Weather Radar tilt calibration
What is the source of tilt information display on ND?
Is it from a tilt sensor or is it coming from the selector switch on the control panel?
In many aircraft it is taken from control panel.
There are comparison thresholds before a failure annunciation like red ANT is displayed.If ANT fail comes ,then weather radar image will not be there.This is considered as major failure like RT unit failure and Control panel failure.
If the difference between control panel tilt command and actual tilt of antenna is only 0.1 to 0.24 you may not get red ANT fail indication.
Depending on the altitude you are flying it is possible to miss ground scan if antenna tilt is few tenths of degree away from normal value.