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[17JUN22] PMDG 737 Development Update - Sometimes You Just Can't Do Anything Right...

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    [17JUN22] PMDG 737 Development Update - Sometimes You Just Can't Do Anything Right...


    Happy Friday and welcome to the weekend! This week I have a couple of small points for you- really just to bring you up to speed on where we are, what we are doing, and how things are going.

    Before we begin: This post is primarily focused on giving you a real-time look at how we change development priorities in order to advance products toward release. Honestly the topic is a bit insanely dull to me, but many of you have expressed an interest in knowing how we handle changes behind the scenes, so here is a real-time look.

    PMDG 737-700: Pending Update
    This update cycle has a number of of fixes/tweaks and new capabilities added to it, but most of them are really small functionality items. The larger focus has been on continued upgrades to targeted areas of the flight deck visual fidelity and improvements in animation algorithms that have proven problematic for many users in the form of "hitchy" or "granular" or "low fps" animations in things like the yoke, column, throttles, etc.

    We are happy to report that we have made really good progress toward smoothing these things out. To give credit where it is due- a couple members of the user community made observations about the "low fps" that got the investigative progress going in the right direction- and we found that animations tied to complex systems where we intentionally limit the computation speed in order to avoid flooding the processor with floating point computations is where things break down. So a reimagining of some key areas related to the measurement and passing of time and processor cycles was called for- and this is miserably complex work that is taking a bit longer than we had planned.

    The good news is that the results are starting to show and we are relatively confident we will be able to apply this technique to just about every area of animation to smooth things out. It might take a few update cycles to get through all of it- but the first round of it is focused on the main offenders sitting right in your central workstation on the airplane.

    So those of you who have participated in the conversations on this topic here in the forum, and those who have answered questions publicly and privately- please do pat yourselves on the back- nice job in helping us zero in on the core of the problem!

    Oops, I did it again:
    Anyone who has ever worked with computer animation will tell you that one of the hardest things to animate WELL is an object that spins really fast. Wheels, windshield wipers, fan hubs, and trim wheels. I hate all of them. We spent a ton of time getting the trim wheel animation correct in the 737 prior to release- and then along the way someone (who shall remain nameless because he signs the paychecks <cough>) accidentally reverted that section of code to "original source" which then took the 737 trim wheel animation back to a version that was implemented in the 737NGX in 2010. And nobody noticed.

    After seeing a number of complaints about it here in the forum, I finally got around to looking at it more closely and realized that it was indeed hopelessly broken... A day re-engineering it to approximately what I remembered it to be prior to breaking it in the first place- and we were ready to go. We issued a new build to our beta testers on Monday, thinking "good- we can get this fixed and push an update on Wednesday."

    Then the beta team began to agitate about some problems in the animation and some really unwanted behavior in the sounds associated with the trim wheel. By Wednesday afternoon, Alex and I were working on this together trying to un-<censored> the trimwheel logic for the second time in a week.

    We are almost finished- but need a few more days to hand it off to the beta team for testing and evaluation.

    Since the trim wheel is central to the entire airplane- we have opted to sit on our hands with respect to a new update until Alex and I finish getting this un-<censored>. Or, to be more candid, until Alex finishes fixing the parts I have now broken three times. Nothing like having your development partner sabotage your forward progress.

    PMDG 737-700 Update Estimate?:
    We are currently hoping to put the update back into testing on Sunday, which will hopefully give us a validation to release the next update mid week.

    Provided nobody breaks anything.

    PMDG 737-700 into MS Marketplace:
    We have held our fire on moving the 737-700 to Marketplace because we want to get a few more things corrected before we expand the user base via marketplace. Primarily, our concern is the incompatibility between our product and gamepad/twist grip/dual rudder axis controllers. This simply hasn't gotten the attention it needs yet- and we think it is ill informed to add the product to marketplace until we have a solution in place. I am desperately hoping the next update cycle (after the one in testing) will include a fix for these controller issues... Stay tuned for more.

    We have some exciting news with the upcoming 600 release: The beta team will be getting a version of the 600 over the weekend that has the new PMDG Lateral Flight Path Model that has been under development for two years. The new LFPM encompasses the entire lateral flight path process, including the flight director logic in order to give a far more accurate, more true-to-life lateral flight path model that has been sorely needed in our entire product catalog for some time.

