I’ve been wondering why I’m always seeing four red lights on short final, and I’ve figured it out. When they exist in MSFS, the visual glide slope indicators (VGSI) such as PAPI and VASI are almost always placed too far down the runway. They are also often missing or incorrectly configured (2 box vs 4 box, right side vs left side).
Focusing on placement down the runway, the MSFS standard of PAPI placement 1000’ from the threshold causes an improperly high glidepath and a long landing on shorter runways. However, many short runways (2500-4000’ in length) in the real world use a PAPI location that is only 400-800’ from the threshold. This can cause a differential of threshold crossing height (TCH) of up to 40’, but even more simply, we can assume that the PAPI location is the desired touchdown location. In the cases of incorrect placement, touching down 700’ farther down the runway, for example, will take the aircraft out of the preferred “first third” landing zone of the runway, possibly even halfway down the runway in some shorter-runway cases.
Here are some in-game examples, using raytracing distance to the runway threshold and setting the nominal eye height to the both the in-game PAPI TCH and that of the correct TCH, as indicated in the airport/facility directory (if the lights were correctly placed).
Here is Williamsport, PA, Runway 12 on the in-game PAPI, which produces a TCH of 65’:
This is 20’ higher than the correct TCH of 45, as pictured here (note where the 2-bar PAPI should be located, 325 closer to the threshold, as verified in both photogrammetry and Google Earth):
Here is the airport/facility directory entry to back this position:
Here is KAUN Runway 7. In-game TCH is 62’:
The correct TCH at KAUN 7 is 21’, due to a PAPI that is a whopping 600’ closer to the threshold in real life compared to the in-game counterpart. Here’s the result:
Even though I have MANY more, here’s the last example in Chatham, MA, with an in-game TCH of 53’:
This is the perspective from a correct RL TCH of 39’, due to a PAPI that is 380’ closer to the threshold in real life:
Finally, and this could warrant a topic on its own, but if I’m on an instrument approach and upon break out, see a 4-bar PAPI on the left, when it’s supposed to be a 2-bar PAPI on the right, that’s cause for a go-around because the fact it’s different than what I briefed on the approach briefing. A mis-identified VGSI could mean I’m approaching the wrong runway or at the wrong airport. This can happen on a visual approach as well.
If Asobo is going for realism, teaching pilots to get the correct sight picture, establish the correct glidepath, to land in the correct touchdown zone, and to roll out within the remaining runway length, this all needs to be fixed.
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