Throwing passengers out of the plane in cruise...

[virtuali]

The message "The loaded flight plan from KLAS doesn't match the one on SimBrief" is not really the problem, it comes out because for some reason you have a *default* MSFS Flight plan starting at KLAS and ending at KLAS so, you get the message because the arrival airport doesn't match the one on Simbrief.

However, this shows GSX surely read the passengers number correctly, including the CDU entering part:

PMDG_Handler setting Passengers to 370

I tried here, using your simbrief username, and the passengers number is set correctly in the center CDU, 12 in first, 42 in business and 316 in economy, total 370 so, everything is ok as far GSX goes, suggesting the airplane must have changed the passengers number after GSX boarded.

[virtuali]

So it is something with the PAYLOAD import process within the 777 CDU.  Now I am not sure why the PMDG payload read 189 passengers when simbrief has 370 and GSX loaded 370.

This confirms my suspicion the airplane set the passengers number after GSX. And GSX always gives the airplane code the highest priority, even over Simbrief.

[psolk]

Yes, I've posted in the PMDG forum to see why their values don't match so it was not GSX so I do apologize however now you know if anyone else runs into this...

[psolk]

Umberto,
I had a chance to do a bit more testing and have opened a ticket with PMDG.

Apparently the 777 is not using accurate Simbrief values which is what is throwing off GSX.

So this really highlights itself if you use GSX together with the 777
Here are my steps:
Import Simbrief plan into EFB
Load Simbrief plan in CDU
Clicking SET PAYLOAD this changes all the simbrief payload values which is critical as GSX uses those values to calculate the number of passengers to deboard

Enabling GSX boarding AFTER Set Payload sets everything BACK to matching Simbrief. Alternatively you can go into Payload on the 3rd CDU and manually adjust Payload to match simbrief.

It makes no sense though. PMDG is using Simbrief Fuel loads but ignoring the passenger/cargo numbers which subsequently causes GSX to de-board the wrong number of passengers as it reads from the PMDG CDU numbers for deboarding.

As I said, i opened a ticket to see why they are ignoring simbrief values other than ZFW and Fuel Load and inserting their own values for the rest.  You can also watch it happen by bringing up the 3rd CDU and the Payload page.  When you press SET PAYLOAD on the primary CDU you can see PMDG overwrite the numbers in the lower CDU...

[psolk]

Unfortunately PMDG will not fix this so GSX will either remain broken in terms of passenger numbers (Due to PMDG, not GSX being broken) unless GSX can read the deboarding number from Simbrief instead of PMDG to keep the passenger numbers consistent...
is that possible?

Hmmmm.  Just thinking, if PMDG are saying the simbrief numbers create incorrect CG and GSX is loading those numbers then GSX is loading incorrect numbers... 

Frustrating one...

[Darewell]

« Set Payload » doesn’t change any Simbrief values (it wouldn’t make any sense, it’s not possible), it just imports the Simbrief ZFW value.

Just use GSX integration, there is absolutely no point importing the payload with the native Simbrief PMDG uplink (which in fact just import the OFP ZFW) if you then override these values with GSX.

The reason you lost passengers is because you used the PMDG import AFTER GSX had already set the correct values, so PMDG replaced the values set by GSX.

GSX will set xxx passengers and will deboard the same value as long as you don’t use the PMDG payload import or changes the values yourself.

PMDG doesn’t care about passengers numbers, they just import the ZFW, so most of the time you’ll have less passengers and more cargo than the OFP planned.

CG is not an issue, you just have to trim correctly for takeoff, have been using the GSX import for the last one year without any issues. At least you don’t always have more or less the same CG, it adds some variety in the handling.

In my opinion it’s more realistic to have 370 passengers and less cargo than 190 passengers and a lot of cargo, we’re not flying the B77F

PMDG probably imports the ZFW because it’s easier to just set that value, instead of allocating the passengers values between the different classes and the cargo between the cargo compartments.

[psolk]

« Set Payload » doesn’t change any Simbrief values (it wouldn’t make any sense, it’s not possible), it just imports the Simbrief ZFW value.

Just use GSX integration, there is absolutely no point importing the payload with the native Simbrief PMDG uplink (which in fact just import the OFP ZFW) if you then override these values with GSX.

The reason you lost passengers is because you used the PMDG import AFTER GSX had already set the correct values, so PMDG replaced the values set by GSX.

GSX will set xxx passengers and will deboard the same value as long as you don’t use the PMDG payload import or changes the values yourself.

PMDG doesn’t care about passengers numbers, they just import the ZFW, so most of the time you’ll have less passengers and more cargo than the OFP planned.

CG is not an issue, you just have to trim correctly for takeoff, have been using the GSX import for the last one year without any issues. At least you don’t always have more or less the same CG, it adds some variety in the handling.

