GEKtheReaper

FD horizontal guiding when landing

Recommended Posts

Hello guys,

been flying the NGX a while now and currently in P3D v4. Wanted to ask this q a long time ago but thought, neh, you must be doing something wrong. Today I finaly post my issue:

I fly the NGX manualy on TO up to 10.000 and try to land it also manualy. I get near the ARP in VNAV and LNAV, I activate VOR LOC before intercepting the landing heading and finaly after succsesfuly catching the H-beam, I activate the APP mode and wait until the AP starts it's descent on the G/S. After cathing the GS, I deactivate A/T and AP and start flying manualy towards the RWY.

My problem: the H-Guidance bar of the FD does not seam to guide me at all. Just today I landed in EDDM with 3kt wind on RWY HDG (so no wind at all), I could clearly see that I was not centered with the RWY, but the FD bar would not react quick enough to show me were I should point the nose of the ACFT. I will react somethime if I continue to fly of RWY center but it's way too late and too little. The V FD-bar seems to do it's job quite nicely but it also reacts with some latency.

I must add that I have good frames and mostly no stutters at all.

 

Would be glad to hear from you guys.

BR,

Gerald

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Always look to the FMA to see what the boxes are doing.  For roll control (please, call it roll not horizontal) you should see a small letter white LOC that changes to green large letters on capture.  Same for the pitch control (again, please call it pitch not vertical) that changes from a white to green GS.  All this assumes you have the ILS set up and FD is operating.

Share this post


Link to post
Share on other sites

Thank you @downscc for your reply and correction of terms. I will surely use them from now on.

As explained above, I wait for the G/S capture and also get the confirmed autoland mode on the FD  (so I'm perfectly established) and it's not that the roll won't budge at all, but the movement (guiding) is so small and seems late.

Another addition: even with CAT III autoland (DUAL CH) the 737 "walses (dances)" it's way towards the RWY (left-right-left-right.....) with no wind at all! It looks like the roll angle get's small correction but delayed somehow, so that the plane has to constantly roll to the other side to compensate. It does land on it's own and perfectly centered in the end.

If I'm allowed to make a comparison: the newest BUS works astonishing well even with heavy crosswinds. Centered to the FD, you will fly "sideways" towards the RWY...

Share this post


Link to post
Share on other sites

For a test i would deactivate AS4 and try again. If you can't reproduce the problem also try then switching Chaseplane off.

Share this post


Link to post
Share on other sites
10 hours ago, GEKtheReaper said:

Another addition: even with CAT III autoland (DUAL CH) the 737 "walses (dances)" it's way towards the RWY (left-right-left-right.....) with no wind at all! It looks like the roll angle get's small correction but delayed somehow, so that the plane has to constantly roll to the other side to compensate. It does land on it's own and perfectly centered in the end.

That is not normal so something in your configuration is interfering.

Share this post


Link to post
Share on other sites

I tried to find some videos and did get this:

 

Look from minute 30:25 (manual) and you will see that the FD roll guidance dances from side to side while the pilot does little roll adjustements.

If you pause the video exactly at:

30:23 you can see the diamond slightly to the left (correct), a minimum roll towards the left (actualy correct) but the FD to the right (I assume: wrong).

30:26 diamond left, FD centered with plane flying level (no roll at all).

30:36 same as above

etc.

The roll FD guidance is IMHO not nuch help if this guy wouldnt have looked towards the RWY.

Am I allowed to post a comparison video from another vendor?

Share this post


Link to post
Share on other sites

I found a nice Cockpit view Video here:

From minute 6 you can observe CP roll corrections and the FD roll guide stay's spot on (the diamond is also centered). During the roll corrections you don't get to see the "bouncy" FD.

Share this post


Link to post
Share on other sites

Videos from other sources won't help to find YOUR problem.

You should do as suggested to narrow down where your simulator has problems.

Share this post


Link to post
Share on other sites

I have noticed what I believe Gerald is posting about. I tend to had fly more than most and what I have noticed is only when hand flying that I can more than a few degrees off of what the FD lateral guidance should be indicating (HDG/LOC/LNAV) and the roll bar is dead center. If I correct back it's like the roll bar follows what I am doing. If I blindly follow the FD I will overshoot headings. The real world 737 does not behave this way. I have seen this behavior in FSX, P3D v3 and v4. I recall the 777 doing the same thing but a while back there was an update and now the FD roll bar behaves more accurately the way you would expect.

