Understanding Compass Turning Errors
Compass turning errors occur when you’re turning near headings of North and South. These errors are caused by the way the magnetic compass behaves in a banked turn due to the tilt of the compass card.
In a turn from a heading of North:
- The compass initially shows a turn in the opposite direction.
- It lags behind the actual turn.
- To remember this, use: North = Opposite → “NO”
In a turn from a heading of South:
- The compass shows a turn in the correct direction, but it does so faster than the aircraft is actually turning.
- It leads the actual heading.
In turns from East or West:
- There are no turning errors.
How to Remember
The made-up word COSUN helps:
- CO = Compass Overshoots turns from South
- SUN = Compass Undershoots turns from North
Even though “COSUN” isn’t a real word, it’s a fun and effective mnemonic to remember how your compass behaves in turns.
