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GOLF

Runway ILS heading and heading indicator don't match?

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Hi guys,I'm trying to learn the proper way to conduct ILS approaches. To determine the proper runway heading, I check the ILS heading off of the world map and then use this heading for the ILS approach.However, this heading rarely appears to match my heading indicator on the plane. In experimenting on the ground, if I move my plane from airport to airport, the starting heading (e.g the heading lined up with the runway) rarely matches the ILS heading given in the world map. Sometimes its +3, sometimes its +1, sometimes its -1 or so. Occassionally it is correct. Am I doing something wrong with my instruments or is there another way to determine the proper heading for the runway? Its a bit frustrating in 0 visibility to have no idea which way the runway is truly facing!

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Well, runways headings are rounded down (hence they rarely match exactly).Runway 32 could actually be 324 magnetic. Or 316.You are doing it right.

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To provide a little more detail:Suppose I want to make an ILS landing at Cancun (MMUN), runway 12.I check the ILS heading from the world map and find that the ILS heading is 122.However, when I move to MMUN runway 12, my heading indicator actually indicates a heading of 125. Thus, I am +3 degrees off of the listed ILS heading.However, at Bridgetown, Barbados, my heading indicator is exactly the same as the ILS heading (which escapes me at the moment).Sometimes my heading indicator will be -1 off of the listed ILS heading, sometimes up to +3. In zero visibility, this means I have no idea which heading to actually fly to intercept the runway (which, incidentally, nearly killed a lot of virtual air passengers last night on a real weather approach to Anchorage)I don't know if the problem is with the map, my system, or a realism setting.

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FS is working correctly. You are seeing the difference between True North and Magnetic North. FS has programed into the sim the ISOGONIC lines as per their release date. Isogonic Lines very over a period of time and are updated in the sim with each release.If the airport is on a zero Isongonic line the True and Mag North are identical.

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Jim is correct.I purchased a disc lesson from KING schools on a Navigation subject and the "True North and Magnetic North" topic was covered. Also on Jeppesen and the FAA Terminal charts the subject is covered as well. It is actually mind blowwing to somone like me that the the ability exsist to have a method of corrodinating the "True North and Magnetic North" numbers. Agian this really is amazing when you read and find that the North Pole "spot" changes. Hey Mt. Everest keeps getting higher each year (I think they stated somthing like an 8th of an inch with new GPS tech. ((Please do not use 1/8th inch as a quote as I am sure I am off a hair one way or the other)) I know that on the FAA web site you can access many articles from there text books:"Pilot's Handbook of Aeronatical Knowledge" code FAA-H-8083-25and"Insturment Flying Handbook" code FAA-H-8083-15 Both are on the web site www.faa.govAlso, I think its great the question you raised. As long as we all remember we cant really know all of the different topics as experts then we wont go crazy when we discover for ourselfs issues like the one you raised here. Remember Pilots have to know much but very few are true experts in all the subject matters that make up todays infomation in Navigation.Lastly if you go through the lessons in FS9 or FSX and make sure you can fly VOR to VOR then go into AK (where there is are often gaps where VOR ranges dont overlap) and you can ADF and NDB in conjunction with the avalible VOR;s and make it, then you are on your way. You must tell yourself thet "if the GPS goes out and the back up GPS goes out "then what". It may seem old and not exciting but will lay the ground foundation of thought processes to apply the newer tech devices. Assuming you what to approch FS in a real as possible framework.With this dont get me wrong. I will time to time jump in a large Boeing and start FS with the jets running and bolt off and try to intercept an ILS and tell myself what the heck. You cant be all business all the time. Take care and I hope the www.faa.gov books help you out. Thank you.Mark.System:OS:MS Windows XP Professional, Ver 2002 Service Pack 2 Hardware:Intel Pentium® 4 CPU 2.802.84 GHz, 3.00 GB of RAM Radeon X1600 Pro 512MB running a 21/19.6 Sony Flat Screen Tubed Monitorand a 17/16 NEC/Mitsubishi Tubed MonitorGeForce FX 5200 128MB running a NEC/Mitsubishi 18 Flat Panel

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Also, if you have gyro drift enabled in FSX, don't forget to check the heading from time to time. It will require corrections.

