ILS Flight Director Influenced by Course Selector

[Joni]

So are we saying that ED modelled it wrong then?

 

Correct, that's why I posted it on the bugs forum.

 

I just uploaded a veeeery old video to you tube where I flew an ILS approach in a 1970 Tomahawk and not even with that old systems is the FD influenced by the course selector. Of course it does not depend on how modern the system is but how the system is built: a single signal tracking.

 

http://youtu.be/Y9f1ZI8JIzI

 

You might want to wait a few minutes for the video to upload.

[Rongor]

This is some poor judgement on your side, piston. You conveniently post a bug report but even after 8 pages of discussion refuse to deliver any evidence for your claim.

There isn't even evidence for assuming there is a flight director at all in this simulation. The term "flight director" isn't mentioned a single time in the 670 pages manual of this sim. Yet you claim there is one, simply judging by the looks of those two yellow bars.

Advised to notice the related pages in the manual (which would enlighten you how to understand those two steering bars) you refuse to face those descriptions, solely judged by your religious faith in those bars being a flight director.

 

1. There is no FD in this sim. You don't find a FD in the manual.

2. Those two bars are explained in the manual of this sim, nowhere did you report they wouldn't function as described there.

3. You claim the ED manual is doing no help here because it is addressing a simulation only, yet you don't deliver contradictory statements from some real life document.

 

Think about this and provide some facts.

 

Your real life experience in airliners are facts, your videos may be. But they prove nothing, they are in fact worthless in this context here, because we need knowledge of the A-10C in this case and not of any other aircraft.

 

ED didn't model a flight director at all in this A-10C sim. Hence they didn't model it wrong.

You may wish to have it modeled, but even then we would need some fact telling us there is a FD in the real one. As long as we don't have this, we will be left by the flight manual, which is telling us how to interpret those steering bars. Since they work as described:

No bug.

[majapahit]

This is some poor judgement on your side, piston. You conveniently post a bug report but even after 8 pages of discussion refuse to deliver any evidence for your claim.

There isn't even evidence for assuming there is a flight director at all in this simulation. The term "flight director" isn't mentioned a single time in the 670 pages manual of this sim. Yet you claim there is one, simply judging by the looks of those two yellow bars.

Advised to notice the related pages in the manual (which would enlighten you how to understand those two steering bars) you refuse to face those descriptions, solely judged by your religious faith in those bars being a flight director.

 

1. There is no FD in this sim. You don't find a FD in the manual.

2. Those two bars are explained in the manual of this sim, nowhere did you report they wouldn't function as described there.

3. You claim the ED manual is doing no help here because it is addressing a simulation only, yet you don't deliver contradictory statements from some real life document.

 

Think about this and provide some facts.

 

Your real life experience in airliners are facts, your videos may be. But they prove nothing, they are in fact worthless in this context here, because we need knowledge of the A-10C in this case and not of any other aircraft.

 

ED didn't model a flight director at all in this A-10C sim. Hence they didn't model it wrong.

You may wish to have it modeled, but even then we would need some fact telling us there is a FD in the real one. As long as we don't have this, we will be left by the flight manual, which is telling us how to interpret those steering bars. Since they work as described:

No bug.

 

well, this is a load of hash potato

neither head nor tail

and yes 2 bars in an ADI you Can refer to as FD

unfortunately, these are at present neither Behaving like FD nor ILS

 

well, until above the last marker,

you noticed that,

right?

[Flagrum]

Rongor, he claims that the ADI needles, functioning as steering command bars, are influenced by the course dialled in at the HSI - which should not happen. Instead they should rely solely on the ILS data (once the signal is intercepted at least).

 

That is how I understand it - and at least the RL T.O. supports it:

 

ILS ADI/HSI Display.

(...)After ILS selection and prior to

localizer capture, the bank steering bar on the ADI will be out of

view. Bank steering will not be available until the CDI is within

an equivalent displacement of 2.6 dots. The CDI will move off

the stops and begin displaying valid displacement information.

If steering commands are satisfied, the aircraft will intercept

the localizer inbound course. (...)

