Armadillo1
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Weighting passenger

Fri Sep 06, 2019 2:26 pm

this idea raised again
https://www.thesun.co.uk/travel/8895844 ... save-fuel/


previous topic:
viewtopic.php?t=1377637

the first question is, of course, why not to weight plane by using landing gear movement.

answer from previous topic:
trijetsonly wrote:
Have you ever weighed a large airplane?
It will take up to 20 minutes until the fuel in the tanks stops swapping around and you'll finally be able to record a weight. You can't do that after boarding and that's why aircraft are always weighed with empty tanks.

but may be today, with more complex algorithms, it can be possible even with some moving mass inside the plane?
or with minor and light gear modifications for this?
 
trijetsonly
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Re: Weighting passenger

Fri Sep 06, 2019 3:05 pm

Apart from what I wrote last time my two cents on this specific topic:

- I tend to say that the average passenger today is heavier than the used standard weights of 84 kg (88 for male, 70 for female). Keep in mind that those weights include cabin baggage that is usually between 5 and 15 kg. Using real weights would increase the ZFW used for calculating trip fuel and therefore the total fuel consumption.

- The only real chance to weigh a passenger would be at the boarding gate as not everyone drops baggage or uses the same security checkpoint. Therefore the final weight of all passengers is only available at boarding. That is too late to determine the required trip fuel.

- The required block fuel is not ordered and fueled to the exact kilogram. It is usually ordered (and only displayed) to the next 0,1t = 100 kg. Having real weights for payload opposed to assumed weights has to impact the total fuel by more than 100 kg to make a difference

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flyingphil
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Re: Weighting passenger

Fri Sep 06, 2019 3:39 pm

Using the standard weight per passenger can have safety implications regarding C of G calculations.
https://en.m.wikipedia.org/wiki/Air_Midwest_Flight_5481

There were proposals regarding charging passengers by weight too.. so if someone if morbidly obese they may twice as much as another passenger but they pay the same amount for the ticket..
 
KFTG
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Re: Weighting passenger

Fri Sep 06, 2019 4:19 pm

Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".
 
Eikie
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Re: Weighting passenger

Fri Sep 06, 2019 5:15 pm

KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".

Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)
 
h1fl1er
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Re: Weighting passenger

Fri Sep 06, 2019 5:21 pm

Eikie wrote:
KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".

Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)


wouldn't take that much time really...could weigh them on a pressure mat outside the gate. Step on, beep, recorded.

Use it for a rebate system if you're light...fat people consume more fuel to fly them. They should rightly be paying for this as should people with excessive carryon weight. (already you pay extra for overweight checked baggage)
 
indcwby
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Re: Weighting passenger

Fri Sep 06, 2019 5:25 pm

Eikie wrote:
KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".

Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)


"Although the pilots had totaled up the take-off weight of the aircraft before the flight and determined it to be within limits, the plane was actually overloaded and out of balance due to the use of incorrect Federal Aviation Administration (FAA)-approved passenger weight estimates. When checked, the National Transportation Safety Board found that the actual weight of an average passenger was more than 20 pounds (9 kg) greater than estimated."
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MIflyer12
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Re: Weighting passenger

Fri Sep 06, 2019 5:35 pm

KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".


I don't know what jurisdiction (outside of the U.S.?) or what size aircraft you may be writing about but two overweight guys in row 26 on a 738 are not going to materially change the CG calc. If you think Americans are going to pay by the pound you're in fantasy land.
 
patrickjp93
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Re: Weighting passenger

Fri Sep 06, 2019 5:42 pm

Eikie wrote:
KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".

Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)

Um, Qantas flights from Houston and LAX to Sydney and Melbourne have both been short on fuel thanks to bad guesses on passenger weight, many times actually.

And no, not difficult, time consuming, or expensive to weigh passengers. Simple modifications to procedures and baggage checkout counters can do it in-place.
 
patrickjp93
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Re: Weighting passenger

Fri Sep 06, 2019 5:44 pm

MIflyer12 wrote:
KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".


I don't know what jurisdiction (outside of the U.S.?) or what size aircraft you may be writing about but two overweight guys in row 26 on a 738 are not going to materially change the CG calc. If you think Americans are going to pay by the pound you're in fantasy land.

Mainly applies to long haul, and yes, they'll pay, because other airlines will end up having higher costs, and all will coalesce around the technique. Probably best to start with LCCs, but yes, this WILL come to pass eventually. The benefits are too high for it not to.
 
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zeke
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Re: Weighting passenger

Fri Sep 06, 2019 5:46 pm

The various standard weights used across the industry are not fixed, they are derived by actually weighing sample groups of passengers.
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cpd
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Re: Weighting passenger

Fri Sep 06, 2019 5:49 pm

Eikie wrote:
KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".

Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)


We take a lot of time and effort weighing bags, so why not pax as well if we are going to those efforts?

Can’t be too much harder.
 
zuckie13
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Re: Weighting passenger

Fri Sep 06, 2019 6:15 pm

What do you do if it's an airline like WN with open seating? You may weight folks, but how do you know where they are sitting when you do the CG calculation?

