Inaccurate localiser

[Guest folli]

Hello all!I am new to PMDG747. Just tried a flight but encountered a weird problem during approach and landing. The 747 had successfully captured LOC and GS. But indeed the LOC did not lead to the center of the runway, even it showed as centered in PFD! I let it do the autolanding, and finally it landed on the grass at the side off the runway. The runway grid showed as centered in PFD as well right before flare. But in fact it was displaced (~30m i think). Any hint on this weird behaviour? I have attached a pic that could better describe it. DaveWin7 x64FSXPMDG747 v2.1AIRAC 10083D Light RefluxREX 2.0 OD

[Turbine777 13]

Hi Dave, Please sign your posts with full name per forum rules, thanks.What airport is this and runway? There are a couple reasons this might be, one of which is normal for certain runways that have obstacles or other reasons it may be offset. Have you checked the chart? If able that is.Another reason would be the afcad is bad but again, we need the airport and rwy to better assist you on this.Oh, almost forgot, is it an addon scenery? That could also do it.I have run into this a couple times myself but it's normally the 1st thing I mentioned and offset on purpose.

[Ioan92 63]

Some FSX airports are known to have FUBAR ILS apps.Examples are Venice and Domodedovo coming to mind.Just go manual when that happens.

[Turbine777 13]

It's a little funny but the very 1st post I did in this forum (ok maybe second) was about this problem. I believe it was Dan Downs, or a few people that pointed out the 1st thing I mentioned above and was actually that way in real life. Since then I have found a few airports (runways) in FS that also ended up being actually correct but again, you need to actually look into it rather than writing it off. If it is just a goof, then it's not that hard a fix but like Blidariu mentioned, go manual or always be ready to go manual because it can be easily missed. I actually just did a flight this morning from KBUF to KDFW (The new FSDT KDFW) and 17R brought me in at a very noticable angle so I took control much earlier than I was expecting to. I'm going to do a shorter flight later to check it out when I get home.

[Guest folli]

Thanks all for the reply. The airport is ROAH. No add-on scenery installed for the airport, just the default FSX airport.Here's the chart for ILS36 approach that I used, is there anything I missed out? ROAH ILS36 chartDave Chan

[Turbine777 13]

... is there anything I missed out? ROAH ILS36 chartDave Chan

Yeppers, it's offset, have another look.You will see in the center "LLZ OFF SET 0.63º". That doesn't sound like much but you will just touch the threshold most likely but of course maintain the angle and keep that momentum and deviation, thus end up mowing the grass without manual control. Also look at the LLZ position off to the side of the RWY.

[Ioan92 63]

Yeppers, it's offset, have another look.

Is there an offset for JFK's 22R or left?I once went there and that found out I was really off, heading into the terminals. I just thought it was a strong crosswind but i didn't trust the land 3 app so i went in manual.. landing was almost sideways.

[Turbine777 13]

That's the one I actually questioned haha. It was 22LEdit: Nope I don't think it was 22L after all, or JFK for that matter, I think is was KBOS. So had to be 22R or 15L.Something else to look out for and use is sidesteps. Even FSX default ATC will offer sidesteps on some occasions. I actually just recently saw it for the first time not too long ago.

[Guest folli]

Oh! is that in the box "LLZ OFF SET 0.63'" meaning the localizer is being offset 0.63 degree?Thanks all! learnt a lesson!

[Ioan92 63]

Hah! I can say I've learned a lesson too!:)

[Turbine777 13]

Believe it or not, most of what is often mentioned as an AFCAD issue or FSX'ism of this type I often find is the offset. It was one of the biggest lessons I learned here and fascinated me that simmers knew that much about it haha. Of course now I know most of these peops credentials and probably why I still hang around.

[Guest folli]

I looked more carefully on the chart, it seems that the LLZ is offset to the left of the rwy 36. But I turned out getting offset to the right of the rwy. Can I say it's just intended to show "there is offset", regardless of the direction of the offset?Just one more thing, i suppose the G/S is correct and I can still manually following it while adjusting the direction on my own. is that right?

[Turbine777 13]

Yes, you can still follow it for sure. It's meant for you to, but only down to DH I would think. As to your other question that's weird. I thought it was depicted accurately but really don't know.

[scandinavian13 5,192]

I'm guessing whoever wrote the file for this airport adjusted it to the wrong side. There are a ridiculous amount of airports in FSX, and there are bound to be incorrect entries. To drive the point home, even the FAA messes things up on occasion. KBCB has an incorrect picture on its approach plates (the airport layout is not correct).Here is the approach plate - look at the bottom right:http://204.108.4.16/d-tpp/1010/05475LD12.PDFHere is an aerial view - note where the taxiway 'dodge' actually is:KBCB Sat ViewIt's not a huge deal, but you'd think the FAA would be all about the details...As far as the following the GS goes, you should be at or above the GS as depicted by the instruments or the approach lighting - whichever one you use is up to you. Often, at least in the US, you'll see a note on the chart that says "VGSI and ILS glidepath not coincident" (instruments and approach lighting don't show the same glidepath), which is why I point that out. The bigger question, to me, is why you'd continue to follow this instrument approach when it's severe clear. While it's true some pilots use the LOC even on clear days to align them, if it's not going to help you align yourself, there's little point in using it. If it's visual, let the AP turn you inbound and then disconnect and fly it in yourself. Builds character...DH is really the point at which the decision must be made regarding the continuation of the approach. If you see the "runway environment" you may continue. When the AP must be disconnected (altitude-wise) is governed by a different section, although somewhat related (for Part 121 carriers, specifically: 121.579), which states the altitude must be more "than twice the maximum altitude loss specified in the Airplane Flight Manual for a malfunction of the autopilot under approach conditions, or less than 50 feet below the approved minimum descent altitude or decision height for the facility, whichever is higher."This specifies that the AP must be off, but not that you must follow one method of vertical guidance over the other. I'd argue that you should keep your head up and out and on the VASI as early as you can, however.Kyle

[realpilotsimpilot 11]

If I recall, one of the worst offenders for FUBAR ILS/LOCs is YSSY, which isn't anywhere close to accurate.