HUD ILS guide as a flight director?

I don't claim to be an expert on the French avionics, but I have some doubts about the current implementation of the ILS guide shown on the HUD (the little square you have to superimpose with the FPM to fly a correct approach). Right now it shows the raw ILS deviation, which is not very useful without some sort of reference scale and actually duplicates the role of the localizer deviation vertical line, making the latter redundant.

In other HUD systems that I know (like F-16, 737 and other civilian aircraft), there is also a cue shown on the HUD that you have to superimpose with FPM, but that one works as a flight director. It guides the pilot to intercept and then to stay on the correct path, he simply has to keep the FPM on the cue all the time, and if he drifts away, the cue will tell him not only where he is in relation to the correct path, but also how much bank/pitch he has to apply.

Below is an example how such steering cue works in a 737 - it's the small circle inside the FPM. Notice how it guides the pilot during turn to final and glideslope interception. Raw ILS deviation data is displayed on the scale to the right and compass rose at the bottom of the hud.

American systems are very different from the french/european ones.

AFAIK razbam's implementation is correct.

Read the real M-2000c manual (there is a pdf), this is how it is meant to be.

The dashed line is referred to as the "runway axis, after LOC capture and before GS capture".

The little box is referred to as GS and LOC deviations.

I believe the equivalent of the FD in this case is the presence of the synthetic runway.

On a B737 (or whatever liner), I think the FD can be used because the system knows the runway axis, in the M-2000C that information is not available unless you have a landing waypoint, which makes the synthetic runway available.

On the other hand, there is an autopilot mode that can follow the GS/LOC for automatic approach, possibly it could be used for FD as well but I didn't find any reference to it, that would be what you're looking for.

Read the real M-2000c manual (there is a pdf), this is how it is meant to be.

The dashed line is referred to as the "runway axis, after LOC capture and before GS capture".

The little box is referred to as GS and LOC deviations.

You mean this one?

http://www.avialogs.com/en/aircraft/france/dassault/mirage2000/manuel-pilote-mirage-2000-c.html

Interesting.

First of all, the dashed line is referred to as the "runway axis (after LOC capture and before GS capture)" on the first picture. Note the parenthesis, the text inside it is just a description for the situation on a picutre, not the line itself. The line is simply "runway axis" on the second picture, which shows the situation after both LOC and GS have been captured.

From this manual and pictures, it seems to me that this line is a part of synthetic runway vision and it is a virtual line that goes through the runway centerline, not a simple ILS localizer deviation marker like we have in game.

Second, the box is referred as "fenetre de guidance" - guide window, which to me sounds more like "flight director" than ILS deviation. Also, both pictures have a note "mettre la maquette avion dans la fenetre de guidance", which google translates to "Put the model airplane in the window of guidance". That's what you would do if the window behaved like a proper flight director, but you can't do it right now in DCS, the only moment when FPM is superimposed over the box is when you are exactly on glide path.

American systems are very different from the french/european ones.

AFAIK razbam's implementation is correct.

Airbus follows the same logic, so do Russian planes in Flaming Cliffs (but not sure if that's realistic, didn't check the real manuals).

You mean this one?

http://www.avialogs.com/en/aircraft/france/dassault/mirage2000/manuel-pilote-mirage-2000-c.html

 

Interesting.

First of all, the dashed line is referred to as the "runway axis (after LOC capture and before GS capture)" on the first picture. Note the parenthesis, the text inside it is just a description for the situation on a picutre, not the line itself. The line is simply "runway axis" on the second picture, which shows the situation after both LOC and GS have been captured.

From this manual and pictures, it seems to me that this line is a part of synthetic runway vision and it is a virtual line that goes through the runway centerline, not a simple ILS localizer deviation marker like we have in game.

The description isn't very good in that manual. I still think it is a LOC deviation only (as it is currently is RAZBAM's implementation), because displaying a real runway axis in those conditions require 3 additional info: the runway orientation, the distance and the LOC beam width (a LOC beam width depends on the installation, it's not the same on every airport). Alternatively, runway threshold geo position.

I didn't see any place we enter the course or the beam width, and the distance to ILS is not displayed either (it looks like there is no DME, since the TACAN is used).

This is why the synthetic can only be displayed when a waypoint had been defined.

Second, the box is referred as "fenetre de guidance" - guide window, which to me sounds more like "flight director" than ILS deviation. Also, both pictures have a note "mettre la maquette avion dans la fenetre de guidance", which google translates to "Put the model airplane in the window of guidance". That's what you would do if the window behaved like a proper flight director, but you can't do it right now in DCS, the only moment when FPM is superimposed over the box is when you are exactly on glide path.

fenetre de guidage can mean whatever you want. Put the aircraft model in the box => put yourself in the glide path. Again, not really conclusive.

Also on the same diagram, where the little box is off to the left, the legend says "ECART EXCESSIF LOC", which means "excessive LOC deviation", so this points again to a raw deviation.

Airbus follows the same logic, so do Russian planes in Flaming Cliffs (but not sure if that's realistic, didn't check the real manuals).

Dassault is not Airbus nor any Russian manufacturer and civilian aviation is not military aviation.

They do what they want, so I don't see how this could be used as an argument.

Only a real M-2000C pilot will tell if the current implementation is good or bad, I based my own educated guesses based on my knowledge on avionics and the manual.

 

 

The description isn't very good in that manual. I still think it is a LOC deviation only (as it is currently is RAZBAM's implementation), because displaying a real runway axis in those conditions require 3 additional info: the runway orientation, the distance and the LOC beam width (a LOC beam width depends on the installation, it's not the same on every airport). Alternatively, runway threshold geo position.

I didn't see any place we enter the course or the beam width, and the distance to ILS is not displayed either (it looks like there is no DME, since the TACAN is used).

This is why the synthetic can only be displayed when a waypoint had been defined.

That's why I said the line may be a part of synthetic runway display. No INS airport data - no dashed line. Also note how it goes ideally through the centre line of the synthetic runway depiction on the last picture. That is not possible based on ILS signal alone.

Also on the same diagram, where the little box is off to the left, the legend says "ECART EXCESSIF LOC", which means "excessive LOC deviation", so this points again to a raw deviation.

Except this label applies to the small caret displayed next to the guiding box, not the box itself. This may be just an additional way to inform the pilot that he is not in the place he should be.

Dassault is not Airbus nor any Russian manufacturer and civilian aviation is not military aviation.

They do what they want, so I don't see how this could be used as an argument.

Well, you brought the "French do it different than the rest of the world argument". Or was it "Europeans" first. I'm just pointing out that I don't know about any system that would in real life work like we have it now in DCS M-2000C. It's just impractical and does not give the pilot much useful information.

An example Hud from Dassault themselves follows the same logic I outlined in the first post, but of course you can dismiss it because "military can do what they want".

GQnxPap7yd4

To use virtual runway you need to feed some data into PCN.

- runway threshold coordinates (L/ G/ Z)

- runway heading

- slope

- set altimeter to QFE

Then capture LOC (runway axis, open box on the top) then capture glide (full runway & axis).

Current ILS system isn't finished.

But virtual runway isn't mandatory for ILS landing.