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Posted: Mon Jan 10, 2011 8:48 pm
There appears to be an issue with the original Scenery bgl file that contains PANC.

If one tries to select PANC as a Tower Controller, one ends up being in Lake Hood's Tower (LHD). So it is not possible to be a Tower Controller at PANC, operating from the Tower.

There appears to be an issue with "Lake Hood", or the original Microsoft Compiling of this BGL.. not sure which at this point.

Removing "Lake Hood" enables Tower Control at PANC.

(Curiosity might get the better of me, to try to determine what was wrong, but I am not a "Scenery Guy", so its all a new world to me).

Are there any plans to update any of the P3D scenery BGL files, either to correct flagged errors, or to bring the data more up-to-date with current Real World data ?

A lot of real world Airports have changed since FSX locked in the Airport data, some time before the release of FSX.


Posted: Tue Jan 11, 2011 12:50 pm

I am getting deep into this... and am curious as to what is going wrong here .. maybe it can be fixed by us. (or at least we can do some of the work to determine what needs to be corrected) ?

What are the chances of getting a copy of the original XML file, that got "BComp.exe" compiled to produce the BGL containing PANC ??


The XML that "we" can produce from a Bgl, would appear to be missing decoding some of the bgl content, as the resulting BGL generated from that XML is significantly smaller than the original one.


Posted: Tue Jan 11, 2011 1:21 pm
by N4GIX
Geoff, I opened both the FSX and P3D versions of PANC in ADE9X and see that the Tower freq is listed as 118.30, which is identical to the FSX version.

FSX file is 08/12/2006 253KB

P3D file is 02/10/2010 253KB

The same file size is a pretty good clue that they are at least similar...

Posted: Tue Jan 11, 2011 3:04 pm

Yes, they appear to be the same, and the PANC / "Lake Hood" issue is present in BOTH FSX and P3D.

To see the Issue, you need to attempt to be a CONTROL TOWER at PANC.

You can do this several ways, the simplest being to host a MP session as a Tower Controller, and try to set your Location to PANC.

You will find that even though you select PANC, when you leave the selection menu, P3D will indicate that you are really a Tower Controller at LHD

When you enter the Tower, however, you will find that the Tower is LOCATED at the Correct Position, as PANC tower, but it will think that it is LHD Tower, with LHD Frequencies, and the MP session that you are hosting will indicate that the Host is at LHD !!

REMOVE aiport LHD from the Afcad, and everything works as expected. If you select PANC, you will appear to be at PANC.

I am thinking at this point that there is something very wrong with the AFCAD. If you convert it to XML, and the try to compile it again to bgl, it report a duplicate runway error at LDH. Even after correcting that, so it compiles, the PANC / LDH confusion still exists.

Being my first time, delving into bgl files, I am somewhat lost. There is obvioulsy something wrong, as demonstarted above, but what is causing it still remains a mystery to me.

Anyone joining the session, as another Tower Controller at PANC, will also find they are at PANC, but with LHD info, LHD freqs, and indicating to everyone that they are at LHD..

End result is, that one cannot be a Tower Controller at Anchorage ( PANC ).

One has to wonder if this is happening elsewhere, with other airports.

Why LDH has a TOWER is strange. Its a WATER Airport. Its Tower is PANC. Maybe this is the cause of the problem. There is a Control Facility called "Lake Hood" Tower, with a Freq, and an ATIS, but in real life, it is located in the same physical Control Tower that is PANC Control Tower.

In trying to program this into the bgl, it seems that the TWO Tower Facilities are getting Mixed up.


Posted: Tue Jan 11, 2011 3:44 pm
by Orsor
Geoff - thanks for reporting this issue.

I am going to take a closer look at the 2 airports and question and see if I can figure something out.

Sounds like the PANC control tower view is associated with the wrong airport - LHD in this case.

I wanted to confirm that you said if you removed LHD than it works correctly?


Posted: Tue Jan 11, 2011 9:10 pm
Orsor -- thank you for picking up on this one.

