Fun fact: SpaceX had two marine vessels for recovering rocket payload fairings from the sea. One was called Ms. Tree, the other one Ms. Chief. They are being replaced by a new boat right now, so let's see if they come up with another funny name for her as well.
Flawed weight and balance procedure, so a "nothing bad happened" situation, but "something bad could have happened". So serious in the sense that changes needed to be made to avoid a real issue in the future.
I’m surprised that estimated weight is used at all - surely the plane knows the actual takeoff weight, wouldn’t that be the number that’s checked before taxiing starts? Same with actual weight distribution
How would the plane know it's weight? You could measure the forces on the landing gear, but that would be subject to huge errors (inflation of the tires, stresses from the hydraulics, etc.), much higher than the 1% error required to notice this discrepancy. They do have checks in place, which is how they noticed the issue, but it still comes from keeping track of what goes on the plane.
> As part of the prestart procedure, the flight crew reviewed the flight plan, which gave an expected takeoff weight (TOW) of 66,495 kg (Figure 1), and the load sheet, which gave a TOW of 64,889 kg (Figure 2). They noticed that there was a discrepancy, with the load sheet showing 1,606 kg less than the flight plan. They noted that the number of children shown on the load sheet was higher than expected, at 65, compared to the 29 which were expected on the flight plan. The commander recalled thinking that the number was high but plausible; he had experienced changing loads on the run-up to the temporary grounding as passengers cancelled and altered trips at short notice.
The ground crew needs a good enough weight estimate to determine the proper fuel to add to the tanks, and to plan out the cargo distribution in the cargo hold so they can overlap that work (loading fuel, loading cargo) with the actual passenger boarding of the plane to save wait time for both passengers and the airline.
My understanding is that the amount of fuel loaded onboard the plane for takeoff by the ground crew is determined in part by this estimated weight figure.
If the weight estimate is too low, then it would be possible for the ground crew to load too little fuel, leading to a situation at the destination of nearly or actually running out of fuel.
So it may have been labeled "serious" due to the possibility of not loading enough fuel if the weight estimates are too low by too much.
Serious incident is the grade below accident, because nothing bad actually happened, but in other circumstances it might have.
For example if the aeroplane had been on a relatively short runway, and its passengers consisted entirely of overweight women who were miss-classified as much lighter children, perhaps it would have struggled to clear the runway at calculated power.
Flight crews are not trained to attempt to overrule the computer by explicitly commanding maximum thrust because humans are bad at figuring out if they're accelerating as much as expected - and so in the absence of a check that the plane is performing as anticipated † they are going to have a bad time if the calculations are badly enough wrong.
Why not just always use maximum thrust? Well if you're an aircraft carrier, or maybe even a military base you could definitely do that, but if you're a civilian airfield then the tremendous noise from jet engines at maximum performance is a constant problem and so you want jets to calculate a lower take off power that's still safe in order to reduce noise.
† [in some newer Airbus configurations the plane can work out its real acceleration and which runway you're on and conclude whether it will not successfully take off before it runs out of runway and so caution the pilots to abort before V1 when it's still practical - it doesn't matter why it isn't accelerating what matters is that you won't fly if you don't go fast enough, they can spend as long as they like to troubleshoot when they have stopped]
"Whilst an incorrect takeoff weight was used for aircraft performance planning, the thrust required for the actual TOW and environmental conditions (88.2% N1) was marginally less than the thrust used for the takeoff (88.3% N1). This meant the safe operation of the aircraft was not compromised."
So it was a "something bad could have happened" situation that called for a change in procedure to avoid a future, real problem.
It certainly did have something to do with the aircraft. The weight distribution in the aircraft is actually quite important, and a badly distributed weight can cause instability and a crash. These kinds of reports aren't meant to isolate a cause for the assignment of blame. They are meant to provide comprehensive information about the incidents, including identification of the root causes and the remedies for them.
