Vehicle catapult launch and hand over control to auto pilot

Hello,

I am working in SIL environment and i found the short desciption of the procedure with Mavlink messages to achive this.

The feature i am after is not present in QGroundControlStation so one of the option is for me is to implement it there.

Meanwhile, following the steps from the website i was able to establish the comm with px4 but it is failing on the preflight checks.

Any hints how to set it manually using Mavlink only?

Thank you,
TRAJCE