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Ok, I've done a bit of research on the offsets at some airports around the world.For each, I moved my plane and noted the starting heading. I then checked the listed ILS heading given on the "world map."Here is the difference between my starting heading and the listed ILS heading:Anchorage, AK +4Denver, CO +2Houston, TX +2Austin, TX +2Seattle, WA +2San Antonio, TX +3Miami, FL +1Boston, MA +0Halifax, Nova Scotia +0Kingston, Jamaica +1Martinique +1Barbados +0Bermuda -1Dublin, IR -1Milan, IT -1Athens, GR -1Tehran, Iran 0Hong Kong 0So, my guess (after doing a bit of reading on the matter) is that magnetic north has drifted a bit since whatever date of the airport data FS X uses. I think I can ballpark the correct offset to apply to my ILS approaches given my relative position in the world, I mostly fly Europe, US, and Caribbean so I think these offsets should work. So, for example, if I am flying into Chicago, I will ballpark +1 to +2 degrees to whatever the listed ILS heading is, and hopefully that will work. Does this seem reasonable to those more familiar with ILS approaches?

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This is very confusing.:-( I am finding a few misplaced ILS beacons. Not sure if this is what everyone is talking about.A couple of examples.CYYJ - Rwy 09 - the glide slope lines up directly onto the runway. Rwy 27 - the glide slope lines up about 300 feet right side of same runway. CYQQ - Rwy 20 - the glide slope lines up about 300 feet right side of runway.You can see this problem just by looking at the map view and looking at how the ILS is shown there.Some airports like CYVR with 5 different ILS approaches look perfect.Sure would like to know how to get these beacons back in the correct place as it sure does make for some exciting landings in low vis.By the way, there was no problem with these airports in FS9 so something has changed.

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Golf, this is not the problem I was talking about, though I have noticed it and it is indeed aggravating.What I am talking about is on runways where the ILS is lined up with the runway, if you go to the "world map" and click on the airport to check the ILS heading, often times the listed heading is a few degrees off of the actual heading you will need to fly to connect to the runway. For example, in Barbados, if you fly the listed ILS heading, you will hit the runway, whereas in San Jose, Costa Rica, you must add 2 to the listed ILS heading to line up with the runway. (at least I think this is the case on everyone's, not just mine)As I was flying a low visibility approach to Kingston, Jamaica this morning, I lined myself up on the ILS system and began my approach. Once I found the runway, however, I was lined up about 400 feet to the left. When i visually lined up on the runway (runway 12) my ILS showd the proper glide slope, but showed I was way too far to the right. Thats the problem you are describing, though I haven't encountered it much. Today was the first time as i can recall.

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>>CYYJ - Rwy 09 - the glide slope lines up >directly onto the runway.>Rwy 27 - the glide slope lines up about >300 feet right side of same runway. >CYQQ - Rwy 20 - the glide slope lines up >about 300 feet right side of runway.>Please do not confuse or condem a ILS that does not align perfectly to the center line of a runway. A ILS is a Instrument Landing System and does not always lead you directly to a runway.What you are seeing are offset ILS beams done purposely at some airports and it is up to the PIC to review the current Approach Charts to know where these offsets exsits at.Minimums are normally a little higher when a ILS offset is in use and if the offset goes beyound certain offset degrees then the ILS must become a LDA, SDA, IGS type ILS landing system.Many post continue from time to time to ask these same questions. The reason why you may not have seen these offset ILS approaches in FS9 was because you added a AFCAD for that airport and the author did not understand why the ILS was offset and realigned the Localizer by mistake. Always review the actual approach plate (MS uses Jeppesen for their entire database) before attempting a ILS approach so you are familiar with what too expect.

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An ils localizer guides you to the runway centerline (not "lines you up with the runway") -and can be offset a few degrees. I can't remember the exact number of degrees it is allowed to be offset before it has to be designated an lda/sdf but I seem to remember about 4.If you look at the NOS plates-the part that says "233 degrees 4.7 nm from faf"-the black arrow will actually show the offset-which is of course more obvious on for example a vor approach.http://mywebpages.comcast.net/geofa/pages/rxp-pilot.jpghttp://forums.avsim.net/user_files/164527.jpg

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I can see on VORs I know that FAA only aligns them to mag north only every so often, so they can vary, but I don't see how that would affect a Localizer. It seems you are either aligned to the localizer or you are not. I think the FAA allows localizer courses to be +- 2.5 degrees from the actual runway heading, though I think in general they are set so that at the decision height you are on the extended runway centerline. I'm not sure, but imagine that with Localizers certified for reduced decision height such as CAT III, the track when aligned will be along the centerline. The numbers in the GPS/map view are from the file, while the actual mag heading uses the FS magdec model, but if you are flying the ILS, I don't see why that matters.scott s..

