https://i.gyazo.com/a2658fc2c278618a...16ebb829d0.png
Doesn't it rather depend on the latitude for which the compass was made ?
By the way, suppose I buy a compass for 45N and go use it at 45S : won't it be totally upset and not horizontal ?
How can you have a compass fit to use from -45S to 60N, an amplitude which many long haul aircraft have ? (I know they have real means of measuring heading, but there must be an is a standby/emergency compass in these aircraft as well)
Thanks