RMI pointing to localiser Antenna?!

I don’t know if anybody else noticed, it’s kind of funny in a way and sad at the same time considering Asobo don’t seem to understand how a localiser works.

I was flying the TBM on arrival (base) with the ILS frequency tuned on both sets and bearing pointers set to NAV 1 and NAV 2. I noticed they were actually pointing towards the airport. I’m talking about the bearing pointers here (blue needles) and NOT the CDI.

That is weird obviously as in the real world bearing pointer will never point towards a localiser antenna.

Its a shame we can’t change course manually in FS2020 as soon as an ILS frequency is tuned (at least on the Garmin) because I’m getting a feeling that the localizer works like a VOR in FS2020. I’ll give it a try tomorrow on the steam gauge C172…

Edit: ILS / Localisers appear to work as they should, I tested it with the conventional C172, the course deviation indicator does not respond to changing the OBS, flying in opposite direction creates “reverse sense” etc. The weird thing remains that RMIs and bearing pointers in FS2020 are able to point towards a localiser antenna.

At Dubrovnik airport, ILS runway 11 tuned (110.10), ILS identified correctly (IDU), bearing pointers (blue) visible pointing towards the localiser antenna.

Localizer works exactly like a VOR, just far less deflection range. The localizer needle should be set to the approach heading. So if you are on runway heading then the needle should be pointing at the runway.
I’m sorry, when I read the post I went, “what?” then I read it a couple more times and now I’m going, “hmmmm?”.
Am I not understanding the question?

Nope you are wrong, it works entirely different and you can’t get a bearing from it. Bearing pointers disappear as soon as you select a localiser frequency.

Also it does not matter what course you select, a dot deflection remains a dot deflection. Obviously on a HSI it would be difficult flying with the CDI in the wrong position, but the deflection would not change.

On an OBI like on the steam gauge Cessna the OBS does not serve a purpose once a localiser frequency is tuned.

You have some studying to do my friend, a localizer is not omni-directional.

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No… I am not wrong…
That is why the same gauge is used to fly an ILS as a VOR radial… I am well aware that the ILS signal is not omnidirectional. Would kind of defeat the purpose. I mean the needle centering when you are lined up.
I am obviously not on the same page as you.
The ILS will not give a bearing, agreed. But you said it was pointing at the runway. Not knowing where you were at that point strains my reasoning. If the CDI is set to the runway heading, that would be SOP for using the ILS.
What are you seeing that seems off? Are you saying that the needle centers on the CDI as you rotate the heading?
Or are you talking about the “bearing indicator” on the GARMIN, because THAT will always point at the radio source just like it would if you tuned it to a NDB.

First hit on Google:

“Rotating the OBS has no effect on the operation of the localizer needle, although it is useful to rotate the OBS to put the LOC inbound course under the course index.”

An ILS does not work like a VOR. I’m talking about the bearing pointers, not the CDI. Although the instrument is the same, the working principle is completely different. A bearing pointer, RMI etc. will never point towards a localizer.

Come on buddy… really?
I am trying to understand your post, not take a refresher.

RMI does exactly what it’s name implies. It points in the direction of a radio source. It doesn’t care if it is a TACAN/ILS/NDB or your favorite country station. If the RMI is connected to a receiver, whatever it is tuned to will cause the needle to respond by pointing at the source. It’s sole purpose is give you a BEARING to the station.

No no no no. Wrong a RMI works differently for a NDB and a VOR. In case of ADF it just points to the (non-directional) signal. For VORs it does NOT just point to the signal, it calculates the phase between the variable and reference signal it converts that into a bearing. An ILS works entirely different again with a 90 and 150 KHz lobe pointing towards the stronger signal of the two indicating the deviation. A RMI does NOT point towards a localiser. Apart from it just not working like that, the localizer signal is directional and can’t even be received outside 10 degrees from the final approach course.

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OK, now we are going down a rabbit hole. This is a subject you need to spend more time with. I get that you have google and have done some research but your comprehension is in need of further study. When you get caught up, you can look me up and discuss if you like.
Radio signals of various standards got me home, more times than I care to count. An RMI (Radio Magnetic Indicator) is merely a fancy word salad for radio direction finder. An instrument that has been around as long as radio. It used to be the only radio aid available to us. Even down to being used for non precision instrument approaches.

