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Thunderbird8

Where Does The Sim (747x) Read Ils Bearings From?

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I did my first proving flight in the 747 in FSX recently and I'm pleased to say it went very well! I'm looking forward to flying this wonderful piece of kit. I also found the TO/GA 'screw' after a bit of searching! My question is this; does the sim read ILS frequencies and bearings from FSX itself or from the AIRAC data in the FMC? The reason I ask is that my ILS approach and landing (at EGTG RW09) was a little off-set to the left (by no more than one or two degrees) and I know that whatever the real world or AIRAC datum (I have the latest from Navigraph), to land correctly in FSX you must adhere to the FSX runway bearing. I learned this the hard way using the Level D 767 and having to manually enter the ILS bearing in the Pedestal (anyone who has done this will know what I mean). It's annoying when FSX gets the runway bearings wrong because you have to use them. I suspect there is a conflict between the AIRAC and FSX but can someone shed any light?Thanks. Duncan

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ILS freq/crs is from the navdata file wpNavAPT.txt, but it is a moot point since once you have captured the localizer it will fly whatever course exists within msfs. I think the only thing approach course does is rotate the HSI approach display on the ND when in APPR mode. In other words, if the 747 CDI is centered on the localizer then the default C172 in the same location will also have a centered CDI (course deviation indicator). A localizer only has one course, not at all like a VOR, which has 360 "courses." and the localizer is in msfs.The msfs navdata is quite obsolete, but they don't provide an easy way to update navdata. An AFCAD editor will do it.

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ILS freq/crs is from the navdata file wpNavAPT.txt, but it is a moot point since once you have captured the localizer it will fly whatever course exists within msfs. I think the only thing approach course does is rotate the HSI approach display on the ND when in APPR mode. In other words, if the 747 CDI is centered on the localizer then the default C172 in the same location will also have a centered CDI (course deviation indicator). A localizer only has one course, not at all like a VOR, which has 360 "courses." and the localizer is in msfs.The msfs navdata is quite obsolete, but they don't provide an easy way to update navdata. An AFCAD editor will do it.
Thanks for the reply. I think I have solved the issue by going into the PMDG file within FSX and into the sidstars file (or is it starsids?) and changed the runway ILS bearing (E.G. for Ediburgh, it would mean changing it from 243 to 244 degrees) in the text file to make sure it is the exact same bearing that is in FSXs memory. In my system, I can confirm, that unless this is done the aircraft will not follow the localiser correctly and the aircraft (e.g. when auto-landing) will be off to the number of degrees of the discrepancy. Odd, because it doesn't happen to everyone. What I will need to do is check for any airport I intend to land at. I have Vista 64 Business running by the way. It's a weird thing and many of you reading this won't have this issue, but some do... :(

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Thanks for the reply. I think I have solved the issue
Dan, I apologise for not reading your post properly. I went into the wrong file to amend the data. Will report back.EDIT:OK, here is where I am. The aircraft is tracking the ILS at 093 degrees as you will see on the attached pictures. The runway centerline however runs at 094, so from the pictures you will see that I am going to land a bit off. Which I did. I have changed the file in the aforementioned Navdata file to the correct (FSX) bearing, and I have also changed the sidstar file. As you can see from the pictures the ILS on the FMC is reading 094, but from the ILS NAV display you can clearly see that the aircraft is not tracking the runway centreline. I have poked about on the net and seen this problem mentioned but no solution so far! Please help as it's very frustrating.

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Interesting.I am in slew mode with a C172 on Ry 09 at EGTG, using GO TO AIRPORT to be put in the starting position (which generally lines you up with the runway). The MAG heading set at the starting point is 092 and localizer is centered. I can slew backwards and forwards with out changing heading and stay on the localizer centered dead on, and the MAG heading changes between 92 and 93. So from this test I conclude the runway and the localizer are 092. Open FSX Map and click on the ILS symbol and it says it is 093 degrees. I try slewing at 093 deg instead of 092 and no way does it stay on localizer, so I conclude that mag variation (in FSX world) is right on the borderline here such that a constant true course will be read as either 92 or 93 degrees. Okay, so far so good.Now I check navdata Cycle 0813 for EGTG Ry09 expecting it to be something different based on your complaint but it too indicates 093 for the ILS course. The puzzle is why you think the localizer should be 094? Where does that come from?So I check the current chart at Eurocontrol and the ILS course is 093. Okay, now I have three sources all in agreement within 1 deg, and even within FSX that one degree can be due to mag var within the area.I don't see a problem.In this case both navdata from Navigraph and current chart from Eurocontrol agree and FSX is only off by one degree which can be explained by mag deviation variations.Help me out here.

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Interesting.The puzzle is why you think the localizer should be 094? Where does that come from?Help me out here.
Thanks Dan, I will gladly help you out. For me, in the FSX map screen (at least, the version I have, with SPs 1 and 2) the runway heading as far as the ILS is concerned is 94 (it's 274 the other way)! I cannot post a screen-shot of this right now but I happily will tomorrow if you wish me to confirm it. The add-on scenery I am using for EGTG is the Gary Summons Airports for the south of the UK which many people have and is a mainstream commercial payware product, but just in case I checked at Edinburgh (default airport) and I get the same one degree discrepancy there too. Hope this helps. Duncan

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That is interesting. I also have SPs 1 & 2 and we have different ILS courses. Never expected that. No screen shot necessary.The key point about the ILS course is there is only one course, and it is in MSFS not PMDG. The PMDG simulation "tunes" the nav radio and flys the localizer regardless of selected course.I have seen problems where the ILS did not lead to the landing zone, and this always turns out to be an add-on scenery that messes up the mag deviation. In your case, I assume the 747 is landing on the runway. What is one degree between friends?

