviate from the provisions of a visual
flight rules (VFR) or instrument flight rules (IFR) air traffic clearance except
in an emergency or unless an amended clearance has been obtained. Additionally,
the pilot may request a different clearance from that which has been issued by
air traffic control (ATC) if information available to the pilot makes another
course of action more practicable or if aircraft equipment limitations or
company procedures forbid compliance with the clearance issued. Pilots may also
request clarification or amendment, as appropriate, any time a clearance is not
fully understood, or considered unacceptable because of safety of flight.
Controllers should, in such instances and to the extent of operational
practicality and safety, honor the pilot's request. FAR Part 91.3(a) states:
"The pilot in command of an aircraft is directly responsible for, and is the
final authority as to, the operation of that aircraft." THE PILOT IS RESPONSIBLE
TO REQUEST AN AMENDED CLEARANCE if ATC issues a clearance that would cause a
pilot to deviate from a rule or regulation, or in the pilot's opinion, would
place the aircraft in jeopardy.
(See ICAO term AIR TRAFFIC CONTROL CLEARANCE.)
AIR TRAFFIC CONTROL-
A service operated by appropriate authority to promote the safe, orderly and
expeditious flow of air traffic.
(See ICAO term AIR TRAFFIC CONTROL SERVICE.)
AIR TRAFFIC CONTROL
CLEARANCE [ICAO]- Authorization for an aircraft to proceed under conditions
specified by an air traffic control unit.
Note 1: For convenience, the term air traffic control clearance is frequently
abbreviated to clearance when used in appropriate contexts.
Note 2: The abbreviated term clearance may be prefixed by the words taxi,
takeoff, departure, en route, approach or landing to indicate the particular
portion of flight to which the air traffic control clearance relates.
AIR TRAFFIC CONTROL SERVICE- (See AIR TRAFFIC CONTROL.)
AIR TRAFFIC CONTROL SERVICE [ICAO]- A service provided for the purpose of:
a. Preventing collisions:
2. On the manoeuvring area between aircraft and obstructions;
and
b. Expediting and maintaining an orderly flow of air traffic.
AIR
TRAFFIC CONTROL SPECIALIST- A person authorized to provide air traffic control
service.
(See AIR TRAFFIC CONTROL.)
(See FLIGHT SERVICE STATION.)
(See ICAO term CONTROLLER.)
AIR TRAFFIC CONTROL SYSTEM COMMAND
CENTER- An Air Traffic Operations Service facility consisting of four
operational units.
a. Central Flow Control Function (CFCF). Responsible for
coordination and approval of all major intercenter flow control restrictions
on a system basis in order to obtain maximum utilization of the airspace.
(See QUOTA FLOW CONTROL.)
b. Central Altitude Reservation Function (CARF). Responsible for
coordinating, planning, and approving special user requirements under the
Altitude Reservation (ALTRV) concept.
(See ALTITUDE RESERVATION.)
c. Airport Reservation Office (ARO). Responsible for approving IFR
flights at designated high density traffic airports (John F. Kennedy,
LaGuardia, O'Hare, and Washington National) during specified hours.
(Refer to FAR Part 93 and AIRPORT/FACILITY DIRECTORY.)
d. ATC Contingency Command Post. A facility which enables the FAA
to manage the ATC system when significant portions of the system's
capabilities have been lost or are threatened.
AIR TRAFFIC SERVICE- A
generic term meaning:
a. Flight Information Service:
c. Air Traffic Advisory Service:
d. Air Traffic Control Service:
2. Approach Control Service, or
3. Airport Control Service.
AIRWAY- A Class E airspace area
established in the form of a corridor, the centerline of which is defined by
radio navigational aids.
AIRWAY [ICAO]- A control area or portion
thereof established in the form of corridor equipped with radio navigational
aids.
AIRWAY BEACON- Used to mark airway segments in remote mountain areas. The
light flashes Morse Code to identify the beacon site.
AIT- (See AUTOMATED INFORMATION TRANSFER.)
ALERFA (Alert Phase) [ICAO]- A situation wherein apprehension exists as to
the safety of an aircraft and its occupants.
ALERT AREA- (See SPECIAL USE AIRSPACE.)
ALERT NOTICE- A request originated by a flight service station (FSS) or an
air route traffic control center (ARTCC) for an extensive communication search
for overdue, unreported, or missing aircraft.
ALERTING SERVICE- A service provided to notify appropriate organizations
regarding aircraft in need of search and rescue aid and assist such
organizations as required.
