I only fly to payware airports and i've noticed that on my charts at LPPT rwy 03 FAT is 027* but in my FMS its showing 026* but after i set both courses to 027 per my charts after the localizer has been tracked and captured, my courses then change to 025*? This happens at all airports and if i can remember also happened to default fsx airports.

 

Is this to do with software that calculates MAG VAR ? Thats why you get the difference? I know in the RW plogs pilots can ignore tracks that are different on the flightplan compared to whats showing in the legs page of the FMS.

 

 

Is this to do with software that calculates MAG VAR ? Thats why you get the difference?

 

The mag data in the sim was put into the sim when the original FSX was created over a decade ago. This changes over time (you can see it on just about any airport diagram - http://155.178.201.160/d-tpp/1502/00320AD.PDF - where it will list an annual rate of change by the true north pointer).

Yeh but i'm using payware airports? I don't fly to default airports

Yeh but i'm using payware airports? I don't fly to default airports

 

Doesn't matter.  The magdec.bgl file is from 2005.

 

You can get an updated file here:  http://www.aero.sors.fr/navaids.html

 

Note, this will make your default runways out of sync.

Its ok as i don't use default airports

I've already got that update!

Ignore the mag difference unless it's significant (significant as in when you say 'that's odd').  Focus on what you know, for example the LOC "beam" is about 3 deg wide and it is generally aligned with the runway extended center line.  This is physical reality, the beam is lined up with the runway and that doesn't move no matter what the magnetic poles do; in other words, the magnetic headings are only approximately the true heading. As a convention, the magnetic declination is provided on charts with a year and annual change.  You can use that information to determine if the difference is significant.

 

As far as the autopilot that is actually tracking the LOC beam is concerned, there is only one beam regardless of the course or heading.  The main reason we set the course is so the APPR display is heading up.  There are some other issues involved but the point is a localizer is not like a VOR with 360 radials, there is only one localizer.  I almost forgot to mention that the FAA allows a +/- 6 deg error in the VOR/LOC display, unlike simulation where there is no error and no error is very unrealistic.

Vernon,

It is probably due to the default MagVar data in FSX being out of sync with the AIRAC data. When you set the course manually and then select the 'ILS approach' in the arrivals page of the FMS, it resets the CRS to whats in the AIRAC cycle (not sure why it is setting it to 25° though).

I believe if you select a 'NON ILS approach' you can tune the CRS manually (and still do an ILS approach), the CRS will stay as you set it (haven't done this myself for a while as I normally always use ILS).


Regards
Ian
 

Thanks for the kind response. So is this something that can't be fixed then?

So is this something that can't be fixed then?

The NGX fixes it. PMDG Setup>Options>Simulation>Set FSX LOC CRS>ON. You don't need to concern yourself with it. If the option is on, it's all automactic.

I must have that option off then!

I got back today and checked my settings and i have got fsx loc crs on? so how come i get the difference in course between the MCP and the FMC ?

025 on the MCP and 026 on the FMC which you can't really see

 

 

so how come i get the difference in course between the MCP and the FMC ?

It is explained on page 72 of the Introduction manual  under SET FSX LOC CRS.

Well its not matching it for some reason!

Well its not matching it for some reason!

Vernon

 

I don't know what else to say. Maybe the cats on prune can explain the deal to where it makes sense.