Why are so many of my Navaids 'wrong'?

[martinlest2 58]

It happens depressingly often that ILS landings put me down some way off the centre of the runway, even off the runway altogether. The cockpit instruments close to touchdown show the centre of the localizer correct (although I can see I am on course to touch down in the rough) and when I move the a/c manually to be centre runway for touchdown, they then show me to be off-track.At first I thought this was due to the odd faulty AFCAD, and usually by dragging the Navaid away from where it has been placed (using AFCAD2) I can usually correct the problem. But this is happening so frequently (not always by any means though) that I can't believe so many AFCADs have been uploaded with a navaid 'error'.Can anyone suggest something else that may be wrong with my setup (FS9), AFCADs apart? It is not specific to any one a/c by the way.Thanks,Martin

[Avcomware 1]

Hi, Martin.Can you give us a specific example? Most of the approaches are not perfectly aligned with the runway centerline, most of the ILSs are. Look it up on the Plate. TV

[Egbert Drenth 250]

Hi,If you are using real life charts, most likely it is caused by shifts in magnetic deviation.FS9 uses a MagDev table that is rather old, and in the mean time the earths magnetic field has shifted. (Hence sometimes runway ID's have to be renamed) So on the updated real life maps the magnetic course is shown correctly, but FS9 doesn't.Besides that if I recall correctly it's also a FS9 bug in some areas, not calculating the magnetic deviation correctly.

[martinlest2 58]

Hi. I did think it may have something to do with the MagDev file - though I would have no idea how to go about fixing it. Probably not possible.The example that made me post in frustration was, I found out after, caused by a devious little bgl file lurking in my Addon Scenery/scenery folder. Deleted that and the AFCAD that came with the scenery (UTAA from AVSIM.ru) works just fine now - at least,I haven't tested it, but the cockpit instruments line up properly now when I sit on the centreline of the runway, so I assume all is well again.But, as I said, this seems to happen all too often and there has not often been a culprit like this stray UTAA.bgl file (decoded down to a scasm file, it contained just NAV/ILS info - wrong, for this UTAA installation at least - no idea where the bgl came from). Next time I find the same thing and can't fix it, I'll post back.Thanks again for the comments,Martin

[scott967 62]

I don't think the magdev makes a difference? The runway and localizer course are both compiled in degrees true. Unless an aircraft is trying to fly a specific course, rather than the localizer centerline."SCASM" or "BGLC" ILS commands such as "ILS" or "ILS2" will override the XML ILS code (default FS9 or AFCAD), and can cause problems when FS2k2 scenery is used in FS9. Among other things this will cause a problem where only the primary end ILS works on dual-end installations using the same freq on both ends. scott s..

[tgibson 11]

As said earlier, the most common reason for this problem is that is the way they are in real life (although there are some in FS that are just plain wrong). But most of these approaches are correct - many of them do not bring you to the centerline of the runway.Keep in mind that (as I remember) FS calls all approaches with GS control (in fact perhaps all localizer type approaches) ILS's - many of them are actually not true ILS approaches.Hope this helps,--Tom GibsonCal Classic Propliner Page: http://www.calclassic.comFreeflight Design Shop: http://www.freeflightdesign.comDrop by! ___x_x_(")_x_x___

[martinlest2 58]

Hmmm. Doesn't make it any less annoying though, does it, when landing in, say, a LVL-D 767, all set up for flare on touchdown, and you then suddenly have to disconnect all AP functions and swing the plane across for a manual touchdown (not always very elegantly when so last minute either!). :-)

[claviermichel 0]

Hi Martin,Magnetic deviation is the primary problem. Deviations are compiled in a bgl called magdec. In FS9 the magdec bgl is totally outdated. It was compiled in March 2003 from datas dated 2001. I do have a newer magdec bgl which was created and compiled on December 26, 2006. Although it begins to be slightly outdated it it certainly better than the MSFS original one. Unless you fly to and from airports which are located further north/south than the 56th parallels you should be pretty safe with this newer bgl. If you want to try it PM me your email and I will send it to you over the week-end.Best regards

