PMDG 737 LNAV too aggressive last patch ?

[Bobsk8 12,944]

 

 

Just now, ThomseN_inc said:

You heard what Bobsk8 said. Its all how its supposed to be! 😉

Didn't like it when a real airline pilot disagreed with you, did you?   LOL

[WestAir 2,530]

9 minutes ago, Bobsk8 said:

Didn't like it when a real airline pilot disagreed with you, did you?   LOL

To be fair, he didn't disagree, he said it's good enough for a game. ThomseN is asking "how good is good enough", as opinions on this vary from simmer to simmer.

Edit: To answer the OP, Captain Randazzo has stated numerous times that the aircraft was recently fine tuned to handle the new aggressive gusts and turbulence. My guess is that whenever Asobo gets around to polishing the weather system we'll see far more stable LNAV behaviors across PMDG's product line. Right now the product is acting more aggressive than its real world counterpart as a direct response to the more aggressive weather.

Edited February 21, 2023 by WestAir

[roi1862 611]

1 minute ago, ThomseN_inc said:

You heard what Bobsk8 said. Its all how its supposed to be! 😉

I am not getting excited too much by him.... I am in Avsim from 2014 I think and I know hes smartass comments and his (often) snob comments. Its OK, I still try to stay respectful as he is older than me.  But yes, he is quick to judge and decide what is right and what what is wrong, and more then once has to say he's sorry in the end. 

All good. 

[roi1862 611]

21 minutes ago, WestAir said:

Edit: To answer the OP, Captain Randazzo has stated numerous times that the aircraft was recently fine tuned to handle the new aggressive gusts and turbulence. My guess is that whenever Asobo gets around to polishing the weather system we'll see far more stable LNAV behaviors across PMDG's product line. Right now the product is acting more aggressive than its real world counterpart as a direct response to the more aggressive weather.

Thanks I didn't knew that. However, Fenix is on the same platform and has no problem to implement an almost perfect (IMO) lateral navigation performance. 

But lets drop it please. I don't want to get into another argument of products comparison. All I want in this topic is to understand if others are having the same finding as me. Period.

 

Back to the topic. Found the below statement in pprune.org: 

"A/P and FD commands max bank of 25 degrees. Using LNAV, will normally only command 25 if a sharp turn is required on a SID, holding pattern, or at significant dog-leg in the airway at altitude. Most turns at altitude are shallow, less than 15 degrees."

Edited February 21, 2023 by roi1862
More info

[ThomseN_inc 1,128]

3 minutes ago, roi1862 said:

Thanks I didn't knew that. However, Fenix is on the same platform and has no problem to implement an almost perfect (IMO) lateral navigation performance. 

But lets drop it please. I don't want to get into another argument of products comparison. All I want in this topic is to understand if others are having the same finding as me. Period.

In order to compare the behaviour of the real plane to  PMDGs you can watch a bunch of YT Videos. Its just my non expert opinion that the real thing is much more "gentle" overall in regards of bank angles and roll rates.

Check MightyMKL on YT its a great source.

[ThomseN_inc 1,128]

27 minutes ago, Bobsk8 said:

 

 

Didn't like it when a real airline pilot disagreed with you, did you?   LOL

Are you his spokesperson or something?

Sorry that i am only familiar with Airbus types in RL. But as a passenger on dozens of 737 flight i never had the impression of a somewhat twitchy behaviour like i get in the PMDG 737.

Can't change that. 

[V1ROTA7E 718]

3 hours ago, roi1862 said:

If you tell us that the real thing takes turns in cruise with usually 2 consecutive turns which at least 1 of them at 30 degrees bank angle i would say ok, as i trust you know your thing… 

The issue with the PMDG is that LNAV doesn't appear to compensate for speed. If you scroll your ND range down to 10 during a turn, you can see that the 30 second trend vector overshoots the turn. in the real plane it'll dampen the turn a bit. Again, not perfect, but it's a simulator. I believe the CRJ also suffers from this. At lower speeds you can see that the course line is much more accurate. The only thing the PMDG would really need is LNAV speed compensation, but again, it's a $70 plane. I could list about 50 different things that are not accurate or are out of date on the PMDG when compared to real world 737's, but it works well for what it is. Honestly 98% of simmers wouldn't know the difference to the real thing, but it’s still incredible that they managed to model some of these systems so well with such attention to detail. I could also list 500 other things that are dead nutz on accurate. So weigh the differences...it's a very well modeled plane that will improve over time; I imagine they'll have continual updates, especially when they release the MAX.

Edited February 21, 2023 by V1ROTA7E

[ThomseN_inc 1,128]

11 minutes ago, roi1862 said:

All I want in this topic is to understand if others are having the same finding as me.

Yes i have the same impression. 

[jrw4 626]

42 minutes ago, roi1862 said:

Again. the issue is not on the approaches and low altitude as the plane is allowed as much bank angle as needed anyway

But someone earlier in this thread said that there was a problem with DME arcs. There seems to be some confusion here.

