Terrestrial Magnetism Variation

Question 1

North symbols

Answer 1

True north - diamond/arrow head
Magnetic north - half diamond

Question 2

Causes of compass deviation

Answer 2

Materials its made from (ferro-magnetic).
Fields induced by the aircrafts own electrical systems.

Question 3

Soft magnetism

Answer 3

Temporary.
deviation changes as heading changes.
Deviation worse at higher latitudes (Earths field decreaes, aircrafts field increases)

Question 4

Hard magnetism

Answer 4

Retain their magnetism.
Harder to magnetise intially.
Permanent.

Question 5

Maximum deviation

Answer 5

Near the poles

Question 6

Minimum field

Answer 6

Earth and aircraft fields aligned.
Least compass error.

Question 7

Compass swing

Answer 7

Carried out on ground with engines running.
Moved to a special site where the carinal points are marked.
Site will be free from ferrous/electromagnetic anomalies.
|Aircraft moved to each cardinal ooint where compass heading is recorded, then compared to reference instrument, deviations recorded.

Question 8

When does compass swing occur?

Answer 8

Large change of latitude (dip)
lighting
equipmengt change
Parked for long time
new compass
when specified
Specific ferromagnetic cargo
Heavy landing on a northerly heading