Recently, I download the firmware V3.6 for plane, the tunned parameters was upload to a new pixhawk board while trying to swith the flight mode to Auto, the MP shows RTL mode. Then i notice V3.6 is a testing version, maybe it is a bug in the new version. Here is a warning for everyone.
it is not a bug, if you don't have a GPS lock you switch to AUTO mode the flight mode will show RTL mode. take your plane outside and try again.
We try everything you can imagine, but still remained. actually we can disarm the plane, but without AUTO model, there is no meaning for out flyig, so we test a lot of times, finally it shows the older version of APM don't have this problem.