RTL is not safe and often gets confused! XKF4.SV/SP spikes

@tridge @priseborough I flew 5 miles out, lost video, and hit RTL. During the flight back, RTL often directed the aircraft away from launch and position state seems to be confused/incorrect several times. GPS had a consistent 26 satellites the whole time. GPC.GCrs seems fine and correct. I almost lost the aircraft and would love to know why this is happening. XKF4.SV/SP spikes correlate to the erroneous state. In the log, the 17m 2s spot is a good example.


Seems like it is related to https://github.com/ArduPilot/ardupilot/pull/18008

The EKF rejection fo the GPs measurements was caused by yaw excessive yaw drift during periods of non turning flight. No compass was being used at the time.

The changes introduced by https://github.com/ArduPilot/ardupilot/pull/18008 have helped reduce yaw drift for other users operating without a magnetometer. If the problem persists after you have updated your firmware, please provide a log obtined with LOG_DISARMED=1 and LOG_REPLAY=1