ALNOT- (See ALERT NOTICE.)
ALONG TRACK DISTANCE (LTD) - The distance measured from a point-in-space by
systems using area navigation reference capabilities that are not subject to
slant range errors.
ALPHANUMERIC DISPLAY- Letters and numerals used to show identification,
altitude, beacon code, and other information concerning a target on a radar
display.
(See AUTOMATED RADAR TERMINAL SYSTEMS.)
ALTERNATE AERODROME [ICAO]- An aerodrome to
which an aircraft may proceed when it becomes either impossible or inadvisable
to proceed to or to land at the aerodrome of intended landing.
Note: The aerodrome from which a flight departs may also be an en-route or a
destination alternate aerodrome for the flight.
ALTERNATE AIRPORT- An airport at which an aircraft may land if a landing at
the intended airport becomes inadvisable.
(See ICAO term ALTERNATE AERODROME.)
ALTIMETER SETTING- The
barometric pressure reading used to adjust a pressure altimeter for variations
in existing atmospheric pressure or to the standard altimeter setting (29.92.)
ALTITUDE- The height of a level, point, or object
measured in feet Above Ground Level (AGL) or from Mean Sea Level (MSL.)
a. MSL Altitude- Altitude expressed in feet measured from mean sea
level.
b. AGL Altitude- Altitude expressed in feet measured above ground
level.
c. Indicated Altitude- The altitude as shown by an altimeter. On a
pressure or barometric altimeter it is altitude as shown uncorrected for
instrument error and uncompensated for variation from standard atmospheric
conditions.
(See ICAO term ALTITUDE.)
ALTITUDE [ICAO]- The vertical distance of
a level, a point or an object considered as a point, measured from mean sea
level (MSL.)
ALTITUDE READOUT- An aircraft's altitude, transmitted via the
Mode C transponder feature, that is visually displayed in 100-foot increments on
a radar scope having readout capability.
(See AUTOMATED RADAR TERMINAL SYSTEMS.)
(See ALPHANUMERIC DISPLAY.)
ALTITUDE RESERVATION- Airspace utilization under
prescribed conditions normally employed for the mass movement of aircraft or
other special user requirements which cannot otherwise be accomplished. ALTRV's
are approved by the appropriate FAA facility.
(See AIR TRAFFIC CONTROL SYSTEM COMMAND CENTER.)
ALTITUDE
RESTRICTION- An altitude or altitudes, stated in the order flown, which are to
be maintained until reaching a specific point or time. Altitude restrictions may
be issued by ATC due to traffic, terrain, or other airspace considerations.
ALTITUDE RESTRICTIONS ARE CANCELED- Adherence to previously
imposed altitude restrictions is no longer required during a climb or descent.
ALTRV- (See ALTITUDE RESERVATION.)
AMVER- (See AUTOMATED MUTUAL-ASSISTANCE VESSEL RESCUE SYSTEM
APPROACH CLEARANCE- Authorization by ATC for a pilot to conduct an instrument
approach. The type of instrument approach for which a clearance and other
pertinent information is provided in the approach clearance when required.
(See INSTRUMENT APPROACH PROCEDURE.)
(Refer to AIM and FAR Part 91.)
APPROACH CONTROL FACILITY- A
terminal ATC facility that provides approach control service in a terminal area.
(See APPROACH CONTROL SERVICE.)
(See RADAR APPROACH CONTROL FACILITY.)
APPROACH CONTROL SERVICE-
Air traffic control service provided by an approach control facility for
arriving and departing VFR/IFR aircraft and, on occasion, en route aircraft. At
some airports not served by an approach control facility, the ARTCC provides
limited approach control service.
(See ICAO term APPROACH CONTROL SERVICE.)
APPROACH CONTROL SERVICE
[ICAO]- Air traffic control service for arriving or departing controlled
flights.
APPROACH GATE- An imaginary point used within ATC as a basis for vectoring
aircraft to the final approach course. The gate will be established along the
final approach course 1 mile from the outer marker (or the fix used in lieu of
the outer marker) on the side away from the airport for precision approaches and
1 mile from the final approach fix on the side away from the airport for
nonprecision approaches. In either case when measured along the final approach
course, the gate will be no closer than 5 miles from the landing threshold.
APPROACH LIGHT SYSTEM- (See AIRPORT LIGHTING.)
APPROACH SEQUENCE- The order in which aircraft are positioned while on
approach or awaiting approach clearance.
