Resolved FSXFlight / ForeFlight heading error when GNS v2 turns ON

[bbuckley 133]

I've been trying to track down a nagging problem that wasn't an issue in FSX.  I use FSXFlight to send GPS location & traffic data to an iPad running ForeFlight.  In FSX it worked flawlessly.  But in P3DV4 it has always had ~25 degree left heading error.  I have always assumed it was a P3D issue even though FSXFlight doesn't use the P3D Broadcast GPS function, which is notoriously bad.  But tonight while troubleshooting I was flying an airplane with a pop up GNS v2 installed but not turned on and the heading was perfect.  As soon as I selected the popup GNS and it activated, the aircraft heading display on ForeFlight immediately skewed 25 deg left of the actual heading.  

Does anyone here use GNS v2 and FSXFlight / ForeFlight in P3D4?  @RXP is there any reason this might happen?  

BTW, I have never flown P3DV4 without the RXP GNS v2, it was that important to me that I wouldn't make the leap until it was released. So that's why I never noticed the relationship before.

[RXP 2,338]

Hi Bruce,

This is interesting a finding! Wouldn't this be equivalent to the magvar? or even maybe the (magvar X 2) ?

The GNS V2 also overrides the FS magvar variables so as to make third party gauges in sync with the GNS V2 / GTN magvar values. It is possible there is a sign error.

Otherwise, it is also possible the FSXFlight bridge is not taking in account the magvar, and gets wrong results?

Or simply we wrongfully override TRUE with MAG (or the reverse), or they use TRUE instead of MAG.

I'll review this tomorrow right before releasing the planned update.

[Pgdavis2 3]

+1

[bbuckley 133]

Jean-Luc thanks!  Your support here on the gns v2 has been awesome. 

The flying I’ve been doing has been west US coast, California (12 - 13 E magvar) to Portland (16 E). So the heading error seems to be ~magvar x2?  I’ll check more closely tomorrow and get a few data points with a spread of variations.  But so far I’m just eyeball estimating the error. 

[bbuckley 133]

Tested this morning at KPBI (6 deg W var) and here's 2 pics from ForeFlight before turning on gns v2 and after.  Sure enough, as soon as I selected the gns v2 pop up the track vector and icon flipped right (west var) by 2 x magvar.  And the last pic is from a SOCAL flight with east magvar of 12 deg showing it flips 2 x magvar left for east var.

Thanks!

Bruce

ForeFlight track / hdg without gns v2

Same flight right after turning gns v2 pop up on

Flight in SOCAL (12 E var)

[RXP 2,338]

Hi, initial tests comparing the data out of fsim, with a DTO in the default and the same DTO in the GTN shows the same data for both! Actually the only error is the TKE which has a reversed sign.

Do you mean with the default GPS set to a course, the map shows correct though, or have you tried only with the GTN?

[RXP 2,338]

Addendum: I was not paying attention entirely. Our DTK and BRG are valid, but our MVAR override sign is reversed! Will be changed in the next update, thank you for your finding!

[bbuckley 133]

No problem, thanks for jumping on it.  Just for completeness, I did a flight using the default GPS and changed CRS. HDG, FPL etc and everything tracked fine through  FSXFlight to ForeFlight.  Then repeated using the GNS430 V2 and the 2 x magvar shift reappeared.  Look forward to the next release.

[fppilot 4,355]

Wow! That is quick detection! And great support!

[bbuckley 133]

BTW, Happy to report that gns430 v2.3.5 has resolved the sign error on the magvar and FSXFlight with ForeFlight works perfectly again.  Thanks so much @RXP!

 

[RXP 2,338]

Hi Bruce and thank you for the positive report!

[bbuckley 133]

@RXP  Is it possible this magvar issue has reappeared in the 2.3.9 release?  I've only done one quick flight (P3Dv4.1 still) but it sure looked like the old issue is back.  I can do a better check tonight or tomorrow and provides logs and pics.

[bbuckley 133]

Hi Jean Luc,  I have now confirmed the issue has returned.  Here are two pics I took of the ForeFlight screen flying straight in to KPDX (var 15.7E).  In the first shot I have the RXP GNS off and the track vector looks normal.  In the second shot, I have just turned on the RXP GNS430v2 (2.3.9).  This is in P3Dv4.1.  You can see the track vector immediately shifted what looks like ~30 deg left. 

[RXP 2,338]

Hi, I'd be surprised this issue is back, especially nothing has changed in the code for this since many versions now.

Could this be a recent ForeFlight update (or bug) counterbalancing some GNS counter-balacing code?

NB: I can't see the screenshots, it requires authentication.

[bbuckley 133]

11 hours ago, RXP said:

Could this be a recent ForeFlight update (or bug) counterbalancing some GNS counter-balacing code?

That's possible I guess, although I don't know what you mean by GNS counter-balancing code".  I went back and installed RXP GNS 2.3.6 and the same issue occurs.  But it only occurs when the RXP GNS430 (in my case) is activated.  I flew an airplane where the RXP GNS is only installed as a popup.  After takeoff the FF Track Vector is perfectly normal until I activate the GNS popup, then it immediately shifts 2x MAGVAR.

some info:  P3Dv4.1, Win10, FF 9.5.3, FSXFlight  Can anyone here duplicate issue?

FF Screenshot using default GPS.

FF Screenshot after activating RXP GNS430W popup.

Odd about the links, they are public OneDrive shared links that have always worked.  I recreated links above.

If it's not an RXP GNS issue I have no clue what to do... Activating the RXP GNS rebders ForeFlight very difficult to use.

Thanks for your help!