I was out flying today and had a small issue, the batteries in my transmitter weren’t as charged as I thought. Only a few minutes into my flight I had it warning me that the batteries were low. As I was in Alt Hold mode I throttled down to get the quad back on the ground as quick as I could. At this point the quad was about 50m up and about 75 away. Then the transmitter died! I started to panic, how was I going to get the quad back? As I was wearing my FPV goggles I noticed the quad moving… oh no, its only in Alt Hold so it could be being blown off course. Then it occurred to me, I have setup the transmitter failsafe, it isn’t being blown away, it is returning! That led me to another issue, RTL will leave the quad hovering about 10m off the ground, how do I get it down without waiting for the batteries to die and for it to crash. I have connected my phone via a telemetry link, which gave me an option, using Ardupilot it has a button onscreen to activate Land mode. With some trepidation I pressed it, the quad gracefully lost height and gently landed on the grass.
Another important lesson learned, always check battery levels are at least greater than 50% in your transmitter and ensure that you have activated failsafe systems for your quad!
Happy to hear it all turned out ok, and fortunately you had set-up the failsafe! Did you also setup the low voltage fail-safe which would cause the quadcopter to land when the battery gets low?
Something related happened to me a couple years ago when I was flying a little foamy glider and I decided to do a couple loops. On one of them I guess the G force was too much and out popped the battery which came crashing to the ground… It was at a relatively high altitude and since there was no more power the servos all locked up and it slowly looped down the the ground 
and that was the last of that glider 
There is nothing worse then thinking that all that time and money could be wasted! Was anything in your glider salvageable?
I forgot about the voltage failsafe, I think I have it setup but will check.
Most of the gear was fine except for the motor that was up front so took all of the force. It didnt have anything expensive on board as it was just a fun flyer with only the basics. But its all part of the learning experience fortunately that lesson was not too expensive 
I have found out a possible reason for the sudden death of my transmitter batteries. I just finished a charge using my Turnigy charger (normally I would have pulled out the batteries and charged them with normal AA NiMh plug in charger). It finished the charge in about 1.5 hours with 0.5A charge rate, pumping in a measly 755mAh into the 2000mAh batteries.
I guess the batteries are probably dead then!
Blog post about it 
My Iris also seems to loiter at 10m after a RTL for far to long. I’m guessing there is a parameter in there somewhere to adjust this Alex? I’ve looked, but can’t find it.