DGCA CPL / ATPL Study Notes • Radio Navigation

✈ Chapter 8: VOR
VHF Omnidirectional Range

📋 Contents

1. Introduction & Background 2. Principle of Operation 3. Terminology — Radials & Bearings 4. Frequencies & Channels 5. Identification & Monitoring 6. Types of VOR 7. Range & Coverage 8. DOC (Designated Operational Coverage) 9. Accuracy & Errors 10. Cone of Confusion 11. Cockpit Displays — CDI, RMI, HSI 12. In-Flight Procedures 13. VOR Summary Table 14. Practice Questions (33 Q)

1. Introduction & Background

VOR — VHF Omnidirectional Range — is the primary short-range radio navigation aid used worldwide. It provides magnetic bearing information to/from a ground station and forms the backbone of conventional airway navigation.

Fig 8-1: VOR/DME station with omnidirectional polar diagram

📡 Key Facts

Adopted by ICAO in 1960 as the standard short-range navaid
Operates in the VHF band — immune to static interference and skywave
Provides magnetic bearing to/from the station (azimuth service)
Emission designator: A9W
Co-located with DME → VOR/DME; with TACAN → VORTAC

Frequency Band

108.0 – 117.95 MHz

Total Channels

160 channels

Shared with ILS

108.0 – 111.95 MHz (40 ch)

VOR only

112.0 – 117.95 MHz (120 ch)

Capt Pankaj Pahil | www.ghostaviator.com

2. Principle of Operation

The VOR works by phase comparison of two 30 Hz signals. The phase difference between the two signals equals the aircraft's magnetic bearing from the station (radial).

🔄 The Two Signals

Signal	Name	Modulation	Characteristic
Reference	Omnidirectional reference	FM subcarrier (9960 Hz)	Same phase in ALL directions
Variable	Directional / variphase	AM on carrier	Phase varies with azimuth (limàcon pattern)

The variable signal is created by rotating a limàcon (figure-of-eight) radiation pattern at 30 rev/sec. At magnetic north, both signals are in phase. Moving clockwise, the variable signal phase progressively leads the reference — the phase difference equals the radial.

Fig 8-3: Phase differences at cardinal points (N=0°, E=90°, S=180°, W=270°)

⚡ Exam Tip — Phase = Radial Phase difference (variable − reference) = Radial (QDR) = Magnetic bearing FROM the VOR.
Example: Aircraft due East → phase difference = 90°

Fig 8-4: Radial definition — phase difference equals magnetic bearing FROM station

CVOR vs DVOR Signal Generation

Feature	CVOR (Conventional)	DVOR (Doppler)
Reference signal	FM subcarrier (9960 Hz ±480 Hz)	AM on carrier
Variable signal	AM on carrier (rotating limàcon CW)	FM via Doppler (simulated ACW rotation)
Site error	More susceptible	Less site error — preferred at complex sites
Antenna array	Single rotating antenna	Ring of 48 antennas, switched electronically

3. Terminology — Radials & Bearings

Fig 8-5: Tracking between two VORs and RMI usage

📐 Critical Definitions

Term	Definition	Note
Radial	Magnetic bearing FROM the VOR (QDR)	What the VOR transmits
QDR	Magnetic bearing FROM station to aircraft	RMI tail
QDM	Magnetic heading to fly TO station (no wind)	RMI head
QTE	True bearing FROM station	Apply variation at VOR

⚡ Variation Rule For VOR bearings, apply variation at the VOR station to convert magnetic to true bearing.
This is opposite to ADF/NDB where variation is applied at the aircraft.

