I was flying around a building trying to return from a short pitcure flight. Battery at 79%, controller at 92%, lost signal, pushed RTH button but nothing happend. Remote RTH keeps beeping but the remote had no signal. I am leaving now to see if someone can help me get it off of the small receiving roof. I sent up the Spark and saw it on the small roof but no one was in the building, maybe closed for the weekend, hope it does not rain.