[Joni]

This is some poor judgement on your side, piston. You conveniently post a bug report but even after 8 pages of discussion refuse to deliver any evidence for your claim.

There isn't even evidence for assuming there is a flight director at all in this simulation. The term "flight director" isn't mentioned a single time in the 670 pages manual of this sim. Yet you claim there is one, simply judging by the looks of those two yellow bars.

Advised to notice the related pages in the manual (which would enlighten you how to understand those two steering bars) you refuse to face those descriptions, solely judged by your religious faith in those bars being a flight director.

 

1. There is no FD in this sim. You don't find a FD in the manual.

2. Those two bars are explained in the manual of this sim, nowhere did you report they wouldn't function as described there.

3. You claim the ED manual is doing no help here because it is addressing a simulation only, yet you don't deliver contradictory statements from some real life document.

 

Think about this and provide some facts.

 

Your real life experience in airliners are facts, your videos may be. But they prove nothing, they are in fact worthless in this context here, because we need knowledge of the A-10C in this case and not of any other aircraft.

 

ED didn't model a flight director at all in this A-10C sim. Hence they didn't model it wrong.

You may wish to have it modeled, but even then we would need some fact telling us there is a FD in the real one. As long as we don't have this, we will be left by the flight manual, which is telling us how to interpret those steering bars. Since they work as described:

No bug.

 

 

 

I understand your point of view.

 

 

ADI Bars=Flight Director

 

That is just nomenclature. It does not matter if you call it FD or ADI Bars.

 

I was just trying to help you understand how the system works from my professional point of view. I am sorry if this was not enough.

 

 

Let's conclude this topic and see if it gets somewhere from ED and if it doesn't then we will continue to enjoy it as is now.

 

 

Thanks for your interest.

[Joni]

Rongor, he claims that the ADI needles, functioning as steering command bars, are influenced by the course dialled in at the HSI - which should not happen. Instead they should rely solely on the ILS data (once the signal is intercepted at least).

 

That is how I understand it - and at least the RL T.O. supports it:

 

ILS ADI/HSI Display.

(...)After ILS selection and prior to

localizer capture, the bank steering bar on the ADI will be out of

view. Bank steering will not be available until the CDI is within

an equivalent displacement of 2.6 dots. The CDI will move off

the stops and begin displaying valid displacement information.

If steering commands are satisfied, the aircraft will intercept

the localizer inbound course. (...)

 

Correct

[Rongor]

Then I recommend the OP to edit the thread title, which still claims to address issues with a Flight director (which we don't have in the simulation).

[majapahit]

operating a fighter jet necessitates the educational level of what skippers are required of,

 

wikiing by squads of couch potatoes doesnt quite seem to cut it,

does it

[Joni]

Then I recommend the OP to edit the thread title, which still claims to address issues with a Flight director (which we don't have in the simulation).

 

Just came back from a long absence. Too dissapointed seeing this bug not fixed :cry:

 

The real T.O. supports this.

 

https://www.fbo.gov/index?s=opportunity&mode=form&id=8b388d2fa254a683a486cbd0bad3a2bc&tab=documents&tabmode=list

[Frederf]

The A-10C does have a flight director, the yellow pitch and bank command bars on the ADI. It is by nature a flight director since it gives direct attitude instruction to the pilot.

 

The HSI ILS indications by contrast report positional information to the pilot which requires interpretation to set the required attitude. It is therefore not a flight director. The CDI and GS needles will deflect the correct amount given LLZ/GS signals regardless of the airplane heading or CRS knob setting.

 

The bank steering commands need to have desired course information to calculate the commanded bank. Remember that ILS has no idea which direction the runway is! All it knows is the relative strength of the two localizer signal lobes. The commanded bank will be different for different courses but the same LLZ signal. E.g. when on the center of the localizer the no bank will be commanded if heading matches desired course but will command a bank toward the desired course if the heading does not match. Bank director needle positioning is a function of both the LLZ beam lateral position and the misalignment between the current heading and input course.

 

This course information is set by rotating the CRS knob on the HSI.

 

HSI localizer (CDI) displacement is independent of CRS knob input.

