Why my channel 5 in Mission planner is fluctuating during calibration

i am using apm 2.6 board with firmware ac3. 2.1,FLYSKY 9ch transmitter and reciver. during radio calibration in mission planner when i begins the radio calibration every channel is get to its full range and works perfect except channel 5( which i am using for channel mixing for flight mode selection) is fluctuating continuously. so what should i do i have properly mix channel 5 to accordingly to pwm values for different flight modes.

You can see this fluctuation while doing a radio calibration? Typically you will see only the low and the high pwm values on the live screen there - and the same will be shown on the review screen which comes right after the live screen.

I have a similar indication with my Channel 5 (which I have set up like you describe yours to be - except I’m using a Turnigy 9X transmitter [quite similar to the FLYSKY unit you have).

The only place I see this fluctuation is on Mission Planner’s “tuning” display that is accessed from the HUD display in “Flight Data”. I select “CH5_OUT” to be the parameter to monitor and take a look at the values being sent from the flight computer.

I have selected the GEAR switch to control which flight program I wish to use. When that switch is pointed away from the pilot the output trace stays stable at the lowest pwm value seen during the original radio calibration - at least for a couple of minutes. It will then start randomly fluctuating, but only by two or three pwm.

When that switch is moved so that it points more to the pilot, the fluctuation starts immediately, but this time it goes up or down about 3 pwm centered around the maximum pwm that was shown during the radio calibration.

Can you tell us how much yours is fluctuating? That might help us to understand how serious the problem may be, and possibly what is causing it.