[Guest RonB49]

>Hmmm. Doesn't make it any less annoying though, does it, when>landing in, say, a LVL-D 767, all set up for flare on>touchdown, and you then suddenly have to disconnect all AP>functions and swing the plane across for a manual touchdown>(not always very elegantly when so last minute either!). :-)Again, without knowing what airport and runway that you are alking about it is hard to answer your questions, BUT -- most ILS approaches do not support autoland. the proper procedure is to follow the ILS down to a point where you can see the runway, then uncouple the ILS and handfly the landing.R-

[jvile 1]

>Martinlest2>>Hmmm. Doesn't make it any less annoying though, does it, when>landing in, say, a LVL-D 767, all set up for flare on>touchdown, and you then suddenly have to disconnect all AP>functions and swing the plane across for a manual touchdown>(not always very elegantly when so last minute either!). :-)>Both Scott and Tom Gibson gave you some of the correct answers to you question. Lets review the true and the false in this thread.You are flying a Localizer beam. It maybe a ILS (when GS is present) or it may not be a ILS. Many Localizers in real world are offset by as much as 3 degrees from the True runway heading. This is by design at many airports around the world and FS2004 is based on real world design. You seem to think this is annoying but the truth is, it is done in most cases for safty of all the real world souls on board that B767. You said it is not elegent at the last minute when you have to correct. That tells me you are way behind the performance airplane slot curve of the approach to begin with. Go fly the localizer at PHNL runway 26L and follow the Localizer like you want to do and see where you end up on the ground.You the Pilot have the responsibility to read the approach plate and know if the Localizer is offset by up to 3 degrees. Once you know that and look at the plate it shows you at what distance from the runway you must make the correction to align with the runway. Is that a FS2004 NAVAID problem? No.Your question was, "Why are so many of my Navaids 'wrong'?" In most cases they are not wrong but you are flying the approach wrong. Like Tom said, many Localizers are off center by design but a few are mistakes and can be fixed with AFCAD2. When a Localizer with or without GS starts to exceed 3 degree offset we no longer call it a ILS (LOC+GS). It now becomes a Localizer Directional Aid (LDA, PHNL RWY 26L). It sounds as if you want to autoland a airplane which is for a CAT IIIb touchdown which is below the minimums of a CAT I and CAT II landing. CAT IIIb has no mimimum descent altitude only a RVR (runway visual range). A offset Localizer approach even at 1 degree offset can never be a autoland touchdown.Always review the proper approach plate and if the Localizer is offset then know at what MDA and/or MAP waypoint you must turn that plane to align to the runway.DO NOT accept any magdec.bgl where someone says>Hi Martin,>>Magnetic deviation is the primary problem. Deviations are>compiled in a bgl called magdec. In FS9 the magdec bgl is>totally outdated. It was compiled in March 2003 from datas>dated 2001. >>I do have a newer magdec bgl which was created and compiled on>December 26, 2006. Although it begins to be slightly outdated>it it certainly better than the MSFS original one. Unless you>fly to and from airports which are located further north/south>than the 56th parallels you should be pretty safe with this>newer bgl. If you want to try it PM me your email and I will>send it to you over the week-end.>>Best regardsMagnetic Deviation in FS2004 has nothing to do with a Localizer that aligns to a center line or is offset to a runway. That is done with the large Green triangular symbol (green feather) as seen on the GRID of AFCAD2 at the end of a runway. By the way, UTAA did not come in the Stock FS2004 with any Localizer or ILS type runways. If you have a AFCAD2 with these type precision and non-precision runways then they where added by someone. If that someone offset the Localizer then the approach charts showed it that way or they made a error when adding the Green feather. Adding a any type Localizer or ILS to a runway with AFCAD2 does not add the approach portion to the ATC Engine database. The FS2004 controller does not know a ILS is present and will not instruct you the Pilot or the AI Planes to fly a hard coded XML IAF/FAF and hard floor approach.The Magdec.bgl is one small portion of the overall FS2004 code and changing it destroys other working parts of a airport. The Magdec.bgl is back dated but holds the Isogonic line data for the world mag divations from true north. This is the data that your wet compass uses and you set the DG on the airplane panel to the wet compass. Without this file your wet compass would always point to true north instead of magnetic north regardless of your position in the world. If you really want to get down to the exact Science no compass points to true or magnetic north, it points to magnetic south. Magnetic lines of force have direction based on whose theory you adapt to (right /left hand rule of thumb). Today many Pilots fly with more precise NAVAIDS that FS2004 does its very best to make realistic including the wet compass and its behavior (magdec.bgl). Many of us started flying 50+ years ago and we had to understand our key navigation direction instrument which was the wet compass. We were taught the lead /lags based on a compass spinning and dipping, what part of the world was the actual mag divations we were flying in, where were the constant shifting Isogonic lines, what way does a compass really point, what rules the direction of the lines of force, and what theory is taught for postive particles based on Benjamin Franklin or Neils Bohr. As pilots we were taught Neils Bohr theory.When you are inside your User Airplane every heading including Shift Z is based on a Magnetic North value display. Outside the User Airplane every heading seen with Utilities is based on a True heading with no Isogonic line deviations.The AI Plane does not have a Pilot that can set the DG to the wet compass. The AI Plane uses certain attributes in the XML to guide the plane around in the sky and on approach. The AI Plane uses in those coded XML attributes the back dated magnetic offsets and the True headings based on what part of the approach we write. If someone tampers with the default magdec.bgl, then they also have to rewrite as a simple example all the missed approach headings (1000's in the database) that AI Planes are coded to fly. The GPS reciever line draw can become destorted and not track the runway properly. This will start to cause AI Planes to turn the wrong way if they go around or your User Plane to off track the published missed approach. Like I said this is just a simple example and many examples of corrupting approach code occurs when the magdec.bgl data no longer agrees with all the XML coded data which is both True and Mag headings.

