Ray Proudfoot

Weight of Passsengers - can it be changed?

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I use PFPX for my flight planning and it allows the user to change the weight of adult and child passengers. I've left it at the default values of 168 (adult) + 24 for baggage making it a total of 192lbs for each adult.

If I enter 100 adult pax in PFPX it returns a ZFW of 110,500lbs. That is Empty Weight of 91,300 + 19,200 Payload = 110,500lbs

But if I enter 100 pax in the FMC Payload menu it returns a ZFW of 108,800lbs. That's 1700lbs less suggesting you're using a different weight value for each pax.

Is that an editable value and if so where can I find it?  I would like the numbers in PFPX and the 737-800 to match.

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Hi Ray.

 

If I'm not mistaken, you can edit the weight of the passengers in the PFPX. It's there in the options menu. But as far as I know you can't edit in NGX.

 

What I do on my flights is this: I simply use ZFW from PFPX and I enter it into the FMC. So I let the FMC figure out how much of this will be passenger and cargo.

 

In this way I fly within the parameters of what was calculated in the PFPX. I hope I could help.

 

Best regards

Cristiano Mueller

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Hi Christiano,

Thanks for your reply. I appreciate I can change the pax weights in PFPX but they seem more realistic. 168lbs is 12 stone in English which is a reasonable pax weight assuming a mix of male/female.

PMDG weights are 17lbs per person lighter. That's over a stone. I suppose if the PMDG weights are hard coded I have no option but to change them in PFPX.

Not a biggie but I'm surprised given the number of options the user can change in the aircraft pax weight isn't one of them.

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weight is  weight   as  long  as  you  enter the   final   zfw  that  pfpx  has  given  you

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15 minutes ago, pete_auau said:

weight is  weight   as  long  as  you  enter the   final   zfw  that  pfpx  has  given  you

Yes but doing that changes the number of pax. Ideally I'd like the numbers to tally with PFPX.

Seems the only option is to change PFPX weights. I'll do that.

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18 minutes ago, 19dcavscout said:

Can you just add additional cargo and keep the PAX numbers the same?

Well yes, I could do that but to be honest it’s a lot of piddling around when the simplest solution would be to change the pax weight in the 737. One change and no more problems.

I’ve looked through the various ini files but no mention of it. Hard coded? Really?

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21 minutes ago, Ray Proudfoot said:

Well yes, I could do that but to be honest it’s a lot of piddling around when the simplest solution would be to change the pax weight in the 737. One change and no more problems.

I’ve looked through the various ini files but no mention of it. Hard coded? Really?

Yes you can not chnage them. As some else already written, weight is weight, what you need is the ZFW.

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Hi Ray!

   The NGX uses an average passenger weight of 175 lbs (whatever that is in stones).  Just  change the passenger weight in PFPX when using the PMDG 737NGX.  Most airlines in the US are actually now using much higher weight averages as our population has grown across their midsections!  185-190 lbs + average weight of 40 lbs for luggage has become common.  The PMDG B747-400 uses 195 per passenger not including luggage!  I just adjust the weight constant in PFPX and in TOPCAT for each different aircraft model as necessary.  Using just the total weight as some have suggested does not allow for differences in CG depending on passenger and cargo placement.

 

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Chris / Craig,

Thanks for your replies. I'm surprised it's hard-coded. Perhaps you could consider making it user editable on any future releases.

I shall adjust PFPX but as Craig has mentioned the world (not just the US) is going through an obesity crisis so your hard-coded numbers are, shall we say, somewhat optimistic in the modern world. :wink:

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2 hours ago, Ray Proudfoot said:

Thanks for your replies. I'm surprised it's hard-coded. Perhaps you could consider making it user editable on any future releases.

To what end, though? Weight is weight, in the end.

Doesn't matter if there are 200 passengers at 185 or 212 at 175, if the ZFW is 420.5, then it doesn't matter if it's 200 passengers, 212 passengers, or 1354 gold bars.

It's merely a way to set a generic number of passengers and have a weight associated with it. If that method doesn't fit someone's needs, then they should look to simply setting the ZFW.

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Kyle, given the lengths you have gone to to make the aircraft as real as possible it seems a curious omission. Presumably your 175 lbs also includes baggage which PFPX calculates separately making your pax weight even weirder.

I’ll manually adjust ZFW to match PFPX and ignore pax numbers.

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29 minutes ago, Ray Proudfoot said:

Kyle, given the lengths you have gone to to make the aircraft as real as possible it seems a curious omission. Presumably your 175 lbs also includes baggage which PFPX calculates separately making your pax weight even weirder.

I can see your point, to a certain degree, but not to the level of the assertion here. You're assuming that such a function - with a way to edit the assumed pax weight - would add realism. In reality, the flight crew doesn't even pay attention to this kind of data, so if we're arguing "realism," then the point would be that it would be unrealistic to use the passenger number function.

