Kewl video. Glad for the happy ending. But I have to comment on your assessment...
The RC talks to the UAS directly - with or without an iPad. The iPad is NOT a necessary part of the signal chain. The iPad only RECEIVES data from the RC UNLESS you're flying an automated (waypoint) flight, then SOME PROGRAMS slave the iPad as a Flight Controller (automated missions only). So if your iPad locks up or is even disconnected from the RC during MANNED flight, there will be no effect on the UAV. BUT....if you're slaving the iPad as a flight controller for AUTOMATED missions, THEN and only then can you run into erroneous flight characteristics up to and including RTH mid mission. I've had iPad lock up before due to heat issues. While this will profoundly effect automated flights, it will not have any effect on manual flights.
Not trying to troll here...but it's my firm belief that this was due to either pilot error OR a failure of another kind. When the RC loses connection to the UAV, it will simply stop in space. If it doesn't regain signal, it will go into RTH. That said... There is also the possibility of ERRONEOUS signal interfering with real-time function, but I haven't seen that kind of issue since the Phantom 1.
You should check your flight records - especially joystick positions. They will tell the whole story.
D