Disabling Joystick input during auto mission cause transition to stabilize and disarm

Recently our I have experienced catastrophic failure during auto mission.
The mission composed of followings.

  • Copter takes off from near GCS site with Joystick input from 3DR radio telemetry.
  • RC controller is located in the landing site about 1 km away from GCS
  • Mission is: Take off and waypoint navigation to target site and get back to home location
  • With Joystick input enabled and throttle in middle, copter takes off with AUTO mission and when airborne, Joystick disable <-- This is where problem occur!
  • When the copter reaches its destination, RC signal available and take control to guide the copter to a goal.
  • Then RC switch to AUTO again and the copter get back to its home location and done.

We tested this setup for several time successfully without a glitch.
One day, we started the copter with Joystick enabled, throttle in middle, take off the copter with AUTO mission.
The copter took off nicely as usual however, right after we disable the Joystick input, suddenly the flight mode changed to Stabilized mode and then disable all motors at once. Then nothing left.
The copter crashed from about 20 m high and disintegrated.

Now I am wonder if anybody have experienced such case.
Today we tried to investigate this issue by trying to simulate the case.
I first suspect if no RC input may cause this problem. But this was not the problem.
Even without RC switch ever be ON, the copter behaves normally.

After several attempts, we finally can reproduce the case.
Copter take off with AUTO mission and disable joystick and then flight mode changed to STABILIZE mode and free fall.
Strangely, this happens on and off. The ratio is about 2~3 out of 20 attempts.
I could not exactly tell which causes this problem.
Maybe disabling Joystick in midair simply is not a good idea?
Anybody can help me figure out what may have contributed this problem?


Did you have a GCS failsafe ? You are using RC_Override, right ? before deconnecting joystick are you sending 0 as value ?
Did you have a failsafe set on your RC receiver ?

Lastly, can you share dataflash log from crash or when the bug appeared ? or telemetry log?

Thank you for your reply.
I did check RC failsafe is disabled.
I am using Joystick input from Mission Planner’s panel and it looks like it override the RC.
I don’t know send anything before disabling Joystick. I simply press the disable button on the Joystick input window.
I will share the log file when I get back to work.


Attached is the log I gathered from the copter crashed when disabled joystick input.
Please review the data.

2017-08-16 14-03-20.log (813.6 KB)