    The current expectation is that the 737-600 will deliver with this modernized capability, and the 737-700 will receive an update to build it into that airplane on the same day the 737-600 is released. (And then, obviously, it will be present in all products released going forward of this update.)

    The new LFPM also has a fringe benefit of eliminating a long-standing problem in the vertical flight path caused by the fact that the older LFPM did not accurately compute the distance the airplane would travel in a turn, and this caused vertical errors to accumulate, sometimes becoming noticeable or causing the airplane to depart from the planned vertical path in ways that weren't expected. The new LFPM reduces these accumulated errors, resulting in an associated improvement in the vertical path, which has been waiting for the new LFP in order to improve accuracy.

    Inevitably, our plan is to roll this new LFPM backward through our entire product catalog in Prepar3D as well. There is no defined schedule for doing this yet, as we are entirely committed to the MSFS dev cycle for the near term- but it is likely we will pop it into the P3D product lines in intermediate update cycles along the way. It is hard to predict a schedule for this until we get clear of the 737 release cycle at least.

    PMDG 737-600 Release Plan?:
    We decided to test the new LFPM in the 600 because doing the testing in the 737-700 would potentially mean some disruption to our ability to update that airplane rapidly if warranted. Putting the LFPM into the 600 allows us the freedom to give it adequate testing time where the worst that might happen is a bit of a slide in the release schedule for the 600. Currently we are looking at adding a few weeks to the 600 development in order to get this testing wrapped up effectively.

    I'll have slightly firmer guidance on the 737-600 release plan next week after we see the next version in testing. I

    Since one or two of you are wondering: None of this affects the dev cycle of the 737-800, which is progressing apace.

    PMDG 737-600 in MS Marketplace:
    We have been asked by a number of users if we would consider releasing the 737-600 in marketplace more-or-less concurrently with the release on We are moving in the direction of saying yes here- but there are a couple of items we want to resolve across the 600 and 700 before officially declaring this a sound idea. I suspect the latency between a release and a Marketplace release will be smaller on the 600 than it is on the 700... and likely smaller still for the 800, etc.

    PMDG Universal Flight Tablet:
    Work continues here. This week we are integrating navigraph charts, and also refining simbrief functionality. It is still too early to predict when this will slot into the 737 release cycle, but the team working on this aspect of the airplane is motivated and making incredibly good progress. I suspect holding off on this technology piece until after release of the 700 has given them a chance to really refine what it is we are accomplishing with this piece of the product line- and it is shaping up to be something truly wonderful.

    Far nicer than the clunky first generation EFB we modeled in the NGXu.

    Alright- that was just a small update. We hope you all have a nice weekend ahead. Please do send in pictures of your weekend 737 flying adventures. Or- if you are out there flying for real- tell us about that too! Perhaps I'll share a flying adventure story with you as well here this weekend. Lets see how my wrestling match with the trimwheel goes.

    Thanks everybody- enjoy your Friday!

    Robert S. Randazzo
    PMDG Simulations

    Happy Father’s Day too Robert! 😊
    Michael Codd



      AH! Yes! Same for you, and all the rest of the fathers in our group here. My daughter is traveling this weekend so we'll celebrate after she gets home.

      Robert S. Randazzo
      PMDG Simulations


        Originally posted by rsrandazzo View Post


        Inevitably, our plan is to roll this new LFPM backward through our entire product catalog in Prepar3D as well. There is no defined schedule for doing this yet, as we are entirely committed to the MSFS dev cycle for the near term- but it is likely we will pop it into the P3D product lines in intermediate update cycles along the way. It is hard to predict a schedule for this until we get clear of the 737 release cycle at least.

        Everything sounds good, but this part is especially like music in my ears ! Thank you ! (so this was very well worth receiving an infraction the other day due to that topic LOL)

        best regards
        Manolo Ruiz Carrió


          Amazing working glad a lot of the animations have been figured out, I am still patient on the axis inputs but once it comes, the wait will be worth it. Thanks to the entire PMDG team! Cheers!
          Sergio Gutierrez


            Thank you for the update, Robert.

            One thing I noticed on the -700 that I’m not sure other people are seeing: on approaches, I can only get down to Flaps 30, with the flaps noise still playing even though they’re stuck at 30. Once I touch down on the ground, the flaps go down to 40

            Is there something on my end that I’m doing wrong? Or is this an error with the plane that will be addressed?

            Alex Martin


            • Ephedrin
              Ephedrin commented
              Editing a comment
              Requests for help should really go into their seperate topics in the respective forum, Alex.

