Aviation Electronics / Avionics Glossary

 

Terms

Definition

ACARS

Aircraft Communications Addressing and Reporting System

ACAS

Airborne Collision Avoidance System

ACP

Audio Control Panel

ACS

Audio Control System

A/D

Analog-to-Digital

ADAHRS

Air Data and Attitude Heading Reference System

ADC

Air Data Computer

ADF

Automatic Direction Finder

ADI

Attitude Director Indicator

ADIRS

Air Data Inertial Reference System

ADIRU

Air Data Inertial Reference Unit

ADM

Air Data Module

ADS

(1) Air Data System (2) Automatic Dependent Surveillance

ADS

-A Automatic Dependent Surveillance–Address

ADS-B

Automatic Dependent Surveillance–Broadcast

ADSEL

Address Selective. A SSR system electronically arranged to address each transponder selectively. Only a par­ticular transponder will respond, thus avoiding garbling. ADSEL uses a monopulse technique to provide more accurate bearing measurement.

ADSP

Automatic Dependent Surveillance Panel

AEA

Aircraft Electronics Association

AET

Aircraft Electronics Technician (certified by NCATT)

AFCS

Automatic Flight Control System

AFD

Autopilot Flight Director

AFDC

Autopilot Flight Director Computer

AFDS

Autopilot Flight Director System

AFIS

(1) Airborne Flight Information System (2) Automatic Flight Information Service

AGACS

Automatic Ground-Air Communication System. It is also known as ATCSS or data-link.

AGATE

Advanced General Aviation Transport Experiment

AGC

Automatic Gain Control. AGC is used to maintain the output level of the receiver.

AHC

Attitude Heading Computer

AHRS

Attitude Heading Reference System

AIR DATA

Those parameters that can be derived from knowledge of the air mass surrounding the aircraft.

AIRMETS

Advisories of significant weather that describe conditions at intensities lower than those that trigger sigments.

ALC

Automatic Level Control. A circuit used to maintain the output of a transmitter regardless of variations in the attenua­tion of the system.

ALT

(1) Altimeter (2) Altitude.

ALT HOLD

Altitude Hold Mode

ALTS

Altitude Select

AMLCD

Active Matrix Liquid Crystal Display

AMO

Aviation Maintenance Organization

ANC

Acoustic Noise Cancellation

Annunciator

A system designed to provide warning lights/audio alerts to pilots to warn of off-normal conditions.

ANR

Active Noise Reduction

ANT

Antenna

A/P

Autopilot. A computer-commanded system for controlling aircraft control surfaces.

APC

Autopilot Computer

APS

Autopilot System

ARINC

Aeronautical Radio Inc.

ASD

Aircraft Situation Display

ASDL

Aeronautical Satellite Data-Link

ASR

Airport Surveillance Radar

ASU

Avionics Switching Unit

ASTM

American Society for Testing & Materials

ATCRBS

Air Traffic Control Radar Beacon System

ATCSS

Air Traffic Control Signaling System. A system to provide information between the pilot and air traffic control using the VHF communications transceiver in conjunction with data-link equipment.

ATE

Avionics Training Excellence Award, presented by the Aircraft Electronics Association.

ATI

Instrument Size Unit of Measure (instrument hole, standard 3 1/8 inch instrument cutout is 3ATI)

ATT

Attitude

Avionics

Aviation electronics

Autopilot

An automated flight control system designed to reduce pilot workload by controlling the aircraft along one or more axis.

AWG

American Wire Guage

B RNAV

Basic Area Navigation

BARO

Barometric

Baro-Corrected Altitude

Pressure altitude-corrected local barometric pressure.

BCRS

Back Course

BDI

Bearing Distance Indicator

BGAN

Broadband Global Area Network

Boomset

A lightweight version of a headset used in low-noise cockpits, such as jets.

CAI

Caution Annunciator Indicator

Calibrated Airspeed

Corrected for instrument errors and errors due to position or location of the pressure source. At standard sea-level conditions, CAS is equal to true airspeed (TAS).

Carrier

An AC signal that can be modulated by changing the amplitude, frequency or pulse of the signal.

CASA

Civil Aviation Safety Authority (Australia)

CAT I

Operational Performance Category I. An ILS facility providing operation down to a 60-meter (200 feet) decision height and with runway visual range not less than 800 meters (2,600 feet) and a high probability of approach success.