I’m an airline captain in the real world and have taught ATPL Radio Navigation. :joy:

RMI is not a direction finder, the only thing it does is combine your OBI and RBI together with a compass rose into one instrument. The principles do not change, its still a VOR and an ADF. The RMI is just that - an indicator! Its not a system, it uses the same VOR / LOC receiver as your HSI, it does not all of a sudden become a direction finder…

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Sounds funny… (I’ll give it a go in a minute. unbelievable)
I never tried an ILS Approach with the TBM but in the Steam Gauge C172 it works as it should.
(There is no HSI)

Strange things happen in this Sim that’s why I do VFR flights only in the analog Cessna until they get these things fixed…

I’ve been an avionics tech for 45 years, and I can assure you that an RMI cannot point at a localizer. It can point at a VOR because it is able to resolve which VOR radial the aircraft is currently on. A localizer, though it uses the same frequency range and indicator as a VOR works in a completely different manner. The localizer contains no embedded radial signal like a VOR does. The centering of the CDI needle is controlled solely by the aircraft’s physical position in space in relation to the center of the localizer beam.

An RMI in ADF mode is using still another mechanism to point at the station. In this case, it is using an narrow beam width electrical loop antenna which is capable of determining the direction from which the received signal is coming.

When a Nav receiver is tuned to a localizer, the RMI needle will disappear (on an electronic display), or rotate to the 3 or 9 o’clock position and display an “off” or “nav” flag on a mechanical RMI

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I don’t like to be that guy, but “taught”. :wink:

So a localiser would be kind of like a VOR with only a single radial?

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Should have paid attention in English classes :upside_down_face:

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If English is not your native language, your English is excellent, sir! :clap:

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The localiser itself works as it should but on both the Cessna 172 G1000 and TBM the bearing pointers point towards the localiser antenna :sweat_smile:. Another problem I discovered some time ago is that in Innsbruck for example the approach is aligned with the runway where in real live this should be offset…

Time for Zendesk… again… :sweat_smile:

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Yes, That is the case at many airports and it sucks, because you can’t fly offset approaches. I have no idea why Asobo thought that would be a good idea.

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I think there is also a problem with missing back beams, I noticed at Innsbruck that OEJ has either the front or the back beam missing…

Ok did a flight in the TBM at KSNA
Tuned ILS ISNA 20R 111.75 into NAV 1 and NAV 2

It seems the needles are aligned with the APP course automatically when tuned to an ILS and we can not change the course on the MCP. It’s automatically fixed to the approach course.

When I tuned the NAV to an VOR (SLI 115.7) then I am able to select the course on the MCP.

I don’t know if this works like that on the real world Garmin…

Not exactly. A VOR works by generating two modulating signals. One is fixed and referenced to magnetic north, the other waveform rotates 360 degrees, 30 times per second. The specific radial an aircraft is on is determined by the phase shift between the fixed and rotating waveforms The 270 degree radial would define the line where the phase shift between the fixed and rotating waveform is 270 electrical degrees. (The waveforms are AC signals in the upper part of the audio frequency range). If you listen to a VOR morse code identifier on a Nav receiver with headsets, you will hear a low pitched “flutter” sound in the background which is the 30 Hz rotating signal.

An ILS localizer works on a different principle. The localizer antenna consists of an an array of directional antennas mounted side-by-side - (as many as 10 to 15 discrete antennas). All antennas radiate on the same radio frequency. The antennas on the left side of the array are modulated by a 90 Hz audio AC waveform. The antennas on the right side are modulated by a 150 Hz audio waveform. In effect this produces two overlapping beams. When an aircraft is on the runway centerline. The two received waveforms will be equal. If the 90 Hz signal is stronger, the airplane is left of the centerline, if the 150 Hz signal is stronger the aircraft is right of centerline. Which signal is stronger depends only on the aircraft’s physical location in relation to the runway centerline.

There are actually some similarities between how a localizer works and the old-fashioned A/N low frequency radio range used in the 1930’s and 40’s.

There is no actual “radial” like there is with a VOR, which is why an RMI cannot point at the localizer.

An RMI only works as a true “radio direction finder” when it is being driven by an NDB receiver.

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