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Weighing Airliners  
User currently offlineCovert From Ghana, joined Oct 2001, 1451 posts, RR: 2
Posted (11 years 11 months 3 weeks 2 days ago) and read 3028 times:


Hello,

I was wondering how before each flight the weights of the aircraft is devired. Do they just take the amount of pax and times it by the standard and the fuel/cargo load and add it to the operating weight, or do they have some mechanism that can weigh itself inside the airplane? I have heard some pre-flight 747 cockpit conversations, and the flight engineer always reported before the checklist, "we weigh...."

Sincerely,
covert


thank goodness for TCAS !
14 replies: All unread, jump to last
 
User currently offlineB747skipper From , joined Dec 1969, posts, RR:
Reply 1, posted (11 years 11 months 3 weeks 1 day 23 hours ago) and read 2994 times:

Standard weights apply generally to domestic flights (in USA) - while overseas actual weight of bags is verified before loading...
xxx
I have a personal rule of thumb, over and above "regulations" and "procedures" - each adult passenger (his body + his baggage) weighs a total of 100 kilos as far as I am concerned, children 2 to 12 age go for 50 kilos, and infants are not accounted for weight...
xxx
So if an agent tells me that I have 330 passengers, 20 children and 5 infants, I quickly compute 330x100 = 33,000 kilos, 20x50 = 1,000 kilos... bottom line is my passengers and baggage total is 34,000 kilos... and I know that I have 355 passengers on board... our plane operating weight includes crew... we know that number... we just have to add the weight of fuel...
xxx
Surprisingly, with their superior scales, and advanced computations, they will find that the weight is 33,315 kilos, next day 34,160 kilos... 34,000 close enough for me... takes me 30 seconds to compute, for them - 1 hour...
xxx
These standard numbers never failed me, no matter where I am... and my plane does not feel different with 500 kilos error, nor can I see the different speeds on the chart... shall V2 speed be 174.2 knots or 174.4 knots, beats me, I know you guys fly better than me (with your FS practice), for me it is plus or minus a couple of knots, the best you can expect from me - sorry...
 Wink/being sarcastic
(s) Skipper


User currently offlineCovert From Ghana, joined Oct 2001, 1451 posts, RR: 2
Reply 2, posted (11 years 11 months 3 weeks 1 day 23 hours ago) and read 2963 times:


Thank you so much skipper, it is pretty intiguing that a simple mental calculation can produce near to the same result as a multi-million dollar technical innovation...

Sincerely,
covert

by the way is there any case where the situation entails a "screw it" we have to put the plane on the scale?



thank goodness for TCAS !
User currently offlineXFSUgimpLB41x From United States of America, joined Aug 2000, 4200 posts, RR: 37
Reply 3, posted (11 years 11 months 3 weeks 1 day 21 hours ago) and read 2945 times:

If you are carrying like a football team.. situations like that you will want to go for a higher weight per person than standard.


Chicks dig winglets.
User currently offlineLoadcontroller From Switzerland, joined Feb 2002, 85 posts, RR: 5
Reply 4, posted (11 years 11 months 3 weeks 1 day 4 hours ago) and read 2826 times:

Only valid for aircrafts departing out of ZRH:

Each airline has its so called "standard passenger weight" witch includes carry on baggage.
As how I mainly work for LX these are the followings: Male 88 kgs, female 70 kgs, children 35 kgs and infants 0 kgs. There is also the option: adults 84 kgs, children 35 kgs, infants 0 kgs. That much about passengers.

Cargo and mail: Just get the exact weight from a scale...

Baggage: Lots of airlines use standard weights per piece. But in my personal opinion it is more accurate, if you use actual bag weights as we do it in ZRH.
The standard bag weights would be calculated as following: You take the same flight for the last six weeks operating the same day. The amount of baggage weighed over a scale gives us the appropriate weight we'll have to expect for the today's flight. I assume that other stations do it a similar way, but most probably they do not weigh the bags of every flight.

I had the opportunity in JNB to follow an evaluation of average passenger weights. Each passenger had to stand on a scale before check-in. After I had a chat with the Loadcontroller of this flight - you cannot imagine how accurate these figures are...

By the way, B747Skipper, I have read so many posts from you. All of them are very good and informative. Please allow me to add you to my respected user's list.

Loadcontroller


User currently offlineMirrodie From United States of America, joined Apr 2000, 7443 posts, RR: 62
Reply 5, posted (11 years 11 months 3 weeks 1 day 4 hours ago) and read 2826 times:
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Actually, Covert, Skipper is just pulling your leg.

