Something that's puzzled me for a while...
When you extend the runway centreline on approach, does anyone know what the VNAV vertical deviation scale on the ND (or EHSI for classic flyers) is actually telling you?
For example, if you're below profile according to the vertical scale, what is that scale referenced to? Is it where the track line intersects the magenta extended centreline (but how would this work if you're downwind and parallel to the magenta line?), or is it referenced to something else?
Thanks
