I was watching a movie and they were talking about a "compass dance" and some magnetic mountains that can originate it. So, Since my lovely quad was just beside me, I am thinking, would be nice to have with us, while we are out there Flying, a good old compass, just to check if there are some interferences? I mean a mechanical compass?
or it is just useless and I should go back watch the movie?
btw the movies is Flight of Phoenix
or it is just useless and I should go back watch the movie?

btw the movies is Flight of Phoenix