Just when I think I am doing things correctly I hear some do it a different way. I have a Phantom 1.1.1 ver 4.00. I power up the quad..get all the proper led flashes. The last being two sets of rapid green flashes followed by slow green flashes. That's when I may do the compass dance. Now, I see some say they power up the quad and immediately flip the S1 switch to enter compass calibration. Why do that?