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metzgergva

GS indicator pressure sensitive?

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You know that in Europe we have much lower TAs than in other parts of the world and by wrong doing it happened to me that I was still on STD when I was approaching the GS. I realized it last minute and switched to the actual pressure and to my surprise the GS indicator bug moved. I think this should not be the case. Maybe someone can check it? Thanks

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If you are on RAW DATA, it should not be affected. Glide paths are completely independent pieces of equipment on the ground. In fact, it's independent from the localizer and has a different frequency.

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The GS is a radio beam and should not be affected by any pressure settings. If it is there's something wrong somewhere!

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For sure one should not fly an intercept to the GS with an offset in pressure settings, but as confirmed, if you happen to do so it should not have an influence on the GS position and the aircraft following it. It should be independent from the pressure setting. So I hope PMDG will pick up this small issue and correct it.

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and has a different frequency.
Wrong. Both the LOC and GS work on the same frequency. How in earths name can you otherwise both receive LOC and GS while tuned to 111.9 for example? http://www.ead.euroc..._2011-01-13.pdf Take a look to that EGCC aerodrome chart. I'm gonna talk 05R. The LOC is in front of runway 23L (other side), at 111.55 and identifier I-MC. the GS is located near taxiway W across the runway, showing also frequency 111.55 and identifier I-MC. Now tell me I'm wrong! But you were right in the part they work independent, but not on different freqs.

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Wrong. Both the LOC and GS work on the same frequency. How in earths name can you otherwise both receive LOC and GS while tuned to 111.9 for example? http://www.ead.euroc..._2011-01-13.pdf Take a look to that EGCC aerodrome chart. I'm gonna talk 05R. The LOC is in front of runway 23L (other side), at 111.55 and identifier I-MC. the GS is located near taxiway W across the runway, showing also frequency 111.55 and identifier I-MC. Now tell me I'm wrong! But you were right in the part they work independent, but not on different freqs.
Actually the glideslope is transmitted on a different frequenzy coupled to the localiser. "The GP signal is transmitted on a carrier frequency between 329.15 and 335 MHz" (from wiki) Thats why they work independant :)

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Maybe by setting the ILS freq to 111.55 for example, the localizer works on that frequency, but the g/s on a frequency that is coupled to the one of the localizer: by setting 111.55 in the nav radios, the g/s "knows" what other, different frequency to listen to.

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Then tell me how on earth 111.55 can receive the high frequencies?
The ILS system onboard the aircraft has an UHF receiver for glide slope, which automatically picks up the correct GS frequency when the LOC frequency is tuned. This system is "invisible" to the user, the only thing that needs to be done is to tune the LOC frequency. So yes, essentially LOC and GS are on separate frequencies.

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Then tell me how on earth 111.55 can receive the high frequencies?
The UHF freq for the glidepath is tuned automatically.. The ILS consist of to transmitters, an VHF localiser and an UHF Glideslope transmitter.. Just as the airplane has the VOR/LOC antenna, it also has a GS UHF Antenna..The glideslope freq is coupled to the LOC freq, and as said before it is tuned autumatically :)

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The pressure-setting dependent GS-pointer happened to me as well - but it is not a GS indication from the antenna but from the GP (glide path) calculated by VNAV. I have not looked into the manuals yet, but this was my interpretation of the event. My explanation from the top of my head: ILS shows as GS on the FMA, the VNAV stuff shows as GP. Somebody please correct me if I'm wrong.

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