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I wanted to check something, so I added 45 deg to the ILS course in wpNavAPT.txt navdata file. But as you see in the attch photo, I am still on a 093 final course. Apparently, the ILS course in the navdata file does not mean much. I have to play with this a little more to fully understand what is going on.Regardless, I am right on runway centerline, land just a few feet right of the centerline and the localizer needle stayed centered all the way down. Interesting.

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I wanted to check something, so I added 45 deg to the ILS course in wpNavAPT.txt navdata file. But as you see in the attch photo, I am still on a 093 final course. Apparently, the ILS course in the navdata file does not mean much. I have to play with this a little more to fully understand what is going on.Regardless, I am right on runway centerline, land just a few feet right of the centerline and the localizer needle stayed centered all the way down. Interesting.
DanThanks for your continued assistance on this one. I have had an idea that I will test later and get back to you. What if the software developer of my addon scenery used the proper centerline? That would be (I think) 92 degrees and would in fact explain why the erroneous tracking was left to right, rather than right to left. It would not however explain why the FSX map still shows 94 degrees. I woke up during the night and thought of that! Very sad I know... Will report back ASAP! Obviously this does not explain why the default airport at Edinburgh was off too. But at least it might solve one thing.

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Duncan,Looks like a registry problem to me.Please apply the FSX/FS9 Registry Repair Tool.It can be accessed via this link as mentioned in the pinned subjects above:http://www.flight1.com/view.asp?page=library Almost sure it will help.Regards,Harry
HarryThanks for the message. I will persevere with my theory and test it to check if it's true first though. I have never heard of the registry repair tool. What does it do exactly?

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Hello Duncan, [ I will persevere with my theory and test it to check if it's true first though.] Wonder if that will solve your offset Localizer tracking, but of course... give it a try. [ I have never heard of the registry repair tool. What does it do exactly?]It's mentioned in the 'pinned' items, relating to FS9 registry problems.However this little program can also be used to fix FSX registry where needed.Looking at your screenshots I see that the AP is not tracking the LOC but flying offset to the runway.The Localizer deviation signal is correctly indicating your position relative to the runway centerline.This indicates to me that runway and localizer are well aligned.My experience is that this situation is caused by a registry bug, that can be 'repaired' using mentioned program.Take your time to try it.Regards,Harry

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Some FS functions and add-ons get the path to the FS root directory from the declaration in the registry. If it is incorrect, which can happen if both versions of FS are installed, the wrong set of various data files is accessed.This tool sets an ambiguous definition to the path you specify. This happened to FSX beta testers who returned to FS9. Since I'm not an FSX user, I do not know if separate declarations are now used. Anyway, give it a try just to insure the entry is correct.

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Okay, after much testing the definitive answer is that the PMDG FMS programs (737/747/MD11) read the ILS course from the navdata wpNavAPT.txt file, but it uses the runway heading field only (it ignores the ILS course field, for explanation of fields see: http://ops.precisionmanuals.com/wiki/NAVDATA_Data_Dictionary ).Also, an importantly, the A/P will fly the ILS localizer course that is a part of the airport scenery (changable with an AFCAD editor) regardless of the information provided in the navdata. The only impact that a course value in navdata that is not the same as the course data that is in the scenery is the APPR mode ND will be rotated. The attached photo illustrates this quite vividly where I am on approach to KMEM 18C and the scenery localizer course is 177 and I have modified the navdata localizer course to be 200.As for folks who find their PMDG aircraft is tracking off course, please look for the problem in a scenery add-on that corrupts either the magdev.bgl data or the msfs registry information. In the past couple of years that I've been immersed (too deeply) in this hobby the problem has always gone back to scenery add-ons.By the way, the screen shot is the FS9 MD11:

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Okay, after much testing the definitive answer is that the PMDG FMS programs (737/747/MD11) read the ILS course from the navdata wpNavAPT.txt file, but it uses the runway heading field only (it ignores the ILS course field, for explanation of fields see: http://ops.precisionmanuals.com/wiki/NAVDATA_Data_Dictionary ).Also, an importantly, the A/P will fly the ILS localizer course that is a part of the airport scenery (changable with an AFCAD editor) regardless of the information provided in the navdata. The only impact that a course value in navdata that is not the same as the course data that is in the scenery is the APPR mode ND will be rotated. The attached photo illustrates this quite vividly where I am on approach to KMEM 18C and the scenery localizer course is 177 and I have modified the navdata localizer course to be 200.As for folks who find their PMDG aircraft is tracking off course, please look for the problem in a scenery add-on that corrupts either the magdev.bgl data or the msfs registry information. In the past couple of years that I've been immersed (too deeply) in this hobby the problem has always gone back to scenery add-ons.By the way, the screen shot is the FS9 MD11:
DanThanks again, however I have noticed the problem with default airports too (e.g. Edinburgh). Will that registry fix program people have mentioned fix that do you think?Duncan

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