As I wait for my replacement Phantom, I have been continuing trying to learn as much about this bird prior to getting mine off the ground for the first time. Please excuse the possibility that I might be over complicating something here: 1. The information I have up to this point is that GPS mode is optional but highly recommended. That being said, if the Phantom should lose GPS signal for whatever reason, can you switch to another mode to manually (attempt) to bring it home? I've seen some of the horror stories about Phantoms running away and it appears related to lost or corrupted GPS signal. When it decides to run away, can you intervene and override that decision? 2. Relative to question #1, is a GPS signal required for successful flight? In other words, can this be flown without a GPS signal?....Like manually indoors in a gym for example when a GPS signal may not be present? Do you need to calibrate it to just hover or fly? 3. I'm reading and seeing videos relative to GoPro. They all seem to suggest to turn off GPS to eliminate all the micro corrections that show up as unstable video. With Q #1 and #2 in mind, then is the Phantom at risk at this point? 4. If you bring the Phantom down to replace the battery, can you change the battery on the fly? Or do you need to go through the whole calibration process again? I'm just a little confused about some of the standard flight preparations. Seems like this is dependent on GPS 100% of the time from what I can see. Or am I missing something? Just a little commentary, this 'running away' issue that people are experiencing is what scared me away from the AR drone. I personally also had an issue with anything flying over a WiFi signal. So I backed out. I didn't find this forum until after I received my first Phantom. (I sent it back because the props didn't fit). But I didn't think this issue would come up with an RC grade transmitter/receiver. Now I'm second guessing my decision to go ahead with this. I bought Hero 3 and have some bucks tied up in this. And after checking out the instructional videos, I'm scratching my head a little at all the hoops you have to jump through to calibrate. It just seems a little hokey to have to go through all those gyrations spinning around in circles and whatnot for such a high tech device. Can someone give me a warm and fuzzy about this? Thanks.