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How Accurate Are Luggage Scales At Airports?

Renato1

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When I weigh my luggage, I use two techniques. Most accurate is weighing myself on scales, then weighing myself with scales and suitcase, and finding the difference. Less accurate is using digital hand scales, which requires a bit of technique, and I calibrate against my first more accurate tecnique.

Result has been that my first technique has nearly always given the same result as the airport check-in scales of various airlines, at least at the first leg of the flight. But not always - sometimes a kilo over, sometimes a kilo under - which I find odd. I can understand that difference when I use the digital hand scales, because there is some variation in repeatability, even when trying to use the exact same technique.

In Sweden last year, I put my wife's suitcase on one machine, and the weight was exactly what I had previously hand weighed. But my suitcase on another machine was 3kgs higher than what I'd hand weighed. Seemed suspicious to me.

On our flight last week, we checked in at Qatar's Venice check-in, and my wife's suitcase was 22 kg and mine was 26kg - pretty close to what my digital hand scales had given earlier.

We flew to Doha, stayed a couple of days, and bought nothing (as we'd been there last year). Then we repacked the suitcases as we initially had, and checked in at Doha for the trip home - where my wife's suitcase had mysteriously grown to 25kg and mine to 29kg.

It didn't matter in this case as the weights were still within limit. But it would have been very problematic had I packed to 30kgs in the first instance - as when over 32kg, they make you reduce the weight.

Moral of the story, if this happens to you, and excess baggage fees or weight reduction comes into the equation, insist on using another weighing machine.....or two....or three.

Anybody else been suspicious of luggage weights at airports?
Regards,
Renato
 

Austman

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Airport scales can for sure be inaccurate.

I sometimes weigh my carry on at all the scales as I pass them on the way to security. The differences can be a couple of kg! But a majority of the scales tend to fairly closely agree with each other. Not 100% agreement, but close.
 

jpp42

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Goods have been sold by weight for millenia, and for that same time there have been traders who have sought to defraud their clients with improper scales. Hence, the regulation of weights and measures had long been an interest of governments. Airlines are selling a service based on weight and hence come under these regulations. All this is to say, that all airport scales should have a certification placard with the local agency responsible for certification, a due date for re-inspection, etc. These agencies will also typically investigate complaints.

In most Western countries, penalties for fraud are high and I would expect if scales are inaccurate this is mostly going to be due to indifference in maintenance practices rather than conspiracy, and is just as likely to be in favour of the customer. But I cannot be sure about everywhere - especially if local managers are given incentives based on how much excess baggage they sell, there could be a motivation to tamper with the scales.
 

moa999

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And I'd be very surprised (at least in Australia) if each check-in unit isn't checked regularly using a standard weight block. Eg. 20kg
 

Renato1

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Goods have been sold by weight for millenia, and for that same time there have been traders who have sought to defraud their clients with improper scales. Hence, the regulation of weights and measures had long been an interest of governments. Airlines are selling a service based on weight and hence come under these regulations. All this is to say, that all airport scales should have a certification placard with the local agency responsible for certification, a due date for re-inspection, etc. These agencies will also typically investigate complaints.

In most Western countries, penalties for fraud are high and I would expect if scales are inaccurate this is mostly going to be due to indifference in maintenance practices rather than conspiracy, and is just as likely to be in favour of the customer. But I cannot be sure about everywhere - especially if local managers are given incentives based on how much excess baggage they sell, there could be a motivation to tamper with the scales.
I guess it depends on the reliabilty of the equipment and frequency of calibration - those weighing machines get a pretty good work out.

Oddly enough, I had a similar problem. The digital hand scales I'd had for about four years, which were consistent with the other scales I'd stood on, finally had it's CR2032 battery go flat. I replaced the battery with a new one, and the hand scales were suddenly reading about 2kg less than they should have. Luckily I'd just bought a cheap one from Aldi which worked fine. I still haven't gotten around to figuring out what went wrong with the first one - though I'll be trying other brands of batteries to see if they are the solution.

It occurred to me that if I'd replaced the CR2032 battery overseas, I might have had egg on my face had I queried the weight readings at the airport.
Regards,
Renato
 

amaroo

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We have luggage with inbuilt scales (not an external hand held device) and I always take an interest between the luggage scale and checkin scale all over the World.

Based on this - I’d say the airport scales are pretty accurate.
 

Forg

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If anyone’s interested enough in the question “How often are check-in luggage scales calibrated?”, my better-half works in the same FedGov department that holds all the standards for measures & does stuff like checking petrol-bowser accuracy. National Measurement Institute. Apparently there’s a hotline which is intended for reporting problems with accuracy (eg. If your car has a 40L tank & you just paid for 60L of petrol, or you’re VERY sure you didn’t go over 20kg for that bag yet the airline charged you for 26kg), and she thinks you can also ask questions about required calibration frequency.
 