While my armchair opinion is that ~1500kg mis-calculation of payload on a Boeing 737 is minor - this is one of those problems you should treat pretty seriously as it might have repercussions on other flights.
Yeah, they intentionally include a safety margin in the amount of fuel to bring. Doesn't make it OK just to miscalculate the payload weight and assume the margin will save you.
Wow. That's is insane. It appears to be the airline operator (their IT system), not the airline manufacturer that's at fault here though. So it seems a bit weird that this is categorised as a Boeing issue?
Seen this a couple times in articles about Boeing.
Another article had a title about how an airline cancelled all their Boeing orders.
Reality, they cancelled all their Airbus orders too (clearly stated in the article) ... and the airline reiterated in the article would continue just flying Boeing planes and in the future planned to buy a different model of Boeing instead of the one they canceled.
But the title implied something different, and the comments were filled about how this was a big deal for Airbus... and the typical tribal riffing off the title.
The issue was first noticed by the aircraft regarding the weight difference. So i guess, they have to report an issue to drill down the root cause. This is because several things could be the root cause. It could also have been possible that the weighing scale (i don't know the technical term) of the plane was faulty. Point being they need to report it as an issue. But i didn't see anywhere in the report that it mentioned airline manufacture was at fault?
It concludes that the IT system used by the operator was at fault.
Yet the article also says it assigns a female adult, and a child a specific weight.
Which means the weight is a ballpark anyhow. They aren't weighing anyone until totalled when on the plane.
Would they blame overweight people, if a bunch of over average people got on, and skewed that??
edit: just re-skimmed the article, I still don't get how a statistically averaged weight, which can be wildly variable for specific flights, causes issue because it was wrong.
Am I missing something? Is the average supposed to mostly be OK, thus not requiring fuel changes and delays for almost all flights, sav the outliers?
There's a big difference between using a mean weight for the correct category of people—which, by definition, will on average be correct, though you might occasionally get enough very overweight people to make it slightly off—and using a mean weight for the wrong category entirely, and thus ending up systematically skewing your calculations.
Just to pull some numbers out of, ah, thin air for an example, if you were using 110lbs as the average weight of a child and 160lbs as the average weight of an adult woman, your airplane seats about 200, and roughly one-third of your passengers are adult women, half of whom use "miss" as their title, that works out to 50 lbs difference * ~30 passengers = 1500lbs.
I guess. I just envision a random scenario where a league of... overweight women, are all on the same flight.
This seems to be in the UK, so what if an all female travel group, from the US, for the portly, showed up? When I visited the US, there seemed to be an inordinate amount of people in scooters that were quite.. large.
At least, this is what was in my head.
Then again, I just realised... do they have to buy two seats? Maybe I'm over analyzing all of this.
To the best of my knowledge, there's no systematic requirement for very overweight people to buy multiple seats—though I recall hearing a couple of such people note that they tended to do so for their own comfort.
I would also point out, though, that it's just as likely that there would be something like a gymnastics or other sports team on a plane, which I think should be somewhat under the average weight (despite the extra muscle mass).
What little I remember from the 737MAX issue is that manufacturers are generally thought of as (and regulated as if they were) providing fully complete systems and processes to airlines, so even for things like maintenance or day to day operations—while technically shared liability between the manufacture and airline—generally falls more on the manufacturer to ensure the safety and consistency of. That said, could just be a quirk of the reporting that we're seeing the manufacturer side of it and not the airline side here.
It could, but practically speaking the difference between a full-size adult and a very heavy adult tends to be constrained by the physical limits of the seating capacity, requiring passengers that could be overweight enough to impact the flight safety constraints to buy two seats.
From what I understand passenger planes and cargo planes alike need to balance and distribute the mass onboard. If they don't they could run into aerodynamic issues. It's a enter of mass vs center of lift kind of thing. However the balance would have to be really far off for anything serious to happen.
It's even dumber-sounding than that (though there are safety margins built into the system).