ADI bank director needle is dependent on CRS knob input.

 

Gray text: wrong info

 

Notice that the ADI pitch/bank needles also function in non-ILS navigation. In this case the desired height and course are given by the EGI which may derive the course information from point-to-point calculation or manually by pilot input on the CRS knob. Settings in the menus determine which mode is in use.

Edited November 21, 2017 by Frederf

[Frederf]

My conclusion could be hasty.

 

Indeed it is possible to generate steering data logically from the rate of signal mix change which would obviate to need to know the desired course. My conclusion is only reasonable if the system being of the less-sophisticated design which requires course information to be manually entered.

 

The fact that the ADI steering bars must be stowed for a back localizer approach may suggest a rate-of-change based steering logic which would be entirely unable to reconcile the reversed signal. On the other hand an OBS-knob based logic could be fixed by simply dialing in the reciprocal (which would show correct steering but may be disallowed for other reasons).

 

Associated thought: Without the system knowing distance and the angular nature of the beam wouldn't the system become increasingly sensitive in bank when as distance is reduced? Would that be a problem?

 

The A-10's command pointers are hidden in bank until 2.6 dots CDI deflection and hidden in pitch until +-0.5 dot of center G/S. Initial vertical steering is -2° until capture and then to center G/S thereafter. Maximum bank command is 30° pre-G/S capture and 15° post-G/S capture.

 

The F-16 ILS FD requires a manual number to be typed into the system for steering cues. I mention this as a contemporary example.

 

One interesting suggestion reading throught he manual is that the ADI steering bars are automatically stowed and deployed based on the operating mode. The physical switch is a preference which does not necessarily result in the bars being present in able (e.g. HARS) nor being stowed (TISL/FM homing).

 

The ADI steering does seem very sophisticated. I would not be surprised if it was able to derive steering information without an entered course on the HSI. But then again it would not surprise me if it was more basic and did depend on the CRS knob. This is a toughie.

[Frederf]

Bust my buttons that's gotta be right. I was in those pages but focusing on other elements. A big hole in Figure FO-7 Sheet 3 for HSI COURSE SET Control row and ILS column says it all.

 

Interesting that radio alt rate is the chosen controller for gain reduction. It's not foolproof but I can't think of a better one.

[MonnieRock]

Hello Everyone,

 

Has anyone acknowledged this thread from Eagle Dynamics?

 

Should one of us make a support ticket at Eagle Dynamics?( I will if no one else feels they want to)

 

I just made a quick mission to test in NTTR latest (2.1.1.11317.285) and it seems to still be a problem.

 

Happy Simming,

Monnie

[Joni]

Yeap It is still a bug.

 

Like I said in my first post, this has nothing to do on how you may think an FD works. It has to do on how an ILS is built, and it it built on a SINGLE beam that the reciever (aircraft) gets. Therefore it is not affected by course selector since it is acquiring ONE signal.

 

Take my word as a 15 years pilot career on my back. Otherwise just read how an ILS is built :)

[drPhibes]

Yeap It is still a bug.

 

Like I said in my first post, this has nothing to do on how you may think an FD works. It has to do on how an ILS is built, and it it built on a SINGLE beam that the reciever (aircraft) gets. Therefore it is not affected by course selector since it is acquiring ONE signal.

 

Take my word as a 15 years pilot career on my back. Otherwise just read how an ILS is built :)

 

I'm nitpicking, but what do you mean about it being a "single beam"? The localizer and glide path(-slope for the non-ICAO folks) are two separate systems operating at different frequencies at separate locations. While it may appear as "one beam" to the pilot who just sets the LOC frequency in his/her nav receiver (with the corresponding GP freq being auto tuned due to standardized frequency pairing), saying that a 110.1MHz signal from one end of the runway and a 334.4MHz signal from 400-ish meters from the opposite runway end is a single beam is a bit of a stretch of the term "single".