✓ Example Aircraft on radial 090° from a VOR where local variation = 10°W
QDR = 090°M → QTE = 090° − 10° = 080°T (subtract westerly variation)

Capt Pankaj Pahil | www.ghostaviator.com

4. Frequencies & Channels

Band	Range	Channels	Notes
Lower VOR band	108.000 – 111.975 MHz	40 channels	Shared with ILS Localiser — even tenths = VOR (108.0, 108.2…); odd tenths = ILS
Upper VOR band	112.000 – 117.975 MHz	120 channels	VOR exclusive

⚡ Frequency Sharing (108–112 MHz) Even tenths (108.0, 108.2, 108.4…) = VOR | Odd tenths (108.1, 108.3…) = ILS Localiser.
This allows 40 VOR + 40 ILS channels in the shared band.

📡 Emission Designator: A9W A = Amplitude modulation (DSB full carrier) | 9 = Composite signal | W = Combination (telephony + telegraphy + navigation)

5. Identification & Monitoring

Station Identification

📻 Ident Methods

3-letter Morse code transmitted every 10 seconds on a 1020 Hz subcarrier
Some stations also broadcast voice ATIS on the VOR frequency
Keyed at 7 words per minute

Special Beacon Types

Type	Ident Signal	Purpose	Use?
TST	TST in Morse	Test beacon — under maintenance/calibration	❌ DO NOT USE
VOT	Continuous dots	VOR Test facility — checks aircraft VOR equipment	✓ Ground test only

⚠ VOT Test Limits When checking with a VOT, the aircraft must read 000° ± 4° (FROM) or 180° ± 4° (TO).
Maximum permissible error = ±4°

Monitoring

🔍 Automatic Site Monitor

Built-in monitor checks VOR bearing accuracy continuously
If bearing error exceeds ±1° → station shuts down or switches to standby transmitter
During standby switchover: ident is suppressed for 30 seconds
Rule: NEVER USE a VOR when no ident is heard

Capt Pankaj Pahil | www.ghostaviator.com

6. Types of VOR

Type	Full Name	Power	Use
CVOR	Conventional VOR	Standard	En-route navigation
DVOR	Doppler VOR	Standard	Sites with terrain/structure interference
TVOR	Terminal VOR	Low (≤50W)	Airfields — short range approach/departure
VOT	VOR Test facility	Very low	Ground equipment check only
VORTAC	VOR + TACAN	Standard	Civil (VOR) + Military (TACAN bearing + DME)
VOR/DME	VOR + DME	Standard	Provides bearing + distance

📡 DVOR — Doppler Mechanism

AM carrier = reference signal
Ring of 48 antennas switched electronically to simulate a rotating antenna
Doppler effect creates the FM variable signal
Simulated rotation is anticlockwise (opposite to CVOR) — receiver processes identically
Less susceptible to multipath site errors than CVOR

7. Range & Coverage

VOR is a line-of-sight (LOS) system. Range depends on aircraft altitude and terrain.

📡 LOS Range Formula

Range (NM) = 1.25 × (√H_tx + √H_rx)

Where H = height in feet above terrain.
Note: Coefficient 1.25 is used for all DGCA exam calculations (some texts show 1.23, but exam answers verify with 1.25).

✓ Example Aircraft at 10,000 ft, VOR antenna at 100 ft above terrain:
Range = 1.25 × (√10000 + √100) = 1.25 × (100 + 10) = 1.25 × 110 = 137.5 NM

Capt Pankaj Pahil | www.ghostaviator.com

8. DOC — Designated Operational Coverage

Fig 8-7: DOC diagram showing range/altitude pairs

📐 DOC Definition

Specifies the range and altitude within which the VOR provides reliable navigation service
Published as a range/altitude pair — e.g., 50 NM / FL 250
Means: reliable up to 50 NM from the station at or below FL 250
Valid day AND night (unlike NDB/ADF which has a day-only DOC)

✓ VOR DOC vs ADF DOC VOR DOC is valid day and night — VHF is not affected by skywave.
NDB/ADF DOC is day only — MF/LF skywave at night causes bearing errors.

