let me preface everything by saying that I am a newbee and have only flowen my P2V less than a week and about 7 times. I have noticed that my altitude as reported by my iPhone 4 DJI app, says I am always higher than what I believe. for example, today, I was actuall at about 60ft and it reported about 100 ft. is this normal? I believe that the P2V uses barometric pressure to determine altitude (read that somewhere, don't know for a fact), if that's the case I am sure it is not very accurate. what is a normal tolerance +/- 20ft? also, I think the reported altitude is from home position, not sea level, is that correct? thanks for the experience!