  • Upvote 1

Share this post


Link to post
Share on other sites
10 hours ago, JoeFackel said:

Videos from other sources won't help to find YOUR problem.

You should do as suggested to narrow down where your simulator has problems.

Hello Joe,

just did what you recommended (fair weather theme in p3d, no ASP4, no ChasePlane, no wind) and the behaviour was exactly like in the videos above.

 

1 hour ago, Ralgh said:

I have noticed what I believe Gerald is posting about. I tend to had fly more than most and what I have noticed is only when hand flying that I can more than a few degrees off of what the FD lateral guidance should be indicating (HDG/LOC/LNAV) and the roll bar is dead center. If I correct back it's like the roll bar follows what I am doing. If I blindly follow the FD I will overshoot headings. The real world 737 does not behave this way. I have seen this behavior in FSX, P3D v3 and v4. I recall the 777 doing the same thing but a while back there was an update and now the FD roll bar behaves more accurately the way you would expect.

Correct! Exactly this happens to me also! You have to always pinpoint the RWY visualy to land on it's centre (otherwise I always overshoot). There is no way to land the 737 without visual cues of the RWY (or at least I'm incapable of doing it and found no video of someone else doing it manualy in low vis).

With the FSL, I'm mostly dead on center using only instruments (FD).

Share this post


Link to post
Share on other sites
45 minutes ago, GEKtheReaper said:

There is no way to land the 737 without visual cues of the RWY (or at least I'm incapable of doing it and found no video of someone else doing it manualy in low vis).

I've done this without noticing any lag error in the FD roll command.  One example off the top of my head is the PANC RNAV(RNP)33 approach that I flew from HOPER which means I used the FD to fly a 270 deg loop and roll out on short final.  I was near minimums and there being no approach lights, only REILs, I was right on 33 centerline when I broke out at about 750 ft AGL and saw the REILS. Vis was so low I didn't see much else, and this is why i remember that approach so clearly.

The problem you describe is unusual, even if there are two or three reporting it.... I've not seen it reported before in the nearly 5 years that the product has been released.  I don't have a clue what it might be and based on a few comments above I suspect it might have more to do with a lack of understanding of how a FD performs.  For example,  the roll bar will be centered if you are off course and correcting as intended by the FD.  The roll bar is not course deviation indicator, it is a steering command bar.

Share this post


Link to post
Share on other sites
8 minutes ago, downscc said:

For example,  the roll bar will be centered if you are off course and correcting as intended by the FD.  The roll bar is not course deviation indicator, it is a steering command bar.

Correct but in this case flying wings level several degrees off of the heading bug in HDG mode the roll bar is centered when it should be showing deflection toward the selected heading. 

Share this post


Link to post
Share on other sites
7 hours ago, GEKtheReaper said:

Hello Joe,

just did what you recommended (fair weather theme in p3d, no ASP4, no ChasePlane, no wind) and the behaviour was exactly like in the videos above.

 

Correct! Exactly this happens to me also! You have to always pinpoint the RWY visualy to land on it's centre (otherwise I always overshoot). There is no way to land the 737 without visual cues of the RWY (or at least I'm incapable of doing it and found no video of someone else doing it manualy in low vis).

With the FSL, I'm mostly dead on center using only instruments (FD).

Your FD is making me dizzy. The RW FD is nowhere near that active. Something is definitely buggy.

Share this post


Link to post
Share on other sites
On 28/08/2017 at 8:19 PM, GEKtheReaper said:

Look from minute 30:25 (manual) and you will see that the FD roll guidance dances from side to side while the pilot does little roll adjustements

Whilst I can't and won't dispute that the FD looks extremely (too) active as Matt says, I would dispute that it is actually indicating incorrectly (i.e. showing the wrong steering commands) in the video posted.

The pilot is hugely overcontrolling. Given there is no wind (ref ND) he really just needed to let go of the damn stick and let the aeroplane sort itself out! When he was putting in those big, sharp roll inputs, the FD was moving in the opposite direction because he was rolling much too far for the correction required.

Share this post


Link to post
Share on other sites

Dear Simon,

I will start with: Yes! It seams that the pilot is overcontrolling the 737 (he's definately not the best pilot out there). He is hugely wrong with following the descent path (G/S) also. But IMHO the video clearly shows that the FD is wrong!

First: To be clear on something: I'm not a real pilot but I understand how the FD works. The FD should point you (HDG and pitch) in the right direction that would be necesary to follow a certain path. The FD would also compensate for example for crosswinds. E.g.: On the G/S with crosswind from left and centered FD , you will actually fly sideways towards the RWY. You ACFT will still be on the G/S with centered diamond but the HDG will be something else then the RWY HDG because the nose will be pointing in the direction from where the wind blows.

