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Posted (edited)
On 27.05.2020 at 14:28, albar965 said:

I show the data as it is presented in the source.

Hi Alex!

I just wanted to clarify:

1)the range of nav aids is taken from navigraph (if it is active)?

2)ILS beam width for visual display only?

 

Edited by niksan29

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On 6/21/2020 at 11:23 AM, niksan29 said:

1)the range of nav aids is taken from navigraph (if it is active)?

Yes for VOR.
Sort of for NDB. There it is calculated based on the NDB type (H, HH, Compass Locator, ...).
Range is not available in Navigraph for ILS where I use a fixed value of 27 NM. X-Plane and FSX/P3D provide a range but I'm not sure if this makes sense.

On 6/21/2020 at 11:23 AM, niksan29 said:

2)ILS beam width for visual display only?

Beam width is provided in FSX/P3D only and there are really ILS with different values (look at stock ENHF). You can also see this while flying as far as I remember. Navigraph and X-Plane do not provide this value and I use a fixed width for drawing only.

Hope this is not too confusing.🙃

Alex

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Posted (edited)

Hi Alex!

I have a question again:

why is the center of the ILS beam in this case drawn with a noticeable offset relative to the center of the runway,according to 2008 AIRAC, the difference between the course ILS and the runway is only one degree:

Spoiler

wmsa.jpg

 

there's no published offset on Jepp charts (15-Jun-2018 is the latest): 

Spoiler

wmsa2.jpg

 

in another example, the course of ILS almost ideally align to the center of the runway, despite the fact that the difference  between the course ILS and the runway is already 2 degrees(according to 2008 AIRAC):

Spoiler

ugsb.jpg

 

I understand that this data is not created by you, it is read from the Navigraph database, but maybe you know why  are they drawn this way and not otherwise?

Edited by niksan29

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ISB has a magnetic bearing of exactly 149° in the Navigraph source database (using 1909 here, have no other source database).
Runway true bearing is given as 149.672 and rounded up to 150 for number display. The runway is still rotated by the exact and not the rounded number.

Runway bearing comes as true value in the source and does not need conversion for display.

To display the ILS I have to convert the magnetic bearing to true and since LNM uses the current declination calculated using the WMM (World Magnetic Model) there might be differences in some cases. ILS do not come with declination information in the source data (depends on source: Navigraph, P3D or X-Plane).
Above causes also the inconsistency at UGSB. True course matches but magnetic not.

I followed ILS and runway at WMSA with measurement lines and all is perfectly ok. So, even the ~0.7° discrepancy is visible in the display. Which is no wonder due to ILS transmitter location being 2.2 NM away from the entry.

Lots of fun all this stuff. Discrepancies in sources, different magnetic variances, VORs calibrated ages ago, renamed runways and whatnot.🙃

Alex

 

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