How does the Phantom control its elevation as terrain changes? What I am asking is does it maintain a certain height versus sea level or does it maintain its height to maintain a distance from the ground. Perhaps an example of what I am thinking about will make my question more straight forward. The street in front of my house is 700 feet elevation. The street goes up to the right of my house and climbs to about 900 feet. If I takeoff in front of my house and have the bird rise to 100 feet what will happen if I tell it to fly to the right following the street? Will it stay 100 feet over the road the entire way, or will it gradually get closer to the road and hit the ground as it gets halfway where there elevation is 800 feet above sea level?