Brissy1

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Yes I've also found a discrepancy at an Australian airport, can't remember which one. Qantas scales at the oversize check-in were 1 or 2 kg different than at the check-in counter. You'd think that wouldn't matter but I've seen tourist charged for that sort of overweight amount at ADL.
 

kpc

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I have a hand held digital weighing scale...found it similar to most airports' within 0.5 kg. Recently +1 flew D7 and her bag weighed 20.8 kg...she had only paid for 20kg. Nothing was said :)
 

Brissy1

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Ah that reminds me, checking staff once told me they are allowed to accept up to ??kg over. I think it was only up to 1 kilo and would be airline specific, and might only be enough to correct their own sometimes inaccurate scales.
Also I think that a suitcase of clothes that you weigh after being in air conditioning for days, then left outside in a humid Asian climate for several hours, might weigh kg more by the time you get to the airport
 

Renato1

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If anyone’s interested enough in the question “How often are check-in luggage scales calibrated?”, my better-half works in the same FedGov department that holds all the standards for measures & does stuff like checking petrol-bowser accuracy. National Measurement Institute. Apparently there’s a hotline which is intended for reporting problems with accuracy (eg. If your car has a 40L tank & you just paid for 60L of petrol, or you’re VERY sure you didn’t go over 20kg for that bag yet the airline charged you for 26kg), and she thinks you can also ask questions about required calibration frequency.
I suspect that there will likely be a lot less problems in places like Australia, compared to other countries - like Italy, USA, Qatar and Sweden - where I've had cause to be suspicious of the weighing accuracy.
Regards,
Renato
Yes I've also found a discrepancy at an Australian airport, can't remember which one. Qantas scales at the oversize check-in were 1 or 2 kg different than at the check-in counter. You'd think that wouldn't matter but I've seen tourist charged for that sort of overweight amount at ADL.
Fascinating example, thanks.
Problem is that those in charge of check-in may well be unaware that their machines may be inaccurate from time to time. I suppose they'd only notice when a string of people start complaining.
Regards,
Renato


I have a hand held digital weighing scale...found it similar to most airports' within 0.5 kg. Recently +1 flew D7 and her bag weighed 20.8 kg...she had only paid for 20kg. Nothing was said :)
It's not uncommon for 1kg to be let through. I suspect because some may know that their scales may only be accurate to within plus or minus a kilogram. I've noticed with Jetstar at Dempasar several times that their scales read a kilo more than mine, but let the extra kilo on each suitcase through (I wondered if that would have been the case with RyanAir?).

Also, you can be lucky with digital scales' accuracy. My original one cost around $25, and I always found it finicky to repeat and reproduce the same answer (in comparison to using normal bathroom scales).

But one day I saw Aldi getting rid of their digital scales for $7 each, and have found them more accurate with less variation in the range of results for the same weighing, than the more expensive one.
Regards,
Renato
 

TonyD

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Had a case recently with Jetstar at OOL and went through the process in detail . My wife and son were travelling together - so allowed 14kg of hand luggage - weighed at home 12.6kg - weighed at check in counter area 12.6kg - ( dont know why she didnt get tagged but didnt ) . The crew came down the queue with mobile scales and said your 2kg over, pay $60 ! and didnt even show the result . She was so shocked but didnt have time to go back outside and weigh again so was forced to pay . weighed same bags on return from Sydney next day 12.5kg . Spoke to JQ OOL manager and eventually got a $50 voucher back - basically they all said we were lying .
What i have learnt is airport owns fixed scales airline owns mobile scales . All are calibrated by NMI every 6 months - BUT mobile scales are prone to be knocked about by their nature
Here's the kicker - Jetstar staff are paid a commission on extra luggage charges in the terminal - I have been told first hand that they have KPIs for it but some will take on full on and some shy away
 

Brissy1

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Had a case recently with Jetstar at OOL and went through the process in detail . My wife and son were travelling together - so allowed 14kg of hand luggage - weighed at home 12.6kg - weighed at check in counter area 12.6kg - ( dont know why she didnt get tagged but didnt ) . The crew came down the queue with mobile scales and said your 2kg over, pay $60 ! and didnt even show the result . She was so shocked but didnt have time to go back outside and weigh again so was forced to pay . weighed same bags on return from Sydney next day 12.5kg . Spoke to JQ OOL manager and eventually got a $50 voucher back - basically they all said we were lying .
What i have learnt is airport owns fixed scales airline owns mobile scales . All are calibrated by NMI every 6 months - BUT mobile scales are prone to be knocked about by their nature
Here's the kicker - Jetstar staff are paid a commission on extra luggage charges in the terminal - I have been told first hand that they have KPIs for it but some will take on full on and some shy away
Financial incentives/commissions... well that worked well for banks! A smart employer should know that it doesn't work were the job involves more than just revenue collecting, it distorts employee behaviour in providing what is the best (for the company) customer service.
Would they mention perhaps that although one bag was 9kg, the other was under the limit? No? Because going from 12.6kg to 16kg is not what possibly happened.
 