In my opinion it’s more realistic to have 370 passengers and less cargo than 190 passengers and a lot of cargo, we’re not flying the B77F

PMDG probably imports the ZFW because it’s easier to just set that value, instead of allocating the passengers values between the different classes and the cargo between the cargo compartments.

PMDG is saying they are setting the values they do because simbrief is not calculating accurate CG values with it's flight planning.  So if you use Simbrief/GSX values you do not know if the CG is accurate and PMDG is saying the numbers Simbrief/GSX are importing are not accurate. 

So they take the ZFW and modify the load to have an accurate balanced CG.  They do allocate values to payload themselves which is why they do not match Simbrief and GSX. 

I agree it is more realistic to have 370 passengers but how is CG not an issue if you do not know if it is nose heavy or tail heavy for the given weight? 

[Darewell]

« Set Payload » doesn’t change any Simbrief values (it wouldn’t make any sense, it’s not possible), it just imports the Simbrief ZFW value.

Just use GSX integration, there is absolutely no point importing the payload with the native Simbrief PMDG uplink (which in fact just import the OFP ZFW) if you then override these values with GSX.

The reason you lost passengers is because you used the PMDG import AFTER GSX had already set the correct values, so PMDG replaced the values set by GSX.

GSX will set xxx passengers and will deboard the same value as long as you don’t use the PMDG payload import or changes the values yourself.

PMDG doesn’t care about passengers numbers, they just import the ZFW, so most of the time you’ll have less passengers and more cargo than the OFP planned.

CG is not an issue, you just have to trim correctly for takeoff, have been using the GSX import for the last one year without any issues. At least you don’t always have more or less the same CG, it adds some variety in the handling.

In my opinion it’s more realistic to have 370 passengers and less cargo than 190 passengers and a lot of cargo, we’re not flying the B77F

PMDG probably imports the ZFW because it’s easier to just set that value, instead of allocating the passengers values between the different classes and the cargo between the cargo compartments.

PMDG is saying they are setting the values they do because simbrief is not calculating accurate CG values with it's flight planning.  So if you use Simbrief/GSX values you do not know if the CG is accurate and PMDG is saying the numbers Simbrief/GSX are importing are not accurate. 

So they take the ZFW and modify the load to have an accurate balanced CG.  They do allocate values to payload themselves which is why they do not match Simbrief and GSX. 

I agree it is more realistic to have 370 passengers but how is CG not an issue if you do not know if it is nose heavy or tail heavy for the given weight?

You can see the actual CG directly in the FMC and trim accordingly I don’t follow you here. You don’t use any « CG value calculated by Simbrief ».

The actual CG value is shown in the various payload pages or by simply pressing the empty CG field in the first takeoff page, it will automatically show the actual CG based on the current loading, and giving you the correct takeoff trim setting.

In real life you would get that value on your final load sheet.

[psolk]

I follow you...  So ensure GSX has loaded it's values not PMDG's then click on the empty CG field (which is what I usually do anyway)

[Darewell]

I follow you...  So ensure GSX has loaded it's values not PMDG's then click on the empty CG field (which is what I usually do anyway)

Yes have been doing that since GSX implemented that integration, and even before that I was already loading the aircraft myself.

To ensure GSX has done its job you can also click the ZFW field(it will show in the scratchpad the current ZFW)  in PERF INIT and verify it matches your OFP.

As long as you trim for your current CG (the value you get from the PMDG itself so it doesn’t lie) your takeoffs will be perfectly balanced.

In fact you can experiment, play with the passengers and cargo loading and observe the CG value, and see how the takeoff trim setting changes. As long as you’re in the green band you’re fine.

In fact I’m sure having the cabin full is pretty much helping having a nice CG…

[psolk]

I follow you...  So ensure GSX has loaded it's values not PMDG's then click on the empty CG field (which is what I usually do anyway)

Yes have been doing that since GSX implemented that integration, and even before that I was already loading the aircraft myself.

To ensure GSX has done its job you can also click the ZFW field(it will show in the scratchpad the current ZFW)  in PERF INIT and verify it matches your OFP.

As long as you trim for your current CG (the value you get from the PMDG itself so it doesn’t lie) your takeoffs will be perfectly balanced.

In fact you can experiment, play with the passengers and cargo loading and observe the CG value, and see how the takeoff trim setting changes. As long as you’re in the green band you’re fine.

In fact I’m sure having the cabin full is pretty much helping having a nice CG…

The interesting thing is according to PMDG those values from Simbrief that GSX is using are not a "balanced" CG which is why they take the simbrief ZFW and then adjust the payload to get their own CG.  According to them Simbrief is not a Load Planner and weight is weight, pilots don't care so they just adjust the simbrief variables and put passengers in cargo to "make it work"    For a company that is so detail oriented to just say weight is weight seems a bit obtuse.  I agree with @Darewell varying cargo weights and passenger numbers add to the experience. 

So PMDG advise "not" to use the Simbrief and subsequently GSX numbers but then the GSX number of passengers for deboarding is not the same as boarding because PMDG changes them.

