I've seen this anomaly in my passenger count when loading my ZFW into the FMC in both the 738 and the 77W, and I'm wondering if somebody could point my in the right direction..

Example:

I generate my flight plan in SimBrief and it gives me a PAX count of 324 for the 77W, RKSI to VHHH.

This gives me a ZFW of 206.0

When I manually enter the ZFW number into the payload tab in the FMC, it doesn't give me a PAX count of 324, instead it gives 200. The cabin layout shows 9/12 in Business, 114/250 in economy for example, lots of missing seats.

GSX then uses this 200 count also when I start boarding.

My question is this..

If I enter the PAX numbers manually into the 3 classes on the aircraft, bringing the count up to 324, will this change the ZFW? and is this bad given the initial calculation SimBrief provided?  Will the plane be unbalanced and make TO impossible?

I don't understand why SimBrief gives me that ZFW with the PAX count it chose (using Random during setup), for the aircraft to then use that ZFW and give me a lower PAX count.

It happens with the 738 too so its obviously a Boeing thing or a PMDG, or both.

I hope that makes sense, thanks fellas

16 minutes ago, El Diablito said:

I've seen this anomaly in my passenger count when loading my ZFW into the FMC in both the 738 and the 77W, and I'm wondering if somebody could point my in the right direction..

Example:

I generate my flight plan in SimBrief and it gives me a PAX count of 324 for the 77W, RKSI to VHHH.

This gives me a ZFW of 206.0

When I manually enter the ZFW number into the payload tab in the FMC, it doesn't give me a PAX count of 324, instead it gives 200. The cabin layout shows 9/12 in Business, 114/250 in economy for example, lots of missing seats.

GSX then uses this 200 count also when I start boarding.

My question is this..

If I enter the PAX numbers manually into the 3 classes on the aircraft, bringing the count up to 324, will this change the ZFW? and is this bad given the initial calculation SimBrief provided?  Will the plane be unbalanced and make TO impossible?

I don't understand why SimBrief gives me that ZFW with the PAX count it chose (using Random during setup), for the aircraft to then use that ZFW and give me a lower PAX count.

It happens with the 738 too so its obviously a Boeing thing or a PMDG, or both.

I hope that makes sense, thanks fellas

Why enter it manually, just click the passenger and fuel load in the FMC, easy peasy . 

I wouldn't worry about the actual number of simulated people. What matter in the end is the take off weight you actually start with. And that should be in the same ballpark than what Simbrief calculated with.

3 hours ago, El Diablito said:

I've seen this anomaly in my passenger count when loading my ZFW into the FMC in both the 738 and the 77W, and I'm wondering if somebody could point my in the right direction..

Example:

I generate my flight plan in SimBrief and it gives me a PAX count of 324 for the 77W, RKSI to VHHH.

This gives me a ZFW of 206.0

When I manually enter the ZFW number into the payload tab in the FMC, it doesn't give me a PAX count of 324, instead it gives 200. The cabin layout shows 9/12 in Business, 114/250 in economy for example, lots of missing seats.

GSX then uses this 200 count also when I start boarding.

My question is this..

If I enter the PAX numbers manually into the 3 classes on the aircraft, bringing the count up to 324, will this change the ZFW? and is this bad given the initial calculation SimBrief provided?  Will the plane be unbalanced and make TO impossible?

I don't understand why SimBrief gives me that ZFW with the PAX count it chose (using Random during setup), for the aircraft to then use that ZFW and give me a lower PAX count.

It happens with the 738 too so its obviously a Boeing thing or a PMDG, or both.

I hope that makes sense, thanks fellas

If you notice the Simbrief loadout you will see that it has indeed adjusted ZFW, Passengers and Cargo.

Things to consider:  

If you import the Flightplan and Set Payload then PMDG will indeed change the numbers completely and take a large number of passengers and convert them to baggage for CG.

GSX can overcome this and set ZFW Passengers and Cargo

So when doing it manually you enter the ZFW, set the passenger number manually then go to Cargo and DECREASE the cargo load.  I usually have to remove around 20,000 lbs of baggage/cargo to get the ZFW back to Simbrief.  You also have to do it in that order.  Set ZFW, Adjust Passengers, Reduce Cargo  If  you do that "prior" to requesting boarding it GSX will use those numbers.  

This is my workflow (which is unnecessary but also provides redundancy in case something doesn't work as planned.)

Load 777

Release all ground vehicles

Load Simbrief F/P into EFB

Select Route in FMC

DO NOT select Payload, this changes all of the numbers to PMDG's but select Fuel and Load Rte

Activate Rte

(Now this part is redundant, if you select  Request Boarding in GSX it "should" automatically change all these values in the lower CDU when you Request Boarding but this is a failsafe)

Go to Payload in the CDU

Manually enter passengers to match Simbrief then reduce payload to reduce ZFW back to simbrief numbers

Request Boarding in GSX.  After GSX asks if you want to board Crew you should hear a series of clicks.  That is GSX "trying" to input the passengers/cargo into the lower center CDU.  If you look down you can watch it happen.  I tend to oversee that to ensure it goes properly and if not then revert back to the steps highlighted above as a worst case.  

I know you don't "have to " worry about it, all PMDG really cares about is the ZFW and CG but I like things to line up LOL....

Hope that was clear.

 

Edited February 19, 20251 yr by psolk

14 hours ago, Bobsk8 said:

Why enter it manually, just click the passenger and fuel load in the FMC, easy peasy . 

My question is why do the numbers not add up, why does PMDG decrease the load. I never manually add but was wondering if I did would the ZFW be affected.