            • Stearmandriver
              Stearmandriver commented
              Editing a comment
              You're likely too fast, and seeing the flap load relief feature ("blowback"). The real airplane does this if you overspeed flaps 40, 30, 25, 15, or 10... flaps automatically retract by one position. I was testing this just a little while back; works correctly in the PMDG.

            Thank you very much Robert and thanks as well to the rest of the team that this topic got the attention it needed and that you finally were able to find the right solution to sort this out. For me personally this is the thing i looked the most for.

            And sorry for putting my finger all the time on that topic

            Thanks !

            Sascha Brandenburg


              Great update, looking forward to the things that I'm happy with at the minute getting better.
              Bring it on fellas !!!
              Andrew Bolton


                Thanks for the update Robert.

                Not sure if you want to go into detail about this, but how are you doing the EFB? It has always been said that EFBs in C++ can’t currently support things like simbrief and navigraph, which is why the AS CRJ doesn’t have them. So AS has switched to an HTML EFB for the A330. I guess what I’m trying to say is, have you had to revert to a HTML based EFB or has something opened up in C++ allowing these connections
                Joe Colehouse


                  Interesting, but any progress on how we can raise the landing gear after take-off? Or did I miss it? ;-)

                  Gareth Wilkinson


                  • Kevin Hall
                    Kevin Hall commented
                    Editing a comment
                    I assign toggle landing gear to a joystick button. Works for me.

                  • Stearmandriver
                    Stearmandriver commented
                    Editing a comment
                    There never has been any problem with gear retraction. The standard sim bindings for this work normally.

                  • Airrich
                    Airrich commented
                    Editing a comment
                    I applied some recommended tweaks to my honeycomb bravo. It still doesn't completely work right, but all I have to do is move the LG gear lever twice to get it to work. It's becoming second nature now. If they fix it, I will have to relearn it.

                  Thank you for the “dull” update! I am one of those strange ones that actually appreciate these.

                  and if it's any consolation, Boeing only solved their VNAV issues with FMC Update 14 in sept 2019. 😅


                    Thankyou Robert for updating us hope all goes well and looking forward to the 600.
                    Danny Z.Cebis


                      Thanks for the update. Really hoping the new efb will have the ability to launch on other windows or iPads.
                      Dave Gray


                        Thanks for the update Robert. Looking forward to seeing the unbroken trim wheel animation in action.


                          Thats great, really happy to hear the trim wheel is getting fixed! thanks for the update!
                          Amir Khanevadegi


                            i look forward to EFB come in 737-700 =)

                            Best Regards Petter
                            Petter Storvik


                              Do you have any plans to update the sensitive parts of the rudder movement?
                              Even if you step on the leader even a little, the aircraft rotates a lot, which is very unrealistic.
                              It feels like a plastic toy, not a heavy aircraft.
                              Some people say can adjust the sensitivity in the settings, but I use the keyboard to control the rudder. So I can't set the sensitivity setting.
                              Kim young ju


                                Thanks for the update Rob.

                                Originally posted by redsonssi View Post
                                Do you have any plans to update the sensitive parts of the rudder movement?
                                Even if you step on the leader even a little, the aircraft rotates a lot, which is very unrealistic.
                                It feels like a plastic toy, not a heavy aircraft.
                                Some people say can adjust the sensitivity in the settings, but I use the keyboard to control the rudder. So I can't set the sensitivity setting.
                                I do find, even with sensitivity adjustments that the 737 lacks momentum.. or a weighty feel on the ground, especially on t/o and landing. Can feel a bit light. I only find one plane really does it well in the sim and that is the A320 by FBW.


                                  This post raises some fascinating questions about your version control strategy -- Pull requests are a good thing!
                                  Tom Burns



                                  • Want2BFlyin
                                    Want2BFlyin commented
                                    Editing a comment
                                    I was thinking exactly the same thing. Then I remembered a time when I had accidentally wiped out half of the history for a branch in version control. Thankfully it was a minor branch used exclusively for experimentation, but that was a pretty big "oh, crap" moment.