CAT I Enhanced

An ILS approach to lower-than-standard Category I and, in some cases, to Category II minimums, based on guidance-to-touchdown provided by a Category III-capable head-up guidance system, per FAA Order 8400.13.

CAT II

Operational Performance Category II. An ILS facility providing operation down to a 30-meter (100 feet) decision height and with runway visual range not less than 400 meters (1,200 feet) and a high probability of approach success.

CAT IIIa

Operational Performance Category IIIa. An ILS facility providing operation with no decision height limit to and along the surface of the runway with external visual reference during final phase of landing and with a runway visual range of not less than 20

CAT IIIb

Operational Performance Category IIIb. An ILS facility providing operation with no decision height limit to and along the surface of the runway without reliance on external visual reference; and subsequently taxiing with external visual range of not less

CAT IIIc

Operational Performance Category IIIc. An ILS facility providing operation with no decision height limit to and along the surface of the runway and taxiways without reliance on external visual reference.

CODEC

Coder/Decoder

CDI

Course Deviation Indicator

CFIT

Controlled Flight Into Terrain

Com or Comm

Communications Receiver

Compass Locator

A low-power radio beacon, used in conjunction with ILS. A compass locator has a two-letter identification and a range of at least 15 miles.

Cone of Confusion

An inverted conical shaped area extending vertically above a VOR ground facility that is void of the bearing signal.

Contour

Contour or iso-contour refers to a weather radar display presentation that blanks the echo returns in the center of a storm cell. The area blanked out is called contour and corresponds to the return levels that exceed a predetermined threshold.

CNS

Communications, Navigation, Surveillance

CNS/ATM

Communications, Navigation, Surveillance / Air Traffic Management

CPDLC

Controller-Pilot Data-Link Communications

CRS

Certified Repair Station

CRT

Cathode Ray Tube

CTAF

Common Traffic Advisory Frequency

CV/DFDR

Cockpit Voice and Digital Flight Data Recorder

CVR

Cockpit Voice Recorder

CWS

Control Wheel Steering

DA

Drift Angle. The angle between heading and track. It is due to the effect of wind currents. Sometimes called the crab angle.

Data-Link

A system that allows exchange of digital data over an RF link. ATCSS is a data-link system used by the air traffic control system. ACARS is a data-link system used by airline command, control and management system, using VHF communication frequencies.

DER

Designated Engineering Representative

DG

Directional Gyro

DGPS

Differential Global Positioning System

DH

Decision Height

DME

Distance Measuring Equipment. A system that provides distance information from a ground station to an aircraft.

DNC

Direct Noise Cancelling

DO-160

RTCA Document 160, “Environmental Conditions and Test Procedures for Airborne Equipment,” issued 12/04/89.

DO-178

RTCA Document 178, “Software Considerations in Airborne Systems and Equipment Certification,” issued 03/22/85.

DP

Departure Procedures

DSP

Digital Signal Processing, used with some ANR headsets.

DUAT

Direct User Access Terminal

Duplex

A communications operation that uses the simultaneous operation of the transmit and receive equipment at two locations.

EADI

Electronic Attitude Director Indicator

EASA

European Aviation Safety Agency

Echo

The portion of the radiated energy reflected back to the antenna from the target (WXR).

EFB

Electronic Flight Bag

EFD

Electronic Flight Display

EFIS

Electronic Flight Instrument System

EGPWS

Enhanced Ground Proximity Warning System

EGT

Exhaust Gas Temperature

EHSI

Electronic Horizontal Situation Indicator

EICAS

Engine Indication Crew Alerting System

E-LSA

Experimental Light-Sport Aircraft. Ultralights and unregistered aircraft that fit the description of LSA; kit-built aircraft that do not meet the experimental amateur-built rules; or aircraft originally built as a Special-LSA (S-LSA).

ELT

Emergency Locator Transmitter

ENC

Electronic Noise Cancelling

ENR

Electronic Noise Reduction

FADEC

Full Authority Digital Engine Control

FBO

Fixed Base Operator

FDRS

Flight Data Recorder System

FDU

Flux Detector Unit

FF

Fuel Flow

FIS-B

Flight Information Services–Broadcast

FITS

FAA Industry Training Standard

Flight Director

An enhanced attitude direction indicator equipped with course prompter bars (F/D or FD).

