DME & VOR

Question 1

What is DME?

Answer 1

Distance Measuring Equipment

Question 2

How does DME Work?

Answer 2

Distance is calculated by measuring the elapsed time between the transmission and reception of a pulse pair.

Question 3

Why are two DME frequencies used?

Answer 3

To avoid aircraft interrogating each other.

Question 4

What waveband does DME operate in?

Answer 4

UHF

Question 5

DME is accurate to within…

Answer 5

1nm

Question 6

What is the major error associated with DME?

Answer 6

Slant Error

Question 7

What are some uses for DME?

Answer 7

Co-location with VOR to provide range and bearing
Provides positive ranges for aircraft flying the same track on the same DME
Co-location with precision approach aid to provide range from touchdown
Enhances holding pattern accuracy
Accurate area Navigation if coupled with a suitable computer
Military use for Tanking

Question 8

What is a VOR?

Answer 8

VHF Omni-Directional Radio Range

Question 9

Describe a VOR

Answer 9

System that automatically and continuously provides an aircraft with an accurate magnetic bearing from a beacon, using the principle ‘bearing by phase comparison’.

Question 10

What two signals does a VOR use?

Answer 10

Reference Signal - transmitted Omni-directionally.

Variable Signal -Transmitted by a circular array of aerials around the Reference Signal antenna, simulating a revolving antenna.

They are transmitted simultaneously but the simulated rotation causes a phase difference.

Question 11

What is the dark spot of a VOR known as?

Answer 11

Cone of Confusion or
Cone of Silence

Question 12

What is OBS?

Answer 12

Omni-Bearing Selector

Question 13

Describe an Earlier Form OBS

Answer 13

Displays only VOR information.

Shows deflection left or right of pre-selected QDM.

Shows whether the aircraft is generally heading to or from the beacon.

Question 14

Describe a Later Form OBS

Answer 14

Shows all the same information as earlier form, but for the purposes of the Instrument Landing System as well as VOR.

Includes a Fail Flag when no signal is being received.

Question 15

When flying inbound and outbound to a VOR, when are you flying the radial?

Answer 15

When flying inbound to the beacon, the magnetic course will be the reciprocal of the radial.

When flying outbound from the beacon, the magnetic course will be the same as the radial.

Question 16

What is VOR limited to?

Answer 16

Line of Sight

Question 17

What are some VOR Errors?

Answer 17

Site Errors
Propagation Errors
Equipment Errors
Interference Errors

Question 18

What is a Site Error of a VOR?

Answer 18

Poor beacon siting can produce reflected signals from high ground and buildings that can cause bearing errors.

Question 19

What is the Propagation Error of a VOR?

Answer 19

Caused by uneven propagation over long distance or irregular terrain.

Question 20

What is the Equipment Error of a VOR?

Answer 20

Caused by incorrect tuning or calibration.

Question 21

What is the Interference Error of a VOR?

Answer 21

The narrow operating bands limits the number of channels available, and high flying aircraft run the risk of receiving signals from more than one VOR on the same frequency when at or near the protected range of a beacon.

Question 22

What are some uses for VOR?

Answer 22

Homing to a Station
Maintaining track along an airway centreline
Obtaining a Position line
Flying Instrument Approaches
Obtaining a fix with two or more VORs
Broadcast ATIS and other information

Question 23

What is the maximum allowed aggregate errors of VOR?

Answer 23

A total of +/- 5 Degrees

Question 24

Does the range of reliable VOR operation increase or decrease with height?

Answer 24

Reliable VOR Range increases with Height