My second time out with my new P2 V+ v3 - since I am a novice, I removed the gimbal/camera while I practice technique and build skills, fly in Phantom mode, had 6+ satellites and calibrated compass. While flying boxes, my Phantom rapidly ascended to it's flight ceiling of 400 feet and just hovered, and hovered nicely! However, none of the controls worked so I figured I'd lost the 5.8GHz signal. Anyway, it hovered there for about 2 hours (seemed like, but was only a few minutes). None of the controls worked so I turned the RC off and back on - I know, probably not necessary since it already lost the signal. So, after a few minutes it very, very slowly started to descend, eventually right in to my waiting arms! Freaked me Out!!! Now the question is why? I realized there is an electrical substation exactly one block over from my field, so I think it was in interference issue - time to find a new field! But why did it fly to the ceiling height (now set at 200 ft), and not the RTH height of 66 feet (now 100 ft). Or maybe the battery reached it's critical level and that's why it started descending on it's own... Now, I have Reward stickers on, and know I think I need a locator, in addition to the Assistant Locator I can use once I put the camera back on. I kind of like the Drone Mods locator but not sure yet. I'll be practicing with my Syma X5C till I get the locator installed. Scared the Sh** out of me though. I had two batteries left but just went on home.