I read the section on the HGS in the Operation Manual (part 2), but some things are still unclear to me.
I can enter runway length and touchdown zone elevation in the HGS control panel, but it does not seem to change anything displayed on the HGS. Should this somehow help indicating the runway on the display?
Same with the glide-slope angle value, does not seem to change anything on the display.
Also I cannot change the active mode. In the standby mode field I can select through the modes described in the manual, but no matter which flight-phase I'm in, I cannot get it into the active mode field, it stays on PRI.
Is there maybe a guide or a video on how to use the HGS, for example as guidance on an approached with bad visibility?