Flew 16,000 feet today without loss of signal. A few minor blips but 5 bars were showing for both RC and video. I was using my windsurfer as I flew 6000 ft over open water across a lake then continued above the trees at approx 200ft. I only turned it around due to concern with battery. I have no idea how much further I could've flown however, as soon as I turned it around with it facing back towards the "home point" I noticed a significant drop in signal. That weak signal continued for roughly a 1/2 mile, not sure why the signal would be weaker upon facing in the direct of home. Landed with nealry 40% battery therefore, I likely could've continued further until signal began to fade.