So why do I say that the FD is wrong?

1. Under no circumstances (so close to touchdown) will you have the diamond to the left (thus you flying to the right of the RWY) with a centered FD with no wind at all. This would only apply if you fly an intersecting course towards your path (from right to left). Observing the ND in the video you will see the pilot flying a HDG of 280...281 (minute 30:23).

2. Since the FD should be related to ACFT HDG and not to ACFT roll, if the pilot banks the ACFT short left/right without a change in HDG, there is absolutely no reason at all to see the FD acting like a pogo stick from left to right. This behaviour would be induced by using the rudder pedals since they will yaw the ACFT towards a diferent HDG. In the real cockpit view you will also see the roll adjustements but the FD will not budge from the middle.

Feel free to correct me if I'm wrong since as I stated above, I'm not a real pilot.

 

22 hours ago, downscc said:

I've done this without noticing any lag error in the FD roll command.  One example off the top of my head is the PANC RNAV(RNP)33 approach that I flew from HOPER which means I used the FD to fly a 270 deg loop and roll out on short final.  I was near minimums and there being no approach lights, only REILs, I was right on 33 centerline when I broke out at about 750 ft AGL and saw the REILS. Vis was so low I didn't see much else, and this is why i remember that approach so clearly.

The problem you describe is unusual, even if there are two or three reporting it.... I've not seen it reported before in the nearly 5 years that the product has been released.  I don't have a clue what it might be and based on a few comments above I suspect it might have more to do with a lack of understanding of how a FD performs.  For example,  the roll bar will be centered if you are off course and correcting as intended by the FD.  The roll bar is not course deviation indicator, it is a steering command bar.

You can't realy say that only 2 (or less) people are having this issue because there are a plethora of ways to land the ACFT (I fly it since 3 years now in FSX, FSX:SE and now P3D and decided only now to ask about it (not exactly to report an issue).

You have users that boght it and have no clue how it works, users that don't register to the forums, users that do full autoland, users that land manualy but disc AP only on MINIMUMS, users that use HUGS or HUD to land (which btw works perfect), users that land manualy but always eyeball the RWY (<- this is me) and so on.

To be able to assess an issue you will have to try it out.

1. Therefore if my understanding of the FD is right, bank your ACFT L/R that quick so that the HDG stays the same. If the FD will mowe out of the center, It's clearly wrong.

2. (I like to test myself). Just before intersecting the VOR, cover the top half of your monitor with a clouth and try to land. I'm willing to bet that you will not land centered on the RWY.

 

PS: I can land the FSL even with sidewind following just the FD and only after many successful landings in low vis with it, I decided to open this thread. I'm unable to do the same with the 737 (which is now on heavy duty since I currently have only P3D v4 installed ;) ).

Share this post


Link to post
Share on other sites

Gerald,

How does it fly with the HUD?

Just a piece of real world advice, don't do what the FD is telling you, do what the airplane is telling you.  :smile:

blaustern

 

  • Upvote 1

Share this post


Link to post
Share on other sites

@Bluestar With HUD I always hold that "small circle" in the TD zone of the RWY and land all the time (well not perfect but) pretty good (but again, I have to have a visual on the RWY for that).

Share this post


Link to post
Share on other sites
1 hour ago, GEKtheReaper said:

The FD should point you (HDG and pitch) in the right direction that would be necesary to follow a certain path.

No -- it provides steering commands to achieve a particular trajectory. Thus your statement...

1 hour ago, GEKtheReaper said:

Since the FD should be related to ACFT HDG and not to ACFT roll, if the pilot banks the ACFT short left/right without a change in HDG, there is absolutely no reason at all to see the FD acting like a pogo stick from left to right.

...is not quite correct.

The FD does not care about the aircraft's heading as such, it commands a roll (I suppose more accurately a rate of heading change -- I haven't looked what it does in unbalanced flight) in order to achieve the target heading. If only a small roll is required, the FD bar will only deflect a small amount. If you roll further/change heading more quickly than the FD has calculated it would like you to, you will indeed "roll past" the FD and it will deflect in the opposite direction, which is what is happening here.

1 hour ago, GEKtheReaper said:

Observing the ND in the video you will see the pilot flying a HDG of 280...281 (minute 30:23).