What he meant to say was that they weigh in at scales, just like boxers do.

"And in THIS corner, weighing in at xx,xxx lbs, .........the UNDISPUTED lightweight quiet queen of the skies"

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Photo © Prana Mahen




In all seriousness, what Skipper said rings true. Technology I doubt will ever surpass the human mind.



Forum moderator 2001-2010; He's a pedantic, pontificating, pretentious bastard, a belligerent old fart, a worthless st
User currently offlineB747skipper From , joined Dec 1969, posts, RR:
Reply 6, posted (11 years 11 months 3 weeks 1 day ago) and read 2802 times:

Forgot to mention - at least for the 747 - passenger aircraft - if it "fits the cabin" (or the belly) the aircraft will fly fine... we use a rule of thumb as well to find our "CG" (center of gravity) - the "stab setting", we multiply the gross weight of the aircraft (i.e. 360,000 kg = 3.6) x 2 = 7.2 units nose up...
xxx
We set the stab trim at 7.2... (people on the ground take also the best part of one hour to compute that - and will find - that it is 7.0 or 7.4... the "whale" does not know the difference)...
xxx
I have had "wild parties" on board of airplanes, where most of the passengers found theirselves in the rear cabin (Cabin E) and dancing in the aisles, again, the aircraft does not seem to care about that...
xxx
With a cargo aircraft, it is not so easy... it takes a loadmaster with sharp pencils and a good load planning sheet, you can get in deep troubles, that gentleman deserves his entire salary... A loadmaster is part of normal crew in most cargo operations... while they sleep during cruise, they work hard when on the ground, loading or offloading pallets...
xxx
Loadmaster is a good job for those of you interested in a lot of travel, with a fairly decent salary, and does not require special qualifications, except some classroom study and a week or two on the aircraft with a loadmaster to learn the job... Sure is nicer than being a flight attendant - moreover, little boxes do not complain about poor cabin service and absence of inflight movies...
xxx
Those of you interessed by such positions, in the USA, apply with Atlas Air Cargo in New York (JFK airport) - in Europe, check with Cargolux, an outstanding company.
xxx
(s) Skipper  Wink/being sarcastic


User currently offlineLeezyjet From United Kingdom, joined Oct 2001, 4042 posts, RR: 53
Reply 7, posted (11 years 11 months 3 weeks 1 day ago) and read 2799 times:

Just about every airline I've dispatched uses the standard weights for passengers of :

male - 88kgs
female - 70kgs
child - 35kgs
inf - 0 kgs

Some airlines though just use a standard "adult weight" of 80kgs.

Standard bag weights tend to differ though from airline to airline and whether that flight is international or domestic.

At the moment, my airline uses standard bag weights of 15kgs on all flights except for LHR-LOS-LHR where we use actual bag weights (for obvious reasons).

We have literally (last 4 days) just had a guy in weighing all the baggage containers as they come off the a/c to find out how inaccurate our bag weights are using the standard weights. Some flights have been having upto 4500kgs more weight than what the standard bag weights are.

Some of the a/c are able to weigh themselves, our A340's and some of the newer 744's do this, but a loadsheet is still required. The loadsheet is then cross checked against what the a/c thinks it weighs. There is a slight margin for discrepancies taken into account (not sure how much tho.)

To get our weights we work out the following (just a basic rundown)

Basic weight + catering + crew = Dry Operating Weight

Dry Operating weight + Pax + deadload (bags/freight/etc) = Zero Fuel Weight

Zero Fuel Weight + Fuel - Taxi Fuel = Take Off Weight

Take Off Weight - Trip Fuel = Landing Weight.

The a/c themselves get re-weighed every so often. The put a set of scales under each wheel and pull the a/c onto the scales. They take the readings and add them together. They then swap the scales around and re-weigh the a/c. This is done 3 times and they then take the average weight as the basic aircraft weight. (the people that have been weighing our bags also weigh the a/c using the same scales that they use to weigh the a/c).

B747skipper says that people on the ground take the best part of 1 hour to compute the info. Don't know which airline he works for, but I can produce a manual loadsheet for an A321/A320/B737 from scratch in less than 10 mins, and about 20mins for a B747 and for a computerised loadsheet, about 5 mins for shorthaul, 8-10 for longhaul. Sure we could do a rough calculation, but for legal reasons we can't dispatch an a/c on some rough calculations. The loadsheet is a legal document that has to be produced in accordance with the regulations of the particular airline and with the governing authorites (in the UK, the CAA) telling the f/deck crew how much the a/c weighs, what the trim setting is and how many pax are onboard along with some other bits of info.