[roi1862 611]

13 minutes ago, V1ROTA7E said:

The issue with the PMDG is that LNAV doesn't appear to compensate for speed. If you scroll your ND range down to 10 during a turn, you can see that the 30 second trend vector overshoots the turn. in the real plane it'll dampen the turn a bit. Again, not perfect, but it's a simulator. I believe the CRJ also suffers from this. At lower speeds you can see that the course line is much more accurate. The only thing the PMDG would really need is LNAV speed compensation, but again, it's a $70 plane. I could list about 50 other different things that are not accurate or out of date on most 737's at the moment, but it works well for what it is, and 98% of simmers wouldn't know the difference to the real thing. I could also list 500 other things that are dead nutz on accurate. So weight the difference...it's a very well modeled plane that will improve over time as I imagine they'll have continual updates, especially when they release the MAX.

Thank for your input ! I was thinking something in this direction. My theory was the it simply do not start the turn early enough, and once its understanding it, autopilot is sharpening the turn in order to catch the path. 

As i said before, i don't want to get into the claims of product price vs results. Ill just say the Fenix is a product of $60. And ill stop here.

[V1ROTA7E 718]

1 minute ago, roi1862 said:

Thank for your input ! I was thinking something in this direction. My theory was the it simply do not start the turn early enough, and once its understanding it, autopilot is sharpening the turn in order to catch the path. 

As i said before, i don't want to get into the claims of product price vs results. Ill just say the Fenix is a product of $60. And ill stop here.

And the FBW is free. My point was, manage your expectations. Never flown an airbus, but I really enjoy the fenix, and its autoflight system is beautifully modeled…I think lol. I’m by no means making excuses for PMDG… there are quirks that are highly annoying…even on the 747-4/8 when I flew that, and when voicing my concerns, I was called a fraud on their forum. I’m not sure things will be fixed, so I’ve just learned to roll with it, and hope for the best because until someone is around to ‘one up’ them, they’re really all we’ve got for high fidelity Boeing stuff. 

[roi1862 611]

5 minutes ago, V1ROTA7E said:

And the FBW is free. My point was, manage your expectations. Never flown an airbus, but I really enjoy the fenix, and its autoflight system is beautifully modeled…I think lol. I’m by no means making excuses for PMDG… there are quirks that are highly annoying…even on the 747-4/8 when I flew that, and when voicing my concerns, I was called a fraud on their forum. I’m not sure things will be fixed, so I’ve just learned to roll with it, and hope for the best because until someone is around to ‘one up’ them, they’re really all we’ve got for high fidelity Boeing stuff. 

I know, its all good. its just a game (ok ok, simulator 🙂 ), all my original post intention was to simply understand if others experiencing it, or maybe I understood the systems wrong etc... I did not say that now the product is complete rubbish and i wont use it anymore because the LNAV cruise bank rate is incorrect. and i even concluded the post with: "Other than that its a great plane ! "

Edited February 21, 2023 by roi1862
typo

[Stearmandriver 2,333]

1 hour ago, WestAir said:

To be fair, he didn't disagree, he said it's good enough for a game. ThomseN is asking "how good is good enough", as opinions on this vary from simmer to simmer.

Edit: To answer the OP, Captain Randazzo has stated numerous times that the aircraft was recently fine tuned to handle the new aggressive gusts and turbulence. My guess is that whenever Asobo gets around to polishing the weather system we'll see far more stable LNAV behaviors across PMDG's product line. Right now the product is acting more aggressive than its real world counterpart as a direct response to the more aggressive weather.

I'll kind of disagree that it's good enough, though it is a matter of perspective.  Good enough for a game?  Of course.

But the way it is now, it is at once too twitchy, and not quite precise enough.  This manifests most significantly during complex RNAV (usually RNP) procedures.  LNAV is fine for enroute and normal RNAV procedures in the PMDG.  It does struggle with the complex stuff though.  

This strikes me as both a reaction to the MSFS atmospherics, and a need for better LNAV path calculations from PMDG.  This has been improved once (significantly), with more coming along with full ARINC-424 compatibility such as RF legs.

I won't really complain about what we have now, as it does a decent job at remaining on course even in gusty winds.  The procedure I use to test it is the non-public RNVM 05 into PAPG; this is one long RF leg through about 140 degrees of arc to roll wings level on final at about 300ft, so it makes a complex test.  There are wind conditions the PMDG cannot remain on course in.  In the real airplane, a smooth bank angle is maintained through the whole arc and you never, ever, deviate from centerline, not even a little bit.

[Bobsk8 12,944]

I just did an AP approach  into KOMA  using a procedure turn outbound on the LOC radial, and I forgot to reset the bank limiter back to 25,  ( it was still at 10) and I quickly noticed that the turn was going to be way too wide. I moved the limiter to 30, and the turn tighten up with no problem. So  the bank limiter works when you are on autopilot and NAV mode. 

[roi1862 611]

30 minutes ago, Bobsk8 said:

I just did an AP approach  into KOMA  using a procedure turn outbound on the LOC radial, and I forgot to reset the bank limiter back to 25,  ( it was still at 10) and I quickly noticed that the turn was going to be way too wide. I moved the limiter to 30, and the turn tighten up with no problem. So  the bank limiter works when you are on autopilot and NAV mode. 

First things first, you pretty much describing the phenomena i mentioned above. Starting turns gently and sharpening them fast to achieve path. I recommend you to try the same thing and this time leave the HDG bank limiter at 10. See what will happen. 

If it still affect your bank angle limit while you in LNAV mode, you can open a ticket to PMDG. I never encounter it yet.