I noticed the phantom shows altitude 0 on the ground before being launched. You could be down in a valley or up in a mountain and it would still show 0. Hence result the following questions: 1. Doesn't flying from top of a 4000 ft mountain and lifting the phantom 800ft in the air, pause a potential problem for air traffic? 2. If flying from top of a mountain towards the valley in ground station mode, shouldn't we be able to set negative altitudes? I believe DJI set the altitudes in the ground stations from 0 and up, but that does not give any protection as someone could fly the phantom into a tree or a building. So why not allow negative altitudes? Would be nice if ground station could incorporate elevation and then flight path could use absolute altitudes instead of relative, allowing not only to avoid buildings, but also dipping into valleys. Thoughts?