If everyone has to stop and be weighed, it will increase boarding time.
If it's displayed anywhere a passenger might see, someone will sue over having their weight disclosed, or, sue over the airlines and government having a database of people's weights.
How does the person in a wheelchair get weighed?
 
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northstardc4m
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Re: Weighting passenger

Fri Sep 06, 2019 6:43 pm

Ok let me explain something...

The second any public or private enterprise engaged in interstate commerce tries to charge a customer (note specifically customer in this case refers to a single person) more or less on body weight they are going to get smacked with a discrimination lawsuit, there are lawyers that chomp at the bit waiting for this kind of thing. This is not something to be taken lightly or ignored, and the cost of fighting each one will make every other factor shed any real significance to the bottom line very quickly.

In countries outside the US you may also get lovely things like Human Rights violations... these are not things any sane legal department is going to let themselves get drawn into unless they can show a definite need, which they can't as the current system operates fine as far as the law is concerned.

You can claim US5481 shows something but the overweight issue was not the direct cause of the accident and it won't stand up as an example if someone tries to use it as a legal justification.
Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety.
 
Armadillo1
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Re: Weighting passenger

Fri Sep 06, 2019 6:50 pm

h1fl1er wrote:
They should rightly be paying for this as should people with excessive carryon weight. (already you pay extra for overweight checked baggage)

Oh, i wait for this comment.
what about light passengers? should them paying less?
 
KFTG
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Re: Weighting passenger

Fri Sep 06, 2019 7:32 pm

northstardc4m wrote:
Ok let me explain something...

The second any public or private enterprise engaged in interstate commerce tries to charge a customer (note specifically customer in this case refers to a single person) more or less on body weight they are going to get smacked with a discrimination lawsuit, there are lawyers that chomp at the bit waiting for this kind of thing. This is not something to be taken lightly or ignored, and the cost of fighting each one will make every other factor shed any real significance to the bottom line very quickly.

In countries outside the US you may also get lovely things like Human Rights violations... these are not things any sane legal department is going to let themselves get drawn into unless they can show a definite need, which they can't as the current system operates fine as far as the law is concerned.

You can claim US5481 shows something but the overweight issue was not the direct cause of the accident and it won't stand up as an example if someone tries to use it as a legal justification.


A discrimination lawsuit? What law is broken by weighing passengers?
 
KFTG
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Re: Weighting passenger

Fri Sep 06, 2019 7:33 pm

Armadillo1 wrote:
h1fl1er wrote:
They should rightly be paying for this as should people with excessive carryon weight. (already you pay extra for overweight checked baggage)

Oh, i wait for this comment.
what about light passengers? should them paying less?

That's one way to incentivze healthier lifestyles.
 
77H
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Re: Weighting passenger

Fri Sep 06, 2019 8:10 pm

Prior to boarding a flight from NRT-HNL the gate agents made an announcement asking for volunteers to be weighed with the baggage. Each volunteer was provided a piece of paper detailing the reason behind weighing passengers. I volunteered and was asked to stand in a separate line where each volunteer stepped on a pressure mat prior to going down the jet bridge.

Weights do get updated using sample passengers but this is the only time I’d ever experienced this and I fly regularly.

77H
 
Wingtips56
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Re: Weighting passenger

Fri Sep 06, 2019 8:38 pm

U.S. rules changed on 1JAN1980 for aircraft of 10 seats or less (commuter airliners of the day, such as Cesnna 402s and Piper Navajos), where we had to go by actual weight rather than using standard weights. We didn't actually weigh the passengers, but we did have to ask them how much they weighed. Not a popular question at all, and we did have little paper slips to write on if they didn't want to proclaim their weight out loud. I think people were probably pretty honest about it, as they seemed to be shaken by the question and must have figured it mattered. We also weighed the checked baggage and and sometimes carry-ons if they looked heavy.
So I think an airline could go forward with actual weights in this way, without putting everyone on the scales. Even back in 1979-1980, we agents felt the average weights were too low.
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northstardc4m
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Re: Weighting passenger

Fri Sep 06, 2019 8:46 pm

KFTG wrote:
northstardc4m wrote:
Ok let me explain something...

The second any public or private enterprise engaged in interstate commerce tries to charge a customer (note specifically customer in this case refers to a single person) more or less on body weight they are going to get smacked with a discrimination lawsuit, there are lawyers that chomp at the bit waiting for this kind of thing. This is not something to be taken lightly or ignored, and the cost of fighting each one will make every other factor shed any real significance to the bottom line very quickly.

In countries outside the US you may also get lovely things like Human Rights violations... these are not things any sane legal department is going to let themselves get drawn into unless they can show a definite need, which they can't as the current system operates fine as far as the law is concerned.

You can claim US5481 shows something but the overweight issue was not the direct cause of the accident and it won't stand up as an example if someone tries to use it as a legal justification.


A discrimination lawsuit? What law is broken by weighing passengers?
The second you change a price based on it you are discriminating.