If you have a flight which is performance-limited, they will limit baggage hold (checked) bags which are weighed and force you to carry that same bag into the cabin (where it is not weighed and added to the performance calculations).
I seem to recall that there are specific weights used for aircraft where the passengers are overwhelmingly different from typical adults (think of an NFL football team flying to/from a game), but that general variances among passengers do not need adjustments to performance.
If my airline operates a charter flight with non-standard passengers (like your NFL example), the FAA requires that we ask passengers for their weight prior to boarding or actually weigh them at the door. If I recall correctly, we must do this for all chartered flights and not only sports teams, but I’d have to look it up to be certain.
To my knowledge no airline accounts for general variances among passengers leaving Mississippi as opposed to, say, Colorado. The standard passenger weights do change in the winter vs the summer to account for heavier clothing.
It's not just weight, but also distribution. I've been on small regional aircraft (think 16 to 32 seats) where the flight crew has asked passengers to change seats in order to get a better balance of weight across the aircraft.
I took a helicopter flight once where your seat was determined solely by your weight and that of the other passengers. I felt bad for the person that paid the same as me and got the middle rear, while I got to hang out the front door.
In a sense, it's not too terribly low; the end result here was that the plane took off outside of the correct flight envelope but well within a safe and controllable envelope (given a loading difference that - back of the napkin calculation - is 2% of its dry weight).
But AAIB pursues this sort of thing aggressively, under the principle of "Don't assume everything is safe because the O-rings didn't fail if the O-rings are showing not-understood ablation."
The plane took off without a problem, so this was within the error tolerance. You could imagine cases (e.g. charter flights full of women) where it could be an issue, though.
It has enormous margin during all-engine takeoff performance, so it's not at all surprising that the takeoff continued successfully.
The performance calcs are done to ensure safety in a one-engine inoperative case.
The performance calculations for all multi-engine turbojets require at least a balanced field (simplified meaning: that you can experience an engine failure at the most adverse moment in the takeoff sequence and either bring the aircraft to a halt on the runway surface [including EMAS or other stopway surface] or you can continue the takeoff and meet initial obstacle clearance and second stage climb requirements with the most adverse engine inoperative and maximum thrust from the working engine).
That's why this is a serious deviation, even though turbofan engines rarely fail. 737s do reduced power takeoffs as a matter of economic optimization. The error here caused too little power to be commanded during the takeoff.
If the cargo and the passengers aren't distributed and weight accounted for properly the typical calculations you make to take off based on weight stop working... potentially entirely / catastrophically. It has happened before resulting in crashes.
A few overweight passengers can't do that, but a combo of too many passengers and etc can have an impact.
This is a real concern for some operators. It’s a particular issue in Samoa, where there is a really bad obesity problem.
(One of the local airlines used to charge for excess passenger weight as well as luggage)
TLDR: 5481 crashed because the figure used as the average weight of a person for the purposes of calculating the planes centre of gravity was from before America got fat.
>> Following this serious incident, the operator introduced a daily check to ensure adult females were referred to as Ms on the relevant documentation, with a secondary check by Operations staff against passenger loads. A more formal system of checks was introduced on 24 July 2020.
Surely the solution is to fix the software? Miss is the 'appropriate' title for an unmarried woman or girl. Why not have a person select 'adult' or 'child' when booking (I'm pretty sure most airlines I fly with do this already).
It's fascinating that this issue occurred; I'd be shocked if the gestalt of data doesn't have enough information to know every passenger's age.
Pure speculation on my part, but it may be a data-hiding issue - if they realized late in design that the passenger manifest system had to feed into the weight estimator, but the passenger manifest (for privacy reasons, or simple "Don't access more data than you need" coding best-practices reasons) only had access to passenger names, surnames, prefixes, and IDs.
It shouldn't have happened (clearly, that's the point an engineer should be pulling the red lever on schedule and doing the work to get the data that's needed to the service that needs it, including clearing legal hurdles for privacy, if necessary), but I can easily imagine it happening if quality took a back-seat to deadlines.
