It didn't fly out of range, the reciever hung. It was on but it just locked up. It didn't brown out either it just went into "lights on but no one home mode". And stayed like that till I disconnected it.
It was fine again after I rebooted it. I had a bit of trouble with this RX very early on but I re-bound it and it seemed to work fine, range checked fine, and did work OK for all the previous flights. It's in the bin now !! It was an FRsky reciever. I did a bit of looking about on the net and found that there was a batch of them where the odd one suffered from this kind of fault. I've used heaps of these recievers and never had a problem but you can be unlucky and it did give me a warning as well which I should have headed. I thaught I had resolved it with a rebind. Obviously not Tho'