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Flight Instrument White Flag


roadrabbit
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:book:

 

What is the white flag indicating on the left of the HSI when doing an ILS approach? It appears behind the red glide-slope warning flag and the glide path chevron indicator. I can find no reference to it anywhere, but it is very distracting!

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Maybe this is a To-From indicator? When you're flying a VOR/TACAN there should be a little triangle that points towards the source, this is there on the A-10 HSI when in TCN mode, pretty sure it wouldn't be with ILS mode though since you should already know which way the airfield is by then because you're dialing the RWY Final into the CDI.

Warning: Nothing I say is automatically correct, even if I think it is.

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Maybe this is a To-From indicator? When you're flying a VOR/TACAN there should be a little triangle that points towards the source, this is there on the A-10 HSI when in TCN mode, pretty sure it wouldn't be with ILS mode though since you should already know which way the airfield is by then because you're dialing the RWY Final into the CDI.

To/From is strictly a VOR feature because there's no assumption that it will be paired with DME. TACAN doesn't have it, usually because fix passage and moving to or from the fix can be easily determined by what the DME is saying.

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:blush: er, I meant the ADI!

 

The white flag is now a triangle just to the right of the glide-path scale. It is behind both the glide-path 'needle' and the red flag (when the red flag is visible).

 

When I take off with the ILS set and selected the glide-path needle is off scale at the top, which makes sense. The red flag is not in view. But this white triangle is now there, centre scale, about 2.5 x size of glide-path needle. When I open the thrust levers this flag moves slightly upscale. There is also a white indicator behind it which occasionally moves into view.

 

I think it would be best if I took a screen shot - can anyone explain to this tyro just how to do it?


Edited by roadrabbit
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Alpine Systems PC with Intel i7-2600K @ 3.40/3.70 GHz. NVidia GTX590 Graphics. 24 Gb RAM (24 Gb usable!). 64 bit. Windows 7 PRO SP1. 3 x Samsung P2370 monitors. Thrustmaster HOTAS. TrackIR5. :joystick:

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:blush: er, I meant the ADI!

 

The white flag is now a triangle just to the right of the glide-path scale. It is behind both the glide-path 'needle' and the red flag (when the red flag is visible).

 

When I take off with the ILS set and selected the glide-path needle is off scale at the top, which makes sense. The red flag is not in view. But this white triangle is now there, centre scale, about 2.5 x size of glide-path needle. When I open the thrust levers this flag moves slightly upscale. There is also a white indicator behind it which occasionally moves into view.

 

I think it would be best if I took a screen shot - can anyone explain to this tyro just how to do it?

This white triangle - it's not an Angle of Attack indicator, is it?

 

I am looking at page 499 of the Flight Manual which states, under ILS Final Approach, "maintain landing glide slope angle of attack as indicated on ADI and AoA indexer lights".

 

If this is correct, does anyone know how to read and use it? I can't find out anything else that possibly refers.

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To/From is strictly a VOR feature because there's no assumption that it will be paired with DME. TACAN doesn't have it, usually because fix passage and moving to or from the fix can be easily determined by what the DME is saying.

 

Well I thought I remembered seeing it somewhere on the HSI, or thats a fantasy that loomed to the surface from somewhere.

 

This white triangle - it's not an Angle of Attack indicator, is it?

 

I am looking at page 499 of the Flight Manual which states, under ILS Final Approach, "maintain landing glide slope angle of attack as indicated on ADI and AoA indexer lights".

 

If this is correct, does anyone know how to read and use it? I can't find out anything else that possibly refers.

 

I don't know why it would be an AOA indicator because there are already two indicators for AOA in the cockpit. One is the mentioned Indexer, the other is the AOA indicator proper which is immediately below the UHF repeater.

 

I think what you're reading is just poorly worded. It means maintain glideslope with the GS indicator on the ADI and maintain the correct AOA as indicated by the Indexer, which are two separate instruments.

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Warning: Nothing I say is automatically correct, even if I think it is.

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The white triangle you speak of is a bug that has gone uncorrected for more than a year. It is an extraneous piece of geometry that has no function in the game, and does not exist in the real airplane.

 

^^ This. Very annoying indeed.

 

 

To/From is strictly a VOR feature because there's no assumption that it will be paired with DME. TACAN doesn't have it, usually because fix passage and moving to or from the fix can be easily determined by what the DME is saying.

 

Not sure about the A-10, however I have flown several aircraft with TACAN and they all had/have a TO/FROM flag. Whether you have DME or not isn't really much of a factor as the primary reference for station direction is the bearing needle rather than TO/FROM which is more for additional SA.


Edited by Kaiza
[url=http://www.aef-hq.com.au/aef4/forumdisplay.php?262-Digital-Combat-Simulator][SIGPIC]http://img856.imageshack.us/img856/2500/a10161sqnsignitureedite.png[/SIGPIC][/url]
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Huh, mystery solved.

 

Which aircraft did you fly with TACAN? And were you trained to interpret DME reversal as station passage instead of the to/from flip?

