I was never happy with the compass on my D-180. Today I decided to relocate it. But how to find the best location with the least magnetic interference? Was about to remove the whisky compass from another plane when it hit me? The iPhone has a very sensitive compass. If there is any interference it blanks out and gives you message that you must move from this location and reset it. It worked like a charm. My old location was really bad. My hope is that the new one is much better. We'll see?