Renato1

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Had a case recently with Jetstar at OOL and went through the process in detail . My wife and son were travelling together - so allowed 14kg of hand luggage - weighed at home 12.6kg - weighed at check in counter area 12.6kg - ( dont know why she didnt get tagged but didnt ) . The crew came down the queue with mobile scales and said your 2kg over, pay $60 ! and didnt even show the result . She was so shocked but didnt have time to go back outside and weigh again so was forced to pay . weighed same bags on return from Sydney next day 12.5kg . Spoke to JQ OOL manager and eventually got a $50 voucher back - basically they all said we were lying .
What i have learnt is airport owns fixed scales airline owns mobile scales . All are calibrated by NMI every 6 months - BUT mobile scales are prone to be knocked about by their nature
Here's the kicker - Jetstar staff are paid a commission on extra luggage charges in the terminal - I have been told first hand that they have KPIs for it but some will take on full on and some shy away
That is absolutely ASTOUNDING.

I looked up OOL thinking it was some third world place, but it was Gold Coast - which doubly astounded me.

I opine that Jetstar will soon be facing big fines for reasons described by Jpp42 and Forg above.

First question I would have asked the Jetstar weigher was his or her name, and to show me the certified calibration sticker on the hand held scales, that showed when it was last calibrated and when it is due for the next calibration.

Second thing I would have done is pull out my own digital scales, which I always carry in my check-in luggage - and which I always calibrate against my bathroom scales (Note Well - Bathroom scales can be inaccurate and vary by up to around 1,5kg from scales to scales when just weighing the same thing, and often have a listed tolerance of either +/- 0.3 or +/- 0.5kgs, but the difference between weighing one's self and one's self holding the luggage is more accurate, as it eliminates variation between scales).

Asssuming all in my favour, third thing I would have done is lodged complaints with ACCC and the National Weights and Measures organisations.

I opine that the $50 voucher was insufficient recompense - as it was not the full amount, nor was it cash.

Hand held digital scales are notoriously finicky, as I described above, Just to get close to repeatability, means having to put the strap on the scales in exactly the same place, tugging the straps up lightly in exactly the same way before pushing the zeroing button, then holding them exactly the same way while taking the reading - and even then there is no guarantee of getting the same reading for the same item.
Regards,
Renato.
 

TonyD

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First question I would have asked the Jetstar weigher was his or her name, and to show me the certified calibration sticker on the hand held scales, that showed when it was last calibrated and when it is due for the next calibration.


[/QUOTE]

Indeed we are a lot smarter now and know the drill - my last trip i was 6.4kg but still insisted on checking . The better half is okay with JQ - for me - for this and a number of reason I am going back to QF
 

Vic

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You first measurement technique is actually less accurate, since you're making two measurements you're doubling the measurement uncertainty. You are also introducing variations due to changing weight distribution on the scale between loaded and unloaded measurement, meaning youre not repeating the same measurement.
 

DC3

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... Jetstar at OOL .... The crew came down the queue with mobile scales and said your 2kg over, pay $60 ! and didnt even show the result ..... basically they all said we were lying ...
Liars. LOL.

Well it is Jetstar and with those cheap fares that they sell they need to get the extra money from you somehow. :mad:
 

DC3

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... I looked up OOL thinking it was some third world place, but it was Gold Coast ...
Well, you are close. OOL is just a massive food court that has some departure/arrival gates attached.
 

Renato1

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You first measurement technique is actually less accurate, since you're making two measurements you're doubling the measurement uncertainty. You are also introducing variations due to changing weight distribution on the scale between loaded and unloaded measurement, meaning youre not repeating the same measurement.
What isn't known is whether the +/- 0.3 or 0.5kg relates to putting a standard weight on the scales in the same spot, or to people putting their feet in different positions on the scale - which does have an effect on accuracy, as you rightly point out.

All I know is that I have three bathroom scales at home, one of which consistently reads 1.6kg less than the highest reading one, and the third reads in between the other two. Thus no way of having confidence as to which is giving the right answer.

Yet by measuring myself, with and without luggage, and being very careful not to move the scales, and to put my feet on exactly the same position, I get repeatable results off each machine matching each other - which vary within a range of around 0.3kg. And more often than not, that weight figure accords very closely with the scales at the airport - which is why I get suspicious at airport check-ins the less frequent times when the weight figure from my technique is significantly different from theirs.

I used the difference method with bathroom scales in italy two and a half weeks ago. I measured the parcel we were about to send as being 9.4 kg. The scales at the post office had it weighing 9.2kg.

I think that's pretty accurate for most purposes.
Regards,
Renato

P.S. - I forgot to mention one thing in relation to the accuracy of bathroom scales. While they do often have tolerances of +/- 0.3kg or +/- 0.5kg written on their boxes or sometimes on a label on the unit, if one repeatedly steps on them in the same foot position and weighs one's self, the weight results only usually vary by 0.1kg on some units to 0.2kg on other ones. It's not like the results vary by 0.6kg or 1kg, as the tolerances would suggest.
 
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moa999

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which is why I get suspicious at airport check-ins the less frequent times when the weight figure from my technique is significantly different from theirs.
If expect a professional scale would be cleaned, tared to zero, and then checked with a known (say 20.0kg) weight regularly.
 

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