Why in some cases, the angles are different for the same PAPI?

Can PAPI lights quickly change angle at the command of a dispatcher? i think it can't be so really...

For example,Lugano: PAPI angles for both runways are indicated 4.17, and in none of the APPR schemes does this angle exis/not required...

Spoiler

APPR the ISG runway 01, we must use an angle of 6( use only after passing  D3.7 ILU), how PAPI angles can be simultaneously with an angle of 4.17 and 6?🙄

And, why do we need such an angle(4.17) if it is not used anywhere?🤥

Another example, USSS, for the runway 26R, two different angles 3 and 3.17 are indicated (3.17 is prohibited for b747), how do angles switch?

Spoiler

 

Edited September 9, 20196 yr by niksan29

@niksan29

I don't know either because in the same papi there are different flight paths, but I think you shouldn't worry about it, in FSX / P3D all the flight paths are 3º degrees.

regards

If you read the LSZA comments on page 10-0A, it explains that there are two PAPIs for Rwy 01, only one of which is active at a given time.  The 6 deg PAPI is only illuminated when specially certified crews are performing the high-angle IGS approach, and 4.17 at all other times.

On the USSS plate, I see 3.17 deg for rwy 26R, and 3.0 for 08L

Regards

 

5 minutes ago, E69_Brisafresca said:

@niksan29

I don't know either because in the same papi there are different flight paths, but I think you shouldn't worry about it, in FSX / P3D all the flight paths are 3º degrees.

Perhaps that's true for default airports, but I know that ADE allows you to set PAPI angles other than 3.0 deg in the airport file.  If you fly a 3.0 deg PAPI glideslope on that Lugano approach, you're going to fly through one of those nasty towering cumulogranite clouds off the approach end of the runway.

 

1 hour ago, w6kd said:

Perhaps that's true for default airports, but I know that ADE allows you to set PAPI angles other than 3.0 deg in the airport file.  If you fly a 3.0 deg PAPI glideslope on that Lugano approach, you're going to fly through one of those nasty towering cumulogranite clouds off the approach end of the runway. 

 

interesting, I didn't know, I'll have to learn how to do it

Thank you

2 hours ago, w6kd said:

If you read the LSZA comments on page 10-0A, it explains that there are two PAPIs for Rwy 01, only one of which is active at a given time.  The 6 deg PAPI is only illuminated when specially certified crews are performing the high-angle IGS approach, and 4.17 at all other times.

yes, it is, but the question remains: why is angle 4.17 needed if it is not used in any of the appr schemes?

may be, case if all of a sudden we cannot use existing appr schemes?  for example, all of our navigation equipment has failed and we will no longer be able to go to the alternate airport?

2 hours ago, w6kd said:

On the USSS plate, I see 3.17 deg for rwy 26R, and 3.0 for 08L

you're right, I was just inattentive...

57 minutes ago, E69_Brisafresca said:

interesting, I didn't know, I'll have to learn how to do it

yes, in most paid scenes the angle of the PAPI is corresponds to the real angle world and often it differs from standard angle 3;)

and yes, this can be easily changed through the afcad editors like many other parameters, for example, the approach lights system;)

Edited September 9, 20196 yr by niksan29

 PAPI angles and ILS glide paths are not the same thing. IIRC, PAPI's are based on obstruction/terrain clearance +/- 10 degrees from the runway centerline, up to around 4 miles from the threshold and also set for a pilot eye to wheel height which of course can vary from aircraft to aircraft which will then vary somewhat from airport to airport (why it's published on the plate). An ILS loc is routinely calibrated for obstacle/terrain clearance on a much narrower path out to a much further distance.

 I remember reading of a Global Express that crashed into the ground just prior to the runway in Nova Scotia because of the PAPI's being set for a shorter eye to wheel height. This particular operator accustomed to operating a smaller bizjet into the airport upgraded to the Global and wasn't aware that the difference in eye to wheel height could play such a drastic role.

