Always think through what you are going to do before you take off.
I had decided that I wanted to try the Follow-Me option in AndroPilot. Turned on my Taranis transmitter, but then left it sitting on the bench with the throttle down, and all the switches in default positions. I connected the 3DR radio to my Google Nexus 7 running AndoPilot. I hit the button on the tablet to arm the drone, and took it off entirely from the tablet. I was flying using the virtual sticks on the screen of the tablet, which was not extremely intuitive because there’s no tactile feedback on the tablet. I’d raised the drone up to about 40 feet, and was trying to find the button to attempt follow me. It didn’t appear to be moving towards me, or doing anything very predictable. My friend near the bench asked what it took to take control from the RC transmitter, and I said just start flipping switches. I continued to fly for about another 30 seconds when I asked him to flip return to launch. (I’ve got that set on a switch of it’s own, using channel 7 of the transmitter.) He was getting concerned because I’d drifted halfway to the trees, and putting the copter in the trees 40 feet up was likely to be a total loss. He flipped the flight mode switch going to loiter. The copter stopped and tumbled out of the sky.
Afterwards he pointed out that before a flight we really needed to discuss what was supposed to happen, and what he could do to recover before the flight begins.
The reason the copter fell out of the sky was that he changed the flight mode without moving the throttle from zero, so when the copter took over it dropped the throttle and fell out of the sky. If he’d just changed the RTL switch things probably would have been just fine. My transmitter is set differently from his. I’ve got all 8 channels configured, with channel 7 being it’s own switch that only deals with the RTL command. He’s got an older firmware and uses RTL as one of his flight modes.
I asked for one thing to happen, and he did something else. He didn’t know exactly what I wanted, and by the time I needed it I wasn’t in a position to explain it quickly. The broken parts can be replaced for $15 from the original place I bought my X, or I can use another supplier and get other parts. I’ve bought an entirely second frame already with nothing mounted on it for only $12 so I might go that route instead of ordering more parts, or I may move parts to run on my new BumbleBee platform.