[martinlest2 58]

Thanks a lot for the replies, especially Jim for taking the trouble to write so extensively.Although I have been using FS for several years and consider myself an expert in SOME areas, there are obviously other areas where I have many things to learn (must be the same for most people!). Some of this is fairly new to me, I freely admit. For instance I do not really see what I am supposed to do in order to "review the proper approach plate" - as I have never come across the term 'approach plate' before.. What exactly am I supposed to be reviewing on the instruments?In clear weather all this is less of a problem but I do find it hard to predict where I am going to touch down in strong crosswinds as the a/c is obviously crabbing its way to the threshold in any case. That's when things can become less than elegant at the last moment.I did update the FS9 magdev file (possibly from AVSIM??) some time ago, but as far as I can see this has made no difference to the 'wrong' navaids (and that's why I put wrong in inverted commas - they are probably not incorrect as such at all, as you say Jim, or to where a/c decide to touch down.I do realise by the way that I am not going to be able to autoland at just any airport of my choosing - I only use the this when available in the a/c I am flying (like Level-D) and at airports I know support it.Whatever, I will have to do a bit more research on this, based on Jim's reply perhaps. Unfortunately I am just preparing to go abroad for some months, so this is perhaps not the best time for me to be spending hours with FS9, but I will save this thread to my PC and review it all when I can (any any further comments that get added).Thanks again for your time guys,Martin

[RFields5421 1]