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Zeke2517
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Re: Weighting passenger

Fri Sep 06, 2019 9:19 pm

I don’t know. Unlike race or gender (or whatever) weight has a specific impact on safety and performance.

Also, discrimination only means making a decision based on criteria. Like, choosing whether to take off with or without fuel. It’s only illegal if you discriminate based on things that don’t affect the thing that is being decided, like race or gender in most cases.

So basically a very heavy person would be suing an airline because they cost more to transport, which suddenly becomes a less effective argument.

That being said, public relations are very different than courts of law.
 
Armadillo1
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Re: Weighting passenger

Fri Sep 06, 2019 9:22 pm

i am weight 110+kg and my wife 52kg.
Should i be fined for overweight if i travel alone? if i travel with wife? with grandchildren?
 
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northstardc4m
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Re: Weighting passenger

Fri Sep 06, 2019 10:34 pm

Zeke2517 wrote:
I don’t know. Unlike race or gender (or whatever) weight has a specific impact on safety and performance.

Also, discrimination only means making a decision based on criteria. Like, choosing whether to take off with or without fuel. It’s only illegal if you discriminate based on things that don’t affect the thing that is being decided, like race or gender in most cases.

So basically a very heavy person would be suing an airline because they cost more to transport, which suddenly becomes a less effective argument.

That being said, public relations are very different than courts of law.


Oh no, there are several problems for any attempt to implement it...

A> Discrimination based on weight will start hitting things like Tall people (including defined disabilities like Gigantism) also athletes and people with high muscle mass, high water retention, pregnant women... anyone with any form of disability and the ADA will throw the book at them. Anyone in a definable visible group and the ACLU will jump all over it... start putting in exceptions and any good lawyer will rip it apart as discrimination by omission.

B> Pre-existing business practice would work against the airlines... what's suddenly changed? Courts are unlikely to let the airlines suddenly change such an impacting practice without good reason, and no saving a few bucks would NOT qualify. They can't suddenly argue a safety aspect for example, nor has anything meaningfully changed as far as costs of operation go that can be attributed to weight of passengers...

C> It also becomes a political hot potato... with things both sides of the spectrum would jump on (Beer belly is an American right right vs discrimination is wrong on any front left)... have fun with that.

There is absolutely no way any airline will touch this.
Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety.
 
h1fl1er
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Re: Weighting passenger

Fri Sep 06, 2019 11:13 pm

northstardc4m wrote:
Ok let me explain something...

The second any public or private enterprise engaged in interstate commerce tries to charge a customer (note specifically customer in this case refers to a single person) more or less on body weight they are going to get smacked with a discrimination lawsuit, there are lawyers that chomp at the bit waiting for this kind of thing. This is not something to be taken lightly or ignored, and the cost of fighting each one will make every other factor shed any real significance to the bottom line very quickly.

In countries outside the US you may also get lovely things like Human Rights violations... these are not things any sane legal department is going to let themselves get drawn into unless they can show a definite need, which they can't as the current system operates fine as far as the law is concerned.

You can claim US5481 shows something but the overweight issue was not the direct cause of the accident and it won't stand up as an example if someone tries to use it as a legal justification.


excessively overweight people are already denied service when weight is an issue on amusement park rides and skydiving.

a charter airplane, something single engine, would also make this an issue. What you're saying isn't true. There is no human right to be fat and to have objective attributes ignored...I'd like to see you point out the federal legislation in question to buttress your claim. This isn't a disability.


Oh, i wait for this comment.
what about light passengers? should them paying less?


yes. fat people are not entitled to have their excess weight subsidized by the thin.

like cargo, airfare should be billed by distance and weight.
Last edited by h1fl1er on Fri Sep 06, 2019 11:18 pm, edited 2 times in total.
 
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northstardc4m
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Re: Weighting passenger

Fri Sep 06, 2019 11:18 pm

And there you go... Making the assumption that sinks you... Heavy doesnt necessarily mean fat. And nothing you said covers any of the points I've made before. Nor does an amusement park or skydiving fall under interstate commerce rules.

Would you like to try again?

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h1fl1er
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Re: Weighting passenger

Fri Sep 06, 2019 11:23 pm

northstardc4m wrote:
And there you go... Making the assumption that sinks you... Heavy doesnt necessarily mean fat. And nothing you said covers any of the points I've made before. Nor does an amusement park or skydiving fall under interstate commerce rules.

Would you like to try again?

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of course they do.

if you have a law degree, please let me know now before I bury you in Dormant Commerce Clause. Besides, Commerce Clause jurisprudence is utterly (and I mean utterly) irrelevant to what would be an Equal Protection claim which does not depend upon interstate commerce nexus. But since I'm up, had you been to law school you would understand that the Supreme Court has quite literally found so little limit to the scope of Congress' power under the Commerce Clause that a popular phrase in law school is that they can regulate "hot dog stands." Only recently did SCOTUS refuse to extend Commerce Clause powers; whether this marks a watershed in the Court is debatable in the overall context of Federal vs. State legislative authority.

