Magnetic Compass Flashcards
What is a lubber line?
What is Magnetic Dip?
Up near the poles the compass will tend to dip towards the earth to follow magnetic lines. The closer you go towards the poles, the more noticable to dip will be and the less and less reliable the compass becomes
What is compass variation?
The magnetic north (somewhere up in Nunavit right now) and true north (the actual very top of the planet) are not in the same place.
Variation is the difference between true north and magnetic north.
What are isogonic lines?
Lines of equal magnetic variation. (Variation is the difference between magnetic north and true north)
What is an Agonic Line?
A line with zero degrees of magnetic variation the sits more or less right under magnetic north. In Canada this agonic line runs just to the West of Thunder Bay.
When we plot our track on a map for a cross country, is that track true or magnetic? Why do we correct for the variation after that?
Maps are oriented around True North, therefor when we draw a track, it is our True Track.
We then correct our True Track with the magnetic variation to get our Magnetic Track. We use our magnetic track when we atually turn on course because while we fly by our heading indicator, our heading indicator is set by the compass.
**You should also correct for your compass’ deviation (which is on a placard in the cockpit)
What is Magnetic Deviation?
The difference between the reading from your compass inside the aircraft and what it would read if it was outside the aircraft and away from all that metal.
Compass Swinging is how deviation is dealth with and is done once a year.
What is Northerly Turning Error and what causes it?
On turns from the North, the compass will lag
On turns from the South, the compass will lead
NORTH LAGS and South Leads
This effect is greatest on headings of North and South and least noticable on headings of East and West
This is caused my magnetic dip.
What are acceleration and deceleration errors?
One East or West headings only, an acceleration of the AC will cause the compass to register a turn to the North
A deceleration will show a turn to the South
The compass is kind of unreliable in a lot of ways, what did engineers do to help deal with it that almost no one is using?
They smashed a gyro and a compass together to make the Gyro Compass!
A slaved gyro-magnetic minimizes…
- Oscillations and turning errors that a mag compass has (mahnetic dip)
- The effects of precessions
Exam Question about the RMI and HSI
