DGCA Air Navigation: Vor Questions
315 exam-style Vor questions for the DGCA Air Navigationpaper (CPL & ATPL). The first 12 are free below with answers and explanations — sign up free to practise all of them with progress tracking.
- Q1
An aircraft is required to approach a VOR station via the 244° radial. In order to obtain correct sense indications the deviation indicator should be set to:
- A 064° with the TO flag showing
- B064° with the FROM flag showing
- C 244° with the FROM flag showing
- D 244° with the TO flag showing
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Correct answer: A. 064° with the TO flag showing
To approach the station along the 244 radial the aircraft tracks inbound on 064, so the omni-bearing selector is set to 064 and correct sensing then gives a TO indication.
- Q2
What is the maximum theoretical range that an aircraft at FL150 can receive signals from a VOR situated 609 feet above MSL?
- A184 NM
- B 220 NM
- C147 NM
- D 156 NM
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Correct answer: A. 184 NM
Using the VHF range formula 1.25 times the sum of the square roots of the heights in feet, with 15000 ft and 609 ft, gives about 1.25 x (122 + 25), roughly 184 NM.
- Q3
An RMI slaved to a remote indicating compass has gone unserviceable and is locked on to a reading of 090°. The tail of the VOR pointer shows 135°. The available information from the VOR is:
- ARadial 135°, relative bearing unknown
- B Radial unknown, relative bearing 225°
- C Radial unknown, relative bearing 045°
- D Radial 315°, relative bearing unknown
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Correct answer: A. Radial 135°, relative bearing unknown
The tail of the VOR needle indicates the radial, so 135 is the radial the aircraft is on; because the compass card is frozen at a false 090, the relative bearing to the station cannot be determined.
- Q4
Which of the following statements concerning the variable, or directional, signal of a conventional VOR is correct?
- A The rotation of the variable signal at a rate of 30 times per second gives it the characteristics of a 30 Hz amplitude modulation
- BThe transmitter varies the amplitude of the variable signal by 30 Hz each time it rotates
- C The transmitter changes the frequency of the variable signal by 30 Hz either side of the allocated frequency each time it rotates
- DThe receiver adds 30 Hz to the variable signal before combining it with the reference signal
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Correct answer: A. The rotation of the variable signal at a rate of 30 times per second gives it the characteristics of a 30 Hz amplitude modulation
The variable, or directional, VOR signal effectively rotates at 30 revolutions per second, and it is this 30 Hz rotation that gives the signal its directional character.
- Q5
The maximum theoretical range at which an aircraft at FL230 may receive signals from a VOR facility sited at mean sea level is:
- A 190 NM
- B230 NM
- C 170 NM
- D 151 NM
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Correct answer: A. 190 NM
Line-of-sight range is approximately 1.23 times the square root of the height in feet; for an aircraft at FL230 over a sea-level station this gives roughly 1.23 × √23000 ≈ 187 NM, closest to 190 NM.
- Q6
If an aircraft flies along a VOR radial it will follow a:
- Agreat circle track
- Brhumbline track
- C line of constant bearing
- Dconstant magnetic track
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Correct answer: A. great circle track
A VOR radial is a fixed magnetic bearing radiating from the station and, being a straight line over the ground from the transmitter, it is flown as a great-circle track.
- Q7
Transmissions from VOR facilities may be adversely affected by:
- A uneven propagation over irregular ground surfaces
- B static interference
- C night effect
- D quadrantal error
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Correct answer: A. uneven propagation over irregular ground surfaces
VOR bearings can be corrupted by uneven propagation and reflections as the signal passes over irregular or mountainous terrain, producing site and scalloping errors.
- Q8
An aircraft at 6400 FT will be able to receive a VOR groundstation at 100 FT above MSL at an approximate maximum range of :
- A 110 NM
- B 90 NM
- C 100 NM
- D 120 NM
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Correct answer: A. 110 NM
Applying 1.23 times the sum of the square roots of the heights, 1.23 × (√6400 + √100) = 1.23 × 90 ≈ 110 NM is the approximate maximum reception range.
- Q9
Frequency of VOR:
- A108.0–117.95 MHz
- B118.0–136.975 MHz
- C88.0–107.9 MHz
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Correct answer: A. 108.0–117.95 MHz
VOR operates in the VHF band, 108.0–117.95 MHz, for navigation signals.
- Q10
If VOR bearing information is used beyond the published protection range, errors could be caused by:
- A interference from other transmitters
- B noise from precipitation static exceeding the signal strength of the transmitter
- Csky wave interference from the same transmitter
- D sky wave interference from distant transmitters on the same frequency
Show answer
Correct answer: A. interference from other transmitters
Beyond the published protection range a VOR is no longer safeguarded from co-channel stations, so bearing errors can arise from interference by other transmitters using the same frequency.
- Q11
An aircraft at FL 100 should be able to receive a VOR groundstation at 100 FT above MSL at an approximate maximum range of :
- A 135 NM
- B 123 NM
- C 130 NM
- D142 NM
Show answer
Correct answer: A. 135 NM
Line-of-sight range is about 1.23 × (√10000 + √100) = 1.23 × 110 ≈ 135 NM for FL100 over a station at 100 ft above mean sea level.
- Q12
An aircraft is 100 NM from a VOR facility. Assuming no error when using a deviation indicator where 1 dot = 2° deviation, how many dots deviation from the centre line of the instrument will represent the limits of the airway boundary? (Assume that the airway is 10 NM wide)
- A1.5
- B 3.0
- C4.5
- D 6.0
Show answer
Correct answer: A. 1.5
The 10 NM airway gives 5 NM either side of centreline; at 100 NM range 5 NM subtends about 3° by the one-in-sixty rule, and at 2° per dot that is 1.5 dots to the airway boundary.
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