9. Accuracy & Errors

Error Source	Value	Notes
Site/terrain error	±1°	Multipath reflections; DVOR less susceptible
Propagation / scalloping	±1°	Bending of VHF waves; needle oscillation in affected areas
Airborne equipment	±3°	Receiver and aircraft installation accuracy
Total system error	±5°	ICAO specification (RSS combination)

⚠ Airway Width — 1:60 Rule At distance D, lateral error = D × error° / 60.
To maintain ±5 NM half-width with ±5° error: D = (5 × 60) / 5 = 60 NM per leg?
Standard formula for max beacon spacing: max_spacing = 600 / error_degrees
• For ±5° error: 600/5 = 120 NM • For ±5.5° error: 600/5.5 ≈ 109 NM

⚡ Scalloping Rapid oscillation of VOR bearing indication caused by multipath interference. The CDI needle “scallops” back and forth. More pronounced in mountainous terrain; DVOR is less susceptible.

Capt Pankaj Pahil | www.ghostaviator.com

10. Cone of Confusion

Fig 8-8: Cone of confusion — unreliable signal area directly overhead the VOR

⚠ Cone of Confusion — Overhead VOR Indications

OFF flag may appear on CDI/VOR indicator
TO/FROM indicator alternates rapidly
CDI needle oscillates / swings
Extends approximately ±50° from vertical (antenna design dependent)
Normal and temporary — do not attempt corrections while in the cone

✓ Station Passage Technique 1. Note the moment TO/FROM flag flips to FROM → that is station passage.
2. CDI will settle after exiting the cone (typically within 1–2 minutes at normal speeds).

11. Cockpit Displays — CDI, RMI, HSI

11.1 CDI — Course Deviation Indicator

Fig 8-9: CDI / OBS (Omni Bearing Selector) deviation indicator

Fig 8-10: Left/Right CDI indications for various radial/OBS combinations

Fig 8-11: TO/FROM indications on CDI

📐 CDI Key Facts

Parameter	Value
Sensitivity	2° per dot
Full Scale Deflection (FSD)	±10° (= ±5 dots)
TO indication	QDM is within ±80° of OBS setting
FROM indication	QDR is within ±80° of OBS setting
OFF indication	OBS is ~90° away from QDM/QDR (ambiguous zone)

⚡ CDI Sense — Critical Rule The CDI only shows correct turn direction when the OBS setting matches your actual desired track. If OBS is set wrong, the needle sense can be reversed — this is the classic DGCA CDI trap!

⚠ CDI Worked Example Aircraft on 152° radial, OBS = 329° (TO). Desired radial = 149°. Aircraft is 3° to the RIGHT of desired track.
Therefore aircraft is to the LEFT of the 329° course → CDI bar deflects RIGHT (fly right).
Deflection = 3° ÷ 2°/dot = 1.5 dots right.

11.2 RMI — Radio Magnetic Indicator

Fig 8-12: RMI reading example — phase difference to bearing conversion

Fig 8-13: RMI display and geometry

📐 RMI Key Facts

Needle Part	Reading	Equivalent
Head (arrowhead)	Points TO the station	QDM — magnetic bearing TO station
Tail	Points AWAY from station	QDR — radial — magnetic bearing FROM station

The RMI compass card rotates with aircraft heading, so the needle always reads magnetic bearings (not relative bearings).

✓ RMI Worked Examples (from page 128 Q1–4)

Q1-4: Four RMI diagrams for worked examples

Q1: Heading 360°, needle head at 071° → QDM = 071°, QDR = 251°
Q2: Heading 090°, needle head at 159° → QDM = 159°, QDR = 339°
Q3: Heading 220°, needle head at 345° → QDM = 345°, QDR = 165°
Q4: Heading 270°, needle head at 063° → QDM = 063°, QDR = 243°

11.3 HSI — Horizontal Situation Indicator

Fig 8-15: CDI deviation bar within HSI display

Fig 8-17: Full HSI display with course pointer and heading

📐 HSI Key Facts

Parameter	Standard HSI	Narrow-bar HSI
Sensitivity	5° per dot	2° per dot
Dots each side	2 dots	2 dots
FSD	±10°	±4°

The HSI course pointer rotates with aircraft heading → the deviation bar always shows correct turn direction regardless of OBS setting. No CDI sense reversal.