(See ICAO term APPROACH SEQUENCE.)
APPROACH SEQUENCE [ICAO]- The
order in which two or more aircraft are cleared to approach to land at the
aerodrome.
APPROACH SPEED- The recommended speed contained in aircraft
manuals used by pilots when making an approach to landing. This speed will vary
for different segments of an approach as well as for aircraft weight and
configuration.
APPROPRIATE ATS AUTHORITY [ICAO]- The relevant authority designated by the
State responsible for providing air traffic services in the airspace concerned.
In the United States, the "appropriate ATS authority" is the Program Director
for Air Traffic Operations, ATO-1.
APPROPRIATE AUTHORITY-
a. Regarding flight over the high seas: the relevant authority is
the State of Registry.
b. Regarding flight over other than the high seas: the relevant
authority is the State having sovereignty over the territory being
overflown.
APPROPRIATE OBSTACLE CLEARANCE MINIMUM ALTITUDE-
Any of the following:
(See Minimum IFR Altitude- MIA.)
(See Minimum En Route Altitude- MEA.)
(See Minimum Obstruction Clearance Altitude- MOCA.)
(See Minimum Vectoring Altitude- MVA.)
APPROPRIATE TERRAIN
CLEARANCE MINIMUM ALTITUDE- Any of the following:
(See Minimum IFR Altitude- MIA.)
(See Minimum En Route Altitude- MEA.)
(See Minimum Obstruction Clearance Altitude- MOCA.)
(See Minimum Vectoring Altitude- MVA.)
APRON- A defined area on an
airport or heliport intended to accommodate aircraft for purposes of loading or
unloading passengers or cargo, refueling, parking, or maintenance. With regard
to seaplanes, a ramp is used for access to the apron from the water.
APRON [ICAO]- A defined area, on a land
aerodrome, intended to accommodate aircraft for purposes of loading or unloading
passengers, mail or cargo, refueling, parking or maintenance.
ARC- The track over the ground of an aircraft flying at a constant distance
from a navigational aid by reference to distance measuring equipment (DME).
AREA CONTROL CENTER [ICAO]- An ICAO term for an air traffic control facility
primarily responsible for ATC services being provided IFR aircraft during the en
route phase of flight. The U.S. equivalent facility is an air route traffic
control center (ARTCC).
AREA NAVIGATION- A method of navigation that permits aircraft operation on
any desired course within the coverage of station-referenced navigation signals
or within the limits of a self-contained system capability. Random area
navigation routes are direct routes, based on area navigation capability,
between waypoints defined in terms of latitude/longitude coordinates,
degree/distance fixes, or offsets from published or established routes/airways
at a specified distance and direction. The major types of equipment are:
a. VORTAC referenced or Course Line Computer (CLC) systems, which
account for the greatest number of RNAV units in use. To function, the CLC
must be within the service range of a VORTAC.
b. OMEGA/VLF, although two separate systems, can be considered as
one operationally. A long-range navigation system based upon Very Low
Frequency radio signals transmitted from a total of 17 stations worldwide.
c. Inertial (INS) systems, which are totally self-contained and
require no information from external references. They provide aircraft
position and navigation information in response to signals resulting from
inertial effects on components within the system.
d. MLS Area Navigation (MLS/RNAV), which provides area navigation
with reference to an MLS ground facility.
e. LORAN-C is a long-range radio navigation system that uses ground
waves transmitted at low frequency to provide user position information at
ranges of up to 600 to 1,200 nautical miles at both en route and approach
altitudes. The usable signal coverage areas are determined by the
signal-to-noise ratio, the envelope-to-cycle difference, and the geometric
relationship between the positions of the user and the transmitting
stations.
f. GPS-is a space-base radio positioning, navigation, and
time-transfer system. The system provides highly accurate position and
velocity information, and precise time, on a continuous global basis, to an
unlimited number of properly equipped users. The system is unaffected by
weather, and provides a worldwide common grid reference system.
(See ICAO term AREA NAVIGATION.)
AREA NAVIGATION [ICAO]- A method
of navigation which permits aircraft operation on any desired flight path within
the coverage of station-referenced navigation aids or within the limits of the
capability of self-contained aids, or a combination of these.
AREA NAVIGATION (RNAV) APPROACH CONFIGURATION:
a. STANDARD T- An RNAV approach whose design allows direct flight
to any one of three initial approach fixes (IAF) and eliminates the need for
procedure turns. The standard design is to align the procedure on the extended
centerline with the missed approach point (MAP) at the runway threshold, the
final approach fix (FAF), and the initial approach/intermediate fix (IAF/IF).
