ianwood
Taco Wrangler
1. The Phantom already reports compass error when it detects bad data, (out of range or rapidly changing values.)
That is the system guessing and it's often wrong. DJI has made it more likely to not error out even when the data is bad but even still it sometimes falses positive. This is when the compass error pops up yet it still flies normally. We've all seen it.
2. You still have GPS to hold position. You correct for wind as you go. The trip may be a curve or even a spiral but your can get there unless the wind is faster than the bird can fly in.
No. You don't have any GPS hold without the compass. The drone gets pushed by the wind. It calculates a heading and distance to correct. How does it fly on that heading when it doesn't know where that heading is relative to its orientation? It can hunt for it. This would look like TBE. Big circles.
3.You never even need to yaw the craft. Fly by pitch and roll only as if the craft was in Homelock mode. If there is yaw drift, it will be very small and you can correct for it as you go.
How does it know which way home is relative to its orientation? If there is no wind or a perfectly stable wind (unlikely at low altitudes), it could figure it out. But more likely, the wind will change just enough for it to need to correct so it will be constantly hunting which would result in circles.
Without the compass, GPS is mostly useless. It's not like using GPS on the ground where there is no drift.