That is correct. When I removed LHD completely from the bgl file, then the Tower Control was reported to be correctly at PANC, with the PANC frequencies.

If I just "edited" LHD, then that did not result in correct operation.

Note: When I say "removed", I mean converting the bgl to XML, editing the XML, and then recompiling back to blg. ( as opposed to adding another .bgl in order to attempt to remove the LHD airport ).


Posted: Wed Jan 12, 2011 10:30 am
by N4GIX
Oh, I see what you mean now. I set up a "Tower" scenario years ago when it was first described by (whoever it was) from ACES, but only played with it a few times as an observer so I could watch AI traffic.

I must say that I was pleasantly surprised to find that by simply editing the paths in ADE9X to point to the ..\Prepar3D folder rather than the ..\FSX folder I was able to load PANC! :)

Now I wonder what would happen if one were to use ADE9X to remove the tower from LHD entirely? It may well be that the attempt to link the two airports via a common tower is what is confusing the sim...

Also, keep in mind that all BGL "tools" are based on "best guesses" because there has never been any official SDK for that format provided by MS/ACES, so it's very possible that there are mistaken assumptions that've been made...

Posted: Wed Jan 12, 2011 11:37 am

Yes, if one REMOVES airport LHD, then one can spawn in, and appear to be in, the PANC Tower.

I assume it can be FIXED .. Orsor says he will look at it.

The question then arises, if it can be fixed, what good is the fix if it does not become parts of the official release of P3D. The whole subject of Scenery/Nav updates is very complex, as existing scenery additions may be based on the current, out of date scenery etc.

I am hoping that these type of updates might be seen to be more managable in the P3D environment, as a given P3D solution would typically be installed & run in a closed environment. Compatability with other system, with different scenery build, might not be so important. IF a given solution wants to update scenery, it can do that update across its own solution, and that will not impact on anyone else.

In FSX, the problem is more far reaching. For example, I can fix the PANC issue on my MP server, with a scenery update, but that does not do any connecting players any good, if they do not also install an update.

You have only to look at an environemnt like Vatsim ( FSX, FS2004, Xplane and each one of those with potenetial scenery updates). Virtually eveyone flying on Vatsim, is really flying in a slightly different world .. some have the latest new runways added, other are still simulating the world, as it was back in the 90's.

This may be reluctantly acceptable in a Gaming environment, but maybe not in a Commercial simulation environment.


Not having a SDK for the BGL format, is highly restrictive. I hope that Locheed considers addressing this, now they are supporting a Commercial Simulator. Either by producing a SDK, or a full bgl de-complier, that produces XML that can be re-compiled with the SDK's bglcomp, to produce an identical bgl file as the original.( or at least one that contains "ALL" the original data ).


Posted: Fri Jan 14, 2011 12:17 pm
by Orsor
Good news, I fixed this on my machine, I think you should be able to as well using any airport .xml editing tool.

It seems as if the root problem is that the Multiplayer ATC chooses incorrectly when placing the special tower "cockpit".

In the case of PANC and LHD, the LHD ARP (airport reference point) is actually closer to the PANC tower, than the ARP for PANC and it seems to choose based on that.

So I edited the airport .xml for PANC to move the ARP point to be the PANC tower location.

When I launch a MP session now and choose ATC at PANC it tells me I'm at PANC now, not LHD.

Let me know if this works for you. This a good find, and we should be able to design tests on new airport data to prevent most of these cases in the future.

Thanks Geoff!

Posted: Fri Jan 14, 2011 1:36 pm

Thanks for the feedback. Yes, I can edit the LHD ARP on my system, and that will fix it for me.

(Sorry, this reply has GROWN, to be somewhat longer than I ahd expected, when I started typing)

But what is the longer term solution ?

How will these corrections be addressed in the future ?

There was never any corrections issued my MS for FSX.

Will future versions of P3D, contain fixes, or will the bgl file set remain fixed, or will there we additional bgl files to fix existing ones ??

Has any though been given to this, or how systems can be updated in a consisten way in the future.