 

(and just for the record, I have been working for the world's largest ILS manufacturer for 10 years, in test and R&D, so I don't need to look up how it works)

[Joni]

I'm nitpicking, but what do you mean about it being a "single beam"? The localizer and glide path(-slope for the non-ICAO folks) are two separate systems operating at different frequencies at separate locations. While it may appear as "one beam" to the pilot who just sets the LOC frequency in his/her nav receiver (with the corresponding GP freq being auto tuned due to standardized frequency pairing), saying that a 110.1MHz signal from one end of the runway and a 334.4MHz signal from 400-ish meters from the opposite runway end is a single beam is a bit of a stretch of the term "single".

 

(and just for the record, I have been working for the world's largest ILS manufacturer for 10 years, in test and R&D, so I don't need to look up how it works)

 

It is called single beam in aviation because it provides one direction... The beam is just one, we are not talking about frequencies here, just beams.

[Joni]

Think of the beam as a pulse on a radar, it doesnt matter the frequency, the pulse can be just one in one direction.

[MstrCmdr]

I hate having to be so damn precise with the CRS knob. I just don't land it in IMC since it is not an all weather attack aircraft (in the game). I scratched all ILS out of checklists. It has to be a module specific issue because the MiG21 has a built in ILS and it works just fine. It is programmed by channel and not frequency. It cannot be too difficult to rework the A10 to ILS. Heck maybe they did this to make us buy an NS430 mod for the A10 lol!

 

I found this thread because i was looking into the navionics of the Yak52. It would be nice if VOR and ILS were accurately simulated. They could add fake VOR stations just to provide some density. Otherwise I wonder what the point of the Yak52 is going to be. I'm not buying it unless it has radio navigation and ILS simulated accurately.

 

I feel like I'm trolling because the depth the team went to to provide such an A10 simulator is breathtaking.

 

[Edit] See below

Edited November 26, 2017 by Mstr&Cmdr

[Joni]

Navigation part of dcs is poor. The important thing here is that the community often dont understand how things work and basic bugs like this one take an eternity to be addressed.

[PiedDroit]

I'm nitpicking, but what do you mean about it being a "single beam"? The localizer and glide path(-slope for the non-ICAO folks) are two separate systems operating at different frequencies at separate locations. While it may appear as "one beam" to the pilot who just sets the LOC frequency in his/her nav receiver (with the corresponding GP freq being auto tuned due to standardized frequency pairing), saying that a 110.1MHz signal from one end of the runway and a 334.4MHz signal from 400-ish meters from the opposite runway end is a single beam is a bit of a stretch of the term "single".

 

(and just for the record, I have been working for the world's largest ILS manufacturer for 10 years, in test and R&D, so I don't need to look up how it works)

 

Hi folks, I don't know about the military systems but I can give some insights on the civilian A/C ILS systems, from the avionics point of view.

 

The ILS is actually two beams, one for LOC and one for G/S, the G/S frequency is deduced from the ILS frequency (as in drPhibes's post).

The ILS receiver can only compute a deviation value (angular deviation), one for each beam.

This means it can tell you if if the ILS antenna is on the beam or not.

If you get a zero deviation, then you are on the beam, if you get non zero deviation, you are not on the beam. It's quite simple

 

The problem is that the deviation you get doesn't tell you anything about the orientation of the aircraft with relationship to the beam.

This is where the course setting is useful, it gives the flight guidance computer that missing information.

 

The autopilot will try to follow the course that has been input by the user, and also tries to keep the aircraft with zero deviation.

If the course is totally wrong (against current heading), the autopilot might even refuse to engage the approach mode.

If the course is off, the aircraft, while riding the beam perfectly, will try to follow the course, then leave the beam, then correct again because of the deviation, etc.

When closer to the runway the deviations are given more importance than the course, because the aircraft is already well aligned and the course setting is usually not very accuracte (1 degree accuracy at best), but at the beginning of the LOC beam capture, the course setting has a significant impact on the autopilot and FD behaviour.

 

So, unless you are using two ILS receivers (this is not the case on airliners, they only use one at a time), the autopilot and FD need the course information.