The other two IAF's will be established perpendicular to the IF.
b. MODIFIED T- An RNAV approach design for single or multiple
runways where terrain or operational constraints do not allow for the standard
T. The "T" may be modified by increasing or decreasing the angle from the
corner IAF(s) to the IF or by eliminating one or both corner IAF's.
c. STANDARD I- An RNAV approach design for a single runway with
both corner IAF's eliminated. Course reversal or radar vectoring may be
required at busy terminals with multiple runways.
d. TERMINAL ARRIVAL AREA (TAA)- The TAA is controlled airspace
established in conjunction with the Standard or Modified T and I RNAV approach
configurations. In the standard TAA, there are three areas: straight-in, left
base, and right base. The arc boundaries of the three areas of the TAA are
published portions of the approach and allow aircraft to transition from the
en route structure direct to the nearest IAF. TAA's will also eliminate or
reduce feeder routes, departure extensions, and procedure turns or course
reversal.
1. STRAIGHT-IN AREA- A 30NM arc centered on the IF bounded by a
straight line extending through the IF perpendicular to the intermediate
course.
2. LEFT BASE AREA- A 30NM arc centered on the right corner IAF.
The area shares a boundary with the straight-in area except that it extends
out for 30NM from the IAF and is bounded on the other side by a line
extending from the IF through the FAF to the arc.
3. RIGHT BASE AREA- A 30NM arc centered on the left corner IAF.
The area shares a boundary with the straight-in area except that it extends
out for 30NM from the IAF and is bounded on the other side by a line
extending from the IF through the FAF to the arc.
ARINC- An acronym for
Aeronautical Radio, Inc., a corporation largely owned by a group of airlines.
ARINC is licensed by the FCC as an aeronautical station and contracted by the
FAA to provide communications support for air traffic control and meteorological
services in portions of international airspace.
ARMY AVIATION FLIGHT INFORMATION BULLETIN- A bulletin that provides air
operation data covering Army, National Guard, and Army Reserve aviation
activities.
ARO- (See AIRPORT RESERVATION OFFICE.)
ARRESTING SYSTEM- A safety device consisting of two major components, namely,
engaging or catching devices and energy absorption devices for the purpose of
arresting both tailhook and/or nontailhook-equipped aircraft. It is used to
prevent aircraft from overrunning runways when the aircraft cannot be stopped
after landing or during aborted takeoff. Arresting systems have various names;
e.g., arresting gear, hook device, wire barrier cable.
ARRIVAL AIRCRAFT INTERVAL- An internally generated
program in hundredths of minutes based upon the AAR. AAI is the desired optimum
interval between successive arrival aircraft over the vertex.
ARRIVAL CENTER- The ARTCC having jurisdiction for the impacted airport.
ARRIVAL DELAY- A parameter which specifies a period of time in which no
aircraft will be metered for arrival at the specified airport.
ARRIVAL SECTOR- An operational control sector containing one or more meter
fixes.
ARRIVAL SECTOR ADVISORY LIST- An ordered list of data on arrivals displayed
at the PVD/MDM of the sector which controls the meter fix.
ARRIVAL SEQUENCING PROGRAM- The automated program designed to assist in
sequencing aircraft destined for the same airport.
ARRIVAL TIME- The time an aircraft touches down on arrival.
ARSR- (See AIR ROUTE SURVEILLANCE RADAR.)
ARTCC- (See AIR ROUTE TRAFFIC CONTROL CENTER.)
ARTS- (See AUTOMATED RADAR TERMINAL SYSTEMS.)
ASD- (See AIRCRAFT SITUATION DISPLAY.)
ASDA- (See ACCELERATE-STOP DISTANCE AVAILABLE.)
ASDA [ICAO]- (See ICAO Term ACCELERATE-STOP DISTANCE AVAILABLE.)
ASDE- (See AIRPORT SURFACE DETECTION EQUIPMENT.)
ASLAR- (See AIRCRAFT SURGE LAUNCH AND RECOVERY.)
ASP- (See ARRIVAL SEQUENCING PROGRAM.)
ASR- (See AIRPORT SURVEILLANCE RADAR.)
ASR APPROACH- (See SURVEILLANCE APPROACH.)
ATC- (See AIR TRAFFIC CONTROL.)