This is an approach plate - for the CATIII ILS RWY 19R at KMCI - Kansas City Internationalhttp://204.108.4.16/d-tpp/0806/00780I19RC3.PDFIt tells you the IAF, which headings you must fly, what altitudes you need to be at when you cross intersection checkpoints, where the missed approach holding point is located.And a lot more.Now there is a little bit of an issue with using this plate and an aircraft like the Level-D with an updated FMS database.Flight Simulator 2004 is a October 2002 world with Oct 2002 navigation data.It is possible to update individual airports approach databases. Jim is one of few people who can do so correctly.Adding a localizer and a glidepath to an airport with AFCAD or another scenery design tool does not add approaches.This approach isn't too bad because it is still very close to the FS2004 approach - but at some airports your FMS will have frequencies and other data which does not match the FS world.It may match the real world, but not the FS2004 world.I'm lucky enough to have a complete Jeppsen US and Canada set from 2004, which works great. I also have the DOD Supplement for the major airports of Mexico, Caribbean, Central and South America.I have the FS2004 version of SimPlates which works great for much of the rest of the world - yes the data is old but it matches FS2004 very well, and also works very well with FSX - which has a data date of April 2005.Most US approach plates can be found from links on www.airnav.com under the airport. Many non-US approach plates can be found from the Vatsim regional sites.Approach plates and charts are the road maps of the FS world. I'm sure old pilots like Jim cringe at the lack of awareness of the surroundings which Flight Simulator trains into us pretend pilots.FS makes it too easy to stay completely inside the cockpit and never look out the windows. FS makes it too easy to be surprised by things like terrain. Too easy to not understand how to fly a proper missed approach, too easy to get disoriented with where the aircraft and the airport are in relation to each other.One last thing, this was taught to me my another old pilot - your goal when you approach the runway is not a smooth landing. Your goal is a successful proper missed approach. You must be ready to go around, including knowing the proper missed approach procedures programmed in to FS2004, every time you approach a runway.If anything is squirrley about the landing, go around. On the second approach you will know if there is deviation and be ready to turn off the autopilot and land correctly with having to make large last minute changes.I would also suggest you spend a little time in the default C-172 at a big good airport - KLAX, EGLL, EDDF, LFPG, RJAA - and manually fly the ILS to landing. Get comfortable that you can follow the ILS in that aircraft. Then fly some in the King Air, and later the default B737. Then work on your B767.A couple hours a night for a week will build your skill and comfort level tremendously.When I get a little money together and can afford to have a real instructor take me out in a real Cessna - that's a large part of what I do - manually fly an ILS.

[martinlest2 58]

Yes, thanks. Arrogant as it may sound though, I don't think it's really my skill that needs building in this instance (not that I couldn't do with more practice in plenty of different area in FS): as a bit of an 'FS Nut', with quite a lot of free time on my hands when in the UK, I already spend probably an average of at least 3-4 hours a day - and every day pretty much, on FS9. Any more time and my family's going to abandon me altogether!As such, I've flown ILS into most of the major FS airports by now, usually in 737s etc., but sometimes in light aircraft - and most times things go just fine. That's why I wondered whether FS was at fault when things go wrong (although I am not saying I am beyond completely goofing the odd landing of course!): if I can get my landings right at most airports, most of the time, why does this happen at certain airports, and at those, all of the time (until I tweak the AFCAD)? Surely some of the blame must lie with the software, not with the pilot (???).I should say that I rarely fly into default FS airports - mostly because the scenery etc. is so dull/uniform once you're there. Landing at say, UK2000's EGLL, with Aerosoft's AES and so on, is altogether a different experience. It could be therefore that some of the problems stem from 3rd. party sceneries I have installed. And also perhaps, as you suggest, my maybe slightly unreal expectations of how all these airports should perform.I also fly real-world sometimes by the way (props only of course), but never get to practise ILS technique as none of the airfields I land at have it. If I could get permission to land at Heathrow, just for the practice you understand, I'd be a happy bunny, but it just ain't gonna happen, needless to say! :-)Thanks again for the input..M.

[martinlest2 58]

... in fact, I can see Heathrow clearly from where I fly (my usual airfield is EGLK). Very tempting sometimes to head over to have a look, but my killjoy instructor won't let me! :-)

[RFields5421 1]

That's one BIG advantage of flying in the US.The ILS is always on and always available. We have untowered airports with ILS at KHQZ and KGYI (F39 in FS2004) plus towered airports at KTKI, KGVT, KDTO all within easy flying distance of KADS.Though coming back to KADS, I have to fly a visual with a 90 degree turnfrom base to final within the last mile - because there are always bizjets on the straight in approaches which match the ILS.