11.5.3 Instruments- Compasses

Question 1

What must be installed in a position where it can be seen from both pilot stations?

Answer 1

Direction indicator, non stabilised magnetic compass.

Question 2

What is the indicated heading?

Answer 2

The angle between the aircraft’s longitudinal axis, which is shown with the lubber line, and the direction to the North Pole.

Question 3

What is true heading?

Answer 3

True north based on geographic north pole

Question 4

What is the difference between magnetic north and true north?

Answer 4

2000km

Question 5

What is the angle between true north and magnetic north called?

Answer 5

Variation

Question 6

How much does magnetic north move a year?

Answer 6

40 miles per year

Question 7

How often does Jeppesen update their maps?

Answer 7

Every 56 days

Question 8

What is inclination?

Answer 8

The field lines decline to the earths surface.

Question 9

What are names for the horizontal and vertical components of the magnetic field?

Answer 9

Isogonal and Isoclinic

Question 10

At latitudes above 70 degrees the horizontal component is so weak that a compass is not useable, what should be used instead?

Answer 10

Directional gyro or inertial stabilised system.

Question 11

What is hard iron magentism?

Answer 11

Permanent form of magnetism, caused by the presence of iron or steel parts in the structure.

Question 12

What does the effect of hard iron magnetism have on the aircrafts compass?

Answer 12

Bar magnets lying longitudinally, laterally and vertically around the compass position.

Question 13

To analyse the effect of hard iron the imaginary bar magnets are annotated as?

Answer 13

Component P,Q and R

Question 14

What is soft iron magnetism?

Answer 14

Temporary form of magnetism caused by the magnetically soft metallic parts of an aircraft.

Question 15

What does the effect of soft iron magnetism depend upon?

Answer 15

The aircrafts heading and the local angle of dip.

Question 16

Soft iron magnetism: what is a positive deviation?

Answer 16

Deflecting the compass to the right. (Easterly)

Question 17

Soft iron magnetism: what is a negative deviation?

Answer 17

Needle deflects to the left. (Westerly)

Question 18

What is the only electrical part in a direct reading compass?

Answer 18

Light

Question 19

In commercial aircraft what is the direct reading compass called?

Answer 19

Standby

Question 20

What is the lubber line and what does it do?

Answer 20

Vertical line on the standby compass that shows the heading on a rotating compass scale.

Question 21

When is there no influence on the heading direction of the standby compass?

Answer 21

When going north or south.

Question 22

What happens to the standby compass when the aircraft accelerates?

Answer 22

It shows a lower heading.

Question 23

How can deviation be minimised?

Answer 23

Using small adjustable magnets inside the compass called compass compensation.

Question 24

During compass compensation set up how often is the deviation recorded?

Answer 24

Every 90 degrees.

Question 25

What is the B coefficient during compass compensation?

Answer 25

Difference between the east and west deviations, divided by 2.

Question 26

What is the C coefficient during compass compensation?

Answer 26

Difference between the north and south deviations, divided by 2.

Question 27

For a B correction where does the aircraft normally stay pointing?

Answer 27

Easterly

Question 28

For a C correction where does the aircraft stay pointing?

Answer 28

Northerly

Question 29

What is coefficient A?

Answer 29

A constant error which is the same on all headings.

Question 30

How is an error in coefficient A corrected?

Answer 30

Rotating the compass or changing the compass card.

Question 31

What is coefficient B?

Answer 31

Varies as a function of the sine of the compass heading. It is usually associated with fore-and-aft permanent magnetism.

Question 32

How is coefficient B corrected?

Answer 32

Using fore and aft magnets

Question 33

What is coefficient C?

Answer 33

Varies as a function of cosine of heading.

Question 34

What is coefficient C usually associated with?

Answer 34

Athwartship and permanent magnetism.

Question 35

What does Athwartship mean?

Answer 35

Across the aircraft from side to side.

Question 36

How is coefficient C corrected?

Answer 36

With athwartship magnets.

Question 37

What kind of cased light is used in a magnetic compass to avoid deviation?

Answer 37

Brass, with contra-wound filament.

Question 38

What is a flux valve?

Answer 38

Magnetic sensory device that electrically transmits the information to the aircrafts system.

Question 39

What does a flux valve 'Z' mean?

Answer 39

Vertical intensity

Question 40

What does a flux valve 'F' mean?

Answer 40

Total intensity

Question 41

What does a flux valve 'X' mean?

Answer 41

North

Question 42

What does a flux valve 'Y' mean?

Answer 42

East

Question 43

Where is the flux valve located?

Answer 43

Far away from all magnetic fields of the aircraft.

Question 44

How does the pilot monitor the flux system?

Answer 44

With a slaving annunciator

Question 45

What two modes of operation does the flux valve have?

Answer 45

Slave and free

Question 46

What does free mode do in a flux capacitor?

Answer 46

Flux valve disconnected so it does not monitor or auto realign.

Question 47

What does slave mode mean in the flux system?

Answer 47

Default mode, connected and working to information provided by the flux valve.

Question 48

In the flux system how many Hz is the excitor energised with?

Answer 48

400Hz

Question 49

In the flux system where does the output of the coils go?

Answer 49

Selsyn Unit

Question 50

What does a selsyn unit do?

Answer 50

Compares the detected magnetic heading with that indicated on the instrument.

Question 51

After a compass swing the cumulative deviation must not exceed...?

Answer 51

5 degrees

Question 52

Why do modern aircraft not need compass swings?

Answer 52

Because they have INS and GPS.