PMDG Forum Rules

1) SIGN YOUR POSTS. Since 1997, we have asked users to sign their real name, first and last, to all posts in the PMDG forum. We do this in order to keep conversations personal and familiar. You took the time to be here, we want to get to know you. This is one of the few rigid rules that we enforce regularly. We do so because we feel that forums in which users must engage one another personally are generally warmer, more collegial and friendly. Posts that are unsigned will be quietly removed without comment by the moderators, so to make your life easy- we recommend enabling your forum signature so that you never need to remember. Do this by clicking the username pull-down at the top right, then selecting "User Settings." You will find the signature editor on the ACCOUNT tab, about half way down the page. Look for "Edit Post Signature." Be sure to click the "Show Signatures" box.

2) BE NICE. We are all simmers here and no matter our differences of opinion, we share a common love of aviation, computing and simulation. Treat everyone else in the forum with respect even when you disagree. If someone frustrates you, walk away from the conversation or ask for a moderator to get involved. Speaking of Moderators, they prefer not to be treated as "The Thought Police" but if any behavior infringes on the enjoyment of another user or is otherwise considered to be unacceptable in the moderator's judgment, it will be addressed in keeping with our view of ensuring that this forum remains a healthy environment for all simmers.

3) BE LAWFUL: Any behavior that infringes upon the law, such as discussion or solicitation of piracy, threats, intimidation or abuse will be handled unsympathetically by the moderators. Threats and intimidation may, at the moderator's discretion, be provided to law enforcement for handling.

4) BE FACTUAL: When you post, always be factual. Moderators will remove posts that are determined not to be factually accurate.

5) RESPECT COPYRIGHTS: Posting of copyrighted material such as flight manuals owned by Boeing or various airlines is not allowed in this forum. If you have questions related to copyrighted material, please contact a forum moderator for clarification.

6) RESPECT PMDG: We love to hear what you like about our products. We also like to hear what you think can be improved, or what isn't working. Please do tell us and we will always treat your feedback with value. Just be sure to treat the team respectfully, as they do put a significant amount of effort into building and maintaining these great simulation products for you.

7) RESPECT PMDG DEVELOPERS: All of the developers will spend some time here. Given the ratio of developers-to-users, it simply isn't possible for us to answer every post and private message individually. Please know that we do try to read everything, but developer workload is simply too high to manage personal contact with tens-of-thousands of users simultaneously. In most cases, members of the development team will stick to conversations in the forum and will not answer private messages.

8) RESPECT OTHER DEVELOPERS: PMDG has always advocated for a strong development community and we have many friends within this community. Every developer offers something unique that helps to make the simming community larger and more vibrant. We insist that you treat our friends respectfully.

9) RESPECT MODERATORS: Moderators have a tough job, and none of them enjoy having to stomp out negativity. If a moderator has to weigh in to keep a thread peaceful, please respect that effort and refrain from giving the moderator any grief.

10) If you require official support for any of our products please open a support ticket through the support portal,

11) This forum is designed primarily as a vehicle for the PMDG development team to interact with our customers, and for customers to interact with one another in a manner that is positive, supportive and assists in the general advancement of understanding the simulation and helping to make this and future simulations better. Any other use of this forum is not permitted, including but not limited to discussion of pricing policies, business practices, forum moderating policies, advertising of non-PMDG products, promotion of events, services or products that are not approved in advance by PMDG or any other topic deemed unacceptable by any forum administrator

12) HAVE FUN: This is the whole point of it all.
See more
See less

Noticed a bug about icing

  • Filter
  • Time
  • Show
Clear All
new posts

    Noticed a bug about icing

    Short story: PERF INIT includes ice weight into ZFW when you use the LOAD button, causing all related calculations to be wrong, despite some CDU displays correct ZFW.

    Long story:
    I flew from an icing airport to a non-icing one.
    when I was pre-flight I noticed the ZFW in FUEL menu is highlighted, and it shows 300kg more than ZFW in PAYLOAD menu.
    I continued preflight, but kept monitoring the disagreement.
    As I taxi to runway, I noticed "Icing" in PAYLOAD menu went from "none" to 1.3% then to 1.4%, maximum was 1.7%, and the disagreement between FUEL ZFW and PAYLOAD ZFW increases.
    After take off, the icing percentage immediately began to drop, but it seems to show anything less than one whole percent as "none". the disagreement between the ZFWs drops, and finally reaches zero (both PAYLOAD and FUEL shows same ZFW).

    When I was about to land I noticed something wrong with landing Vref settings. I am very used to land the plane around MLW, so I know the Vref should drop from 30/150; 40/143 to 30/149; 40/142 right at 66.7 gross weight (which is IIRC the MLW for 738).
    But it didn't. I waited on and it finally did at 66.4 gross weight.
    The 300kg difference sounded familiar so I checked the ZFW setting in PERF INIT, and sure enough, it was 300kg more than the ZFW shown in both FUEL and PAYLOAD menus (as there's zero ice now, both shows correct ZFW). However, the Gross Weight display in Landing Vref menu was correct.

    So that leads us back to the "nutshell version": PERF INIT incorrectly includes ice weight when inputting your ZFW, causing the FMC to think that your plane is heavier than it actually is.

    The aircraft involved is 737-800 but I would guess that this issue affects all MSFS PMDG 737 family.
    Ching Charng

    Did you open a support ticket with PMDG about this? If you want to report this to PMDG, the best way to do so is with a support ticket in the support portal ( If you have never opened a ticket before, you will need to create a new account there since it does not use either your forum account or your PMDG store account.

    Edit: Also, you can adjust the ZFW on the Perf Init page if it doesn't give you the value that you are expecting to see.
    Tim Lincoln
    My YouTube Channel


    • boris.glevrk`
      boris.glevrk` commented
      Editing a comment
      Well I didn't notice that during pre-flight so (and you cannot change ZFW numbers in fuel menu)... yeah I'll open PMDG support ticket about it.

    I'm lost. I've never seen icing weight as an entry in the PAYLOAD menu, are we talking about MSFS payload or the PMDG FS Actions menu item?
    Dan Downs KCRP
    i7-10700K 32GB 3600MHz 3080Ti


    • Want2BFlyin
      Want2BFlyin commented
      Editing a comment
      The 737 in MSFS simulates the effect of icing by increasing the aircraft's weight. In the Payload section on the MCDU there is a line entry for icing that I think usually says NONE, but will show a percentage if there is ice on the aircraft.

    • cmakris
      cmakris commented
      Editing a comment
      Not the 737. This is how MSFS simulates icing by increasing the weight of the plane. The indication in the FMC is for the user to know that icing exists...

    • Want2BFlyin
      Want2BFlyin commented
      Editing a comment
      I'm honestly not sure what its purpose is other than that it is there. I noticed it on one of my first flights and thought "huh, that's interesting," then never paid any attention to it again.

    Originally posted by DDowns View Post
    I'm lost. I've never seen icing weight as an entry in the PAYLOAD menu, are we talking about MSFS payload or the PMDG FS Actions menu item?
    When you are icing, open FUEL menu from CDU.
    Notice the ZFW is different (and highlighted) from ZFW shown in PAYLOAD (also from CDU)

    And yes there is an icing entry in PAYLOAD. right column, right above "Set empty" there's a "icing NONE or x.x%". It's not input-able but it does exist.
    Ching Charng