Curious question I have that unfortunately since I live in the flat lands of Texas I can't test out. Does the P3 determine height based on where it started as being 0'? So, example... You are at the Grand Canyon and on top of the canyon you take off and then take your P3 down into the canyon valley. Will it show elevation of a negative value?? Or... You start flying toward a mountain with the ground gradually gaining elevation as you get closer. If you fly up the face of the hill and hit the 400' max elevation but the hill is 500' high will it still continue to go up or will you be limited until you change the max height?