When you're up front, you're checking ZFW against ZFW (and CG, obviously). Doesn't matter if you have 100, 200, 300, or 600 people in back. The weights are all estimates anyway, since not everyone weighs 185, and some have 2 bags, some have 0. Again, our inclusion of the function was to give people a way to throw in a simple weight for a flight if they didn't go through the efforts of using PFPX or SimBrief (which do all the weight randomization and calcs for you). The function isn't really aimed at realism at all, because the flight deck isn't concerned at all with that. The function is aimed more at the casual simmer who isn't necessarily planning using a detailed planner that would do the weight calcs for you. What's my ZFW? What's my CG? Done.

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Hi Kyle,

I can see your point too. As you say the crew are only interested in ZFW, not the details. If you hadn't supplied the option to add pax we wouldn't be having this conversation.

I'll ignore the pax option and just make sure my ZFW matches that supplied by PFPX. The only reason I thought it might be relevant is because GSX can determine pax numbers for embarking / disembarking. Or perhaps it just uses the aircraft weight and makes its own calculations. Again, it's not that important to me. Thanks for providing a reasoned argument why it's not really necessary. 👍

My main task at present is trying to tweak PFPX fuel calculations because as it stands I'm way short of fuel for planned trips.

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Yes,

If they would eat right and exercise all their weights could be changed.

Fat chance of that happening.

Sorry Ray, I couldn't resist.

Have a great day! 

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Although I believe most flight crews would be mildly interested in number of pax, the only time they need to know is when declaring an emergency and the number of souls on board needs reported.  Also, carrying families going on vacation will be substantially different from carrying a college football team; therefore, the value that is important is the ZFW.

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So "168lbs is 12 stone in English which is a reasonable pax weight assuming a mix of male/female."

Let's say we have 100 passengers average 168lb... that's 16800lb. If the plane desires 185lb passengers, 16800/185 = 91 passengers averaging 185lb if we wish.

Simply apply the calculation to arrive at the numbers we desire for the software

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...so if we look in the [WEIGHT_AND_BALANCE] section of the aircraft cfg we notice there's no indication for the number of average passengers because it's not relevant for the calculations of flight within the current sim. We can alter the loading of each section that to a degree alter the balance of the aircraft. All along we simply assume our own desired average passenger weight and make the proportional adjustment for the desired software planning.

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Steve, thanks for the tip but as others have said the pax numbers can be ignored really. You’ll probably know PFPX also adds children and infants to the random pax load so entering your formula still has flaws.

And baggage is extra! Closer to 199 lbs per pax.

I’ll just go with the ZFW. 😊

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There's no flaws in that calculation of course. We simply extend it into groups if we wish to separate children. it's the same anywhere in the known universe.

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8 minutes ago, SteveW said:

There's no flaws in that calculation of course. We simply extend it into groups if we wish to separate children. it's the same anywhere in the known universe.

If it made a difference I’d consider it but after all’s said and done I’m hardly likely to need to know souls on board when declaring an emergency.  CG is handled by the aircraft so it really isn’t important.

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6 hours ago, Ray Proudfoot said:

If it made a difference I’d consider it but after all’s said and done I’m hardly likely to need to know souls on board when declaring an emergency.  CG is handled by the aircraft so it really isn’t important.

I'm not posting advice for you and I'm not selling any kind of advice to you. I wanted to expand on Kyle's answer a little as the question does come up occasionally. After all - it's you wanted know if you could put in the average weight that you desired somewhere, and that's basically what my answer does provide you, and you can take it into separate portions if you wanted to do children - your suggestion not mine. No need to worry about it if you've got the better understanding of it now of course.

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9 hours ago, Ray Proudfoot said:

CG is handled by the aircraft so it really isn’t important.

By the way, the weight distribution affecting the aircraft asserted within the aircraft cfg in the [WEIGHT_AND_BALANCE] section isn't to control the balance of the aircraft trim in flight. This is where the software defines how much weight is available to add to each payload area within the aircraft. It is of critical importance to how the aircraft is set.

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14 hours ago, Ray Proudfoot said:

GSX

That herring, again!

14 hours ago, Ray Proudfoot said:

tweak PFPX fuel calculations

Same here

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On 1/29/2019 at 9:35 AM, Ray Proudfoot said:

Steve, thanks for the tip but as others have said the pax numbers can be ignored really. You’ll probably know PFPX also adds children and infants to the random pax load so entering your formula still has flaws.

And baggage is extra! Closer to 199 lbs per pax.

I’ll just go with the ZFW. 😊

Hi Ray

I used to use PFPX but my 'airline' was Adults Only and was much more pleasant environment where the only 'squawk' was a number in the FMC. :biggrin:

I ditched PFPX when it was seemingly unsupported and moved to Simbrief. Haven't missed a beat since.

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