AFL581

Final APP waypoints not aligned with RWY extended centerline

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Good evening ,

Just installed the latest installers on a vanilla P3DV4.

I flew a " delivery " flight from KBFI to CYFB and noticed both times that the waypoints that should be on the RWY extended centerline do NOT line up with the latest but are a few degrees off.

I checked before flight , the database was Navigraph 1707.

Is there some file I should update ?

Is it a known issue within the Sim and should I just ignore it ?


Thanks for your feedbacks .

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1 hour ago, AFL581 said:

Is it a known issue within the Sim and should I just ignore it ?

It's not unusual, in fact one of the change notifications in the Boeing FCOM, if I recall correctly, address this in an advisory regarding the use of LNAV to intercept an ILS localizer.  And that is in the real world.  In the simulator world you have a bunch of different factors including magnetic deviation variance, changes in runway magnetic headings, etc.  I assume the approach you questioned was an ILS.... you should've at least provided enough information for someone not looking over your shoulder to make an assessment and provide an answer.

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I was more thinking about VOR/DME approaches, which may not be aligned with the runways by design. Then again, I'm not sure how many simmers fly those.

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7 hours ago, icemarkom said:

What approach did you fly?

I flew the ILS34 into CYFB.

On the approach chart, waypoints " BILKU " " TIBEG " and " ONGAT " should all be alligned with the LOC, However in the sim , I encounter a fw degrees off.

Iqaluit-ILS-34.png

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As Don mentioned, this is not too surprising for various reasons, including the facts that data in the simulators is rather old, and as you know magnetic variation changes in the world, but stays fixed in the sim. There are many ways this can be attempted to be resolved, but there is one wasy place you can try. In the PMDG section of the FMC, I believe in Simulation section, there is an option to align approach course with P3D. The way I understand that option, it's there to adjust what plane will fly vs. what the dataset (Navigraphs) is telling it it should fly.

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There are many reasons why FMS database points may not be aligned precisely with the ILS final approach course, both in the sim and in the real world.

Firstly, it is possible that the FMS nav database co-ordinates are slightly out, or (not in this case) that they have been established using a different datum. Whilst most of the world (and most aircraft FMCs) use the WGS84 datum, there are some countries (China for instance) which do not and thus any published co-ordinates there which have not been converted to WGS84 will be in (perhaps quite significantly) the wrong place when fed in to a WGS84-based navigation system.

Secondly, how do you know that the FMS position is correct? In other words -- the aeroplane may well be on the magenta line, but how can you be certain that the magenta line is in the right place? Although in theory map shifts should be a thing of the past with GPS, it is not impossible for the FMS position to drift slightly and this is another reason to be circumspect when comparing raw data to FMS location. There is a reason why RNAV approaches are non-precision!

Finally (and most likely) -- are you certain that the airport is in exactly the right place in FSX? It is not impossible (quite common, in fact) for the airfield and/or runway location to be offset slightly -- perhaps by a few metres, perhaps by a whole lot more, depending on how accurately the scenery developer has placed the airfield (and if it's default then all bets are off). This, naturally, will result in a mismatch between the final approach track and any co-ordinate-based waypoints.

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18 hours ago, branks737 said:

Try this website

https://www.aero.sors.fr/navaids3.html

I use it to update navaids, ils etc.

 

Branko

 

I guys, I have used this before and it did correct a lot but apparently not everything, I guess it is just a PC sim after all ;) so , let's live with it .

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11 minutes ago, AFL581 said:

I guys, I have used this before and it did correct a lot but apparently not everything,

If the airport scenery is not in the right place, Herve's update linked above will not fix it.

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2 hours ago, skelsey said:

If the airport scenery is not in the right place, Herve's update linked above will not fix it.

I know , default P3D Airport ... Not much I can do about it, I was thinking that the proximity to the magnetic North pole might have something to do with it.

Anyway, I'll just live with it , no big deal ;)

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Ahhh! If you are close to the pole, you may need to change the magnetic reference you're using! What aircraft was it that you were flying? Then again, this looks south enough to not matter...

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16 hours ago, icemarkom said:

Ahhh! If you are close to the pole, you may need to change the magnetic reference you're using! What aircraft was it that you were flying? Then again, this looks south enough to not matter...

You are right, it's not an easy region to fly in ( Got RW King Air time there ... ) however, the 738 doesn't have the TRUE north option , the BBJ has ...

I updated the to the latest data from Mr Sors and it solved many issues.

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