Hi @Sena,
As per our pymavlink docs:
All system components that communicate via MAVLink are expected to send a HEARTBEAT message at a constant rate of at least 1 Hz. If the autopilot does not receive a heartbeat from your application after this interval, it will trigger a failsafe.
There’s some more info about how to deal with that around the forum - there’s a recent example at the bottom of this comment:
As a more general note, I’d recommend starting with simple bits of code and working your way up to the functionality you actually want. The snippet you provided has some formatting/indentation issues, but also has three while loops that are reliant on a variable that doesn’t change anywhere in the code, which makes it unnecessarily confusing to understand.
When posting examples that you want help with, try to simplify the code down to the simplest example you can that replicates the issue 