This may not be very intuitive to a larger pool of us, and seeing through it (pun intended) requires just a little education, beyond the typical frontline curriculum.
Key takeaways:
+ 3 deg nominal profile (and a commonly adjusted GP) from 50' intersects the ground plane 291 m past the threshold.
+ Annex 14 ICAO standard marking LDA < 2400m have a so-called "aiming point" located at 300 m
+ Annex 14 ICAO standard markings for LDA > 2400 have the "aiming point" located at 400 m
+ ICAO Annex 14 standard for PAPI location is "abeam the aiming point markers" that yields 2 nominal MEHTs (as per above) of 50 and 66' feet
+ in P.A.P.I. the first P. stands for "electronic vertical plane", not that it needs to be aligned with GP of an ILS installation exactly
+ in P.A.P.I. the A stands for APPROACH and not LANDING.
+ any plane should be flown i.a.w. its AFM and not according to any painted rectangles / lightbeams
Sounds a bit rough but not intentionally, a small price for clarity and brevity.