FLIR

Forward-Looking Infrared

FLTA

Forward Looking Terrain Avoidance

FMS

Flight Management System

FREQ

Frequency

FYDS

Flight Director / Yaw Damper System

GCAS

Ground Collision Avoidance System

GDOP

Geometric Dilution of Precision. A term referring to error introduced in a GPS calculation due to the positioning of the satellites and the receiver.

GGS

Global Positioning System Ground Station

GHz

Gigahertz (billion hertz)

Glidepath

The approach path used by an aircraft during an instrument landing or the portion of the glideslope that intersects the localizer. The glidepath does not provide guidance completely to a touch-down point on the runway.

Glideslope

The vertical guidance portion of an ILS system.

GLNS

GPS Landing and Navigation System

GLNU

GPS Landing and Navigation Unit

GLONASS

Global Navigation Satellite System

GLS

GPS Landing System

GLU

GPS Landing Unit

GND

Ground

GNSS

Global Navigation Satellite System

Goniometer

A device that combines the two signals from two loop antennas. The goniometer (or resolver) contains two fixed coils and one rotating coil. The rotating coil is connected to the ADF bearing indicator needle to indicate the relative bearing from the aircra

GPS

(1) Global Positioning System (See NAVSTAR) (2) Global Positioning Satellite

GPWC

Ground Proximity Warning Computer

GPWS

Ground Proximity Warning System

Gray Code

Special binary code used to transmit altitude data between framing pulses of a transponder reply. A cyclic code having only one digit change at a time. Used in Mode C to transmit aircraft barometric altitude. Also known as Gilham code.

GWS

Graphical Weather Services

Gyroscope

A rotating device that will maintain its original plane of rotation, no matter which direction the gyroscope mount is turned.

HDG

Heading

HDG SEL

Heading Select

HDOP

Horizontal Dilution of Precision

Heading

The direction of an aircraft path with respect to magnetic or true north.

Headset

A tool used in the cockpit to improve communications and reduce hearing loss.

HF

High Frequency. The portion of the radio spectrum from 3 to 30 MHz. HF communications systems operate in the 2 to 30 MHz portion of the spectrum.

HHLD

Heading Hold

HSD

High-Speed Data

HSI

Horizontal Situation Indicator. An indicator that displays bearing, glideslope, distance, radio source, course and heading information.

HSL

Heading Select

HUD

Head-Up Display

Hz

Hertz (cycles per second)

IAS

Indicated Airspeed. The speed indicated by a differential pressure airspeed indicator that measures the actual pressure differential in the pitot-static head. It is the actual instrument indication for a given flight condition.

ID

Identifier

Ident

The action of the transponder transmitting an extra pulse along with its identification code (at the request of a controller).

IDS

(1) Integrated Display System (2) Information Display System

IFE

In-Flight Entertainment

IFR

Instrument Flight Rules

ILS

Instrument Landing System. The system provides lateral, along-course and vertical guidance to aircraft attempting a landing.

IMC

Instrument Meteorological Conditions

in. hg.

Inches of Mercury

IND

Indicator

Indicated Altitude

The altitude above mean sea level (uncorrected for temperature).

Intercom System

An electronic device designed to allow headset communication along with transmissions from com, nav and entertainment sources.

ISA

International Standard Atmosphere

ISP

Integrated Switching Panel

IVSI

Instantaneous Vertical Speed Indicator

kHz

Kilohertz (1000 cycles per second)

LAAS

Local Area Augmentation System

LADGPS

Local Area Differential GPS

LCD

Liquid Crystal Display

LDGPS

Local Area Differential Global Positioning Satellite

LMM

Locator Middle Marker. An NDB co-located at the same site as the 75 MHz middle-marker beacon.

LOC

Localizer. The lateral guidance portion of an ILS system.

Lock-On

The condition that exists when the DME receives reply pulses to at least 50 percent of the interrogations. Valid distance information is then available.

LOM

Locator Outer Marker. An NDB co-located at the same site as the 75 MHz outer-marker beacon.

