Many people seems to be blaiming bad GPS coverage for the run-aways.
Well, the software should:
1. Not store home point across power off for 60 secs or more. Then it is most likely not valid any more.
2. Not use GPS home point when HDOP gets too bad. Like +/- 15 meters. Actually the manual should list this value, as that is the safety radius that should be cleared before takeoff.
3. Failsafe when no sat coverage (or bad HDOP) is to just land as far as I know.
Noise will not move your GPS position, so don't blame electronic noise and GPS for flyaways.
The only reason I can see for flyaways are software errors, or the P2V receiving signals from another controller. But it should be coded / locked to the device, such that it will not happen.
In the beginning I tested the failsafe go-home from short distance (Phantom mode, had to turn off remote. Never again. You can't regain control). I tested battery low failsafe hovering 5 ft in the air.
I have (in Naza mode) been outside range, and had the P2 go-home. Switched to ATTI, and took over control when in range. (Can't do in Phantom mode).
I can't really see why it would fly away, except some other controller taking over (should not be possible), or it has an old home location. Or, the go-home only uses the compass, and only uses it once, and it has problems in that spot. But I have the feeling, that it is actually using the compass for turning in the right direction, and using the GPS to do further corrections. And most often the GPS reception should be OK high above ground.
Crashes are a different story, could be the vortex rings if flying in no wind, failing motors/propellers, or other mechanical issues.