APM is working good for me, Loiter Mode no problem, no problem to RTL Mode. But when RTL is actived, the aircraft will be slightly Sway (No Heading control when fly to the home.).

Today when I try "Fly to here". After I click "Fly to here", the aircraft Sway very bigger, obviously the angle of dip
to wrong direction more than 30 degrees, and then can be corrected immediately. Finally began flying toward the target point, no problems during the flight. (In this mode, Heading was controled, nose is pointing to the target point, After I click "Fly to here", not only to the aircraft began to changed the YAW, but also begin to accelerate to the target point)

Each click "Fly to here", after violent shaking, the aircraft begin the normal flying to target point.

Finally, shaking is too great, and aircraft crashed.

Update:

I got a better view of the data when bad happens.

The PErX and PErY changed a lot while the copter is just start move.

Can any body told me what's the meaning of "distance to intermediate target between copter and the next way point "

Update again:

Andropilot running on android phone is used to set the way point by 3DR wireless connecting.

I have a bit lager Rate P but without oscillations, so the copter can reach desired angle very fast in Stable mode.

But if Navigation system let the copter rotate from -30 to +41 then to -17 degrees in less than 1/3 second, my copter may not survive.

Update again and again:

I have a second flight today, with lower Rate P, lower Loiter PID P, lower WP_Acc. YAW_BEHAVIOR = Never change yaw
But also end with crash.
After parameters changes, the copter will shaking less violent, but for longer time , it seems the copter use about 2-3 seconds to dip to wrong direction several times and back, then begin it’s journey to the way point.
Finally, a crash end this test.

Update: again.......

Problem seems solved after update to v3.1rc5. May be it's the GPS Glitch protection works. But I do not know.

Guided works in most of try, but still have this problem happened Occasionally. The picture below shows the peak of the desired roll angle after a new target point have been sent to the copter.

 It's a big risk of flying with Guided mode.

But the Auto works great. Very strange.

First flight tlog

http://www.droneshare.com/view/xrk77w

First flight full log

 20131030172969_crash.log

second flight tlog

http://www.droneshare.com/view/d4mpuef

second flight full log

2013-11-01 17-48 1.log

v3.1rc5  fly log, 2013-11-03 09-22 7.log

error happend in lines around 2716

20131030172969_crash.zip

2013-11-01 17-48 1.log

2013-11-03 09-22 7.log