Sign in to follow this  
Allflight57

Nav data positioning error

Recommended Posts

I have just updated my Navdata the other day to the latest AIRAC for all my addons and when I went to play FS I loaded up the 737 to fly LAS-SNA and the RBELL intersection on the BOACH2 departure was shown off to the right of the runway centerline of 25R when its supposed to be lined up right with the runway extended centerline. Throughout the whole flight using LNAV the plane would have a XTRK error of about 1.5 nm to the right of the LNAV path then it appeared to be crabbing its way along the whole route looking like it wa trying for the path , but never actually got on it and stayed about the same dist away from it the whole flight allthe way down to landing where the runway symbol was way off to the rigth however visually and on the LOC i was perfectly lined up w/ the runway. It is doing this with the 747 too. anyone else have this problem or konw how to fix this? thank you (see pic)http://forums.avsim.net/user_files/172951.jpgTyler

Share this post


Link to post
Help AVSIM continue to serve you!
Please donate today!

You know what, I usually have this problem with the 737NG too. It's never happened with any other aircraft. I would drop Richard Stefan a line at fmsdata{at}navigraph.com. He's in charge of the FMS data. EDIT: I just remembered he left on holiday a few days ago and won't be back until July 1st. I would send the message anyway detailing what the problem is and be sure to list all airports this happens at. As soon as he gets back, he'll let you know he got the message and then either release a revision or the fixes will be in the next AIRAC at that time.Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

Share this post


Link to post

Alright, thanks a lot Ryan for your help. ACtually, would that be an error un the SIDs/STARs since that whole route is made up of ajust a SID and a STAR or is it the AIRAC data? Is there somewhere where i could download a slightly older AIRAC to get me by till when Richard gets back? Tyler

Share this post


Link to post

It is the AIRAC. The SID/STARs only show the route to follow. It's the AIRAC that actually has the coordinates for the airports. The only place I know that would have any other AIRAC is still Navigraph. On the FMS page, at the bottom there should be a link for the 0609 cycle which is the free demo cycle unless someone else has a 070x cycle.Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

Share this post


Link to post

All fixes/waypoints used by the FMC in an approach or arrival come from data in the sidstar text file. The FMC uses the airac data to position runways, airport and navaids. It also uses the airac data for fixes along a route; however, not for arrivals or departures selected from the DEP/ARR screens.I've seen this problem talked about in this forum before, I think it had something to do with a scenery add-on corrupting mag deviation but I am not very sure.

Share this post


Link to post

Hey Guys thanks a lot for all of your replies, Jan-Paul, I read that post and I put that file where it said to but it still is doing the same thing, When im physically on the runway like in position and hold, the nav display will show me exactly where I am, and when I takeoff then it begins drifting way off to the left. I'm just going to download the old navdata until Richard gets back. Thanks a lot for your help. Any other suggestions are welcome too ;)Tyler

Share this post


Link to post

Hi, the wrong rwy display has nothing to do with the madec file in this case. the rwy hdg's in the wpNavAPT.txt do not matcht to them from FS9. If you want to have the RWY display aligned you must enter the rwy hdg's from FS9 (SHIFT + Z) into the txt file. Jan-Paul

Share this post


Link to post

I just re-installed the Old 0609 cycle and its STILL messed up.Tyler

Share this post


Link to post

Hi Ryan, I haven't had the problem at all until i updated all my navdata the other day, and now its screwed up at every airport no matter which sid/star files i have or which AIRAC cycle I have. I managed to fix the L** 767 installing the 0609 demo airac but it still did not correct PMDGs for some reason. I am at the point now of just re-installing the 737 and 747 and seeing if that fixes it. Tyler

Share this post


Link to post

I like the NAVDATA service, but I have to tell you, it is kind of pointless. The only service I would consider truly useful is if they updated the Instrument procedures, which they don't. I manually correct airports I fly to by editing the NAVairports text file so that the runway displays match the FS9 representation perfectly.The problem with the default navdata and the updated ones you purchase is that they are referenced to the actual airports based on real world data. Well, realworld isn't really what goes on in FS9. There is no magnetic field shift like there is in the realworld, so often you end up with airports whose runways have shifted and now you have old SID/STARS for a runway that doesn't exist on FS9!I believe if NAVDATA wants to be really usefull, then they need to start making their procedures for the FS9 world, not the real world. And unless they are revising the SID/STARS as well, then their data updates will actually do more harm than good.It took me 3 cycle updates and lots of headaches to realize this. My NAVairport file is so modified by now that I back it up religiously. Especially because it accounts for all the add-on scenery that is just not present on the default FS9.Mariano

Share this post


Link to post

In my opinion, this is much ado over very little. On one hand, you want navdata that is current so you can fly current routes. This data has changed significantly since FS9 came out including new runways at places like Orlando, St Louis and Houston Bush as well as all new set of RNAV departures at Atlanta and Dallas Ft Worth and Las Vegas (this is just the tip of the changes). On the other hand you want navdata that matches the scenery in FS9 such that final approach course lines up with runway alignment.I have found that, in general, the runway-final course alignments have shifted a few degrees (at the longitudes flown in the US). If I understand the complaint.. this is the problem you want to solve. I personally do not find this a major problem. The runway doesn't "shift," it's latlon coordinates do not change and the landing zone is still at the same point. The coordinates of the final approach fix do not move, and there is still a straight line between it and and the runway. I guess I just don't understand the problem, unless it is the straight line course difference.I've always believed that MSFS should have it's own navigation database (then add-ons wouldn't need them) that could be updated instead of hard-coded constants in the bgl files. This is how the PC-based simulators FAA approved for instrument training solve it (such as On-Top from ASA). But I would never go for navdata being frozen to match a static product. Based on the numbers that use current airac and sidstar data, I would say I am not alone in that feeling.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this