For the record, I'm new to this site (awesome) yet have flown before but have what I perceive a question I haven't seen asked in the hours of reading I've done so far. Why does the compass have so much bearing on what happens? I mean, if I'm in the woods and someone gives me coordinates lat/long I can figure out where I'm going, including direction. I'm baffled why even in a totally failed calibration or even flying near metal can create such havoc when it could essentially fly with gps alone. I've been doing my a ton of reading because I want to take off and land on an aluminum pontoon boat and was trying to see what affects what and why. Any Ideas?