 

I was taught that the bearing needle reversal is primary reference for station passage, however at high altitude DME can be referenced for a large cone. Although where I live there aren't many TACANs, so if I am using one for nav I am normally going there rather than passing over!

 

Something some people may not be aware of is that most military aircraft of the a-10 era didn't not have a DME box at all, instead you would have to use the equivalent TACAN channel for DME. So for example, when you are on vectors for an ILS you would have the TACAN up for SA. Then on the base turn you would change the TACAN channel to the ILS freq and use the TACAN distance for your ILS. Tuning an ILS will only give LOC and GS. I am haven't tried this on the a-10, so I am not sure if ED simulate it or not.

 

Here is how you convert a DME freq to a TACAN channel: http://www.pprune.org/archive/index.php/t-85688.html


Edited by Kaiza
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Something some people may not be aware of is that most military aircraft of the a-10 era didn't not have a DME box at all, instead you would have to use the equivalent TACAN channel for DME.

Yes, but it's the same thing which is why you can tune your DME to every VORTAC if you have one.

Tuning an ILS will only give LOC and GS. I am haven't tried this on the a-10, so I am not sure if ED simulate it or not.

It does, for sure. There is such a thing as a DME being collocated with the ILS but it isn't the norm.

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Yes, but it's the same thing which is why you can tune your DME to every VORTAC if you have one.

 

It does, for sure. There is such a thing as a DME being collocated with the ILS but it isn't the norm.

 

I am not quite sure what you are saying here, and forgive me if I am stating the obvious as I don't know your background, but if there is a co-located DME with an ILS, it will make no difference- you should NOT get the DME distance when you dial up the freq in an A-10C as DME not fitted to the aircraft (I dont know what the game does as my 1.2.5 is fubar, but I suspect it may be modelled incorrectly by having a quick look on youtube). Just because you have an ILS receiver on board an aircraft does not mean you get DME. You have to have a DME box which the A-10C does not. The first give away is there is no 'DME' on the audio panel, + the only reference to DME in the -1 is with respect to TACAN (which as you know you can configure to receive DME). Only aircraft with a DME will display distance when you dial up an ILS freq with a co-located DME. If DCS:A-10C does, it is a bug. If modelled correctly the only way to get distance from a co-located ILS/DME would be to dial up the ILS DME freq in the TACAN box.

 

This may sound strange and confusing to people who have operated IFR in the civi world which have boxes that normally receive both DME and ILS signals when you tune a freq, however this is strangely enough how it works in many military a/c.

 

Forgive me if I have misunderstood your post and gone way off track here, but this is a very common misconception.

 

(Some people may have seen spring tensioned metal flaps under the glare sheilds in some military aircraft. These normally contain tables of comm pre-set freqs and are at times also used for tables that translate DME to TACAN freqs for this reason.)


Edited by Kaiza
[url=http://www.aef-hq.com.au/aef4/forumdisplay.php?262-Digital-Combat-Simulator][SIGPIC]http://img856.imageshack.us/img856/2500/a10161sqnsignitureedite.png[/SIGPIC][/url]
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Kaiza:

I am not quite sure what you are saying here, and forgive me if I am stating the obvious as I don't know your background, but if there is a co-located DME with an ILS, it will make no difference- you should NOT get the DME distance when you dial up the freq in an A-10C as DME not fitted to the aircraft (I dont know what the game does as my 1.2.5 is fubar, but I suspect it may be modelled incorrectly by having a quick look on youtube).

I was saying two things:

 

In instances where you have a VOR and TACAN colocated (a VORTAC) users of the VOR can tune their DME equipment--if they have it--to the station since the DME mechanism provided by TACAN is the same. If you don't have a DME in the airplane, you can't. VOR and TACAN use different technology, but the DME component of TACAN navigation is the same and would be available to anyone with DME equipment.

 

For purposes of the game this is a hypothetical since the A-10 in the game doesn't have a separate DME, and there are no airbases on the map where there is an ILS and DME placed together last I looked.

Just because you have an ILS receiver on board an aircraft does not mean you get DME. You have to have a DME box which the A-10C does not. The first give away is there is no 'DME' on the audio panel, + the only reference to DME in the -1 is with respect to TACAN (which as you know you can configure to receive DME). Only aircraft with a DME will display distance when you dial up an ILS freq with a co-located DME. If DCS:A-10C does, it is a bug. If modelled correctly the only way to get distance from a co-located ILS/DME would be to dial up the ILS DME freq in the TACAN box.

Which was what my second point was. Again, the user would have to dial it up on the DME equipment, independently of their Nav radio.

This may sound strange and confusing to people who have operated IFR in the civi world which have boxes that normally receive both DME and ILS signals when you tune a freq, however this is strangely enough how it works in many military a/c.

Older RNAV equipment combined data from both the Nav and DME radios, but cheaper GA stuff does not. Now that RNAV capability is provided by GPS, you tend to see less and less DME boxes in GA planes. So it's arguable that most civilian pilots, unless they're trained on the older RNAV equipment that is out there, have probably never seen it.


Edited by Headspace
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