A strange fall and the value of the channels


Could you tell me please on two issues:
My configuration is F405 CTR + x8r receiver + x9d transmitter

  1. Copter in landing mode, did not reduce the speed at the set height. He just fell to the ground at a high speed. The log of this flight…

  2. The attached picture from this flight shows that the C8 channel takes the minimum value several times. On C8 I have assigned arming copter and for the entire flight I did not touch this channel. In FS settings, the transmitter is set to No Pulse. This is a bug of the firmware or everything is as it should be? Could it be that the copter disarmed right in the flight?

Log file: