Critical Navigation Failure during takeoff

During takeoff in mission mode, the failure-message “Critical Navigation Failure” was issued and the drone went into failsafe mode (attitude control). Logdata shows a constant 3D-fix for the entire flight, minimum 13 satellites were seen, no GPS jamming occurred according to the logfile:

The vehicle is a VTOL-Tailsitter with the GPS antenna mounted on the back. Due to wind, the wing pitched 25° up, so that the antenna might have been shaded as shown here:

But according to the logfile GPS-reception was ok as mentioned above (3D-fix, 13 satellites minimum, no jamming) so I am not sure if that could be the explanation. Any help is welcome, thanks!

Hello,

You have excessive vibrations transferred to the autopilot. I think it is related with this.