Naples Capodichino

LIRN does not have centerline lighting. Take a look at this video, for example:

https://youtu.be/YERKL1qzuT4?t=169

Duplicate XSG-6623 Done

Further investigation led me to the conclusion that something is wrong with the magnetic declination in that are. X-Plane report a 4W magvar whereas in the area the magvar is 2E. The navaids and the offset looks correct, however the front courses reported are still wrong. Even the rwy headings looks incorrect (235 instead of 236 and 055 instead of 056). I looked into the earth_nav_data files and everything looks correct as per Italian AIP. Is there a way to check whether the magdec is wrong in X-Plane?

I don't know where you are getting these numbers from.
Loading at LIRN, the magnetic declination reported by X-Plane is 3.55 East.
The real value is 3.43 East: https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml#declination
So the difference between X-Plane and reality is about one tenth of one degree.

THe 4W value is read from the Load Airport UI in X-Plane, bottom left. But it could be maybe simply a display issue? Still I don't know why in LIRN the front course of the ILS are wrong whereas, for instance, in LMML (more or less same area) the ILS are all correct. As I said, the offset is correct for both ILSs, only the front course reported are incorrect. You can refer to the JeppView ILS-06 charts for LIRN for the correct front course.

I don't believe what any UI says, I believe what the simulation says. To me that looks like there's a bug in the UI.

You can see the magnetic variation at your aircraft location in dataref editor. The dataref is sim/flightmodel/position/magnetic_variation
The offset localizer (NPC) has a true course of 56.5 and a little bit. With the real world variation of -3.43, this yields a front course of about 53.1 degrees. That doesn't lead to the runway precisely, because the localizer from this side is offset (as published). So, I don't see any problem with the localizer, I see a problem with the X-Plane airport picker UI displaying the wrong variation.

EDIT: The airport selection UI is indeed wrong. I have filed an internal bug for that: XPD-9759 Closed

Hi Phillip, I pefectly know that the localizer is offset and does not lead to the runway in a straight line (I'm a commercial pilot by the way for a business airline). I'll try to explain better: the raw offset displacement between the runway and the localizer is CORRECT (3 degress), the front course reported in the Garmin or any other VOR/LOC gauge is INCORRECT (049 instead of 053). I believe what you say regarding both the Magvar in X-Plane and the localizer value (that I checked personally is as you said). Still Jeppesen report the magvar in the area as being 2E (again you can check Jeppesen or Lido charts) and I'm puzzled why considering 3 degrees of nominal displacement I see in the Garmin 7 degrees of displacement 056-49 = 7 instead of 056-53 = 3

As I explained on the duplicate bug XSG-6623 Done already, it is entirely possible the Jeppesen charts use a different magnetic variation, and that in turn might also be different from the one the Italian AIP uses. The procedure was likely approved and charted many years ago. So I don't really care what the chart says the magnetic variation should be, because that might have been correct only at the time the procedure was approved. I trust the International Geomagnetic Reference Field (IGRF) model.

Does that look about right?
https://gatewaybugs.x-plane.com/secure/attachment/21174/Screen+Shot+2018-12-19+at+05.22.59.png
https://gatewaybugs.x-plane.com/secure/attachment/21175/Screen%20Shot%202018-12-19%20at%2005.31.59.png

@Robin please check the following:

1. NPC LOC is in the database with a 52.736 degrees true course, whilst the GS has a 58.039 true course. Even though the GS true course is not used for the LOC, that seems wrong. In fact, both values seem wrong with the correct mag var of about -3.5. Given the magvar, the truth is probably somewhere in the middle, at around 56.5 degrees true. You can test by illegally flying the ILS approach as an RNAV overlay and then tweaking the LOC to align with it. 56.5 seems to work quite well
2. The INPL DME has been switched off in real life. Only the NPC approach does have a DME. The other side now uses the NAP DME instead. http://www.ead.eurocontrol.int/eadbasic/pamslight-643A33EAD25E823DD232E7324813CF76/L52YHILY3X3PW/EN/AIP/AD/LI_AD_2_LIRN_en_2018-12-06.pdf

Thanks Philipp to look into this further

According to your findings the NPC LOC true course should be indeed 56.5 ! That will give the desired 53 degrees NPC LOC front course

Hi Philipp, I did more extensive testing and I found that taking as a reference the magvar of 2018 lead to inconsistencies in all ILS in Italy.

The Italian AIP takes as a reference datum for magvar the 2005 value and all radio facilities are calibrated according to that value. This is why, despite a correct true offset of the ILS 06 in Naples, the front course was always wrong.

You can test this on all front courses in all ILS in Italy. Not a single ILS is like the one published by Jeppsesen or Lido.

Also in the RC2 the new ILS 06 TRUE course is wrong as it gives a wrong "geometrical" offset against the runway true course.

I know I can be a pain in the ass but every country as a different datum for magvar (i.e. brazil 2018, France 2015, Italy 2005) and this lead to ILS front courses and VOR radials different from the one published officially.

This is not an Italian problem, this exists everywhere in the world.
VOR stations carry a "station variation" rather than using the actual magnetic variation. That is why the VOR course rarely matches the magnetic course when flying on a VOR radial. X-Plane knows this and simulates this discrepancy - VORs have station variations that are published once and not changed for many years, while the real magnetic variation moves. X-Plane does exactly that, which is why the magnetic courses over the ground do not match the magnetic courses of the VOR radials. Just like they don't complete match in the real world either.
The LIRN 06 is correct geometrically in RC2 - it matches the RNAV overlay procedure to greater accuracy than necessary by regulation.

Please see attached image

We can easily skew the localizer a bit more to align with the RNAV points. That will NOT dramatically change the readout of its magnetic course however - because that value is calculated, not programmed. And the calculation is according to current real-world magnetic variation, and not according to 2005 values. This is not a problem, because the same effect is true in the real world - if you had a hypothetical 0 wind day and you were flying the localizer precisely, your magnetic compass would show the magnetic course of 2018 and not the value on your chart.

Thanks Phillip, yes please try to skew the ILS to 54.547 so at least geometrically is correct. I know that the value is calculated. Regarding the magnetic readout I'll ask to some of my colleagues working for Ryanair and Easyjet whether they read 051 or 053. I found an interesting article on SkyVector https://skyvector.com/content/magnetic-course-numbers-few-degrees#comment-569 regarding those discrepancies occuring in real life too.

*update

I started working on an update

Awesome