"The incident occurred due to a simple flaw in the programming of the IT system, which was due to the meaning of the title ‘Miss’ being interpreted by the system as a child and not an adult female. This was because in the country where the system was programmed, Miss is a child and Ms is an adult female."
Not sure what the country in question is - the report doesn't name it.
> The system programming was not carried out in the UK, and in the country where it was performed the title Miss was used for a child, and Ms for an adult female, hence the error.
In what country is Miss used for under 18 and Ms. for over? In the US and UK, Miss just means "unmarried woman" no matter the age. So yes, its appropriate for an under 18y old, but its also appropriate for an over 18 year old.
I cannot quite exclude another idea, that the age-related framing of the mistake is simply a cover-up for a much more prosaic error, perhaps of embarassing quality.
Yes, but you wouldn’t choose to use Ms. for a 8-year old.
So if you’re presented with Ms. and Miss as options in a form, and neither has to do with marriage status, it’s natural that Miss will refer to the young.
Well, an unmarried woman is "supposed to be" (if we are going to care about these ridiculously sexist honorifics) "Ms" (and the software specifically did work if this was used).
Even if you guess the marital status "right", you will still offend many. Why should women be defined according to marital status, especially when men are not?
Unmarried men occasionally get the title 'Master' although I've only come across that in more formal situations.
I also never said we should or shouldn't use the terms. I don't have an opinion on that and it's not a debate or argument I'm going to waste my time on. I was simply explaining how they are conventionally used. This kind of thing was taught in schools as recently as 20 years ago as part of explanations on how to write and format letters.
Interesting! I've come across it in so few places in my life (and not recently) so I wasn't aware.
Edit:
It seems using it until the age of 12 is a convention in the US. Using it until 18 is the convention in the UK. Another argument for why software shouldn't make decisions using terms that can mean different things to different people :)
Not anymore, that is. It used to be an abbreviation for two appellations, one of which was associated with an unmarried gentleman. It's rarely used outside of the British Commonwealth, anymore. Except on Fresh Prince, of course.
I suppose the other appellation you are referring to is “Master”, but I understood its standard abbreviation to be M., not Mr., and it to be conventionally used for boys too young to be addressed as Mister (and before that, it was the term from which Mister was derived, and, before that, a title of guild rank), not a general title of unmarried (gentle- or otherwise) men.
Nope, it's definitely Mr., which possibly explains why "Master" practically disappeared. And while it may have been used to address boys, it could be comparable to Mme and Mlle in French. An older but still unmarried woman would be addressed as madame, but the marriage distinction still exists otherwise. "Master Bruce (Wayne)" was definitely not a boy, as an example in (something like) literature.
I actually thought Ms. was not promoted as less-sexist, but as a way to handle divorcees, and eventually merged to be a marital status-independent title. I see now that I was wrong [0].
I got this impression from my father. When I was little I would help stamp and address sales mailers he would send out, and he always used Ms. When I asked him, he said start with Ms. and let them correct you if they want something different. But, some divorced women get angry at being referred to as Mrs.
Yeah, you shouldn't be estimating weight based on a social nicety that's interpreted differently across cultures and by people of different generations.
I put it in quotes to try and avoid this type of retort. Whether or not they're still used or are now considered inappropriate, the meaning behind the terms hasn't changed. FWIW I still see the terms used occasionally in the UK with 'Master' being used for an unmarried male.
The explanation which you present as settled usage is wrong and dated. There are too many women who will (rightly in my view) take offense at being titled Miss or Mrs. — so using such titles is only "appropriate" if you are deliberately trying to anger some portion of the population.
