Is a Card Compass Correct in a Climb?

MBDiagMan

MBDiagMan

Final Approach
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I have a card compass in both my planes and it has always seemed to be pretty close even while climbing? Have others experienced the same thing? I hesitate to reset the DG in a climb, but am I just being too picky?
 
Should be unless you’ve got a heck of a zoom climb going.
 
It gets wonked (please excuse the technical term) when you are accelerating - climb is reasonably steady state.
 
Capt. Geoffrey Thorpe said:
It gets wonked (please excuse the technical term) when you are accelerating - climb is reasonably steady state.
Click to expand...

There are also bank errors. So I can envision that any offset from horizontal could induce small errors, depending on the heading. Probably tiny enough not to matter unless very close to the magnetic pole.
 
We could let this devolve further into a heroically pedantic exercise, but to that end allow me to say that banking does not necessarily imply turning, and a plane that was banked but not turning could still have compass errors.

Your turn!
 
FastEddieB said:
We could let this devolve further into a heroically pedantic exercise, but to that end allow me to say that banking does not necessarily imply turning, and a plane that was banked but not turning could still have compass errors.

Your turn!
Click to expand...
If you are banked, but maintaining a constant heading and velocity, the compass will still be sitting "level" and will not have an error. Pick one up and tilt it back and forth - nothing happens. Accelerate it in any direction and the card turns.
Don't make me create a video. :)
 
Capt. Geoffrey Thorpe said:
If you are banked, but maintaining a constant heading and velocity, the compass will still be sitting "level" and will not have an error.
Click to expand...

I think you’re wrong. At altitude it will be banked and the magnets will want to point slightly down towards the magnetic pole closest, causing a small error.

But I look forward to the video! But be sure to do it at altitude!
 
Nope, the card floats "level" in that case. If you're banked enough that the card tilts, it's likely no longer free to turn and you have other issues.
 
The airplane should be in a level flight attitude when the compass is swung, so presumably there could be undocumented errors in a climb or descent attitude, but I’ve never seen anything substantial enough to question it beyond reasonable accuracy.

Now, if you’re dead reckoning to Hawaii, that might be a different matter. ;)
 
Attitude itself won't affect the card until it gets so severe that the card binds.

Accelleration of various sorts (either straight line velocity changes or turns) will cause the textbook lag/lead or ands errors.
 
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