It is technically illegal for an a/c to depart without a loadsheet being produced and a copy being held at the station of departure, and if anything were to happen to the a/c, the loadsheet and any other paperwork is confiscated and the dispatcher automatically gets suspended pending the investiagation. If it turns out the dispatcher made a mistake that caused the a/c to crash, they could end up in jail.

 Smile





"She Rolls, 45 knots, 90, 135, nose comes up to 20 degrees, she's airborne - She flies, Concorde Flies"
User currently offlineB747skipper From , joined Dec 1969, posts, RR:
Reply 8, posted (11 years 11 months 3 weeks 23 hours ago) and read 2769 times:

Dear Leezyjet -
All you statements are fully correct - same applies for my airline...
My "quick and dirty" computations are done with the only purpose of a crosscheck of the numbers presented by traffic agents... If my own number is 33,500 payload, and they show a loadsheet of 21,783 kilos, I immediately question "their mistake", unless our passengers are like the 7 dwarfs...
xxx
Everyone is human, and could make mistakes... I avoid my own by having a mental estimate of the numbers to expect. I had a serious incident once with a cargo aircraft which was loaded with a kilo payload but assumed to be in pounds by a loadmaster who made a grave mistake...
xxx
My wife is too pretty and young... I do not want her to enjoy my life insurance too early in life...
xxx
Always smiling  Smile/happy/getting dizzy
(s) Skipper


User currently offlineAWspicious From , joined Dec 1969, posts, RR:
Reply 9, posted (11 years 11 months 3 weeks 21 hours ago) and read 2745 times:

"Technology I doubt will ever surpass the human mind."
You haven't read about the winning candidates for the "Darwinian Awards", have you?  Smile/happy/getting dizzy

So, with the exception of fuel (and oil?), all other weights remain the same for the duration of a flight, I assume?


aw


User currently offlineB747skipper From , joined Dec 1969, posts, RR:
Reply 10, posted (11 years 11 months 3 weeks 20 hours ago) and read 2742 times:

Well - I understand that some food (beans) get changed into gases... then exhausted through the outflow valves... no wonder they get dirty...
xxx
So, for landing weight, I instruct the flight engineer to deduct 10 kilos of catering for landing weight... consumed by passengers with good metabolism...
xxx
Nice to know that some contrails have perfumes...
(s) Skipper


User currently offlineLeezyjet From United Kingdom, joined Oct 2001, 4042 posts, RR: 53
Reply 11, posted (11 years 11 months 3 weeks 8 hours ago) and read 2696 times:

747Skipper,

Think I misinterpreted your original posting. I thought that you were having a dig at the groundstaff for being slow. Yes alot of f/deck crews do their rough calculations as you say so they know approx what to expect on the loadsheet. my bad....  Smile

We are assessing the standard bag weights at the moment due to a couple of incidents where our a/c nearly didn't get airborne out of LAX, as they were heavier than expected due to standard bag weights being used.

 Smile



"She Rolls, 45 knots, 90, 135, nose comes up to 20 degrees, she's airborne - She flies, Concorde Flies"
User currently offlineAWA22 From , joined Dec 1969, posts, RR:
Reply 12, posted (11 years 11 months 2 weeks 3 days 1 hour ago) and read 2578 times:

At my airline we use 25 pounds for bags on domestic flights and 35 pounds for international flights, pax weigh 180 pounds in summer and 185 pounds in winter. We use the actual weight of cargo and mail.

User currently offlineXXXX10 From United Kingdom, joined Jan 2000, 777 posts, RR: 0
Reply 13, posted (11 years 11 months 1 week 4 days 10 hours ago) and read 2524 times:

I have always wanted to know this:

When the passengers eat the food does the a/c weight change?

Don't the passengers (and the toilet tanks) just get heavier by the same amount?


User currently offlineL-188 From United States of America, joined Jul 1999, 29800 posts, RR: 58
Reply 14, posted (11 years 11 months 1 week 4 days 9 hours ago) and read 2490 times:

Yeah the numbers that we used to use when I worked for Reeve, if my memory works is....

170lbs summer weight
175lbs winter weight.
35lbs per bag.
60lbs per duffel bag, you know those big army ones.

Freight and mail used their actual weights either from our scale or the post offices.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
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