Hmmm.... 

I am with you though, I prefer a full cabin so I am going to go with Simbrief and GSX numbers and if I get an out of CG warning I will address it.    If I notice issues my backup plan is to let PMDG do it's thing but see if I can change the passenger numbers after landing but before deboarding and see if that will trick GSX into offloading the same number of passengers as boarding. 

Thank you though, you confirmed what I was thinking about just using GSX and simbrief and then computing the CG via the CDU

[virtuali]

The interesting thing is according to PMDG those values from Simbrief that GSX is using are not a "balanced" CG which is why they take the simbrief ZFW and then adjust the payload to get their own CG. 

I guess PMDG is referring to the distribution of cargo between FWD, AFT and Bulk zones, which is the only thing I can think of. GSX doesn't take anything from Simbrief performance calculator, it only takes the dispatched plan, and there, Cargo is expressed as a single figure, there's no distribution done by Simbrief.

What GSX does next, depends (as explained in the manual where the PMDG integration is covered) if your airplane profile on Simbrief assumes a standard passenger weight or not.

- If the passenger weight in the flight plan is the standard one, GSX will enter the Passenger number distributed over three classes (the CDU has 1st, business and economy, while the modeled cabin has only business and economy, this it's a confirmed bug of the CDU but it won't affect this too much) and will distribute the (single) cargo weight reported by Simbrief in the 3 cargo holds.

- If the passenger weight is not standard, GSX will JUST enter ZFW, and the airplane will do the rest, just AS IF you typed the ZFW yourself. GSX is not doing any weight distribution here.

So, I guess the only possible issue PMDG is referring to here, is how GSX distributes the (single) cargo weight it got from Simbrief across the 3 holds (when it's not using the ZFW method), and the answer it very simple: it distributes cargo EXACTLY like the PMDG CDU does, when you set the "Cargo Level" to a certain value, and of course we derived it by making a chart of the various values, to understand the CDU own strategy, which is as follows:


Cargo Level       FWD        AFT      Bulk      CG
      10%      1817.59   1547.89    354.50   25.5%
      33%      5999.03   5108.87   1170.09   25.3%
      50%      9087.96   7739.46   1772.58   25.1%
      66%     11997.08  10216.92   2339.90   24.9%
     100%     18177.87  15480.58   3545.54   24.6%


The above Table is what the PMDG CDU sets if you set a certain Cargo Level, and it's basically perfectly linear, the Cargo is always distributed according to these values:

FWD 48.86%
AFT 41.61%
Bulk 9.53%

Again, this is without GSX involved, it's just what you'll get when you set a certain Cargo "Level" in the CDU, from 0% to 100%, the distribution is always the same, the CG% changes slightly.


Now let's put GSX into the picture, and try a real world example using Simbrief. I made a flight plan from LSZH to KLAX in Simbrief, which called for:

290 Passengers
6577 kg of Cargo
ZFW 200161 kgs

Since the passenger weight is standard, GSX explicitly set the Passengers number and distributed Cargo, with the *Airplane* calculating the ZFW, and this is what we have in the CDU after GSX set the values:

7 Pax in 1st, 42 in Business, 241 in Economy

Total Pax = 290 CORRECT

3213 kg in FWD hold
2736 kg in AFT hold
626 kg in Bulk hold

Total Cargo = 6575  (2kg difference is rounding), and if we calculate the distribution:

3213 is 48.86% of 6577
2736 is 41.61% of 6577
626 is 9.53% of 6577

So, again, not only GSX took the correct amount of Cargo from Simbrief, but it also distributed it exactly AS IF you typed a Cargo Level without even using GSX. And of course, the ZFW calculated by the airplane is CORRECT too, at 200.2 Tons, which matches our Simbrief plan of 200161 kgs.

So, I really don't know what else is to say or why there's a need to change these values after GSX already set them correctly from Simbrief.

[psolk]

Thank you for such a thorough explanation as always Umberto.   
It sounds like perhaps the PMDG team does not fully understand what GSX is doing and I prefer the method GSX is using to PMDG's version of taking the Simbrief numbers and throwing a bunch of passengers into Cargo to get their preferred CG...   That is what PMDG is modifying the CDU numbers from simbrief to accomodate.  So they are taking passengers from Simbrief and moving them to cargo for a desired CG. They say Simbrief does not take CG into effect but it sounds like you have!
Amazing work, thank you again.

[Captain Kevin]

It sounds like perhaps the PMDG team does not fully understand what GSX is doing and I prefer the method GSX is using to PMDG's version of taking the Simbrief numbers and throwing a bunch of passengers into Cargo to get their preferred CG...

Not understanding or choosing to ignore, because there's a difference.

[psolk]

Indeed!  it does seem like they want to be very dismissive of doing anything but allowing them to manipulate the numbers themselves despite it "appearing" GSX has found a better way to do it than turning passengers into cargo!