Navigational Instruments

Question 1

What is an ADF?

Answer 1

Automatic Direction Finder

Question 2

What is an NDB?

Answer 2

Non-Directional Beacon

Question 3

What is a VOR?

Answer 3

VHF Omni-Directional Radio Range

Question 4

What is DME?

Answer 4

Distance Measuring Equipment

Question 5

What is a TACAN?

Answer 5

Tactical Air Navigation System (Military)

Question 6

What is an ILS?

Answer 6

Instrument Landing System

Question 7

What are some common errors of ADF?

Answer 7

Designated Operational Coverage
Mountain Effect
Static Interference
Night Effect
Station Interference
Coastal Refractions
Lack of Failure Warnings

Question 8

What are some errors of VOR?

Answer 8

Site Error
Propagation Error
Airborne Equipment Error

Question 9

How accurate is VOR site error monitored to?

Answer 9

+-1 Degree Accuracy

Question 10

What is the aggregated total error of VOR system?

Answer 10

+-5 Degree Accuracy

Question 11

Which is more accurate, VOR or ADF?

Answer 11

VOR is more accurate and reliable

Question 12

What are the advantages of DME?

Answer 12

A VOR/DME can be used to make an Instrument Approach to an airfield.

If ‘Frequency Paired’ with a VOR, the DME can be auto tuned with the VOR.

Simple to use and to calculate groundspeed.

A very accurate ‘fix’ can be obtained using two DMEs

Question 13

What is the main disadvantage of DME?

Answer 13

Only gives lant range, so not accurate at high altitudes over the DME station.

Question 14

What does the ILS consist of?

Answer 14

The localiser transmitter
The glide path transmitter
The outer marker
The approach lighting system (On suitable runway)

Question 15

Describe Category I ILS

Answer 15

Guidance information down to a decision height (DH) of not less than 200 ft.

Question 16

Describe Category II ILS

Answer 16

Improved equipment provide for approaches and a decision height (DH) of not less than 100 ft.

Question 17

Describe Category III ILS

Answer 17

Further safeguards enable approaches which provide guidance to ‘touchdown’ and ‘roll out’ along the runway, i.e. no DH.

Question 18

What are some advantages of ILS?

Answer 18

Pilot interpreted and simple to use

‘Precision’ Approaches possible.

Can be coupled to auto-pilot for automatic approach and landings.

Question 19

What are some disadvantages of ILS?

Answer 19

Subject to interference from commercial VHF radio.

Reflections can create ‘false’ glide paths.

Shortage of frequencies.

Question 20

What is a Precision Approach System?

Answer 20

One that gives you glidepath information. ILS.