🔷 CDI vs RMI vs HSI Comparison

Summary comparison: RMI, CDI, and HSI displays side by side

12. In-Flight Procedures

Fig 8-23: In-flight VOR tracking procedures

Fig 8-24: VOR/DME approach procedure

✓ Outbound Tracking (away from VOR)

Set OBS to desired outbound radial (e.g., 090° for east outbound)
FROM flag appears
Wind correction: CDI drifts right → turn right to correct (normal sense with FROM selected)

✓ Inbound Tracking (toward VOR)

Set OBS to inbound track (reciprocal of radial, e.g., 270° for inbound on 090° radial)
TO flag appears
CDI normal sense — fly toward the needle

📡 Station Passage Indications

Primary: TO → FROM flag change
CDI needle may swing briefly
OFF flag may appear momentarily in cone of confusion
Log time of station passage for flight planning

Capt Pankaj Pahil | www.ghostaviator.com

13. VOR Summary Table

Complete VOR Summary Table

Parameter	Value / Detail
Frequency band	108.0 – 117.95 MHz (VHF)
Total channels	160 (40 shared with ILS + 120 VOR only)
Emission designator	A9W
Principle	Phase comparison of two 30 Hz signals
Ident interval	3-letter Morse every 10 s (1020 Hz tone)
Monitor trigger	±1° bearing error → auto-shutdown
VOT tolerance	±4°
Site error	±1°
Total system accuracy	±5°
DOC validity	Day AND night
LOS range formula	1.25 × (√H₁ + √H₂) NM (H in feet)
CDI sensitivity	2°/dot, FSD ±10°
HSI sensitivity	5°/dot standard (FSD ±10°); 2°/dot narrow
Radial (QDR)	Magnetic bearing FROM VOR to aircraft
Variation applied at	VOR station (not aircraft)
Cone of confusion	±50° from vertical — OFF flag, needle oscillates

14. Practice Questions

⚡ Instructions Click “Show Answer” to reveal the correct answer and explanation. All questions are DGCA CPL/ATPL standard.

Q1. What is the frequency band used by VOR?

(a) 225–400 MHz

(b) 108–117.95 MHz

(c) 190–1750 kHz

(d) 962–1213 MHz

Answer: (b)
VOR operates in the VHF band, 108.0–117.95 MHz. (a) = UHF military TACAN; (c) = NDB/ADF MF/LF band; (d) = DME UHF.

Q2. The principle of operation of a VOR is:

(a) Comparison of two 9960 Hz signals

(b) Pulse timing like DME

(c) Phase comparison of two 30 Hz signals

(d) Amplitude comparison of two signals

Answer: (c)
VOR uses phase comparison of two 30 Hz signals. The reference is omnidirectional (FM subcarrier); the variable rotates (AM on carrier). Their phase difference = radial.

Q3. A VOR radial is defined as:

(a) Magnetic heading to fly to the station

(b) True bearing from aircraft to station

(c) Magnetic heading of the aircraft

(d) Magnetic bearing FROM the station to the aircraft (QDR)

Answer: (d)
A radial = QDR = magnetic bearing FROM VOR to aircraft. Aircraft on the 090° radial is due east of the station.

Q4. A VOR station antenna is at 100 ft; aircraft at 3,600 ft. Using coefficient 1.25, maximum LOS range is:

(a) 87.5 NM

(b) 75 NM

(c) 100 NM

(d) 62.5 NM

Answer: (a)
Range = 1.25 × (√3600 + √100) = 1.25 × (60 + 10) = 1.25 × 70 = 87.5 NM.

Q5. Which statement about a VOT is correct?

