Tried again today to get a safe waypoint flight and made some progress, though it revealed that the root of the "off track" problem is probably our satellite internet service. For several months I’ve noticed a consistent error when viewing Google Earth, an “offset” of my tracks and waypoints of 160 – 200 feet. No help from Google and our internet provider didn’t have a clue, though they did suggest it might be a latency problem. That is the most likely cause but why did it start suddenly? They have no idea. Yesterday I almost crashed into a tree line when the Phantom took off in what appeared to be the wrong direction (GS mission). Today, just to be very safe, I set a 100 foot on-a-side triangular waypoint mission. As before the Phantom took off properly, then went right when I expected it to go left. I then set a single waypoint about 100 feet away and 80 degrees to my left. The Phantom flew away to the waypoint but at about a 20 degree angle. That was enough to convince me that the Google Earth data I'd cached using our satellite internet has to be seriously affecting these missions. I was flying again at a neighbor’s pasture and it turns out he’s having a similar problem with Google Earth — but his provider is Dish, whereas ours in Wildblue — completely different satellites. So, tomorrow I will find “real” internet and cache the Google Earth maps on my iPad again. Not exactly convenient but better, I guess, than trying to calculate the error factor in order to adjust the mission tracks. I'll post again once I've made more tests but in the meantime, be very careful if you're using satellite internet to prepare your Ground Station missions.