LORAN

Long-Range Navigation. A system using a ground facility composed of a master station and a slave station. The airborne receiver computes the position of the aircraft by using two or more received master-slave pairs of signals.

LORAN-A

Operates at 1850, 1900 and 1950 kHz. LORAN-C operates at 100 kHz. LORAN-A was replaced by LORAN-C in 1980.

LORAN-C

Long-Range Navigation System

LRU

Line Replaceable Unit

LSA

Light-Sport Aircraft. Small, simple, low-performance, low-energy aircraft limited to 1,320 pounds maximum takeoff weight; one or two occupants; single engine; maximum stall speed of 45 knots; maximum airspeed in level flight of 120 knots; fixed landing ge

Lubber Line

A fixed line placed on an indicator to indicate the front-to-rear axis of the aircraft.

MAP

Missed Approach Point

Marker Beacon

A transmitter operating at 75 MHz that provides identification of a particular position along an airway or on the approach to an instrument runway. The marker beacon is continuously tone-modulated by a 400-Hz, a 1,300-Hz or a 3,000-Hz tone. Marker beacons

MB

Marker Beacon

MCBF

Mean Cycles Between Failures

MDA

Minimum Descent Altitude

MEL

Minimum Equipment List. The list of equipment the FAA requires onboard and working on an aircraft before flying.

MF

Medium Frequency. The portion of the radio spectrum from 300 kHz to 3 MHz.

MFD

Multi-Function Display

MFDS

Multi-Function Display System

MHz

Megahertz (million cycles per second)

MIC

Microphone. Also refers to the output signal of the microphone.

MILSPEC

Military Specifications

MKR

(1) Marker (2) Marker Beacon

MLS

Microwave Landing System

MOA

Military Operations Area

Mode A

The pulse format for an identification code interrogation of an ATC RBS transponder.

Mode B

An optional mode for transponder interrogation.

Mode C

The pulse format for an altitude information interrogation of an ATC RBS transponder.

Mode D

An unassigned, optional transponder mode.

Mode S

(1) Mode Select (a transponder format to allow discrete interrogation and data-link capability (2) Selective interrogation mode of SSR

Moving-Map Display

An electronic display that provides course and position infor­mation, frequently superimposed over ground features, including nav sources, airports and roads for improved flying situational awareness.

MRO

Maintenance Repair and Overhaul

MSG

Message

MSP

Mode S Specific Protocol

MSSS

Mode S Specific Services

MTBF

Mean Time Between Failures. A performance figure calculated by dividing the total unit flying hours (airborne) accrued in a period of time by the number of unit failures that occurred during the same time. Where total unit hours are available, this may be

MTTF

Mean Time To Failure. A performance figure calculated by dividing the sum­mation of times to failure for a sample of failed items by the number of failed items in the sample. The same item failing N times constitutes N failed items in the sample. This is

Muting

The process of either automatically or manually reducing the volume of a source. Typically found on music inputs for the pilot and co-pilot (automatic on receipt of transmissions) and on marker-beacon receivers (manual following station pas­sage).

NACO

National Aeronautical Chart Office

Nautical Mile (nmi)

Equivalent to 6,076.1 feet, or approximately 1.15 statute miles.

NAS

National Airspace System

Nav

Navigation or Navigation Receiver

Navaid

Navigational Aid

Nav/Com

A combination navigation and communications receiver.

Navigation Datacard

A medium holding the customized navigation database.

NAVSTAR

The NAVSTAR global positioning system (GPS) is a system using 24 satellites, all reporting precise time signals, along with location keys. Eight satellites are in each of three 63-degree inclined plane circular orbits at 11,000 nmi in altitude. The system

NCATT

National Center for Aircraft Technician Training

ND

Navigation Display. An EFIS presentation substituting for the horizontal situation indicator (HSI).

NDB

Non-Directional Radio Beacon. A ground station designed specifically for ADF use that operates in the 190-to-550-kHz range. Transmits a continuous carrier with either 400 or 1020 Hz modulation (keyed) to provide identification.

Nearest

Function of GPS and LORAN units to find the nearest airport, navaid, intersection, etc., used to reduce pilot stress in abnormal situations.

Nexcom

Next Generation Communications

NFF

No Fault Found

Nexrad

Next Generation Radar

NGATS

Next Generation Air Transportation System

NM or NMI

Nautical Mile

Noise

Undesired random electromagnetic disturbances or spurious signals that are not part of the transmitted or received signal.