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"What you are seeing are offset ILS beams done purposely at some airports and it is up to the PIC to review the current Approach Charts to know where these offsets exsits at."Can see I didn't understand the original problem.However, although the above statement, "in quotes", does refer to some airports, CYYJ and CYQQ are not one of them. I have the instrument procedure books that contain this information and they both show straight in approaches.I will need to have a look at the magnetic problem though. Looks very confusing.*:-*

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Eek,Now I'm thoroughly confused. I thought the magnetic drift of the pole was the answer. Basically, I simply want to know what heading to fly once I'm centered on the localizer. If I fly the course listed on the ILS hdg in the map, I will end up off the localizer, usually flying to the left of the center line. Sorry to be so dense and thanks for the answers.

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>You have to "bracket the heading" and adjust for the wind.>e.g.-start on the published heading-see where the needle>moves-and then adjust your heading to "crab" into the wind to>keep the needle centered.>http://mywebpages.comcast.net/geofa/pages/rxp-pilot.jpgI was hoping someone would make this point and Geofa finally did.:-)Shot a runway 29 localiser approach today and pattern altitude winds were nearly 90 degree crosswind at 25....my wind correction angle was 15 degrees left of 290 or 275....yet we tracked the localizer just fine. It was a hand full near the touchdown point but was a good learning experience:-)

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Might try real approach charts, and see if you have any better success. They are pretty easy to find for most aiprorts. Here are the charts for CYYJ: http://charts.ivao.ca/CAP2/CYYJ.pdfThis won't help if the game is simply off, but it might help if the heading is off, but the localizer is tracking correctly. Also, as an earlier poster said, always good to study the flight plan (and approach plates) before you take off, so you have a better idea of what to expect, and correct if things aren't going right, upon approach and landing.

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What Golf posted IS the major bug. And Im finding it more andmore. This has nothing to do with offsets or magnetic or true north.Its more like p-poor programming. But this is nothing new, itsbeen prevalent since the days of FS5. I used to fix 'em myselfbut havent done it in a while. Guess I'll have to figure it outagain. Its not a big deal if your flying a GA, youve got lotsof time to correct. But it sure is frustrating if your flyinga heavy and youve been following the gs/loc all the way down,finally break out of the soup 1200 AGL only to find yourself3 or 4 hundred feet left or right of the runway. As he saysyou can look at the map view. But thats not "as real as it gets"now is it ?

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This post has addressed many different issues such as bracket the headingoffset ILS beams magnetic drift of the pole Isogonic Lines etc I had to read the original problem several times before I realized what the issue was.The reason you see a slight difference in the headings is done purposly in FS9/FSX Heading values are read from different sources in FS9/FSX based on where you look. The MAP Mode and GPS read the ILS Approach code heading. USER AIRPLANE reads the RUNWAY and the ILS properties heading (excluding offsets, winds, etc.)I suppose the best exsmple is to show where the values are different then explain why.Here is a typical airport with a Runway 8 and the ILS properties for that same runwayRunway Heading="89.98"ILS says

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I have no experience writing approach code for AI traffic, but...Assuming you mean 26L at Honolulu, the course of 304 is because the approach to that runway is an LDA/DME, ("localiser-type directional aid") and not an ILS. The approach has quite high minima with a late turn of 45 degrees onto the rwy: http://www.naco.faa.gov/d-tpp/0701/00754LDAD26L.PDF FSX accurately reproduces the published approach.The point about Victoria, is that the published approach is not an offset - even slightly (http://www.czvr.ca/_Pilot_Resources/_Charts/PDF/CYYJ/CYYJ%20ILS%20DME%20RWY%2027.pdf), yet the FSX ILS will take you down to a point to the right of the rwy. I have some difficulty accepting that this is deliberate.http://forums.avsim.net/user_files/164677.jpg

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JeffThank you I did mean to say 26L but used that as a example. We are trying to answer the original post question of the 1 to 2 degree difference and not the problem that you see with CYYJ. The 26L LDA approach at PHNL is nothing but a way to help understand that the MAP MODE always reads the Approach data in FS9/FSX and not the Runway Property ILS data (heading). CYYJ is a total different problem and could be another post by itself. Now I don't know why Canada listed the RWY 27 ILS LAT/LON (see current Jepp chart) as being which is a 1.25 degree difference. Even if the LAT/LON is corrected for rwy 27, the ILS heading in MAP MODE and the Runway heading are still off which is what we are trying to explain based on the original post. Everything else I already said above on why this is done purposly still applies.

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Attached to this post is the fix for ILS RWY 27 for CYYJ in FSX.Unzip and place the single small CYYJ_ILS_fix.bgl into the FSX SceneryGlobalscenery folder. Start FSX and sit on RWY 27. Open MAP MODE or the GPS and you will see the ILS is corrected using the proper LAT/LON values.I am also uploading to AVSIM so everyone can download the fix.

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