I flew the mini after I bought it with no issues, after selling to a friend he has experienced a flyaway of sorts, but it only went straight up without any stick input. He got it to come down using the left stick, and when it was about 15 feet off the ground hovering it took off again, straight up. It never drifted at all, and he let it go for a while to see if it would stop. It got to around 300 feet before he again used the control to bring it back down. Is it simply radio interference or is it something more serious? Thanks for any insight or suggestions. I do not have access to logs or flight data at the moment.