What you claim is false; there is no discrimination whatsoever in charging per pound...I'm surprised you even made the claim.

Throwing a bunch of human rights jargon up or appealing to illusory federal statutes (which was it again?) cannot transform this into a plausible legal claim.

In addition, weight is NOT a federally protected attribute like sex or race or marital status. There are groups that would certainly like it to be, but it is not.
 
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northstardc4m
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Re: Weighting passenger

Fri Sep 06, 2019 11:29 pm

Ok I could post on and on and you obviously have set your mind and won't listen because I'd only be quoting others... But yes but then I wonder why no airline has tried it then of you are so sure it's a good idea?
Last edited by northstardc4m on Fri Sep 06, 2019 11:29 pm, edited 2 times in total.
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Starlionblue
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Re: Weighting passenger

Fri Sep 06, 2019 11:44 pm

Armadillo1 wrote:

the first question is, of course, why not to weight plane by using landing gear movement.


When boarding, the aircraft is outside, and moves around in the wind enough to affect any such sensing. This is why aircraft weighing must be carried out in a closed hangar.

Weighing individual pax on anything larger than a light aircraft seems like a lot of effort for questionable gain.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
TWA902fly
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Re: Weighting passenger

Fri Sep 06, 2019 11:51 pm

Perhaps you could claim discrimination based on sex, since men generally have larger body frames than women.

'902
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cpd
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Re: Weighting passenger

Sat Sep 07, 2019 12:01 am

KFTG wrote:
Armadillo1 wrote:
h1fl1er wrote:
They should rightly be paying for this as should people with excessive carryon weight. (already you pay extra for overweight checked baggage)

Oh, i wait for this comment.
what about light passengers? should them paying less?

That's one way to incentivze healthier lifestyles.


But some people are just heavier because they are taller. I’m 175cm high and under 60kg, so that puts me at the extreme end as I’m very fit. But someone at 2 metres is of course going to be heavier.

The luggage allowance is not a problem for me as I’ve got more than 45kg allowed by my status and only used about 27kg last time I flew, that’s with a big bike bag as well.

If you are doing helicopter spotting in Sydney, you’ll likely be weighed while holding your cameras...
 
Charleytuna
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Re: Weighting passenger

Sat Sep 07, 2019 12:28 am

Pax are freight. Really makes perfect sense to charge per pound incl. Luggage. It's fair also. Sorry for your bad luck being huge but isn't it all just tarrif ? If it could be reasonably implemented, why not? Isn't fuel consumption proportional to weight? I've always thought it was a no brainier.
 
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FredrikHAD
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Re: Weighting passenger

Sat Sep 07, 2019 7:49 am

Eikie wrote:
KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".

Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)

One of the deadliest crashes in Sweden, albeit with ”only” 18 dead, was certainly due to CoG being too far aft. The report in swedish only (nowadays they have a summary in english, but in 1990 there was none):

https://www.havkom.se/assets/reports/RL-C-1990_12-SE-IZO.pdf
https://aviation-safety.net/database/record.php?id=19890508-4

Beach 99, 14 pax, 2 crew (one free pax seat in the rear row).
Cargo; one bag (~10 kg) and one sack with post (~2 kg), loaded in the nose conpartment. Standard calc (used by crew) says 10 kg each, giving 20kg in the nose.
Some of the pax in the aft were heavy (not explicitly stated in the report, but ”common knowledge”).
CoG was 13 cm aft of the approved interval.
MAC 17,9-38,4 approved, actual 45%

When the flaps were extended, a sudden and massive nose up pitch was experienced, leading to irreversible stall in a few seconds.

May 18th 2018 a Cubana 732 crashed due to too far aft CoG killing 112, one survivor.

https://aviation-safety.net/database/record.php?id=20180518-0

CoG is an important parameter. In my opinion, methods to weigh planes or pax and cargo should be developed. I’m pretty sure you could weigh a plane even in windy conditions and get a very good estimate on the CoG. One would need to calculate the weight based on how the weight is distributed over some time, say 20 seconds, to compensate for winds and fuel moving in the tanks. I’d be surprised if a very good estimate cannot be calculated using a good algorithm. If this estimate shows you’re close to the limit, a more thorough calculation could be performed or cargo or pax moved to compensate.

/Fredrik
 
WIederling
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Re: Weighting passenger

Sat Sep 07, 2019 8:00 am

northstardc4m wrote:
A discrimination lawsuit? What law is broken by weighing passengers?
The second you change a price based on it you are discriminating.[/quote]

You get fuel at the pump priced per Liter/ Gallon.
is that also "discriminating" against people with fuel hogs?

Same for potatoes. Why should this be different for people that look like potatoes? :-)))))))

then: Need for knowing the exact weight:

with diminishing number of passengers the variance in overall weight for the group increases.
( except when you get outliers from the local Sumo School traveling to Hawaii :-)
Murphy is an optimist
 
Armadillo1
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Re: Weighting passenger

Sat Sep 07, 2019 8:27 am

FredrikHAD wrote:
Some of the pax in the aft were heavy (not explicitly stated in the report, but ”common knowledge”).

on An-2 pax (and skydivers) always placed on order of their weight (heavy ahead, light to aft)
even on An-24 pax has been placed in order of "load card".

