I sent my 3DR Hex on a straight line 600 meter trip in Auto mode.. I forgot that I had set the geofence to 500 meters. When the Hex breached the fence, it went into RTL mode, turned around, and came home. (Which is expected).
I had my GoPro running and when I reviewed the video, I noticed the hex started pitching up and down repeatedly after it turned around to come home. Looking at the logs, I see that there are over 30 RTL events that occurred right after the RTL that the fence breach triggered. It's during all the subsequent RTL's that my Hex was pitching.
When I hit the RTL switch on my transmitter, all that is logged is one RTL event and there is no strange pitching like in the log graph below. I've never seen this before.
Note that the Hex was flying pretty well flat and straight right up until the fence breach... Then the bouncing started. After the RTL events stopped occurring, the Hex returned to normal flight.
Any idea of why this is happening and if so, how can I avoid it?