> Miss and Mrs are marks of the old world, reminders of women's second-class status as wives-to-be (Miss) or simply wives (Mrs). If you are a woman who doesn't use Ms - particularly a woman under 30 who has never even thought of it - then ponder this: how do you want to present yourself to the world? Are you an appendage or an appendage-in-waiting? Don't be branded and marked by old-world convention. Let's kick against those fools at companies such as Atlantic Data. Let's put two fingers up to employers and bureaucrats who want to define us by our marital status. Choose Miss and you are condemned to childish immaturity. Choose Mrs and be condemned as some guy's chattel. Choose Ms and you become an adult woman in charge of your whole life.
The link is an example of a woman eloquently explaining why she prefers "Ms". It is not meant as "evidence" to support my assertion that there are many such women, as that's uncontroversial in most circles.
However, HN is overwhelmingly male (and threads like these illustrate why it is likely to stay that way), so what is obvious elsewhere may not be obvious here.
> There are too many women who will (rightly in my view) take offense at being titled Miss or Mrs. — so using such titles is only "appropriate" if you are deliberately trying to anger some portion of the population.
I still say sir, mam, mister, and miss
(Mrs is generally considered unneeded and overly formal) because I come from a culture that finds them not only to be appropriate but pretty standard, especially when dealing with strangers. You find that declaring them universally acceptable is wrong, but if you came to my state you'd also be equally wrong, and maybe rude.
I do understand that peoples attitudes over generations will change about words. That seems to be the natural evolution of languages, but it also seems we've never overtly adopted a system that deprecates language outside of outrage, which seems inappropriate in itself if you're getting angry with someone who is going out of their way, in their mind, to treat you with respect.
I actually thought Master referred to a child male. I didn't realize it was the male unmarried equivalent of the old Miss.
My family has an interesting habit of addressing mail to my children by these titles. I don't know why or when they started it, but I myself, was never addressed as Master, yet my son is.
I may have been wrong. Apparently it varies by country but in the UK Master is a male < 18 and in the US < 12. I have had it used in relation to myself though when I was in my 20’s so convention around it seems a bit unclear.
The HN post title is severely misleading. From the linked article:
"There was a fault in the system which, when a female passenger checked in for the flight and used or was given the title ‘Miss’, caused the system checked her in as a child. The system allocated them a child’s standard weight of 35 kg as opposed to the correct female standard weight of 69 kg."
So titling it "Root cause: adult females checked in as 'Miss'" is wrong.
The linked article does not even have the word "root".
Not according to the company, which remedied the issue by running a batch script to change people's title to Ms if the other records indicated they were adult females. Apparently the people who check in after the batch script runs the night before takeoff can be safely ignored.
This is a workaround based on the existing programmer error. It doesn't indicate that "ms" is correct in any way, just that it gives the correct result.
You said that since they solved it by changing miss to ms, that means that miss was actually wrong. This is not true. Besides the fact that miss does NOT mean child, what they did was a workaround. They solved it that was because it was simpler. It doesn't indicate that they think miss = child is correct. Most likely they didn't even have access to the code.
The mistake seems to be in looking at the honorific field at all. It's not the miscalculation; it's the fact that it's completely useless for male passengers who make up half of the flight.
Yeah, the issue was not that they were checked in as "miss", which presumably was correct - there is no indication that these women were married, or preferred "ms" - but that the software incorrectly interpreted "miss" as meaning "child".
And also why it did: Cultural norms were different between the unnamed country the software was created in, and used (with one using "miss" exclusively for young women, and the other not).
It's interesting because while Miss technically just means that a woman is unmarried, in practice it's only used for children. Similar to how Master technically just means an unmarried male, but I doubt anyone on here has been called that since second or third grade.
While it would be more correct to call it the proximate cause, I don't know if I would call it "severely misleading". Maybe mildly clickbait-y. It definitely was a cause, and as far as I can tell from the report, they didn't change the system that identified passengers with 'Miss' as children—they just changed it so that 'Miss' as a title for adults was autocorrected to 'Ms'. So to some extent, it seems like they disagree with you on what the root cause was
There is no indication that the people checked in as "miss" were not in fact miss:es. The error was elsewhere. The reason they found a workaround was that it was simpler than changing the software, not that they thought it was correct. Even if they thought it correct, it obviously isn't.