(a) It radiates a continuous tone and is used to check aircraft VOR equipment accuracy on the ground

(b) It is a type of VOR for terminal area use

(c) It stands for ‘VOR on Test’ and should not be used

(d) It provides bearing guidance to the test facility

Answer: (a)
A VOT (VOR Test facility) radiates a continuous Morse dots tone. Used on the ground to verify aircraft VOR receiver accuracy. Aircraft must read 000°(±4°) FROM or 180°(±4°) TO.

Q6. Maximum permissible bearing error when checking VOR airborne equipment using a VOT:

(a) ±4°

(b) ±3°

(c) ±5°

(d) ±2°

Answer: (a)
VOT maximum permissible error = ±4°. Exceeding this requires equipment servicing before use.

Q7. The DOC of a VOR is valid:

(a) During daylight hours only

(b) During night hours only

(c) During twilight periods only

(d) Both day and night

Answer: (d)
VOR DOC is valid day AND night. VHF is immune to skywave propagation. Contrast with NDB/ADF whose DOC is day only.

Q8. Total system accuracy of a VOR is:

(a) ±1°

(b) ±3°

(c) ±5°

(d) ±10°

Answer: (c)
Total VOR accuracy = ±5°: site error ±1° + propagation/scalloping ±1° + airborne equipment ±3° (RSS combination).

Q9. Flying directly over a VOR station, the indications are:

(a) OFF flag appears, TO/FROM alternates, CDI oscillates (cone of confusion)

(b) TO flag, CDI centres

(c) Bearing becomes more accurate

(d) No change — VOR is accurate overhead

Answer: (a)
Overhead VOR = cone of confusion: OFF flag may appear, TO/FROM alternates rapidly, CDI needle oscillates. Normal and temporary.

Q10. On a standard CDI, angular value of one dot deflection:

(a) 5°

(b) 1°

(c) 2°

(d) 10°

Answer: (c)
CDI sensitivity = 2° per dot. Full scale = 5 dots × 2° = ±10°.

Q11. Full Scale Deflection on a standard CDI:

(a) ±5°

(b) ±10°

(c) ±20°

(d) ±2°

Answer: (b)
CDI FSD = ±10° (5 dots × 2°/dot).

Q12. Which RMI statement is correct?

(a) Arrowhead points into the tailwind

(b) Tail indicates QDM

(c) Arrowhead indicates QDM (magnetic bearing TO station)

(d) RMI shows track made good

Answer: (c)
RMI: arrowhead (head) = QDM = bearing TO station. Tail = QDR = radial = bearing FROM station.

Q13. Compared to CVOR, a DVOR:

(a) Operates at higher frequencies

(b) Uses a single rotating antenna

(c) Has a larger cone of confusion

(d) Has less site error due to its electronically switched antenna array

Answer: (d)
DVOR uses a ring of 48 antennas switched electronically. Doppler effect generates FM variable signal. Less susceptible to site errors from terrain/structures.

Q14. Aircraft on 090° radial from VOR. Station variation = 6°E. The QTE is:

(a) 084°T

(b) 096°T

(c) 090°T

(d) 264°T

Answer: (b)
QDR = 090°M. Apply variation at VOR: 090° + 6° (East) = 096°T. (True = Magnetic + East variation)

Q15. Max beacon spacing for airway with ±5 NM half-width, VOR error 5°:

(a) 120 NM

(b) 60 NM

(c) 150 NM

(d) 100 NM

Answer: (a)
Max spacing = (half-width × 60) / error = (5 × 60) / 5 × 2 = 600/5 = 120 NM. (Using the standard 600/error_degrees formula.)

Q16. Max beacon spacing if VOR bearing error is 5.5°:

(a) 120 NM

(b) 100 NM

(c) 109 NM

(d) 80 NM

Answer: (c)
Max spacing = 600 / 5.5 ≈ 109 NM.