                                  That's awesome news specially on the animations part! Glad to see the overall improvement the team is making on the plane and looking forward to the small beast in -600.
                                  Lucas Gama


                                    Woohoo! Glad we could help
                                    - Theo Repro


                                      Thanks for the updates, Robert. The communication is greatly appreciated - yes, sometimes we DO want to know how the sausage is made, just a little bit, especially if the sausage arrives to the plate later than originally indicated.
                                      Herb Schaltegger - Father, husband, lawyer, engineer & getting too old for this $#!t. Do Not Taunt Happy Fun Ball!TM.


                                        Next time you talk to Asobo mention your strategy of un f'ing ; stuff internally before releasing it. Post WU10 it is CTD central for me worse than alpha. Not that they listen .
                                        Aleks Matrosov


                                          Wow, it's nice to have visual improvements but that can't be the most important thing.

                                          The poor power/pitch/trim ratio should be the focus, because it bothers real pilots like me too much. Maybe it goes unnoticed to sims that have never piloted the real thing - but it's still easily noticed compared to the real manual flight on youtube videos.

                                          I guess I have to forget this, as I will never have a B737 with a more faithful manual flight on MSFS.

                                          I don't want to sound boring but this is really very important. Please, Robert, take a look at this, kindly on this matter.
                                          Last edited by Trovis; 17Jun2022, 15:50.
                                          Pedro Guedes


                                          • JasonK
                                            JasonK commented
                                            Editing a comment
                                            Just because something isn’t mentioned, doesn’t mean they are not working on it. At least with other software development projects, some issues may be targeted for later releases for numerous reasons. That could be the complexity of it, or other changes need to happen first in order to address other ones.

                                            Incremental updates require careful planning to map out how and when different bugs and new features make it into that schedule.

                                          • Trovis
                                            Trovis commented
                                            Editing a comment
                                            Okay, but my comment is based on what was posted by RSR. Any presumption beyond what has been said becomes guesswork. I have no way of understanding that this super important topic will be improved, so all I can do is ask for it to be improved. It's funny how people here don't accept criticism, and it should be the other way around, after all this can help us to have a better product. I'm just asking him to improve an aspect that needs improvement, which is completely fair.

                                          Will the updated LNAV will allow us to fly RF legs on RNP approaches or not ?
                                          Jordan Collins


                                            Great update! Nice to hear a lot going on in the background (as most of us appreciated would be happening anyway). Plenty to look forward to - thanks!

                                            Luke Carter | Flight Sim Content Creator & PPL Student Pilot


                                              Thank you for giving us such a nice piece of work

                                              I hope, I really hope in the future we can have a BBJ different cabin configuration (bedroom, bath, meeting room, VIP passenger cabin, and staff cabin) instead of having a bathroom without doors in the middle of the plane, and tow VIP areas almost identical.


                                                Thank you Robert.
                                                Tomas Zima Prague


                                                  Originally posted by fakeflyer737 View Post
                                                  Will the updated LNAV will allow us to fly RF legs on RNP approaches or not ?
                                                  It's a good question. I can't speak for PMDG, but a beta tester on the forum a while back said that the LNAV update was happening in two phases: first, a modification of the flight guidance behavior to precisely track the computed lateral path, and then a transition to the new navdata format that supports RF legs. Kind of sounds to me like this is the former, which is still great news.

                                                  The thing about the "pseudo-waypoint" method in use now is that it actually does a pretty good job of defining the desired lateral path, if done correctly. The magenta line on the ND looks good and follows the desired track... the real problem is that currently the flight guidance doesn't follow the line very well .

                                                  I've built several custom approaches in the PMDG that have 90 degree or greater heading change RF legs to a short final, and I've got them working well, but I have to hand fly them by laying the white turn predictor "noodle" on the ND over the magenta line. The fight director won't track it well enough though (the real airplane flies these approaches with exactly zero deviation from the approach path, it's a thing of beauty.) So if the flight director precision is tightened up, we'll be most of the way there.

                                                  Also great news that this change will at the same time address the VNAV errors that accumulate on these approaches; I appreciate the explanation on that!
                                                  Last edited by Stearmandriver; 17Jun2022, 16:46.
                                                  Andrew Crowley


                                                    Hmm I see. I thought MSFS default data included the correct data for RF legs.
                                                    Jordan Collins


                                                    • Stearmandriver
                                                      Stearmandriver commented
                                                      Editing a comment
                                                      I'm not sure; it might. But it doesn't include other parameters that are needed for complex procedures, so sim aircraft that can fly them are using custom navdata formats. PMDG's format (probably because they were one of the first to do it) does not currently support true RF. But it's nice to know it's coming.