ATCAA- (See ATC ASSIGNED AIRSPACE.)
ATC ADVISES- Used to prefix a message of noncontrol information when it is
relayed to an aircraft by other than an air traffic controller.
ATC ASSIGNED AIRSPACE- Airspace of defined
vertical/lateral limits, assigned by ATC, for the purpose of providing air
traffic segregation between the specified activities being conducted within the
assigned airspace and other IFR air traffic.
(See SPECIAL USE AIRSPACE.)
ATC CLEARANCE- (See AIR TRAFFIC
CLEARANCE.)
ATC CLEARS- Used to prefix an ATC clearance when it is relayed to an aircraft
by other than an air traffic controller.
ATC INSTRUCTIONS- Directives issued by air traffic control for the purpose of
requiring a pilot to take specific actions; e.g., "Turn left heading two five
zero," "Go around," "Clear the runway."
ATCRBS- (See RADAR.)
ATC REQUESTS- Used to prefix an ATC request when it is relayed to an aircraft
by other than an air traffic controller.
ATCSCC- (See AIR TRAFFIC CONTROL SYSTEM COMMAND CENTER.)
ATCSCC DELAY FACTOR- The amount of delay calculated to be assigned prior to
departure.
ATCT- (See TOWER.)
ATIS- (See AUTOMATIC TERMINAL INFORMATION SERVICE.)
ATIS [ICAO]- (See ICAO Term AUTOMATIC TERMINAL INFORMATION SERVICE.)
ATS Route [ICAO]- A specified route designed for channelling the flow of
traffic as necessary for the provision of air traffic services.
Note: The term "ATS Route" is used to mean variously, airway, advisory route,
controlled or uncontrolled route, arrival or departure, etc.
AUTOLAND APPROACH- An autoland approach is a precision instrument approach to
touchdown and, in some cases, through the landing rollout. An autoland approach
is performed by the aircraft autopilot which is receiving position information
and/or steering commands from onboard navigation equipment (See COUPLED
APPROACH.)
Note: Autoland and coupled approaches are flown in VFR and IFR. It is common
for carriers to require their crews to fly coupled approaches and autoland
approaches (if certified) when the weather conditions are less than
approximately 4,000 RVR.
AUTOMATED INFORMATION TRANSFER- A precoordinated process, specifically
defined in facility directives, during which a transfer of altitude control
and/or radar identification is accomplished without verbal coordination between
controllers using information communicated in a full data block.
AUTOMATED MUTUAL-ASSISTANCE VESSEL RESCUE SYSTEM- A facility which can
deliver, in a matter of minutes, a surface picture (SURPIC) of vessels in the
area of a potential or actual search and rescue incident, including their
predicted positions and their characteristics.
(See FAA Order 7110.65, paragraph 10-7-4, IN-FLIGHT
CONTINGENCIES.)
AUTOMATED RADAR TERMINAL SYSTEMS- The generic term for
the ultimate in functional capability afforded by several automation systems.
Each differs in functional capabilities and equipment. ARTS plus a suffix roman
numeral denotes a specific system. A following letter indicates a major
modification to that system. In general, an ARTS displays for the terminal
controller aircraft identification, flight plan data, other flight associated
information; e.g., altitude, speed, and aircraft position symbols in conjunction
with his radar presentation. Normal radar co-exists with the alphanumeric
display. In addition to enhancing visualization of the air traffic situation,
ARTS facilitate intra/inter-facility transfer and coordination of flight
information. These capabilities are enabled by specially designed computers and
subsystems tailored to the radar and communications equipments and operational
requirements of each automated facility. Modular design permits adoption of
improvements in computer software and electronic technologies as they become
available while retaining the characteristics unique to each system.
a. ARTS II. A programmable nontracking, computer-aided display
subsystem capable of modular expansion. ARTS II systems provide a level of
automated air traffic control capability at terminals having low to medium
activity. Flight identification and altitude may be associated with the
display of secondary radar targets. The system has the capability of
communicating with ARTCC's and other ARTS II, IIA, III, and IIIA
facilities.
b. ARTS IIA. A programmable radar-tracking computer subsystem
capable of modular expansion. The ARTS IIA detects, tracks, and predicts
secondary radar targets. The targets are displayed by means of
computer-generated symbols, ground speed, and flight plan data. Although it
does not track primary radar targets, they are displayed coincident with the
secondary radar as well as the symbols and alphanumerics. The system has the
capability of communicating with ARTCC's and other ARTS II, IIA, III, and IIIA
facilities.
c. ARTS III. The Beacon Tracking Level of the modular programmable
automated radar terminal system in use at medium to high activity terminals.
