COMPASS SYSTEMS

Question 1

Describe acceleration errors in Compass systems?

Answer 1

Are maximum in East and West headings and zero on North and South Headings
Northern hemisphere:
On hdg 270 it will show 280
On hdg 090 it will show 080

ANDS in the North
DNAS in the South

Question 2

Describe turning errors in Compass systems?

Answer 2

ONUS in the North
UNOS is the South
No turning errors on East and West

Over-shoot North, under-shoot South (Northern side)

Question 3

What’s a remote indicating compass system?

Answer 3

Combines the use of a gyroscope with the earths lines of flux to give the best of both a DI and a remote indicating compass

Question 4

What are the advantages of a Remote Indicating Compass system?

Answer 4

1. Detector unit can be installed in a remote part of the a/c well away from electrical circuits
2. Flux valve technique senses rather than seeking the earths magnetic meridian which means it’s more sensitive to small changes in H
   H is the horizontal component of magnetic fields
   Greatest at the equator and smallest over the poles
3. Turning- and acceleration errors are minimized
4. Automatically compensates for real and apparent drift. Needs no re-setting

Question 5

What’s the difference between Slaved- and Free Gyro modes?

Answer 5

Slaved: Gyro is monitored by the detector unit element
Free: Gyro is isolated from the detector unit and functions as a straight forward DI

Question 6

When would the Free Gyro mode be used?

Answer 6

Used when flying at latitudes where the value of H is too small to use as a reliable source. That is closer to the poles at high latitudes