VORRadio Navigation — DGCA CPL practice questions
Question 1 of 32
What is the frequency band used by VOR?
All 32 questions — VOR
Radio Navigation · DGCA CPL. The correct option is marked on each.
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
Why: 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
Why: 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 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
Why: Range = 1.25 × (√3600 + √100) = 1.25 × (60 + 10) = 1.25 × 70 = 87.5 NM .
Q4. 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
Why: 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.
Q5. Maximum permissible bearing error when checking VOR airborne equipment using a VOT:
- A.±4°✓
- B.±3°
- C.±5°
- D.±2°
Why: VOT maximum permissible error = ±4° . Exceeding this requires equipment servicing before use.
Q6. 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✓
Why: VOR DOC is valid day AND night . VHF is immune to skywave propagation. Contrast with NDB/ADF whose DOC is day only.
Q7. Total system accuracy of a VOR is:
- A.±1°
- B.±3°
- C.±5°✓
- D.±10°
Why: Total VOR accuracy = ±5° : site error ±1° + propagation/scalloping ±1° + airborne equipment ±3° (RSS combination).
Q8. 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
Why: Overhead VOR = cone of confusion : OFF flag may appear, TO/FROM alternates rapidly, CDI needle oscillates. Normal and temporary.
Q9. On a standard CDI, angular value of one dot deflection:
- A.5°
- B.1°
- C.2°✓
- D.10°
Why: CDI sensitivity = 2° per dot . Full scale = 5 dots × 2° = ±10°.
Q10. Full Scale Deflection on a standard CDI:
- A.±5°
- B.±10°✓
- C.±20°
- D.±2°
Why: CDI FSD = ±10° (5 dots × 2°/dot).
Q11. 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
Why: RMI: arrowhead (head) = QDM = bearing TO station. Tail = QDR = radial = bearing FROM station.
Q12. 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✓
Why: DVOR uses a ring of 48 antennas switched electronically. Doppler effect generates FM variable signal. Less susceptible to site errors from terrain/structures.
Q13. 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
Why: QDR = 090°M. Apply variation at VOR: 090° + 6° (East) = 096°T . (True = Magnetic + East variation)
Q14. 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
Why: Max spacing = (half-width × 60) / error = (5 × 60) / 5 × 2 = 600/5 = 120 NM . (Using the standard 600/error_degrees formula.)
Q15. Max beacon spacing if VOR bearing error is 5.5°:
- A.120 NM
- B.100 NM
- C.109 NM✓
- D.80 NM
Why: Max spacing = 600 / 5.5 ≈ 109 NM .
Q16. 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
Why: 108–112 MHz: even tenths = VOR ( 40 channels ); odd tenths = ILS Localiser (40 channels).
Q17. Total number of VOR channels:
- A.200
- B.160✓
- C.120
- D.40
Why: Total VOR channels = 40 (shared, 108–112) + 120 (VOR only, 112–118) = 160 .
Q18. Aircraft heading 287°, starboard drift 14°. Track made good (radial being flown):
- A.273°
- B.287°
- C.301°✓
- D.315°
Why: Track = Heading + Starboard drift = 287° + 14° = 301° . QDR = track when flying outbound from VOR.
Q19. Aircraft heading 287°, 14° starboard drift. VOR phase difference reading:
- A.273°
- B.287°
- C.301°✓
- D.315°
Why: Phase difference = radial = QDR = Track = 287° + 14° = 301° .
Q20. 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
Why: TO flag illuminates when QDM (bearing to station) is within ±80° of the OBS setting . Not dependent on aircraft heading — geometry only.
Q21. 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
Why: 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.
Q22. 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✓
Why: Exact: 100 × sin(5°) = 100 × 0.0872 ≈ 8.7 NM . Using 1:60: 100 × 5/60 ≈ 8.3 NM.
Q23. VOR variation should be applied at:
- A.Aircraft position
- B.Mid-point between aircraft and station
- C.The VOR station✓
- D.The destination aerodrome
Why: For VOR, variation is applied at the VOR station . Contrast with NDB/ADF: variation applied at the aircraft.
Q24. 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°
Why: QDR (radial) = 045° → RMI tail = 045°. RMI head = QDM = 225° (reciprocal). Answer: head 225°, tail 045°.
Q25. Standard HSI CDI is set to 5°/dot. Full scale deflection is:
- A.5°
- B.10°✓
- C.20°
- D.15°
Why: Standard HSI: 5°/dot × 2 dots = 10° FSD.
Q26. VOR ident transmission interval:
- A.Every 30 seconds
- B.Every 5 seconds
- C.Every 10 seconds✓
- D.Every 15 seconds
Why: VOR Morse ident is transmitted every 10 seconds .
Q27. 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
Why: Auto-monitor: if error >±1° → station shuts down or switches to standby . Ident suppressed for 30 s. Never use VOR without ident.
Q28. 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
Why: VORTAC: civil aircraft receive VOR azimuth + DME distance (via TACAN DME on paired freq). Military: TACAN bearing + DME.
Q29. VOR emission designator:
- A.A9W✓
- B.A2A
- C.N0NA1A
- D.P0N
Why: VOR = A9W . A = AM DSB; 9 = composite signal; W = combination of telephony, telegraphy and navigation.
Q30. 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
Why: 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.
Q31. 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
Why: DVOR: AM carrier = reference; electronically switched 48-antenna ring generates FM variable via Doppler effect. CVOR: FM subcarrier = reference; AM rotating limàcon = variable.
Q32. 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
Why: Aircraft west of VOR flying east (inbound). QDM = 090°. OBS = 090°. QDM is within 80° of OBS → TO .