At YPPH RW03 the MEHT (pilots eye height) over the threshold is 71ft,the TCH (G/S height) is 50ft.
If the difference between the eyeheight and the G/S aerial on your particular aircraft is 21ft,and assuming a precise coupled approach is flown,both the PAPI and GS indicator will indicate on slope.
I would be interested in seeing the MEHT/GS difference for several Cat C & D aircraft.
