Landing Issues

[PanosI]

I haven't notice this but here's a screenshot that it happened to take before a couple of days in very short final (MM in yellow is blinking) at Rodos Diagoras ILS Z Rwy 26.

You can clearly see that I'm half dot down in GS and FD but on the papi's 2 red 2 white, something that I hadn't notice until I saw the pic.



Here (i hope) that it'll show in even larger resolution

https://cdn.discordapp.com/attachments/879993751550959617/1348029741759725639/SERVER___Left_Seat_Panorama_5_-_Precision_Simulator_3_8_2025_10_21_04_PM.png?ex=67cff447&is=67cea2c7&hm=c039b9b2f4b7b22f5436d7128925392064078a16e5bc5f1d6ec6fe3a14ccce6d&;

[Mawea]

You can clearly see that I'm half dot down in GS and FD but on the papi's 2 red 2 white, something that I hadn't notice until I saw the pic.

Hi PanosI,
that is something very close to real live. The difference between eye and papi compared to GS and GS antenna is getting bigger the closer you get to the runway. 10NM out it is not recognized but below 200ft better not trust the PAPI anymore. On the 747 the eye level is even higher but also on smaller airliners, eg A320s, you will have this effect.

[Mariano]

This is correct.

Also, approach charts may have a note stating something along the lines of "VGSI and ILS glidepath not coincident (VGSI angle X.XX/TCH XX')".

In these cases if transitioning to visual, PF should advise the other crew that they are "on the PAPI", so as to avoid PM calling "glideslope" as it slowly wanders away in the PFD (everyone gets on the same page).

Regards,

Mariano

[PanosI]

Hi PanosI,
that is something very close to real live. The difference between eye and papi compared to GS and GS antenna is getting bigger the closer you get to the runway. 10NM out it is not recognized but below 200ft better not trust the PAPI anymore. On the 747 the eye level is even higher but also on smaller airliners, eg A320s, you will have this effect.

This is correct.

Also, approach charts may have a note stating something along the lines of "VGSI and ILS glidepath not coincident (VGSI angle X.XX/TCH XX')".

In these cases if transitioning to visual, PF should advise the other crew that they are "on the PAPI", so as to avoid PM calling "glideslope" as it slowly wanders away in the PFD (everyone gets on the same page).

Regards,

Mariano

It makes sense.

[Captain_al]

Can you provide an approach situ file where this effect starts at 300 feet?

I have never had any problems landing PSX manually under CAT III conditions.

I prefer to see more visually (old eyes) than the Aerowinx visual, so I have always used the WASM using MSFT 2020 and before that P3D. I flew the approach for the first time using the PSX Visual and you are right Hardy, there is no change at 300 feet. You feel the ground effect around 200 feet, but that is it. So it must be like Bluestar mentioned, there is a definite shift at 300 feet, like there is a big wind shift. It reminds me of when I would put in strong winds during Autoland on students doing CAT II/III training so that the LOC would displace enough to warrant a missed approach.

Now I did the same hand flown approach today using WASM as well as the PSX Visual and there was no issue at 300 feet, so not sure what combination of weather/winds cause this displacement at 300 feet with the WASM, but it is just something I notice quite often and I just learn to compensate for it. After all, I do not expect to behave like the simulator or jet exactly.

[dhob]

Not all PAPIs are the same. For Height Group 4 aircraft (747/767/777, A300/310/330/340/350/380, DC-10), the PAPI distance from the threshold must equal the distance to the ILS/GLS/LPV glide path touchdown point plus an additional 300 ft (+50, -0) from the runway threshold.
The PAPI TCH should accommodate the largest aircraft height group normally expected to use the runway.
Whenever a published glide path/descent angle or TCH is not coincident (angles exceed 0.20 degrees or TCH values > 3 feet) with the VGSI angle for a runway, the "Not Coincident" note is published.
The "Not Coincident" note is usually on TERPS charts. PANS-OPS doesn't have the note but publishes a MEHT: Minimum Eye Height over Threshold.
For this approach (ILS RW24), the ILS TCH is 56', while the MEHT published on the taxi chart is 70'. This means that RW24 is set for HG4 aircraft, which is favorable for the 747. The 747 ILS track antennas are located at the front of the nose gear door. The pilot's eye height to the main gear on approach is approximately 35 feet, or 20 feet above the ILS glide slope.
HG4 PAPI placement creates the difference between glide path TCH and VGSI TCH, typically about 16' vertically.
For RW24, the difference is 14 feet, which doesn't fully account for the pilot eye height above the ILS antenna. Even with the PAPI offset, around 100 feet, the PAPI will change to three white and one red.
The bottom line is to follow the ILS/GLS/LPV/VNAV PTH to landing, not the PAPI.
Otherwise, the consequences can be embarrassing: https://asn.flightsafety.org/wikibase/305774