As a GAME, FSX's geographical, airport, and Nav data was "Frozen in time" at some point back during early development of FSX. While that might have been acceptable for a GAME, if P3D is going to be used as a Commercial Simulator, I suspect there is a strong desire to have the simulator match, as closely as possible, current real world data.

New Runways, airport layout changes, frequency changes, old fixes no longer used, new fixes being generated ... if P3D going to make any attempt to keep up with these changes, or will it continue to use an aging dataset. ?

Proably early days to have made too many decisions in this area, but anything you are able to share, would be appreciated.

BTW. What actulaly determines the ARP. Is it a MS FSX/P3D made up position, or do airports have a documeneted real world ARP ?

Finally, you say you EDITED the .xml for PANC.

We do not have the luxury of the original XML for PANC to edit & bglcompile.

All we have is "unoffically" decoded XML, from the .BGL file, that may, or may not compile corectly back to contain all the data from the original .bgl

I believe all currently available "unofficial" bgl decoders, do not extract model info, to be re-compiled back into the .bgl.

Have thing progessed to a state where the .bgl format can be officially released in a SDK, so that developers can stop wasting their time, trying to guess at the format, and base their work on a standardized format, that follows a released SDK.

This might also help to eliminate such oddities, and inconvenineces, like :-

If a Control Tower is removed by an Addon Scenery afcad, and a new Tower is Placed at the airport, then when loading in MP to the Tower Position, the loading process hangs, require one to press ESCAPE to continue the loading process.

Can you enighten us as to waht may be happeing in this situation ?


Posted: Fri Jan 14, 2011 2:18 pm
by Orsor
Hi Geoff,

The ARP is a documented feature of any airport, and comes with the Nav data.

I agree with many of your concerns regarding the future of upgrading airport / nav data and assure you we are working to come up with the best plan. Unfortunately it really is to early to talk about specifics.

I can tell you that now that we known of this particular issue dealing with ATC, that we can design tests to find these and fix them before the next release.

I will have to investigate your last issue next :)

Posted: Fri Jan 14, 2011 2:20 pm
by Legacy Support

Rest assured we are looking at the underlying data update requirements for real world navigation amongst other items. I don't want to give the impression that we are happy with band-aid solutions, we are simply reacting in the forums to issues as they come up, which has a great side benefit of helping to identify areas that need to be addressed. At the same time we are looking at the strategic architectural issues that commercial simulation users require for their systems(such as Lockheed). I am hoping that when we get the current planning cycle out of the way, we will be able to provide more detail on the roadmap.


Posted: Fri Jan 14, 2011 2:41 pm
(deleted by author -- )

Posted: Fri Jan 14, 2011 4:30 pm

Ok, I have sucessully "Patched" the bgl for Anchorage (Panc), to make the ARP for PANC, closer to the PANC tower. ( Actually same lat/long).

Now works as expected. Thanks for pointing me in the right direction.

Cheated, I guess, Hexedited the two Dwords (ARP lat & Long), so the rest of the BGL is 100% intact, as the original. That way did to have to deal with de-compile / re-compile issues.

How "Legal" is this file now ? Is doing this within the License of P3D. ?

Can I use this edited file, within the License, for developement. ?

Could I distribute it with as part of a fuly licensed P3D solution. ?

Can I share this file with other P3D developers ?

If this edited file something appropriate to put on the P3D download area ?

Would it be more appropriate if you put your copy there. ?

( What I do in the FSX world, and the licensing may be very differrnt, but that is not of issue here in the P3D forum, but it does raise some interesting licensing issues for both products.)


Posted: Tue Jan 18, 2011 7:26 pm
by Orsor
Geoff - we provide the SDK as a means to edit and create your own content for Prepar3D.

Part of this is creating new .xml entries in the Prepar3D .xml schema. so you can modify and / or create new airports.

Since I'm a scenery technician not a lawyer, I'm hesitant to comment on the legality and what you can or can't do with the file, but those are good questions we should get answers for! John may be able to help?