So this event was definitely "out of rules"
 
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Starlionblue
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Re: Weighting passenger

Sat Sep 07, 2019 9:01 am

FredrikHAD wrote:
Eikie wrote:
KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".

Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)

One of the deadliest crashes in Sweden, albeit with ”only” 18 dead, was certainly due to CoG being too far aft. The report in swedish only (nowadays they have a summary in english, but in 1990 there was none):

https://www.havkom.se/assets/reports/RL-C-1990_12-SE-IZO.pdf
https://aviation-safety.net/database/record.php?id=19890508-4

Beach 99, 14 pax, 2 crew (one free pax seat in the rear row).
Cargo; one bag (~10 kg) and one sack with post (~2 kg), loaded in the nose conpartment. Standard calc (used by crew) says 10 kg each, giving 20kg in the nose.
Some of the pax in the aft were heavy (not explicitly stated in the report, but ”common knowledge”).
CoG was 13 cm aft of the approved interval.
MAC 17,9-38,4 approved, actual 45%

When the flaps were extended, a sudden and massive nose up pitch was experienced, leading to irreversible stall in a few seconds.

May 18th 2018 a Cubana 732 crashed due to too far aft CoG killing 112, one survivor.

https://aviation-safety.net/database/record.php?id=20180518-0

CoG is an important parameter. In my opinion, methods to weigh planes or pax and cargo should be developed. I’m pretty sure you could weigh a plane even in windy conditions and get a very good estimate on the CoG. One would need to calculate the weight based on how the weight is distributed over some time, say 20 seconds, to compensate for winds and fuel moving in the tanks. I’d be surprised if a very good estimate cannot be calculated using a good algorithm. If this estimate shows you’re close to the limit, a more thorough calculation could be performed or cargo or pax moved to compensate.

/Fredrik


In both those cases, the investigation concluded that CoG was behind the aft limit. This should have been known to the crew before departure. My point is that if proper procedure is followed, CoG will be within limits. There is no need to introduce new procedures when current ones work.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Armadillo1
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Re: Weighting passenger

Sat Sep 07, 2019 9:26 am

offtopic:
According media reports the accident occurred after a contraband crocodile escaped a carry-on bag and entered the cabin. A flight attendant ran off towards the flight deck, followed by passengers. Thus the center of gravity moved too much to the front. The pilots lost control and the aircraft crashed.

https://aviation-safety.net/database/re ... 20100825-0
 
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FredrikHAD
Posts: 439
Joined: Thu Aug 06, 2015 9:44 pm

Re: Weighting passenger

Sat Sep 07, 2019 11:06 am

Starlionblue wrote:
FredrikHAD wrote:
Eikie wrote:
Weighing all passengers takes an enormous amount of time (and money) but will not improve safety.

As far as I know, not a single flight had crashes or otherwise come into trouble due to inaccurate weights. (The flight mentioned above crashed only because it had a technical malfunction regarding the flightcontrols.)

One of the deadliest crashes in Sweden, albeit with ”only” 18 dead, was certainly due to CoG being too far aft. The report in swedish only (nowadays they have a summary in english, but in 1990 there was none):

https://www.havkom.se/assets/reports/RL-C-1990_12-SE-IZO.pdf
https://aviation-safety.net/database/record.php?id=19890508-4

Beach 99, 14 pax, 2 crew (one free pax seat in the rear row).
Cargo; one bag (~10 kg) and one sack with post (~2 kg), loaded in the nose conpartment. Standard calc (used by crew) says 10 kg each, giving 20kg in the nose.
Some of the pax in the aft were heavy (not explicitly stated in the report, but ”common knowledge”).
CoG was 13 cm aft of the approved interval.
MAC 17,9-38,4 approved, actual 45%

When the flaps were extended, a sudden and massive nose up pitch was experienced, leading to irreversible stall in a few seconds.

May 18th 2018 a Cubana 732 crashed due to too far aft CoG killing 112, one survivor.

https://aviation-safety.net/database/record.php?id=20180518-0

CoG is an important parameter. In my opinion, methods to weigh planes or pax and cargo should be developed. I’m pretty sure you could weigh a plane even in windy conditions and get a very good estimate on the CoG. One would need to calculate the weight based on how the weight is distributed over some time, say 20 seconds, to compensate for winds and fuel moving in the tanks. I’d be surprised if a very good estimate cannot be calculated using a good algorithm. If this estimate shows you’re close to the limit, a more thorough calculation could be performed or cargo or pax moved to compensate.

/Fredrik


In both those cases, the investigation concluded that CoG was behind the aft limit. This should have been known to the crew before departure. My point is that if proper procedure is followed, CoG will be within limits. There is no need to introduce new procedures when current ones work.

