Issue with ARCHI waypoint location

[NaughtyGnome]

Hello,

I believe a waypoint’s location is incorrect in the NAVDATA. I hope this is the correct place to raise this.

I was flying into KSFO yesterday (PMDG 737-800) and was instructed to use the Quiet Bridge Visual for RW28R.

The chart for this arrival is shown here

As you can see, it says from ARCHI head 255 degrees until you intercept the SFO 095 Radial

To do this in the FMC, I added a FIX for SFO and put in the 095 Radial; however, it visualised the 095 Radial directly intercepting ARCHI, which is actually on the 091 Radial, as shown here

This was my entry in the FMC on the Fix Page and the subsequent line it created.

As you can see, the 095 radial is intercepting ARCHI, which is incorrect.

Having investigated further with some other folks I can provide another example

Here the point SFO001 is PB/PB based on SFO091/OSI056 and the 255 track as published on the chart for the ARCHI location. As can be seen the ARCHI waypoint is placed on the 095 SFO radial.

I believe the ARCHI location is incorrect in the Data.

So far we have replicated this on the:
PMDG 737-800
PMDG 777-800
FSLabs A321
Fenix A320

I believe the correct coordinates for ARCHI should be
37° 29’ 26.88" N 121° 52’ 31.95" W
The Data page on the Fenix MCDU shows them as:

Can this be looked into?

Thanks

[NAVData]

Hi,
Thank you very much for this detailed report. Wow, much appreciated… good stuff!!

I will verify the reported waypoint and, of course, make the necessary adjustments. This approach is tailored, so it is possible that there may be an error.

I will keep you informed here.

Thanks,
Richard

[NAVData]

Hi,
I have checked the ARCHI waypoint against the FAA, and the coordinates that we offer are correct, and also the Fenix shows the correct coordinates:

Decimal Degrees: 37.49079722, -121.87554167
Decimal Minutes (ie. Fenix): N37° 29.4’, W121° 52.5’
Decimal Minutes Seconds (ARINC standard): N37° 29’ 26.8", W121° 52’ 31.95"

The coordinates are 100% identical to those of the FAA and your notes. It depends only on the format, but all formats show the correct position.

I assume that the main issue is the station declaration of the SFO VOR, which is 17.0E degrees. The calibration was set in 1975 and has never been updated. Now we have 12.9E - the difference is 4.1 degrees, and that seems exactly the difference. I don´t know which magnetic declination the sim uses, but it looks like it is more up to date than 1975

Here from directly from the FAA database:

The station declaration will be updated very seldom, which is why you see such a difference and why you see such a big difference between the current, regional magnetic variation. That’s not what we have in our hands, sorry.

I hope that answers your question somewhat.
Cheers,
Richard

[NaughtyGnome]

It certainly does!

Thank you very much for investigating.

Andrew

[NAVData]

Andrew, due to your report, I have decided to test a possible solution for such “issues”.

It will need time, but I have an idea for a future update. For now, I have marked this posting as “solved,” but I have fully understood the need to find a solution

Cheers
Richard

[NaughtyGnome]

Oh that’s very cool!

Thanks Richard.

Out of pure interest do you know if this would occur In real life if someone programmed in the radials to an FMC?

Thanks

[jpschuchna]

The real FMC would use the station declination of E17. PMDG uses the sim variation model of 2025 and does not consider the coded station declination or procedure variation for constructing CF-Legs. Could be something for PMDG and a future update.

For FIX entries the aircraft would probaly rely on its IRS data tables which would be similar to the MSFS Magdec.bgl from 2025. So same issues there.

Magnetic-Variation-and-Modern-Avionics.pdf