NPA

Non-Precision Approach

OAT

Outside Air Temperature. The uncorrected reading of the outside temperature gauge.

OBS

Omnibearing Selector. A panel instrument that contains the controls and circuits to select an omni bearing and deter­mine the to/from indication.

OEM

Original Equipment Manufacturer

OM

Outer Marker

Omnibearing

The bearing indicated by a navigational receiver on transmissions from an omnidirectional radio range (VOR).

OrbComm

Low earth orbit satellite system used for weather-data transmissions, among other things.

P-Code

The GPS precision code.

Paired Channels

DME channels are paired with a VORTAC or ILS frequency and are automatically selected when the VORTAC or ILS frequency is selected. Most navigation con­trols have this feature.

PAPI

Precision Approach Path Indicators

PAR

Precision Approach Radar. X-band radar that scans a limited area and is part of the ground-controlled approach system.

PD

Profile Descent

PDOP

Position Dilution of Precision. A GPS term for error introduced into the GPS calculations.

Performance Index

A relative number used to compare the performance of different radar systems. It is calculated from transmitter peak power, antenna gain, pulse width, prf, antenna beam width and the receiver noise figure.

PFD

(1) Primary Flight Director (2) Primary Flight Display. An EFIS presentation substituting for the ADI.

Phase Modulation

A signal in which the phase varies (with respect to the original signal) with the amplitude of the modu­latory signal, while the amplitude of the carrier wave remains constant. Similar to a modified frequency modulated signal.

Pitot Pressure

The sum of the static and dynamic pressures, and is the total force per unit area exerted by the air on the surface of a body in motion.

Pitot Tube

A forward-facing probe attached to the outside of the aircraft to sense the relative pressure of the aircraft moving through the atmosphere. Named for Henri Pitot who first used this method of measuring fluid-flow pressure.

PMA

(1) Parts Manufacturing Approval (2) Permanent Magnet Alternator

PMG

Permanent Magnet Generator

PND

Primary Navigation Display

PNR

Passive Noise Reduction

POS

Position

PRAIM

Predictive Receiver Autonomous Integrity Monitoring

Pressure Altitude

The altitude measured above standard pressure level. Based on the relationship of pressure and altitude with respect to a standard atmosphere.

PSR

Primary Surveillance Radar. The part of the ATC system that determines the range and azimuth of an aircraft in a controlled airspace.

PTT

Push To Talk. Also refers to the switching signal that enables the transmitter.

Rabbit Tracks

(1) Rabbit Tracks, or running rabbits, refer to the distinctive display produced by another (alien radar) radar system transmission. (2) The small dots left on the display of handheld GPS units that show the previously flown course.

Radar

Radio Detecting and Ranging. A system that measures distance and bearing to an object.

Radar Mile

The time interval (approximately 12.359 microsec­onds) required for radio waves to travel one nautical mile and return (total of 2 nm).

Radial

A line of direction going out from a VOR station measured as a bearing with respect to magnetic north.

Radome

The protective cover on the aircraft nose that fits over the weather radar system antenna. The radome is transparent at radar frequencies.

RAI

Radio Altimeter Indicator

RAIM

Receiver Autonomous Integrity Monitoring

RALT

Radio Altimeter

RCVR

Receiver

RDMI

Radio Distance Magnetic Indicator

RDP

Radar Data Processing (system)

RDR

Radar

REF

Reference

Reflectivity Factor (Z)

This is a measurement of the ability of a target to reflect the energy from a radar beam.

REL

Relative

Relative Bearing

The bearing of a ground station relative to the direction the aircraft nose points, or the direction of an aircraft to or from an NDB.

Resolution Advisory

A display indication given to the pilot recommending a maneuver to increase vertical separation relative to an intruding aircraft. A resolution advisory also is classified as corrective or preventive.

RF

Radio Frequency. A general term for the range of frequen­cies above 150 kHz to the infrared region (1012 Hz).