In the Swedish case, the crew calculated CoG correctly (with 1989 rules) and was verified afterwards to have been correctly calculated. In hindsight, the nose up attitude on the ground and difficulty to remove the tail pin could/should have given the crew a clue that CoG was off. On larger aircraft I doubt that you have those clues to go on.
If CoG can be correctly calculated with current rules, then weighing pax or aircraft is unnecessary, but I assume the proposal to do so comes from a desire to exclude the possibility of extreme cases to cause CoG to be off even if calculations are done by the book. Will a 737 captain look at the pax in the cabin and determine if all seems OK? Weight balance can be scewed if a group of heavy athletes, skinny or obese people travelling together happens to be in the ”wrong” part of the cabin. It certainly isn’t the most common scenario, but air travel safety is so good that these crazy corner cases might be showing up in statistics as a significant factor. I have no stats to support this claim, though. Perhaps someone else has?
 
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Starlionblue
Posts: 19393
Joined: Fri Feb 27, 2004 9:54 pm

Re: Weighting passenger

Sat Sep 07, 2019 11:56 am

FredrikHAD wrote:
Starlionblue wrote:
FredrikHAD wrote:
One of the deadliest crashes in Sweden, albeit with ”only” 18 dead, was certainly due to CoG being too far aft. The report in swedish only (nowadays they have a summary in english, but in 1990 there was none):

https://www.havkom.se/assets/reports/RL-C-1990_12-SE-IZO.pdf
https://aviation-safety.net/database/record.php?id=19890508-4

Beach 99, 14 pax, 2 crew (one free pax seat in the rear row).
Cargo; one bag (~10 kg) and one sack with post (~2 kg), loaded in the nose conpartment. Standard calc (used by crew) says 10 kg each, giving 20kg in the nose.
Some of the pax in the aft were heavy (not explicitly stated in the report, but ”common knowledge”).
CoG was 13 cm aft of the approved interval.
MAC 17,9-38,4 approved, actual 45%

When the flaps were extended, a sudden and massive nose up pitch was experienced, leading to irreversible stall in a few seconds.

May 18th 2018 a Cubana 732 crashed due to too far aft CoG killing 112, one survivor.

https://aviation-safety.net/database/record.php?id=20180518-0

CoG is an important parameter. In my opinion, methods to weigh planes or pax and cargo should be developed. I’m pretty sure you could weigh a plane even in windy conditions and get a very good estimate on the CoG. One would need to calculate the weight based on how the weight is distributed over some time, say 20 seconds, to compensate for winds and fuel moving in the tanks. I’d be surprised if a very good estimate cannot be calculated using a good algorithm. If this estimate shows you’re close to the limit, a more thorough calculation could be performed or cargo or pax moved to compensate.

/Fredrik


In both those cases, the investigation concluded that CoG was behind the aft limit. This should have been known to the crew before departure. My point is that if proper procedure is followed, CoG will be within limits. There is no need to introduce new procedures when current ones work.

In the Swedish case, the crew calculated CoG correctly (with 1989 rules) and was verified afterwards to have been correctly calculated. In hindsight, the nose up attitude on the ground and difficulty to remove the tail pin could/should have given the crew a clue that CoG was off. On larger aircraft I doubt that you have those clues to go on.
If CoG can be correctly calculated with current rules, then weighing pax or aircraft is unnecessary, but I assume the proposal to do so comes from a desire to exclude the possibility of extreme cases to cause CoG to be off even if calculations are done by the book. Will a 737 captain look at the pax in the cabin and determine if all seems OK? Weight balance can be scewed if a group of heavy athletes, skinny or obese people travelling together happens to be in the ”wrong” part of the cabin. It certainly isn’t the most common scenario, but air travel safety is so good that these crazy corner cases might be showing up in statistics as a significant factor. I have no stats to support this claim, though. Perhaps someone else has?


Didn't quite comprehend that they calculated it correctly. I only skimmed the conclusions. Then again the procedure has now been presumably revised so if correctly used there is no problem.

As you say in larger aircraft you couldn't tell just from body position and such. Then again I think it is harder to get the CoG out of limits purely by moving payload about.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
LH707330
Posts: 2214
Joined: Fri Jun 15, 2012 11:27 pm

Re: Weighting passenger

Sat Sep 07, 2019 7:01 pm

cpd wrote:
KFTG wrote:
Armadillo1 wrote:
Oh, i wait for this comment.
what about light passengers? should them paying less?

That's one way to incentivze healthier lifestyles.


But some people are just heavier because they are taller. I’m 175cm high and under 60kg, so that puts me at the extreme end as I’m very fit. But someone at 2 metres is of course going to be heavier.

I'm one of those people, 1.91 m and 85 kgs. I pay more for food because I cycle a lot and therefore eat more than most others.

