heavy

[daredevil]

how do pilots account for the weight of the passengers on airliners. Is there a scale built into the floor of the cabin that tells pilots how much the people weigh or do you guys work from a base figure in which you assign each person on the passenger manifest a certain amount of weight and then whatever is lef you guys can trade off later for speed or thrust or fuel?

[slingsby]

In lamens terms:
Notional weights are used, Adult, Child and Infant. 80/40/10kgs if memory serves.
All departure weights are based on Maximum TOW, arrival weights are based on LWG, fuel load is determined from the ZFW but generally based on flight plan requirements (optimal performance)
If you are light with pax, then the fuel load will be lighter, you may climb quicker but speed is governed by performace limitations, there are no scales on board the aircraft, so you are reliant on the load controller collating all the check-in info, bag weights and cargo, to get the load sheet correct/planned.
Occasionally if not rarely you get a very obese/fat person, but it would not be prudent to ask for his weight.. only unless you are flying a very small aircraft and weight is at a premium.

[daredevil]

that pretty much clears it up then :ok:

[slingsby]

Mind you some adults are heavier, some are lighter, and that generally evens things out, but all maximum weights are based on the upper/higher weights so no chance (urg@@@ ) of exceeding maximum design weights.

muito obrigada (excuse spelling)

[daredevil]

don't worry about the spelling I'm not local, but I was also wondering why airliners charge you more when your luggage is to heavy, by dishing out the extra cash, can you effectively bride the plane into find some extra weight for you?

[slingsby]

Someone once said for every extra kg of baggage, you have to carry an extra kg of fuel, and for that extra kg of fuel you have to carry another kg of fuel for that extra kg. But generally it's just a penalty for carrying extra baggage, and extra revenue on top.

[daredevil]

but that suggests that the maximum take off weight is flexible, if all the pax did it, wouldn't it cause problems?

[Onan the Clumsy]

As a matter of interest, the FAA just raised the basic adult weight from 170lbs to (I think) 180lbs.

Balance is also an issue, though I assume the pax load can be evenly distributed by either an algorithm in the program that assigns seating or having full loads (right) or by the natural human tendancy to sit apart from other people.

Maybe in a larger a/c, the location of the weight of the pax wouldn't be an issue, even if it was half full and they all sat at the back.

[slingsby]

Balance aka trim does present itself if all the pax are seated in one compartment, this can be overcome by moving underfloor cargo to different positions to counteract trim positions. Overall weight is limited by the structural max permitted by the manufacturer, but then this can be determined by performance, temperature, TODA etc, too many connotations to go into.
Yes if all the pax carried extra weight, then once all check-in has finished, the weight is calculated to the maximum, then offload status is assigned to first cargo, then mail, then baggage. Offloading continues until all the weights are within specified perf tables and a/c limits.

I think Onan, the whole industry is recalculating notional weights across the board, not just the FAA. As the average adult weight in the 80's was 80kgs, it has risen slightly now. (me at 100kgs):=

[GlueBall]

After push back at Santa Fe De Bogota (BOG, SKBO) you might on occasion be directed by Ground Control to taxi unto the scales adjacent midfield of Rwy 13L/31R where actual Gross Weight is recorded by the Airports Authority.

[Point Seven]

Is that to calculate product leaving the country? :p

P7

[Johnavia]

I was once sat on the back row of an A320 on ramp before takeoff at Toulouse when the cabin crew kindly asked if myself and five of my fellow travellers would move to various other seats further towards the front of the Aircraft. This was apparently due to a problem with the weight distribution as expressed by the Captain.
I was surprised, as I didnt think six averagely built back row passengers would effect aircraft performance during take off or cruise etc or effect weight distribution to a great degree.
Any comments?

[Memetic]

Personally as a passenger I would welcome being weighed with my baggage - I tend to always come back with more than I left with if I have been holidaying.

It would simply be a case of you weigh too much pay up or take less baggage and when the total weight is below what my ticket allows, credit my frequent flyer card on a miles for mass basis.

It should really only impact people at the extremes of overpacking or obesity and should allow more accurate fuel planning.

Would be great for business trips, out and back in a day, no hold luggage so plenty of FF miles.

[FlyingForFun]

Seem to remember discussing this in ground school, where we were told that in general you can use a "standard" weight. But if you're flying an aircraft that's been chartered to take a load of rugby players on tour, then the chances are their average weight will be considerably above average - and in this case, you must weigh the passengers. No idea if anyone actually does this or not - comments from the pros?

Also worth noting that this only applies to big aircraft. In light aircraft, the weight of each individual passenger is taken into account. In my aircraft I can carry full fuel and two average sized men, assuming no baggage. Given that I'm roughly average sized, maybe slightly larger than average, if I have a large passenger, I can't fill the fuel tanks up.

FFF
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[jungly]

All the above is entirely correct...however there is legal scope to weigh fat passengers if the airline suspects there are too many fat fokkers on board to up the average.

Unfortunately, so as not to make the pie-eaters feel lardy and hurt their poor fat feelings the requirement is that all passengers, even the little kiddies and grannies must be weighed. A time consuming problem.

There are many stories of aircraft taking an extra few thousand feet to get airborne.....particularly on flights to the good ol' US of Big Macs and Apple Pie.

[knobbygb]

Similar experience to Johnavia. Once on a Bae146 on a delayed late night flight MUC-MAN. The a/c was about 50% loaded and the entire back 10 12 rows were moved forward - apparently for reasons of weight and balance. The aircraft had been about to divert on the inbound to MUC and the airport had opened at the last minute, so perhaps they were carrying loads of extra fuel or somthing?

Anyway, the front of the cabin was really crowded and people kept 'sneaking' to the back - by landing everyone was spread out again!

I know the 146 has a rather pronounced nose-down attitude on approach (due to the lack of leading edge slats). I wonder, does this type of thing make that aircraft more difficult to balance than others, or are longer aircraft (say, 757's) more difficult than the more 'stubby' ones?