My quadcopter dropped

I used pixhawk cube purple and flight my quadcopter in ‘ALT HOLD’ mode without GPS
it flew without a glitch and then suddenly flew up very fast
On the spot, i reduced the throttle but quadcopter was flying up
Finally, i changed mode in ‘Stabilize mode’ after my drone fall down
I upload my flight logs
The drone flew up approximate 04:22, and RC3 channel’s PWM value was ‘1066’ in 04:23
but ALT value was rising up
Why my drone was flew up?
Please Help Me