Q17. Number of VOR channels in the 108–112 MHz band:

(a) 80 total

(b) 160 total

(c) 40 VOR channels (even tenths only)

(d) 20 VOR channels

Answer: (c)
108–112 MHz: even tenths = VOR (40 channels); odd tenths = ILS Localiser (40 channels).

Q18. Total number of VOR channels:

(a) 200

(b) 160

(c) 120

(d) 40

Answer: (b)
Total VOR channels = 40 (shared, 108–112) + 120 (VOR only, 112–118) = 160.

Q19. Aircraft heading 287°, starboard drift 14°. Track made good (radial being flown):

(a) 273°

(b) 287°

(c) 301°

(d) 315°

Answer: (c)
Track = Heading + Starboard drift = 287° + 14° = 301°. QDR = track when flying outbound from VOR.

Q20. Aircraft heading 287°, 14° starboard drift. VOR phase difference reading:

(a) 273°

(b) 287°

(c) 301°

(d) 315°

Answer: (c)
Phase difference = radial = QDR = Track = 287° + 14° = 301°.

Q21. CDI shows TO indication when:

(a) Aircraft is heading toward the station

(b) Aircraft is closer than 10 NM

(c) QDM is within ±80° of OBS-selected course

(d) Aircraft is below the cone of confusion

Answer: (c)
TO flag illuminates when QDM (bearing to station) is within ±80° of the OBS setting. Not dependent on aircraft heading — geometry only.

Q22. Aircraft on 152° radial. OBS set to 329° (TO). CDI indication:

(a) Bar deflects RIGHT — approximately 1.5 dots

(b) Bar deflects LEFT — approximately 1.5 dots

(c) Bar centred

(d) OFF flag

Answer: (a)
OBS 329° TO means desired radial = 149°. Aircraft is on 152° — 3° clockwise of 149° → aircraft is LEFT of the 329° inbound course → bar deflects RIGHT (fly right). 3° ÷ 2°/dot = 1.5 dots.

Q23. At 100 NM from VOR with ±5° total error, lateral displacement is approximately:

(a) 5 NM

(b) 7.5 NM

(c) 8.3 NM

(d) 8.7 NM

Answer: (d)
Exact: 100 × sin(5°) = 100 × 0.0872 ≈ 8.7 NM. Using 1:60: 100 × 5/60 ≈ 8.3 NM.

Q24. VOR variation should be applied at:

(a) Aircraft position

(b) Mid-point between aircraft and station

(c) The VOR station

(d) The destination aerodrome

Answer: (c)
For VOR, variation is applied at the VOR station. Contrast with NDB/ADF: variation applied at the aircraft.

Q25. Aircraft on 045° radial. RMI shows:

(a) Head at 045°, tail at 225°

(b) Head at 225°, tail at 045°

(c) Head and tail both at 045°

(d) Head at 225°, tail at 225°

Answer: (b)
QDR (radial) = 045° → RMI tail = 045°. RMI head = QDM = 225° (reciprocal). Answer: head 225°, tail 045°.

Q26. Standard HSI CDI is set to 5°/dot. Full scale deflection is:

(a) 5°

(b) 10°

(c) 20°

(d) 15°

Answer: (b)
Standard HSI: 5°/dot × 2 dots = 10° FSD.

Q27. VOR ident transmission interval:

(a) Every 30 seconds

(b) Every 5 seconds

(c) Every 10 seconds

(d) Every 15 seconds

Answer: (c)
VOR Morse ident is transmitted every 10 seconds.

Q28. If the VOR auto-monitor detects bearing error >±1°:

(a) Station automatically shuts down or switches to standby, suppressing ident

(b) Transmits a warning tone

(c) Continues at reduced power

(d) Changes frequency

Answer: (a)
Auto-monitor: if error >±1° → station shuts down or switches to standby. Ident suppressed for 30 s. Never use VOR without ident.

