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TO CG

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    TO CG

    Good afternoon all,

    Trying to catch up with the rest of the group here, i just learned the other day that the flightplans from Simbrief can be imported into the EFB (what a fantastic feature). So i'm preflighting an -800 the other day and i started wondering about two other things.

    1.) While waiting on final ZFW load figures, i have access to the estimated ZFW, i typically fill in the performance page of the EFB all the way to the estimated ZFW. Is there a way using the estimated ZFW that i can manually calculate an estimated TOCG? THat way i can run the EFB performance calcs during preflight, and then update with final numbers for a final run when loading is complete.

    2.) As i mentioned earlier somehow i missed the part in the manual talking about importing Simbrief flightplans to the EFB. I've looked to see if there is a way using the ACARs system as it exists or the EFB to bring the final load figures into the cockpit, so far i haven't found a way to do that. But just in case i'm missing it, and the only way to get those figures is to go into the FMC\PMDG menu, wanted to double check with the experts.

    Thnx all.

    Richard Bansa

    #2
    The EFB Manual is here: <P3Dv5>\PMDG\EFB\EFB Documents Library.
    There is no direct way to estimate TO CG from simply an estimated ZFW, there are tables in the Performance Dispatch section in the FCOM but I'm not sure those provide TO CG either, because that value depends as much on the moment arm of the weights and the amount of weight itself.

    I personally do not see an advantage to estimating takeoff with the OPT, only to go back and modify it because it's so quick and easy to read the weights and fuel from the aircraft with a push of a button. Why do it twice? My work flow, using Simbrief's is to run the OFP while I am waiting for the IRS to align such that before that is complete I have the aircraft loaded and the OPT takeoff calculation completed. I activate the datalink and then load the route using the Simbrief Downloader and CO ROUTE feature in the FMS.

    ACARS cannot provide load figures from the OFP.

    I just checked the PD section and no joy for TO CG.
    Last edited by DDowns; 29Jul2020, 21:44.
    Dan Downs KCRP
    i7-10700K 32GB 3600MHz 1080Ti

    Comment


      #3
      Hi Dan - thnx for the repsonse. I guess it's not that big of a deal to wait for the loading to be complete and then get final ZFW and CG and run the calculations. Hopefully when GFO comes online for all, we'll have access to getting the CG into the EFB.

      Richard Bansa

      Comment


        #4
        Originally posted by Slick9 View Post
        Hi Dan - thnx for the repsonse. I guess it's not that big of a deal to wait for the loading to be complete and then get final ZFW and CG and run the calculations. Hopefully when GFO comes online for all, we'll have access to getting the CG into the EFB.

        Richard Bansa
        I am confused why... the EFB calculates the TO CG. Why do you need to have a third source (you have the FMS and EFB)?
        Dan Downs KCRP
        i7-10700K 32GB 3600MHz 1080Ti

        Comment


          #5
          In my EFB, the way I am using it (which could be off) during the takeoff performance calculations, I have to enter both the ZFW & the CG. From what you are saying it seems like the CG is available somewhere in the EFB. I’ll go back to the EFB manual and dig in a little deeper.

          Richard Bansa

          Comment


            #6
            Originally posted by Slick9 View Post
            In my EFB, the way I am using it (which could be off) during the takeoff performance calculations, I have to enter both the ZFW & the CG. From what you are saying it seems like the CG is available somewhere in the EFB. I’ll go back to the EFB manual and dig in a little deeper.

            Richard Bansa
            Yes you are missing an important element. Use the Weight & Balance button and when that screen appears click on the Load from Aircraft button. Now you weights and fuel are in the EFB and the next step is to go to the Fuel tab and enter the planned trip fuel and departure taxi fuel planned and now you have at estimate of LDW.

            After you do the Weight and Balance, then you go to the Takeoff calculator, which will already have the weight and CG from the first page and enter your weather and configuration for takeoff. It calculates the ATM derate and takeoff distance and provides the V speeds and TO Trim.

            Richard, you're missing the most important features of the EFB.
            Dan Downs KCRP
            i7-10700K 32GB 3600MHz 1080Ti

            Comment


              #7
              Thnx for the help on this Dan, I obviously have to delve deeper into the EFB manual. FOr me learning about these features is just as exiting as flying - loving this bird. Thnx again as always.

              Richard Bansa

              Comment


                #8
                In real life we can't do the takeoff calculations before getting the final figures either.
                We are supposed to get the Load Information Document (the paper we use to fill out the EFB Weight and Balance) 8 minutes before offblock.