RFI

Radio Frequency Interference

RHSM

Reduced Horizontal Separation Minima

RLG

Ring Laser Gyro

RLY

Relay

RMI

Radio Magnetic Indicator

R-NAV

Area Navigation

RNG

Range

RNP

Required Navigation Performance

ROC

Rate of Climb

ROD

Rate of Descent

RPM

Revolutions Per Minute

RTE

Route

RTCA

Radio Technical Committee on Aeronautics

RSTP

Repair Station Training Program

Runway Incursion

The act of inadvertently crossing the run­way holding point without ATC clearance.

RVR

Runway Visual Range

RVSM

Reduced Vertical Separation Minimum

Rx

Receiver

SA

Selective Availability (Refers to government detuning of GPS signal for national defense purposes.)

SAT

Static Air Temperature is the total air temperature cor­rected for the Mach effect. Increases in airspeed cause probe temperature to rise presenting erroneous information. SAT is the outside air temperature if the aircraft could be brought to a stop befor

Satcom

Satellite Communications

Satnav

Satellite Navigation

SD

Secure Digital

Search

In this mode, the DME scans from 0 mile to the outer range for a reply pulse pair after transmitting an interrogation pulse pair.

Sensitivity Level Command

An instruction given to the TCAS equipment for control of its threat volume.

SID

Standard Instrument Departure

Sidetone

The reproduction of sounds in a headset (or speak­er) from the transmitter of the same communications set. This allows a person to hear his/her own voice when transmitting.

SIGMETS

Significant Meteorological Advisories

Simplex

A communications operation that uses only a single channel for transmit and receive operations. Communications can take place in only one direction at a time.

SIU

Satellite Interface Unit

Skybound Datawriter

A Jeppesen product designed to allow pilots to update the database of selected aviation GPS receiv­ers and MFDs for reduced cost.

Skywave

A radio wave reflected by the ionosphere. The reflect­ed radio wave may propagate along the layer of the ionosphere or be reflected at some angle.

S-LSA

Special Light-Sport Aircraft. An aircraft that may be used for personal use and for compensation while conducting flight training, rental or towing.

SL

Sensitivity Level

Slant Range

The line-of-sight distance from the aircraft to a DME ground station.

SMS

(1) Short Messaging Service (2) Safety Management System

SNR

Signal-to-Noise Ratio

SPKR

Speaker

Split or Split Mode

Feature of new audio panels that allows concurrent pilot and co-pilot transmissions on two radios with two antennas at the same time.

Spoking

Refers to a display presentation that radiates outward from the display origin like the spokes on a wagon wheel.

SQ or Sql

Squelch

Squall Line

A squall line is a line of thunderstorms and devel­oping thunderstorms.

Squawk

Reply to interrogation signal (XPD).

Squelch

A control and/or circuit that reduces the gain in response of a receiver. The squelch is used to eliminate the output noise of the receiver when a signal is not being received.

Squitter

(1) The random pulse pairs generated by the ground station as a filler signal. (2) The transmission of a specified reply format at a minimum rate without the need to be interro­gated. (Filler pulses transmitted between interrogations) [XPD]. (3) Spontaneo

SSCV/DR

Solid-State Cockpit Voice/Data Recorder

SSCVR

Solid-State Cockpit Voice Recorder

SSFDR

Solid-State Flight Data Recorder

SSR

Secondary Surveillance Radar. A radar-type system that requires a transponder to transmit a reply signal.

Standard Atmosphere

Represents the mean or average properties of the atmosphere. At sea level, static pressure is 29.92 In Hg and temperature is +15° C.

Standby Mode

A DME mode that applies power to the DME RT but the unit does not transmit.

STAR

Standard Terminal Arrival Routes

STARS

Standard Terminal Automation Replacement System

Static Ports

Flush-mounted openings in the skin of the aircraft fuselage used to sense static pressure.

Static Pressure

Ambient atmospheric pressure or static-pres­sure is the force per unit area exerted by the air on the surface of a body at rest relative to the air.

Static Source Error Correction (SSEC)

A correction applied to static source pressure measurements to partly or completely correct for pressure errors that are caused by airflow changes. It is computed as a function of Mach and altitude based on measured errors for a particular static system.

STC

Supplemental Type Certificate

STOL

Short Takeoff and Landing

STP

Standard Temperature and Pressure

SUA

Special Use Airspace

Super-Heterodyne Receiver

A receiver through which the incoming RF signal is mixed to produce a lower intermediate frequency.