Q29. VORTAC provides:

(a) VOR bearing for civil aircraft and TACAN bearing + DME for military aircraft

(b) VOR bearing only

(c) DME for civil and military only

(d) ILS and VOR combined

Answer: (a)
VORTAC: civil aircraft receive VOR azimuth + DME distance (via TACAN DME on paired freq). Military: TACAN bearing + DME.

Q30. VOR emission designator:

(a) A9W

(b) A2A

(c) N0NA1A

(d) P0N

Answer: (a)
VOR = A9W. A = AM DSB; 9 = composite signal; W = combination of telephony, telegraphy and navigation.

Q31. HSI (5°/dot), aircraft is 4° to the right of selected course. CDI bar:

(a) Right by 2 dots

(b) Left by 2 dots

(c) Left, less than 1 dot

(d) Right, less than 1 dot

Answer: (c)
5°/dot HSI. Aircraft 4° RIGHT of course → bar deflects LEFT (fly left to intercept). Magnitude = 4° ÷ 5°/dot = 0.8 dots left = less than 1 dot LEFT.

Q32. DVOR differs from CVOR in that:

(a) Different frequencies

(b) Uses Doppler effect with an array of antennas to generate FM variable signal; AM is the reference

(c) Larger DOC

(d) Uses pulse modulation

Answer: (b)
DVOR: AM carrier = reference; electronically switched 48-antenna ring generates FM variable via Doppler effect. CVOR: FM subcarrier = reference; AM rotating limàcon = variable.

Q33. Aircraft on radial 270°, heading 090° inbound to VOR, OBS set to 090°. TO/FROM indicator shows:

(a) TO

(b) FROM

(c) OFF

(d) Alternating TO/FROM

Answer: (a)
Aircraft west of VOR flying east (inbound). QDM = 090°. OBS = 090°. QDM is within 80° of OBS → TO.

Annex A — HSI Diagrams (Q31)

Annex A: HSI options for Question 31

Annex B — HSI Diagrams (Q32)

Annex B: HSI options for Question 32

Annex C — HSI Diagrams (Q33)

Annex C: HSI options for Question 33

Additional Question Diagrams

Q3 — RMI Options

Q3: Four-option RMI diagram

Q15 — RMI Options

Q15: Four-option RMI diagram

Q25 (RMI) and Q26 (CDI)

Q25 RMI and Q26 CDI diagrams

Q28 — RMI Options

Q28: Four-option RMI diagram

Q30 — CDI Options

Q30: Four-option CDI diagram

DGCA CPL/ATPL Radio Navigation Study Notes
Chapter 8 — VOR (VHF Omnidirectional Range)
Capt Pankaj Pahil | www.ghostaviator.com
For personal study use only. Not to be reproduced without permission.

✈ Chapter 8: VORVHF Omnidirectional Range

📋 Contents

1. Introduction & Background

2. Principle of Operation

CVOR vs DVOR Signal Generation

3. Terminology — Radials & Bearings

4. Frequencies & Channels

5. Identification & Monitoring

Station Identification

Special Beacon Types

Monitoring

6. Types of VOR

7. Range & Coverage

8. DOC — Designated Operational Coverage

9. Accuracy & Errors

10. Cone of Confusion

11. Cockpit Displays — CDI, RMI, HSI

11.1 CDI — Course Deviation Indicator

11.2 RMI — Radio Magnetic Indicator

11.3 HSI — Horizontal Situation Indicator

12. In-Flight Procedures

13. VOR Summary Table

14. Practice Questions

Annex A — HSI Diagrams (Q31)

Annex B — HSI Diagrams (Q32)

Annex C — HSI Diagrams (Q33)

Additional Question Diagrams

Q3 — RMI Options

Q15 — RMI Options

Q25 (RMI) and Q26 (CDI)

Q28 — RMI Options

Q30 — CDI Options

✈ Chapter 8: VOR
VHF Omnidirectional Range