 Also in low visibilty ops, when the ceilings are very low (less than 200 feet), it's common to turn the PAPI's off entirely.

 Some light reading to help explain it better. I'm sure there are better explanations out there, but luckily we're all Google equipped.

https://www.boldmethod.com/learn-to-fly/maneuvers/should-you-use-the-vasi-on-your-final-approach-every-time/

5 hours ago, Rob_Ainscough said:

GLC seems really steep 5.5

I am sure this is because:high obstacles on the way, as is the case with Lugano🏰🗼🏔️

50 minutes ago, Dave_YVR said:

 PAPI angles and ILS glide paths are not the same thing.

Just for clarification, both indicate the same angle.  

On really large aircraft it is not uncommon that the correct GS on the ILS displays as three white and one red on the PAPI.

10 hours ago, niksan29 said:

why is angle 4.17 needed if it is not used in any of the appr schemes?

That's simply the 'normal' approach path you use e.g. for visual approaches.

5 minutes ago, FDEdev said:

Just for clarification, both indicate the same angle.  

As I understand it, sometimes there may be exceptions🧐

 

1 minute ago, FDEdev said:

That's simply the 'normal' approach path you use e.g. for visual approaches.

It seems so😉

And i read this https://www.boldmethod.com/learn-to-fly/maneuvers/should-you-use-the-vasi-on-your-final-approach-every-time/ ,one of the cases: need a PAPI angle 4 in KSBS if you visually acquire the runway well before MDA, or as an aid for visual approach. That is, if we do not use any of the existing approach schemes, we can use papi to help😎

3 minutes ago, niksan29 said:

As I understand it, sometimes there may be exceptions🧐

That is, if we do not use any of the existing approach schemes, we can use papi to help😎

Don't know why there should be difference. If the ILS GS and the PAPI angle would be different, this would be very distracting, nothing else.

Well, that's the whole reason for PAPIs/VASIS, helping to to fly a correct visual approach angle. If you have an ILS GS you don't need a PAPI/VASI.

4 hours ago, Dave_YVR said:

I remember reading of a Global Express that crashed into the ground just prior to the runway in Nova Scotia because of the PAPI's being set for a shorter eye to wheel height.

Just looked at the accident report & video. The reason for this accident wasn't the eye to wheel height, but the fact that they deliberately flew the (unstable!) approach well below the GS.

https://www.youtube.com/watch?v=oLpgrLL5pvU

 

Edited September 10, 20196 yr by FDEdev

8 hours ago, FDEdev said:

Don't know why there should be difference. If the ILS GS and the PAPI angle would be different, this would be very distracting, nothing else.

Well, that's the whole reason for PAPIs/VASIS, helping to to fly a correct visual approach angle. If you have an ILS GS you don't need a PAPI/VASI.

There are exceptions, case in point the ILS LOC X 16 at KHMN (Holloman AFB, NM).  There is a note that the VGSI (in this case a 3.0 deg PAPI) is not coincident with the 2.5 deg ILS G/S.  The PAPI is used for visual approaches, e.g. fighter aircraft flying VFR overhead patterns.

19 hours ago, niksan29 said:

yes, it is, but the question remains: why is angle 4.17 needed if it is not used in any of the appr schemes?

The PAPI is a visual approach aid that is used for visual approach segments (e.g. the final approach after maneuvering from a circling approach) that may or may not be associated with a precision/non-precision instrument approach.

10 hours ago, FDEdev said:

The reason for this accident wasn't the eye to wheel height, but the fact that they deliberately flew the (unstable!) approach well below the GS.

Incorrect, there is no GS at Fox Harbour and the accident was directly related to the eye to wheel height differences between types.  

http://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2007/a07a0134/a07a0134.html#3.0

Papi angles and ILS gp angles are not always the same.

Edited September 10, 20196 yr by Dave_YVR