I rarely use the RTH but recently I tested it and found that although the RTH height is set to 30m, the quad climbs to well above that before it initiates its RTH sequence. I have stopped the climb on more than one occasion so I'm not sure how high it would actually go. As a side note, the same thing happens on tap fly even though I select a point below the horizon. Last tap fly I tried the quad was up almost 400' by the time I realized what was happening.