VOR Operation For Part 2 of RTR (A)


VOR Operation For Part 2 of RTR (A)

 

Generally the examiner in RTR (A) exam will ask you to explain about operation of VOR. It being a very general question, you have to start from basics and go on to explain the full operation part with advantages, disadvantages or limitations along with frequency band and every other detail till the examiner asks you to stop,,,

ALL INFORMATION HERE IS IN POINTS FORMAT FOR EASY UNDERSTANDING, IN CASE YOU WANT TO UNDERSTAND IN DETAIL GO OVER THE vor TUTORIAL VIDEO ALSO PUBLISHED UNDER CATEGORY RADIO TELEPHONY.

VOR

PRINCIPLE OF OPERATION

  • MAIN PRINCIPLE IS BEARING BY PHASE COMPARISON
  • THERE ARE TWO SIGNALS BEING TRANSMITTED SIMULTANEOUSLY, ONE IS CALLED A REFERENCE SIGNAL AND THE OTHER VARIABLE SIGNAL
  • REFERENCE SIGNAL: 996O HZ SUB- CARRIER FREQUENCY MODULATED AT 30 HZ
  • VARIABLE SIGNAL : AMPLITUDE MODULATED
  • COMPARISON BETWEEN THE TWO YIELDS (GIVES) THE DIRECTION OF THE RX
VOR

VOR

 

 

 

 

 

 

 

 

 

 

 

 

 

VOR FREQUENCIES

  • BAND 108 – 112 MHz : SHARED BETWEEN ILS LOCALISER & TVORs – USES FREQUENCIES ON EVEN FIRST DECIMALS – 108.20, 108.25, etc
  • BAND 112 – 117.95 MHz

AIRBORNE EQUIPMENT

  • AERIAL
  • RECEIVER
  • INDICATOR OMNI BEARING SELECTOR TO/FROM INDICATOR , LEFT/RIGHT DEVIATION INDICATOR

IDENTIFICATION

–   3 LETTER MORSE CODE AT A RATE OF 7 WORDS/MIN, ONCE EVERY 10 SEC

–  SPEECH FORM

–  ALSO USED TO PASS SIGNIFICANT WX

MONITORING

–  AUTO MONITORING SYSTEM

–  REMOVE IDENT & NAV COMPONENT OR SWITCH OFF TOTALLY

.  FAILURE OF MONITOR

.  CHANGE IN BRG INFO IN EXCESS OF 1deg

.  REDUCTION OF MORE THAN 15% OF SIGNAL STRENGTH

FAILURE WARNING FLAG

  • FAILURE OF AC RECEIVING EQPT
  • FAILURE OF GROUND STN EQPT
  • FAILURE OF INDICATOR
  • WHEN SIGNALS BEING RECEIVED ARE WEAK OR AC IS OUT OF RANGE

USE OF VOR

  • HOMING ON VOR
  • TAKING A BEARING
  • STATION PASSAGE AND CONE OF CONFUSION
  • IDENTIFICATION
  • MONITORING

CONE OF CONFUSION

tHERE IS A CONE OF CONFUSION IN VOR WHERE THE SIGNAL IS NOT TO BE TRUSTED

ICAO SPECIFICATION – 40 DEG ELEV

IN PRACTICE – 60 TO 80 DEG ELEV

TIME DURATION DEPENDS ON HT & SPD

  INDICATIONS:

NEEDLE OSCILLATES

OFF FLAG

TO / FROM DISPLAY SWINGS

IDENT INTERRUPTED

FACTORS AFFECTING VOR RANGE

  • TRANSMISSION POWER
  • TRANSMITTER & AIRCRAFT HEIGHT (VHF RANGE FORMULA)
  • DOC : PROTECTION RANGE & ALTITUDE (THIS IS PUBLISHED IN AIP AND IS SPECIFIC FOR A PARTICULAR VOR ONLY SO AS TO AVOID CONFUSION AND INTERFERENCE BETWEEN 2 OR MORE VOR’S USING SAME FREQUENCY)
  • NATURE OF TERRAIN

FACTORS AFFECTING ACCURACY

  • SITE ERROR
  • PROPAGATION ERROR
  • AIRBORNE EQUIPMENT ERROR
  • PILOTAGE ERROR
  • INTERFERENCE ERROR

ADVANTAGES AS A NAVIGATIONAL AID 

  • INDICATIONS EASY TO SEE & FOLLOW
  • PROVIDES INFINITE NUMBER OF TRACKS
  • FREE FROM NIGHT EFFECT & STATIC
  • RANGES ACCURATELY FORECAST
  • FREQUENCY PAIRED WITH DME TO GIVE FIXES
  • HAS A FAILURE WARNING DEVICE
  • CHANNEL SPACING BETTER; AERIALS SMALLER

DISADVANTAGES

  • LEFT/RIGHT INDICATIONS DO NOT POINT TO THE BEACON; RMI REQUIRED FOR QDM
  • ONLY POSITION LINES AVAILABLE
  • NUMEROUS BEACONS FOR A LARGE AREA COVERAGE
  • LINE OF SIGHT RANGES ONLY

DOPPLER VOR

SECOND GENERATION VOR

NO MODIFICATION IN AIRBORNE RECEIVER

REDUCES SITE ERROR DUE TO INCREASE IN HORIZONTAL DIMENSION OF AERIAL SYSTEM

REFERENCE SIGNAL AMPLITUDE MODULATED FROM CENTRE AERIAL

VARIABLE SIGNAL FREQUENCY MODULATED FROM 50 AERIALS IN A CIRCLE OF DIA 44 FT

AERIALS ARE ALFORD LOOPS MOUNTED ABOVE A LARGE METALLIC MESH COUNTERPOISE

DVOR

Doppler VOR

 

 

 

 

 

 

 

 

 

 

 

 

TYPES OF VOR BEACONS

  • VOR – WX BROADCAST VOR – BETWEEN BEACON IDENT SIG, AEA & SELECTED A/F WX INFO IS BROADCAST
  • DVOR – DOPPLER VOR
  • TVOR – TERMINAL VOR
  • VOT – TEST VOR TX NOT FOR NAV USE
  • AFIS – SUFFIX TO TVOR
  • ATIS – SUFFIX TO ANY VOR BEACON
  • VORTAC – CO-LOCATED VOR AND TACAN BEACON
  • PVOR – PRECISION VOR
  • COMBINATION – E.G. OBVORTAC
VOR Instrument in cockpit

VOR

 

 

 

 

 

 

 

 

 

 

 

For more details and questions on VOR follow the link below

VOR

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