VIO but falling back to Altitude Mode
Referring to the following statement from Seeker's and Sentinel's docs and with EFK2_AID_MASK == 280, EKF2_HGT_MODE == 3,
If VIO data is not being transmitted, the system will fall back to altitude mode and you will hear “position mode rejected, altitude flight mode”.
I understand that when VIO fails, the 2D x-y position hold obviously fails, but how about the altitude holding capability in Altitude Mode? Does it also go out of the window or does it somehow revert back to fusion of barometric pressure sensor and z-accelerometer?