Terminology » Avionic Systems: Navigational Aids Overview

Avionic Systems: Navigational Aids Overview

avionics navigation gps ils vor

This page covers various avionic systems used as short-range navigational aids, long-range navigational aids, and approach landing navigational aids.

It includes ADF, NDB, VOR, LORAN, OMEGA, MLS, DME, TACAN, GPS, ALS, VASIS, DNS, INS, IRS, RNAV, VORTAC, ILS, LOC, GS, LOC-DME, MB, DGPS navigational aids etc.

The differences between these avionic systems have been mentioned in the tables below.

Short Range Navigational Aids - ADF, NDB, VOR, DME, TACAN, VORTAC, RNAV

Short range systemMeaningPrincipleFrequency of operationSystem locationRF Wireless World Reference
ADFAutomatic Direction FinderProvides Aircraft bearing with respect to Ground StationMFLocated at AircraftADF
NDBNon Directional BeaconGround system used as an Automatic Direction Finder. Transmit for bearing purposesMedium Frequency(MF)Located at Ground
VORVHF Omni Directional RangeProvides Aircraft radial with respect to a Ground StationVHFLocated at Ground and Aircraft
DMEDistance Measuring EquipmentProvides distance between Aircraft and Ground StationUHFlocated at ground and AircraftDME
NDB-DMENDB and DMEGND system with both NDB and DME for bearing and distance purposesMF/UHFLocated at Ground
VOR-DMEVOR and DMEGround system with both the VOR and DME for radial and distance purposesVHF/UHFLocated at Ground
TACANTactical Air NavigationProvides Aircraft bearing and distance with respect to a GND stationUHFLocated at Ground and AircraftTACAN
VORTACVOR and TACANGround System with both VOR and TACAN for bearing and distance purposesVHF,UHFLocated at GroundVORTAC
RNAVRandom Navigation or aRea NavigationProvides Aircraft bearing and distance w.r.t. 3D artificial reference position known as WPTVHF,UHF,SHFLocated at AircraftRNAV

Long Range Navigational Aids - LORAN-C, OMEGA, INS, DNS, GPS

Long Range SystemMeaningPrincipleFrequencySystem LocationRF Wireless World Reference
LORAN-CLong Range Navigation Revision CProvides Aircraft Position Fix-2DLFLocated at Ground,AircraftLORAN
OMEGAOptimized Method for Estimated Guidance AccuracyProvides Aircraft Position fix -2DVLFLocated at Ground, AircraftOMEGA
INS or IRSInertial Navigation or Reference SystemProvides Aircraft velocity-3D and position fix-3D-Located at AircraftINS
DNSDoppler Navigation SystemProvides Aircraft velocity-3D and position fix-3DSHFLocated at AircraftDNS
GPSGlobal Positioning SystemProvides Aircraft Position fix-3DUHFLocated at Ground,Aircraft,Outer spaceGPS

Approach Landing Navigational Aids - ALS, VASIS, ILS, LOC, GS, MB, MLS, DGPS

Approach Landing systemMeaningPrincipleFrequencySystem LocationRF Wireless World Reference
ALSApproach Landing systemProvides visual Aid during landing for IFR precision Aircraft-Located at Ground
VASISVisual Approach Slope Indicator SystemProvides visual aid during landing for VFR and IFR non-precision Aircraft-Located at Ground
ILSInstrument Landing SystemProvides Aircraft guidance for straight flight path landingVHF/UHFLocated at Ground,AircraftILS
LOCLocalizerProvides horizontal guidance during ILS landingVHFlocated at ground,Aircraft
GSGlideslopeProvides vertical guidance during ILS landingUHFlocated at ground,Aircraft
LOC-DMELOC and DMEGround system with both LOC and DME for horizontal guidance during ILS landing and distance purposesVHF/UHFlocated at ground
MBMarker BeaconProvides indication that the Aircraft is in a specific locationVHFlocated at ground,Aircraft
OM,MM,IMOuter Marker, Middle Marker, Inner MarkerProvides indication on how far the Aircraft is with respect to the runway thresholdVHFlocated at ground,Aircraft
MLSMicrowave Landing SystemProvides Aircraft guidance for curved or straight or segmented flight path landingSHFlocated at ground,AircraftMLS
DGPSDifferential GPSGround system used to increase GPS accuracyLF/MF/UHFlocated at groundDGPS