Strange oscillatory behavior in Auto mode

My Setup is Hexa with 4.1.1 firmware.
In auto mission, system started to roll and pitch after a strange noise, immediately switched mode to Alt-Hold after which the system stabilized and the issue disappeared, did motor test and no issues observed, also in stabilize mode, spooled the motors on ground and everything seemed right.
Request support from the forum to understand the issue

I’m attaching the log for reference

Optimize the PID try again

@LL-qinjiale Thanks for the reply, we tuned the system and visually the system was flying well before this flight. i have completed 3 flights of 20 minutes endurance each earlier to this flight.

Can you elaborate more on optimizing the PID’s?

Before continuing, update to ArduCopter 4.1.3 it fixes known bugs