I can offer one bit of advice that WILL save you from a "face plant:" Make sure your first (if very close to you) waypoint is in FRONT of your aircraft's nose!
I can tell you that in at least ONE case, (and don't ask how I know this!), where the first/close by waypoint to get the phantom to an altitude able to clear any nearby obstacles, was DIRECTLY BEHIND (to the rear of) the aircraft. When the "Go" button launched the mission, it took off about two feet straight up. Then proceeded to continue an arc'ed loop with a direct backflip (not turn by yawing), happening so fast, it didn't have time or altitude to recover before becoming a full power, props-down lawn mower.
At that point, of course, control sticks are not functional, because it was on it's MISSION! Switching S1 out of GPS mode, would have returned the sticks functionality, allowing it to be turned off, but at that instant it wasn't something immediately entering one's mind. A quick rush to turn the Phantoms battery off, was the fastest thought to stop the beast from chasing after underground gophers.
Moral: If you need to obtain altitude close by, fly to a waypoint that is in front of the aircraft, and you will have no problem. If you fly to a waypoint that is directly behind you,be sure to remember to put the recorder on first, because it will become one of those unforgettable moments, that you would just as soon have.
Anti-moral: If you want to impress bystanders, (untried), you could set a mission to include a waypoint in full view of your audience, with a second waypoint very close BEHIND that one. I THINK the Phantom will do a mid air flip! You may need another waypoint directly behind that one though, since you may have to "re-invert" in order to get upright again, ... shall I say, "quickly!" I don't think I will be testing this theory, but given enough altitude ...
- Experienced words from the wiser-
-Dale-