I see, thank you. So PX4 needs the barometer for height reference to enable the Failsafe Land mode? Isn’t the IMU sufficient for that? Or at least, shouldn’t there be an IMU-only based Failsafe Land mode, rather than defaulting to disarm or termination, which would result in total vehicle loss?
I forgot that I actually changed that recently: Remove mode_req_local_alt from Descend mode and handle it in FW position controller by sfuhrer · Pull Request #23840 · PX4/PX4-Autopilot · GitHub
Now you don’t need a valid altitude estimation anymore for Descend. This change is in v1.16 and main.