 

10 hours ago, psolk said:

If you import the Flightplan and Set Payload then PMDG will indeed change the numbers completely and take a large number of passengers and convert them to baggage for CG.

Ok, and why does PMDG do that? Why does it not just take the PAX count and ZFW from SimBrief and add them? 

Thx for all the info you posted btw

Sorry for obvious question but is the sb profile the EXACT same aircraft you are using? There are obviously multiple airframes of 777 and 737 as well as different equipment installed (but I don't think the latter has an effect in sim). 

Also the profile may have been uploaded to sb with an older version of the plane maybe? 

Ignore if irrelevant. 

2 hours ago, El Diablito said:

Why does it not just take the PAX count and ZFW from SimBrief and add them? 

Because it is not the number of pax that is important but the ZFW.

Also different airlines /simbrief profiles calculate different weight per single passenger and how much baggage each passenger is taking along.

2 hours ago, El Diablito said:

Ok, and why does PMDG do that? Why does it not just take the PAX count and ZFW from SimBrief and add them? 

Thx for all the info you posted btw

That's just the way they implemented loads for CG...  

They only concern themselves with the ZFW, how the load gets distributed is more important than actually matching Simbrief from a PMDG perspective.  I like my numbers to match like you hence my steps to ensure it does.

Using an accurate SB profile helps but doesn't stop PMDG changing the values and moving passengers to cargo... 

19 hours ago, El Diablito said:

I've seen this anomaly in my passenger count when loading my ZFW into the FMC in both the 738 and the 77W, and I'm wondering if somebody could point my in the right direction..

Example:

I generate my flight plan in SimBrief and it gives me a PAX count of 324 for the 77W, RKSI to VHHH.

This gives me a ZFW of 206.0

When I manually enter the ZFW number into the payload tab in the FMC, it doesn't give me a PAX count of 324, instead it gives 200. The cabin layout shows 9/12 in Business, 114/250 in economy for example, lots of missing seats.

GSX then uses this 200 count also when I start boarding.

My question is this..

If I enter the PAX numbers manually into the 3 classes on the aircraft, bringing the count up to 324, will this change the ZFW? and is this bad given the initial calculation SimBrief provided?  Will the plane be unbalanced and make TO impossible?

I don't understand why SimBrief gives me that ZFW with the PAX count it chose (using Random during setup), for the aircraft to then use that ZFW and give me a lower PAX count.

It happens with the 738 too so its obviously a Boeing thing or a PMDG, or both.

I hope that makes sense, thanks fellas

My experience with PMDG planes is similar - Pax numbers from Simbrief do not match with actual passengers on the plane when you put the ZFW in. I think this is perhaps something to do with how PMDG have modelled payload distribution. You could try putting in the actual passengers numbers in FMC but you might find end ZFW numbers it gives might not match with your paperwork. Again weight discrepancies I think between what simbreif uses for each passenger weight vs what PMDG have modelled. I have raised this with PMDG few months back but I don't think they have any intention of fixing this. Personally I don't bother with it anymore - as long as my ZFW number is -/+ couple hundred kilos on either side of planned figure, I'm good to go. 

With regards plane being unbalanced if you put in passenger numbers manually - No it won't as it distributes the load equally to ensure the C.G limits does not exceed design limits. 

5 hours ago, El Diablito said:

My question is why do the numbers not add up, why does PMDG decrease the load. I never manually add but was wondering if I did would the ZFW be affected.

 

I have no idea, but I have used the simbrief directly inputting into the FMC in hundreds of flights and never had an issue, so that is what I do every time. 

Gotta ensure you are using a simbrief profile that matches your seat and cargo capacity. for the 737 there is a standard and high density configuration and my passenger counts and cargo numbers match up because the  simbrief profile is accurate. I would enter the passenger counts and cargo into the FMC and end up with the correct ZFW. I haven't been paying attention to the 777 profile much because everything is now easier with the 1 touch import but if you want everything to match up you need to find a simbrief pmdg airframe profile that exactly matches the configuration you plan to use.

the 737 ones i use were found on flightsim.to a few years ago. Don't know if they are still up.

Just now, Maxis said:

Gotta ensure you are using a simbrief profile that matches your seat and cargo capacity. for the 737 there is a standard and high density configuration and my passenger counts and cargo numbers match up because the  simbrief profile is accurate. I would enter the passenger counts and cargo into the FMC and end up with the correct ZFW. I haven't been paying attention to the 777 profile much because everything is now easier with the 1 touch import but if you want everything to match up you need to find a simbrief pmdg airframe profile that exactly matches the configuration you plan to use.

the 737 ones i use were found on flightsim.to a few years ago. Don't know if they are still up.

Even with the correct SB profile the numbers will still change when you request payload in the FMC...   PMDG's passenger #'s in the 777 never match Simbrief regardless of profile used.  They only care about ZFW  

Just now, psolk said:

Even with the correct SB profile the numbers will still change when you request payload in the FMC...   PMDG's passenger #'s in the 777 never match Simbrief regardless of profile used.  They only care about ZFW  

Noted .. I will double check this when i get home. With the 737 everything matched up because i used to do it manually so unless they changed something and i haven't been paying attention like i used to.. . Got lazy with the 1 button payload and fuel import feature.

Thanks for all the info, guys. That's a big help. I use the 1 touch load of fuel and payload all the time, I thought maybe adding each class of passenger manually would be fun for some extra cockpit prep but it seems like its a PMDG quirk and a non runner. No big deal.