                Comment


                • Swaluver88
                  Swaluver88 commented
                  Editing a comment
                  *dependent on the airline*

                #9
                In real life we can't do the takeoff calculations before getting the final figures either.
                We are supposed to get the Load Information Document (the paper we use to fill out the EFB Weight and Balance) 8 minutes before offblock.
                Just out of curiosity Emi, who compiles the figures for the Load Information Sheet? Does each flight have a load master that's responsible for this? Just wondering how the whole process works.

                Richard Bansa

                Comment


                  #10
                  Each airline works differently. In my operator we have dispatchers in charge of the flight plan, they could be handling up to 15 flights simultaneously and we have dispatchers in charge of the w&b only, some other operators can have a single person doing everything, depends on the magnitude of the operation. You get some estimated numbers based on the numbers of web checked-in customers and expected cargo that’s included on the OFP (operational flight plan) that we receive at least 3 hours prior to block out time and we use that information to compare the numbers against the final loadsheet, which we are supposed to receive no later than 10 mins before block out time.

                  This is done this way in order to have a more accurate picture with the least amount of LMC (last minute changes) and at the same time give some buffer of time to our dispatch department, in case they need to generate a new loadsheet or ofp for the flight and we avoid getting hit with a “delay”. (OTP is a very important metric)

                  In case we do have some LMC, the loadsheet includes some reference numbers that vary from operator to operator to make adjustments for lmc, could be for example up to +-8 pax or +-1700lbs of cargo, anything above/below that requires a new loadsheet from dispatch. We also compare the ZFW from the final loadsheet against the ofp to make sure we carry enough fuel for the weight that we are carrying. Each operator has a margin of tolerance which varies, could be a difference of +4000 lbs for a 2+ hrs or for longer flights a more strict policy of +2000lbs for 4+hrs flight. This would require generating a new ofp to get updated fuel calculations for the proper takeoff weight.

                  Anyways, we used the final loadsheet numbers to calculate the takeoff speeds and maximum assumed temperature for n1, pretty much one of our final steps before departure.

                  Hope this gives you a better picture on how airlines operate.
                  Last edited by zaguama; 31Jul2020, 21:37.
                  Manuel Zarate

                  Comment


                    #11
                    Richard, I believe what Emi has described applies to virtually all of the major airline operators I know.

                    The Load Master, Aircraft Dispatcher or Red Cap as they are sometimes called is a qualified person who is responsible for overseeing the loading and weight distribution of the aircraft. They will produce the provisional Loadsheet figures for the Captain to check and, if necessary, send any minor last minute changes via ACARS. The Loadsheet is a legal document that only the Captain has authority to sign in the U.K. because in doing so the aircraft is being accepted by him or her as being correctly loaded for the whole of the intended flight.

                    The various aircraft weights and CG data you seem to be worried about are produced by the FMS when we input and/or modify the performance data required for the flight. Depending on the aircraft type, some of this information might be initially obtained from the Flight Plan, the Loadsheet, or automatically generated by the FMS itself, such as the CG, the total Fuel load and the takeoff speeds Emi mentioned.
                    Michael Codd

                    Comment


                      #12
                      Originally posted by Emi View Post
                      In real life we can't do the takeoff calculations before getting the final figures either.
                      We are supposed to get the Load Information Document (the paper we use to fill out the EFB Weight and Balance) 8 minutes before offblock.
                      I'm curious, why specifically 8 minutes.
                      Captain Kevin

                      Kevin Yang

                      Comment


                        #13
                        Originally posted by Slick9 View Post

                        Just out of curiosity Emi, who compiles the figures for the Load Information Sheet? Does each flight have a load master that's responsible for this? Just wondering how the whole process works.

                        Richard Bansa
                        As manuel described earlier those greatly vary between airlines. In *my* airline the ramp agent draws up the LID.
                        He will get the final passenger numbers from the gate agents as soon as the last passenger has passed through the gate (gate closure is STD-15, but if there are still passengers left in the queue they will of course still be allowed to pass).
                        Then he'll get the number of bags loaded and their position in the 4 holds from the loading staff plus any eventual cargo that might be loaded.
                        This is all wrote down in the Load Information Document which we are supposed to get 8 minutes before offblock.

                        Theoretically this should allow the dispatcher sufficient time to collect all the required information between gate closure and the deadline to hand over the information. Also my company calculated that 8 minutes should be enough to allow us to run the takeoff calculations, enter them into the airplnae, run the before start checklist, get clearance and then push on time.
                        If you have a good handling agent those times work just fine and you usually get off a minute or two early.

                        Comment


                          #14
                          Emi, Michael, & Manuel,

                          Just wanted to say a big thanks for the information you posted. Of course with simming we are usually focused on the front end of things, but i often wonder about the many "other" parts that are required to get an airliner airborne safely. Thnx for shedding some light on this.

                          Richard Bansa
                          Last edited by Slick9; 04Aug2020, 15:09.

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