I think some are confusing equality and fairness. Equality would suggest everyone pays the same for a seat, while fairness suggests a spatial price component (a seat) and a weight component (pay for what you need). That's how other freight is charged, say at Fedex or UPS. Sure, many people are overweight, but a larger issue is the overstuffed bags that I see clogging the overheads. If airlines priced X seats, Y bags, and Z total mass, the bag problem would probably go away because people would prioritize and not bring half their household on every trip if they paid by the kg.

As others have mentioned, this is unlikely to take off because of bad PR for whichever airline introduces it, but the idea makes sense.
 
citationjet
Posts: 2510
Joined: Sun Mar 09, 2003 2:26 am

Re: Weighting passenger

Sat Sep 07, 2019 8:04 pm

cpd wrote:
We take a lot of time and effort weighing bags, so why not pax as well if we are going to those efforts?
Can’t be too much harder.


Time an effort are taken to weigh checked bags at the ticket counter so that the airline can collect additional fees and revenue. It has nothing to do with weight and balance of the aircraft. Also, airlines do not typically weigh carry on luggage (except for LH).
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
Woodreau
Posts: 1797
Joined: Mon Sep 24, 2001 6:44 am

Re: Weighting passenger

Sat Sep 07, 2019 9:27 pm

KFTG wrote:
Passengers should be weighed. The accuracy of the CG calculation (and thus the safety of the fight) is more important than anyone feeling "fat shamed".


The actual weight of the passengers and the bags carried or checked by the passengers have no bearing on the calculated weight of the aircraft.

For most flights in the US, every passenger weighs 190lbs in the summer and 195lbs in the winter.
Every bag weighs 30lbs (or 60lbs if it’s a “heavy” bag)

An example of airline math I use:

You bring a legal size carry on - 9x14x22 to the airport. You pack it and weigh it at home on your bathroom scale. It weighs 45lbs.

How much does it weigh on the airplane? It depends.

If you bring it to the airport and check it at the ticket counter, when it’s loaded on the airplane it counts as a 30lb bag.
If you bring it to the boarding gate and valet check it at the jet bridge, when it’s loaded on the airplane it counts as a 20lb bag.
If you board the aircraft and stick it in the overhead bin, it weighs nothing - 0 lbs, because it is “included” in the 190/195lb weight of the passenger.

So it doesn’t matter what your bag weighs or how much the passenger weighs.
That’s the way it’s done for all the flights in the US. Out of all the daily departures for the last 20 years, it’s only been an issue a few times. (It is however unfortunate for the few times it has been an issue.)
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
Max Q
Posts: 7711
Joined: Wed May 09, 2001 12:40 pm

Re: Weighting passenger

Sat Sep 07, 2019 11:31 pm

The 747 Freighter had a ‘self weighing’ system as an option, not sure how many operators used it but it’s been discussed here before and apparently it was pretty accurate
The best contribution to safety is a competent Pilot.


Guns and the love of them by a loud minority are a malignant and deadly cancer inflicted on American society
 
h1fl1er
Posts: 121
Joined: Thu Jun 06, 2019 5:58 pm

Re: Weighting passenger

Mon Sep 09, 2019 4:22 pm

TWA902fly wrote:
Perhaps you could claim discrimination based on sex, since men generally have larger body frames than women.

'902


sex-based discrimination is treated with moderate scrutiny, as opposed to the strict that would be applied to race-based. Courts have accepted that there are legitimate and compelling governmental interests in sex-based discrimination.

Weight is, again, not a federally-protected class.

Discrimination is totally legal and permissible where there is not a protected class issue.
 
Turnhouse1
Posts: 162
Joined: Tue Jun 16, 2015 5:57 pm

Re: Weighting passenger

Mon Sep 09, 2019 10:00 pm

I've never been weighed, but once on a fairly empty Dash 8, I was the 3rd passenger from the front and sitting in row 10, a couple who were seated near the front were moved back for takeoff and landing. The smaller the plane, presumably the more likely it makes a difference.
 
benjjk
Posts: 350
Joined: Fri Aug 08, 2014 4:29 am

Re: Weighting passenger

Tue Sep 10, 2019 3:49 am

h1fl1er wrote:

Oh, i wait for this comment.
what about light passengers? should them paying less?


yes. fat people are not entitled to have their excess weight subsidized by the thin.

like cargo, airfare should be billed by distance and weight.


I know you and many others have some fantasy scenario in your head where you'll pay half the fare you do now because you weigh 50 pounds less than the next guy.

Go and do some back of the napkin calculations and figure out how much a fat person would actually add to the trip costs, e.g a defensible surcharge in price. I'll applaud you if you can present a plausible scenario where the extra costs even approach 1% for a short haul aircraft - let alone a transatlantic flight.

Subsidized by the thin? Come on.
 
Sokes
Posts: 239
Joined: Sat Mar 09, 2019 4:48 pm

Re: Weighting passenger

Tue Sep 10, 2019 12:56 pm

benjjk wrote:
h1fl1er wrote:

Oh, i wait for this comment.
what about light passengers? should them paying less?


yes. fat people are not entitled to have their excess weight subsidized by the thin.

like cargo, airfare should be billed by distance and weight.