Suppressor Pulse

A pulse used to disable L-band avion­ics during the transmitting period of another piece of L-band airborne equipment. It prevents the other avionics onboard the aircraft from being damaged or interfered with by the transmis­sion and any noise associated

SVS

Synthetic Vision System

TA

Traffic Advisory (TCAS)

TACAN

Tactical Air Navigation System, which provides azimuth and distance information to an aircraft from a fixed ground station (as opposed to DME distance information).

Tach

Tachometer

TAD

Terrain Awareness Display

TAF

Terminal Area Forecast (ICAO)

Target

An aircraft within the surveillance range of TCAS.

TAS

True Airspeed

TAT

(1) Total Air Temperature. The air temperature including heat rise due to compressibility. (2) True Air Temperature.

TAU

TAU is the minimum time a flight crew needs to discern a collision threat and take evasive action. It represents the per­formance envelope (speed and path of aircraft) divided by the closure rate of any intruder aircraft (TCAS).

TAWS

Terrain Awareness Warning System

TBO

Time Between Overhauls

TC

Transport Canada

TCCA

Transport Canada Civil Aviation

TCA

(1) Terminal Control Area (2) Throttle Control Assembly

TCAS

Traffic Alert Collision Avoidance System

TCAS I

A baseline system that provides a warning (TA) to the flight crew of the presence of another aircraft (potential collision threat) within the surveillance area. No avoidance maneuver is suggested.

TCAS II

A collision avoidance system providing traffic informa­tion (within 30 nmi) to the flight crew, in addition to the resolu­tion advisories for vertical maneuvers only. A TCAS II-equipped aircraft will coordinate with TCAS II-equipped intruder aircraft to p

TCF

Terrain Clearance Floor

TCN

TACAN

TCU

(1) TACAN Control Unit (2) Telephone Conversion Unit

TDOP

Time Dilution of Precision. A term used to describe the error introduced by variances in the calculated time.

TDR

Transponder

Temperature Probe

A sensor protruding into the airstream to sense air temperature. Requires correct ion to get static air temperature.

TERPS

(1) Terminal En Route Procedures (2) Terminal Instrument Procedures

TFR

Temporary Flight Restrictions

TFT

Thin Film Transistor

TGT

Target

THDG

True Heading

Threat

A target that has satisfied the threat detect ion logic, and thus requires a traffic or resolution advisory (TCAS).

TIAS

True Indicated Airspeed

TIS

Traffic Information Service

TK

Track Angle

TKE

Track Angle Error

To/From Indicator

Indicates whether the omnibearing selected is the course to or from the VOR ground station.

Touchdown

The point at which the predetermined glidepath intercepts the runway.

TPR

Transponder

T/R

(1) Transceiver (see RT) (2) Transmitter Receiver

Track

(1) The actual path, over the ground, traveled by an aircraft (navigation). (2) In this mode, the DME transmits a reduced pulse pair rate after acquiring lock-on (DME). (3) Estimated position and velocity of a single aircraft based on correlated surveilla

TRACON

Terminal Radar Approach Control

Traffic Advisory

Information given to the pilot pertaining to the position of another aircraft in the immediate vicinity. The information contains no suggested maneuvers. (Traffic advisory airspace is 1,200 feet above and below the aircraft and approximately 45 seconds di

TRANS

Transition

Transceiver

A receiver and transmitter combined in a single unit. Same as RT.

Transponder

Avionics equipment that returns an identifying coded signal.

TRK

Track

TRP

Mode S Transponder

True Airspeed

The true velocity of the aircraft through the surrounding air mass.

True Altitude

The exact distance above mean sea level (corrected for temperature).

True Bearing

The bearing of a ground station with respect to true north.

True North

The direction of the north pole from the observer.

TSA

Transportation Security Administration

TSO

Technical Standard Order. Every unit built with a TSO nameplate must meet TSO requirements. TSO operating temperature extremes are not the same as the manufacturing burn-in limits.

TTR

TCAS II Receiver/Transmitter

TTS

Time To Station. An indication that displays the amount of time for an aircraft to reach a selected DME ground station while traveling at a constant speed.