ARTS III detects, tracks, and predicts secondary radar-derived aircraft
targets. These are displayed by means of computer-generated symbols and
alphanumeric characters depicting flight identification, aircraft altitude,
ground speed, and flight plan data. Although it does not track primary
targets, they are displayed coincident with the secondary radar as well as the
symbols and alphanumerics. The system has the capability of communicating with
ARTCC's and other ARTS III facilities.
d. ARTS IIIA. The Radar Tracking and Beacon Tracking Level
(RT&BTL) of the modular, programmable automated radar terminal system.
ARTS IIIA detects, tracks, and predicts primary as well as secondary
radar-derived aircraft targets. This more sophisticated computer-driven system
upgrades the existing ARTS III system by providing improved tracking,
continuous data recording, and fail-soft capabilities.
AUTOMATIC ALTITUDE
REPORT- (See ALTITUDE READOUT.)
AUTOMATIC ALTITUDE REPORTING- That function of a transponder which responds
to Mode C interrogations by transmitting the aircraft's altitude in 100-foot
increments.
AUTOMATIC CARRIER LANDING SYSTEM- U.S. Navy final approach equipment
consisting of precision tracking radar coupled to a computer data link to
provide continuous information to the aircraft, monitoring capability to the
pilot, and a backup approach system.
AUTOMATIC DIRECTION FINDER- An aircraft radio navigation system which senses
and indicates the direction to a L/MF nondirectional radio beacon (NDB) ground
transmitter. Direction is indicated to the pilot as a magnetic bearing or as a
relative bearing to the longitudinal axis of the aircraft depending on the type
of indicator installed in the aircraft. In certain applications, such as
military, ADF operations may be based on airborne and ground transmitters in the
VHF/UHF frequency spectrum.
(See NONDIRECTIONAL BEACON.)
AUTOMATIC TERMINAL INFORMATION
SERVICE- The continuous broadcast of recorded noncontrol information in selected
terminal areas. Its purpose is to improve controller effectiveness and to
relieve frequency congestion by automating the repetitive transmission of
essential but routine information; e.g., "Los Angeles information Alfa. One
three zero zero Coordinated Universal Time. Weather, measured ceiling two
thousand overcast, visibility three, haze, smoke, temperature seven one, dew
point five seven, wind two five zero at five, altimeter two niner niner six.
I-L-S Runway Two Five Left approach in use, Runway Two Five Right closed, advise
you have Alfa."
(See ICAO term AUTOMATIC TERMINAL INFORMATION SERVICE.)
AUTOMATIC
TERMINAL INFORMATION SERVICE [ICAO]- The provision of current, routine
information to arriving and departing aircraft by means of continuous and
repetitive broadcasts throughout the day or a specified portion of the day.
AUTOROTATION- A rotorcraft flight condition in which the lifting rotor is
driven entirely by action of the air when the rotorcraft is in motion.
a. Autorotative Landing/Touchdown Autorotation. Used by a pilot to
indicate that the landing will be made without applying power to the rotor.
b. Low Level Autorotation. Commences at an altitude well below the
traffic pattern, usually below 100 feet AGL and is used primarily for tactical
military training.
c. 180 degrees Autorotation. Initiated from a downwind heading and
is commenced well inside the normal traffic pattern. "Go around" may not be
possible during the latter part of this maneuver.
AVAILABLE LANDING DISTANCE
(ALD)- The portion of a runway available for landing and roll-out for aircraft
cleared for LAHSO. This distance is measured from the landing threshold to the
hold-short point.
AVIATION WEATHER SERVICE- A service provided by the National Weather Service
(NWS) and FAA which collects and disseminates pertinent weather information for
pilots, aircraft operators, and ATC. Available aviation weather reports and
forecasts are displayed at each NWS office and FAA FSS.
(See EN ROUTE FLIGHT ADVISORY SERVICE.)
(See TRANSCRIBED WEATHER BROADCAST.)
(See PILOTS AUTOMATIC TELEPHONE WEATHER ANSWERING SERVICE.)
AWW- (See SEVERE WEATHER FORECAST ALERTS.)
AZIMUTH (MLS)- A magnetic bearing extending from an MLS navigation facility.
Note: azimuth bearings are described as magnetic and are referred to as
"azimuth" in radio telephone communications.