I know you and many others have some fantasy scenario in your head where you'll pay half the fare you do now because you weigh 50 pounds less than the next guy.

Go and do some back of the napkin calculations and figure out how much a fat person would actually add to the trip costs, e.g a defensible surcharge in price. I'll applaud you if you can present a plausible scenario where the extra costs even approach 1% for a short haul aircraft - let alone a transatlantic flight.

Subsidized by the thin? Come on.


On a two hour flight without cargo in an A320/ B737 the extra weight is irrelevant. On a transpacific flight in which some seats can't be sold it's extremely important.
For transatlantic depending on plane type an extra kg body fat may or may not have to be traded for 1 kg cargo.

Getting upset about discrimination doesn't seem logical to me. Who doesn't discriminate while choosing a partner?
By the way: I'm fat. Good for me:

Caesar (according to Shakespeare):
" I want the men around me to be fat, healthy-looking men who sleep at night. That Cassius over there has a lean and hungry look. He thinks too much. Men like him are dangerous."
https://www.sparknotes.com/nofear/shake ... r/page_22/
Why can't the world be a little bit more autistic?
 
h1fl1er
Posts: 121
Joined: Thu Jun 06, 2019 5:58 pm

Re: Weighting passenger

Tue Sep 10, 2019 2:12 pm

benjjk wrote:
h1fl1er wrote:

Oh, i wait for this comment.
what about light passengers? should them paying less?


yes. fat people are not entitled to have their excess weight subsidized by the thin.

like cargo, airfare should be billed by distance and weight.


I know you and many others have some fantasy scenario in your head where you'll pay half the fare you do now because you weigh 50 pounds less than the next guy.

Go and do some back of the napkin calculations and figure out how much a fat person would actually add to the trip costs, e.g a defensible surcharge in price. I'll applaud you if you can present a plausible scenario where the extra costs even approach 1% for a short haul aircraft - let alone a transatlantic flight.

Subsidized by the thin? Come on.


buddy, how much do overweight bags actually add to the trip cost? How about just one overweight bag? Yet they're still charged.

Cargo? It's charged by the oz. Or the g or whatever measure you want to specify. Why not people? If you don't want to weigh everyone then just put a weight surcharge on overweight passengers.

Flying 200ppl all of whom are 20kgs overweight...this is 4t extra and this cost should be shared by the people who impose it. Thin, healthy people are subsidizing fat slobs the world over...it should stop is all I'm saying and this is a good place for the airlines to fairly price tickets.
 
Lrockeagle
Posts: 143
Joined: Wed Oct 06, 2004 1:40 am

Re: Weighting passenger

Tue Sep 10, 2019 3:02 pm

When I worked bag room loading the carts we would occasionally weigh each bag for each flight for the day. Every plane(E145) had 200-400 more pounds of luggage than recorded by using the standard 30lb weight. I reported it and was told to stop weighing bags.
Lrockeagle
14 years ago

I got $20 says AA takes their 787's with GE powerplants. Just a hunch. Any takers?
 
mmo
Posts: 1793
Joined: Thu Apr 18, 2013 3:04 pm

Re: Weighting passenger

Tue Sep 10, 2019 6:05 pm

After commercial flying for almost 35 years, I can count the number of overburns I have been involved with. Most are due to the winds being significantly wrong. The one stunning overweight flight I had was on a freighter out of FRA for the ME during Desert Storm I. We couldn't get our optimum weight and using the performance manual, this was way before EFBs, we were 40-50 thousand pounds above what our load sheet indicated.

In commercial aircraft, speaking 737-A320 and above, there is so much extra performance and padding it is amazing. The only outcome of weighing passengers would be longer delays. It is kind of like measuring with a micrometer, measuring with a grease pencil and cutting with an axe. Not worth it!!
If we weren't all crazy we'd all go insane!
 
benjjk
Posts: 350
Joined: Fri Aug 08, 2014 4:29 am

Re: Weighting passenger

Wed Sep 11, 2019 5:21 am

Sokes wrote:

On a two hour flight without cargo in an A320/ B737 the extra weight is irrelevant. On a transpacific flight in which some seats can't be sold it's extremely important.
For transatlantic depending on plane type an extra kg body fat may or may not have to be traded for 1 kg cargo.


Knowing the exact weight of passengers could help an airline push the performance limits, it's true. It could also backfire if the load is found to be above average so they need to unload to meet legal limits, where using standard weights would have allowed the flight to go ahead. But standard weights are safe as they are more accurate than you might think, and there's a huge safety margin involved.

Currently, it's not quite 1kg for 1kg. An adult male is 77kg (or whatever the airline or jurisdiction has decreed), so when at the limits a person would need to be traded for 77kg of cargo, even if that person only really weighs 50kg.

Sokes wrote:

Getting upset about discrimination doesn't seem logical to me. Who doesn't discriminate while choosing a partner?


Personal choice isn’t relevant here, I mean I can personally refuse to date someone of a specific religion, but as a business it would be illegal to refuse service, or charge more, based on that preference.

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