TVE

Total Vertical Error

TWDL

(1) Terminal Weather Data-Link (2) Two-Way Data-Link

TWDR

Terminal Doppler Weather Radar

TWIP

Terminal Weather Information for Pilots

TWR

Turbulence Weather Radar

TX

Transmit (see XMIT)

UART

Universal Asynchronous Receiver/Transmitter

UHF

Ultra-High Frequency. The portion of the radio spectrum from 300 MHz to 3 GHz.

ULB

Underwater Locator Beacon

Ultralight

A vehicle that is manned by one occupant for recreation or sport purposes.

Unpaired Channel

A DME channel without a corresponding VOR or ILS frequency.

Uplink

The radio transmission path upward from the earth to the aircraft.

USB

Universal Serial Bus

UTC

Universal Coordinated Time

VASI

Visual Approach Slope Indicator

VDL

VHF Data-Link

VDR

VHF Digital Radio

Vertical Speed

The rate of change of pressure altitude, usually calibrated in hundreds of feet per minute.

VFO

Variable Frequency Oscillator

VFR

Visual Flight Rules

VG/DG

Vertical Gyro/Directional Gyro

VGA

Video Graphics Array

VHF

Very High Frequency. The portion of the radio spectrum from 30 to 300 MHz.

V/L VOR / Localizer- 84 -

VMC

(1) Visual Meteorological Conditions (2) Minimum Control Speed with Critical Engine Out

V/NAV

Vertical Navigation

VNE

Never Exceed Speed

VNO

Maximum Structural Cruising Speed

VNR

VHF Navigation Receiver

VOR

VHF Omnidirectional Radio Range. A system that provides bearing information to an aircraft.

VOR/DME

A system in which a VOR and DME station are co-located.

VOR/MB

VOR/Marker Beacon

VORTAC

A system in which a VOR and a TACAN station are co-located.

VOX

Voice Transmission

VPATH

Vertical Path

VREF

Reference Velocity

V/S

Vertical Speed

VSI

Vertical Speed Indicator

VSL

Advisory Vertical Speed Limit Advisory. May be preventive or corrective (TCAS).

VSM

Vertical Separation Minimum

VSO

Stalling Speed in the Landing Configuration

VSWR

Voltage-Standing Wave Ratio. The ratio of the amplitude of the voltage (or electric field) at a voltage maximum to that of an adjacent voltage minimum. VSWR is a measurement of the mismatch between the load and the transmission line.

V/TRK

Vertical Track

VX

Speed for Best Angle of Climb

VY

Speed for Best Rate of Climb

WAAS

Wide Area Augmentation System (method of differential GPS)

WADGNSS

Wide Area Differential Global Navigation Satellite System

Waypoint

A position along a route of flight.

WD

Wind Direction

Whisper-Shout

A sequence of ATC RBS interrogations and suppressions of varying power levels transmitted by TCAS equipment to reduce severity of synchronous interference and multipath problems.

WINDMG

Wind Magnitude

WINDR

Wind Direction

Wing Leveler

Rudimentary autopilot that maintains the wings of the plane level.

WMA

WXR Antenna Pedestal and WXR Waveguide Adapter

WMI

WXR Indicator Mount

WMS

Wide-Area Master Station

WMSC

Weather Message Switching Center

WMSCR

Weather Message Switching Center Replacement

WPT

Waypoint

WRT

WXR Receiver/Transmitter

WX

Weather

WXR

Weather Radar System

WYPT

Waypoint Altitude

X-Channel

A DME channel. There are 126 X-Channels for DME operation. For the first 63 channels, the ground-to-air frequency is 63 MHz below the air-to-ground frequency. For the second 63-X channels, the ground-to-air frequency is 63 MHz above the air-to-ground freq

XCVR

Transceiver

XFR

Transfer

XMIT

Transmit

XMTR

Transmitter

XPD

ATC Transponder (also XPDR, XPNDR, TPR)

XPDR

Transponder

XTK

Crosstrack (crosstrack error)

Yagi

Antenna An antenna with its maximum radiation parallel to the long axis of its array, consisting of a driven dipole,

YD

Yaw Damper

Z-Marker

A marker beacon, sometimes referred to as a station locator, that provides positive identification to the pilot when the aircraft is passing directly over a low-frequency navigation aid.

 

AvionTEq
Van Nuys Airport (VNY), Van Nuys, CA 91406 USA