The FD is not centred at this point: it is very slightly deflected to the left (look at where the FD bar is in comparison to the pitch index symbol: just going through the left edge, not dead centre). The pilot then rolls further to the left than the FD is commanding and so "rolls through" the FD command, and so the roll bar moves to the right.

1 hour ago, GEKtheReaper said:

In the real cockpit view you will also see the roll adjustements but the FD will not budge from the middle.

Look how much smaller the roll inputs are in the real flight deck though. As it happens, if you look at around 6:30 and 6:45, some sharper, larger left roll inputs are made and you will notice that the FD moves across to the right, albeit in a smoother manner than in the sim video (but then the inputs are smoother and smaller also).

Share this post


Link to post
Share on other sites

In the video, it's almost as if the guidance cue is simply hanging from the Sky Pointer.

Even with a 90-degree turn, the F/D smoothly slides over to the side in the real thing. It's pretty slow to correct. The autopilot will very strongly follow the cues, but I don't think I've seen the F/D that jumpy and I've been in some bad turbulence.

I'm heading to the sim in a few weeks. If you guys don't have it sorted out by then, I'll see what a "real sim" does if I get a chance.

  • Upvote 1

Share this post


Link to post
Share on other sites
1 hour ago, Spin737 said:

In the video, it's almost as if the guidance cue is simply hanging from the Sky Pointer.

Even with a 90-degree turn, the F/D smoothly slides over to the side in the real thing. It's pretty slow to correct. The autopilot will very strongly follow the cues, but I don't think I've seen the F/D that jumpy and I've been in some bad turbulence.

I'm heading to the sim in a few weeks. If you guys don't have it sorted out by then, I'll see what a "real sim" does if I get a chance.

Matt,

I don't put as much trust in the F/D as a lot of folks.  For me I find the F/D tends to lag behind what I am trying to do when hand flying.  For that reason I tend to turn it off especially when hand flying visual approaches.  I know I'm just old and old school, but I'm going to do what the airplane is telling me, not the F/D.  :smile:

blaustern

  • Upvote 1

Share this post


Link to post
Share on other sites
42 minutes ago, Bluestar said:

Matt,

I don't put as much trust in the F/D as a lot of folks.  For me I find the F/D tends to lag behind what I am trying to do when hand flying.  For that reason I tend to turn it off especially when hand flying visual approaches.  I know I'm just old and old school, but I'm going to do what the airplane is telling me, not the F/D.  :smile:

blaustern

It's more of a Flight Suggestor for me. I flicked it off coming in to MCO yesterday. Storm on final so we made a short visual to a new runway. F/D wasn't gonna help me much.

Share this post


Link to post
Share on other sites

@skelseyThank you Simon (and all others: @Bluestar, @Spin737) for your time and explanations.

Since I'm certain Simon that you are more experienced then I am, I must trust your judgement and drop my idea of a "broken" FD.

Nevertheless, I think that some of the other users (maybe pilots), that again seem to be more experienced then I am, "feel" the same about the "jumpines" and "lagines" of the FD. Maybe PMDG might have a look into this for further updates.

Regards from lake Constance.

Gerald

Share this post


Link to post
Share on other sites
8 hours ago, GEKtheReaper said:

Maybe PMDG might have a look into this for further updates.

There are not going to be any updates to this product because of its age.  Expect PMDG to work on a major revison along the lines of the QOTSII, just don't expect it soon.

Share this post


Link to post
Share on other sites

I've tried again some landings using the HUD. It is much more easier to follow the Little circle with the ACFT Symbol. It feels more accurate. I also found the difference what was bothering me:

As @skelseyexplained, the FD provides "steering comands". Here is the odd Thing: lets say you Approach EDDM 08L/R and you have 90° sidewind from right (170°). If you are positioned right of the GS (Diamond to the left of the center) and fly RWY HDG, the wind will push you slowly to the left (thus towards the RWY CTR). If the FD will calculate that you will touchdown on the RWY CTR, it will not provide you with a steering command (which teoretically is correct).

It is odd because the FSL FD behaves a bit different. Given the same Approach as above, it will first guide you to the RWY CTR (CTR on GS) and then will tell you to turn your nose slightly into the wind so that the ACFT will remain CTR on GS.

I think that the second example is much more accurate. I have never seen ACFT flying RWY HDG with an Offset to the RWY so that they touch down in the Center of it. What if they have a windshear?

The FSL Approach and FD guidance resembles IMHO the real world. You have to be CTR on the GS all the time and compensate the sidewinds turning the nose into them. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now