Edited November 26, 2017 by PiedDroit

[MstrCmdr]

Not for all modules. I like the MiG21, Mi8, Uh1, A10c, and m2000. The CDU is amazing in the a10. I just hate that CRS needle. I haven't looked into it but the presence of the CRS knob means that VOR must be possible in the real AC right? or maybe its a waypoint path deviation detector.

[Joni]

Hi folks, I don't know about the military systems but I can give some insights on the civilian A/C ILS systems, from the avionics point of view.

 

The ILS is actually two beams, one for LOC and one for G/S, the G/S frequency is deduced from the ILS frequency (as in drPhibes's post).

The ILS receiver can only compute a deviation value (angular deviation), for both beams.

This means it can tell you if if the ILS antenna is on the beam or not.

If you get a zero deviation, then you are on the beam, if you get non zero deviation, you are not on the beam. It's quite simple

 

The problem is that the deviation you get doesn't tell you anything about the orientation of the aircraft with relationship to the beam.

This is where the course is useful, it gives the flight guidance computer that missing information.

 

The autopilot will try to follow the course that has been input by the user, and also tries to keep the aircraft with zero deviation.

If the course is totally wrong (against current heading), the autopilot might even refuse to engage the approach mode.

If the course is off, the aircraft, while riding the beam perfectly, will try to follow the course, then leave the beam, then correct again because of the deviation, etc.

When closer to the runway the deviations are given more importance than the course, because the aircraft is already well aligned and the course setting is usually not very accuracte (1 degree accuracy at best), but at the beginning of the LOC beam capture, the course setting has a significant impact on the autopilot and FD behaviour.

 

So, unless you are using two ILS receivers (this is not the case on airliners, they only use one at a time), the autopilot and FD need the course information.

 

This is totally wrong from my experience. Name one system that uses course selection please. After 15 years ive never seen one.

 

One beam only, talking about LOC ofcourse..

[MstrCmdr]

So I contacted my brother who is a navy pilot and he said he hates VOR. Apparently IRL 9/10 VORs are broken and ATC assumes everyone operates on GPS nowadays. ILS will give you deviation based on what course you put in because magnetic variation changes. ILS is modeled correctly in the A10: you must input the correct CRS for ILS to be accurate. Now the problem is that there are many different precision/non-precision and types of ILS so its kind of hard to define ILS in general since they vary.

 

[EDIT] Direct from him "I've got a few hours in both /G aircraft, and /A single-engine jet and I'm instrument rated. You put in a course that's published on the approach plate and your aircraft calculates the CDI deviation based on your course input. Since magvar changes, you may see published approach plate courses change over time. Think of an ILS like it's just a NAVAID like a VOR/TACAN but confined to a precise cone - if you change the course and center the CDI, you'll change your ground track radial just like you would on a VOR/TACAN. This is very important for approaches such as LDA - Localizer-type Directional Aid. An LDA approach is a non-precision approach that uses the localizer beam of an ILS to offset the final approach course to maintain obstruction (or noise abatement) clearance."

Edited November 26, 2017 by Mstr&Cmdr

[PiedDroit]

This is totally wrong from my experience. Name one system that uses course selection please. After 15 years ive never seen one.

 

One beam only, talking about LOC ofcourse..

 

I can name pretty much all airliners ILS systems.

 

The course setting might be hidden from the user's view, because it is stored in the navigation system.

On an airliner, the FMS has this information and feeds it to the flight guidance system, I believe this is the same thing with military aircraft, hence the use of "airport" navigation points.

The FMS also feed the ILS frequency.

 

When in manual mode (standby nav), the user bypasses the FMS's settings and sets the ILS frequency from the radio management panel using the selection knob.

Once the user validates the frequency (goes from standby to active), he can then set the course value.

 

You might be very experienced as a user, but there are a lot of things going on under the hood that you might not be aware of.

Edited November 26, 2017 by PiedDroit

[Joni]

Im also instrument rated, and the fms has nothing to do. Not even on a cessna with fd its affected by course knob.

 

Magnetic variation... Instrument rated, really? :) The electronic beams point you in the direction by comparing deviation, it doesn matter if you intentionally put the hsi in the wrong orientation.

 

Ill fly next weekend and upload an fd approach so you can see how it works irl.