Non-Directional Beacons (NDB) - Ch 3

Question 1

NDB

Answer 1

A ground based station

Omnidirectional

Transmits to ADF (in AC)

2 Types: - Locator - Enroute

Question 2

NBD Frequency

Answer 2

190kHz - 1750kHz

Question 3

NBD Class

Answer 3

B: +/- 5 degrees

Question 4

ADF Made up of

Answer 4

• Loop antenna - which has two null points
• Sense Antenna - Added to take away null position - carotid pattern which deletes the wrong one
• ADF receiver (onboard the AC)
• Indicator

Question 5

Buttons:

Answer 5

Inner/Outer Knob - Used to tune the STDBY
Double Arrow Button - Swaps use freq. - standby freq.
ADF - Selects the equipment
BFO - Unmute button
Test Button - Knocks beacon over to 90 degrees

Question 6

Cone of Confusion/Silence

Answer 6

Directly overhead NBD signal

It becomes disturbed or even totally disappears

Question 7

Diameter of Cone of Silence

Answer 7

(Height above NDB)(tan40)(2) / (6080ft/nm)

Question 8

A1A Beacons

Answer 8

BFO / Tune button must be selected on to listen to it

Question 9

Fixed Card ADF

Answer 9

Radio Compass - Indicates relative bearing

Question 10

Moving Card ADF

Answer 10

Indicates Magnetic bearing (QDM/QDR)

Question 11

Radio Magnetic Indicator (RMI)

Answer 11

RMI

Question 12

Electronic Nav

Answer 12

Display symbols

EFIS ND

Question 13

Relative Bearing =

Answer 13

= Magnetic Bearing - Magnetic Heading

= QMD - Mag. HDG

Question 14

If moving card breaks

Answer 14

It effectively becomes a fixed card

HDG becomes 000

Question 15

RMI

Answer 15

AFD - Double Ended - single head:QDR - Double Head:QDM (large)

Easier to use

Class B: +/- 5 degrees

Question 16

Left Wind =

Answer 16

Right drift : compass will decrease

Question 17

Right Wind =

Answer 17

= Left Drift : Compass will increase

Question 18

NBD Limited by Power

Answer 18

Varies with square root of power

To double the range you must increase the power by 4, to triple the range you must increase the power by 9

Question 19

NBD consists of

Answer 19

Surface waves and sky waves

Question 20

Limitations for NDBs

Answer 20

Lack of failure flags

Question 21

Errors

Answer 21

Static Interference 
Night Effect
Coastal Refraction
Multipath Propogation 
Quadrantal Error
Bank Angle Error

Question 22

Static Interference

Answer 22

TS - Can render the ADF completely unreliable

Question 23

Night Effect

Answer 23

Due to changes in air density

Worst at sunset and sunrise

Question 24

Coastal Refraction

Answer 24

Waves travel slower over land and faster over the sea

When on coast, no refraction

When abeam, (90) no refraction

Question 25

Multipath Propagation (Mountain Effect)

Answer 25

Waves reflect / bounce off terrain

Leading to multiple paths

Question 26

Bank Angle Error

Answer 26

Design of the loop error

Referred to as Dip

Needle points into the turn

Question 27

Quadrantal Error

Answer 27

AC structure bends the incoming wave

Max: 45 degrees
Min: 90 degrees