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two approaches; one frequency

Steve Bauman 1156360

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In MN (USA), there are two approaches into St. Cloud airport (KSTC) that share the same ILS frequency; 111.90. These are ILS or LOC RWY 31 and ILS or LOC/DME RWY 13.


Neither are marked as a backcourse; and each has its own distinct identification morse code.


I can only seem to pick up one of those identifications; runway 31. I can never hear the proper identification tone for runway 13, and navigation is backcourse for runway 31.


Is there an update that I don't have, does one not exist, or am I doing something wrong?


big thanks

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I just called St. Cloud tower... they turn on and off the different transmitters, depending on what the active runway is!


Would this be found in an afcad update? (I looked and could find no afcad updates for St. Cloud, by the way).


I doubt the tower controllers on VATSIM (Flight Simulator X) can "toggle that switch"; I wonder if it's supposed to happen automatically when an active runway is defined?


thanks for any help

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VATSIM controllers dont use FSX we have our own clients, they have no control over FS.


in FS, it turns on and off by your approach course. for yours, if you are approaching from 31, then 13 turns off, vice versa. same works for the approach lights. the VATSIM controllers arent turning them on/off


if theres no afcad update, you can always do it. download "airport design editor". its freeware and will allow you to edit the airports layout aswell as the instrument approach.

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In the RW the ILS is controlled by a key and can only radiate in one direction or be switched off completly *. In FS the simulator guesses which direction you're landing on and that's the one you will pick up.


For example if you're approaching Heathrow from the west FS will think you're landing eastery so you'll pick up the I-AA (09L) until p[Mod - Happy Thoughts]ing south abeam, at which point FS will then guess you're landing the other way and you'll start receiving the I-RR (27R).


* It's possible through some more advanced controls to also turn off parts of the ILS, i.e. turn off the GP but retain the LLZ and LOC. You can also radiate in the other direction for test purposes, but generally isn't done.

Michael Benson

Importer and Exporter of aluminium tubing from Slough Intl

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Excellent! Yes, I did try listening to the station identification (morse code) from both sides of the ILS; alas, it was always for 31, even on final for 13. Great information though, thanks! I think FSX is guessing 31 is the active, and is leaving that "on".


...or, like the above guy said about the afcad update, it could (and most likely is) entirely my FSX not doing it right. Maybe it doesn't know about the 13 ILS approach at all!


I will search more for the update, and if I can't find it, I'm going to try that free editor to see if I can design it semi-accurately!


thanks to everyone for all the help!

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UPDATE: I set the winds to 130, and started her up. Tuned 111.90, listened to identity. It was for 31.


Viewed flight analysis, said "Show ILS approaches" or whatever that feature is called, and it only showed the 31 approach.


So yes, I just need to update the afcad or make my own "13 approach"!


Still not finding it though (except older versions than the one I already have), so I might have to try that "airport design editor"!


thanks again

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ONE MORE UPDATE: I created my own "ILS or LOC/DME RWY 13 approach". My St. Cloud (KSTC) airport for FSX is here, if anyone wants to try it out:



You have to (unzip and) copy that into this folder:

C:\Program Files\Microsoft Games\Microsoft Flight Simulator X\Addon Scenery\scenery


...and then start the game.


The fella (Mr. Benson) who said that FSX determines the active runway by where you are relative to the airport; you are totally correct. When approaching from the southeast, I got the ident from runway 31; when coming from the northwest, I got the ident from runway 13.


Very cool, thanks everyone! This lets me use the current approach plates for that runway at that airport! It makes for better training when the real-life plates match the sim.

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yes, I wondered the same thing!


here's a trivia question for you... who "comes up with" the morse code signal? In other words, what does it mean?


don't scroll down if you want to answer this yourself!















answer: you enter the identifier for the ILS, and it uses those letters to generate the morse code! I tested it, and it's right on.

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I had actually forgotten that little tidbit, and would have gotten that one wrong if it were asked on my future IFR oral or checkride!


I use only real airports, and I'm focusing on the ones that are around where my training will take place. I took a part 141 ground school for my instrument training, p[Mod - Happy Thoughts]ed that, and got 93% on the IFR written.


Now I'm working some of the "kinks" out of my flying before I start to pay big bucks for it.


Thank you VATSIM, you are very beneficial to my training!

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ooooooh, great question!


I'm not sure how I could correctly identify the source, if the identifier was missing (of course, if the identifier, or morse code, was missing, it would indicate that the signal was not suitable for use in navigation).


I would say that's a trick question, and without the identifier, there is no way to positively identify it.


is that correct?



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