flying while using telemetry on the GCS, the autopilot can be programmed to trigger into failsafe mode if it loses telemetry. In the event that the autopilot stops receiving MAVlink (telemetry protocol) heartbeat messages for more than 20 sec, the GCS failsafe (FS_GCS_ENABL, 0=Disabled, 1=Enabled) will trigger the autopilot to go into long failsafe and change the flight mode to RTL.
Setup.
Set FS_GCS_ENABL to 1 to enable it.
Connect to the Mission Planner via telemetry. Verify on the bottom right corner of the HUD that you are “flying” in a non auto mode (Manual, Stabilize, FBW are ok).
Unplug one of the telemetry radios. After a few minutes power off your autopilot. (Remember the autopilot will not go into failsafe until 20 seconds of MAVlink inactivity have passed).
Connect your autopilot to the mission planner and pull the logs. Verify on the log that the autopilot went into RTL after 20 sec of MAVlink inactivity.