Pixhawk system error after take off flight modes keep on switching to Auto,RTL,FBWA and manual

i did not toggle the switch of my flight modes but in my ground station mission planner giving command randomly to Auto,FBWA,RTL and manual i really dont understand why. please help me to analyze my logs,…

https://drive.google.com/file/d/14lwW_v-A2JvLZF6u1MnmzDJ65mPrlOD5/view?usp=sharing

heres my logs what exactly happened to my plane…

https://drive.google.com/file/d/1Q5m1myLK7EH8IwLhkJLPb5JylrRlrWvP/view?usp=sharing

heres the log where the plane crashed please help me to sort out what really is the problem…

All the mode changes are done by RC command, be it an actual receiver, or RC_OVERRIDE from a joystick on GCS.

what do you think are the problem coming from my remote control? i never use switches to change modes but pixhawk keeps on random changes with flight modes…

Well, unless you have a RC controller that logs every input internally, like a Graupner , its no way to tell what the RC radio sent.
All your in-flight mode changes are logged with MODE_REASON_TX_COMMAND , but as mentioned before, that could be input thru GCS joystick, but I doubt that, as you would know you had one.
Also; the small fluctuations on 1 us looks like a typical RC radio:
Screenshot%20from%202018-11-05%2010-06-05