I am currently in Lindos a village of Rhodes island in Greece. Two days ago I decided to climbe up behind Acropolis where there is a big cave to fly my phantom 4 that I have been flying for 120 flights back home without any problems. I have beegn testing all modes both indoors and outdoors in strong winds. This day I could not get any GPS position even though 50% of the sky was visible. I decided to fly anyhow as I have good experience of that from trying the modes out earlier. I hand started it and flew into the cave. When I flew out into the open and outside the cliff. I received a "max altitude reached" call and when I tried to bring it back it uncontrolled drifted and disconnected. Fortunately we later found the drone upside down with two arms broken after hours of search. I have the whole episode recorded if any of you are interested in seeing it I can upload the sequence when I get home. I guess lesson learned is "don't fly without GPS position"