Please bear with me as this is a very basic question and many of you will undoubtedly roll your eyes in disbelief. However, I'm a big believer in asking when I don't know something, so here we go. I noticed that generally Heading Indicators have two knobs. I understand what they do mechanically, but I'm unclear as to how to use one of them. I often use the bug ring to set the desired heading when using the autopilot. However I don't understand how the other knob (the one that turns the compass card) is used in the real world and under what circumstances. Could someone give me a real life scenario under which they would use the knob that turns the compass card?
Thanks a bunch.