I interpreted the title as a cheeky anti-woke poke. The double meaning, being that referring to an adult female as "miss" rather than "Ms" has long been frowned upon (because of defining women by their marital status), and because it was offensive it caused a "serious incident".
I also assumed that the the title had been editorialized/was click-bait until I read the pdf and the incident was filed and issued by the AAIB as a 'Serious Incident'.
Which is understandable given that the flight was 1,244 kg overweight at take off due to a programming error that assumed a 'Miss' = 35 kg / passenger instead of the correct average weight of an adult female of 69 kg.
True that the actual incident was a lot different than the title suggested (and I assumed) but taking off a ton heavier than what the manifest stated is a ‘bit of a problem’ to use the English art of understatement.
The root cause wasn't that adult females were checked in as "miss" (which implies it was done against, or regardless of their own intentions).
The root cause was that the system assumed "miss" = "child". So it's a case of a mislabelled category.
The real root cause was a mistranslation: "in the country [India?] where [system programming] was performed the title Miss was used for a child, and Ms for an adult female".
a) the assumption that country in question was likely English-speaking (which increases the risk of translation mistakes, due to the "false friend" effect)
b) the fact that India is a powerhouse when it comes to offshoring software development.
If it's not the case, well, I wonder if someone is able to identify the country? Out of sheer linguistic curiosity
The reason that the mislabeled category was a problem was that the system used those cultural honorifics to estimate takeoff weight.
The reason takeoff weight was estimated using those categories, rather than from more accurate birthdate data, or calculated from actual weight data, was...
Seems like dirty hacks, all over the place. Your boarding pass doesn't usually have your date of birth, and it seems the system that estimates the weight only has access to the boarding pass info/passenger manifest. The BP does have your title, although it makes me wonder how they differentiate between adult man or child.
Because people don't want their weight tied to their real names and passport numbers in yet another database that will be leaked or monetized at some point.
It would certainly be a first in the last 20 years to board a flight and feel like I still had privacy, but overall I'm just really surprised that airliners don't include weight sensors that are used for this. It's a big enough deal that I can't check my 51 lb bag without paying huge fees. It's a big enough deal that when a double-digit number of females were mistaken for children, the Air Accidents Investigation Branch in the UK wrote it up as a serious incident. So in the end I'm just blown away that we're using heuristics based on broad age groups and gender, and not weighing people's carry-ons.
I thought that given the complexity of trim in modern airliners with massive fuel-tanks on long hauls, etc. that aircraft would include integrated weight / balance sensors.
They should. Getting the correct amount of fuel load is essential particularly on long haul flights. They also have to factor in whether they might need to divert on to another airport if their destination is shut for some reason and / or there are storms that needs flying around. Get the fuel load wrong and someone's going to have to ditch the plane or glide the rest of the way to the nearest airport. The Gimli glider incident comes to mind here.
> The system programming was not carried out in the UK, and in the country where it was performed the title Miss was used for a child, and Ms for an adult female, hence the error. A manual solution for correcting the problem was quickly identified that involved a team identifying upcoming flights, checking each booking, and changing all adult females with the title ‘Miss’ to ‘Ms’, which overcame the problem. Subsequently, this work was shared between two teams, and the process was completed every afternoon and evening for the next day’s flights. It was checked again every morning, where possible, before flights departed...
> The upgrade programmers adapted a piece of software, which changed the title of any adult female from Miss to Ms automatically, and this was implemented on 17 July 2020. This adaptation was only capable of changing bookings before check-in. Any passenger bookings with the title Miss already checked in, including online up to 24 hours before departure, would not be amended. On 20 July 2020, the programmer was making enhancements to the program to improve its performance. This should not have stopped the program from working, but as this was a ‘fix’, it could not be known for sure.
IT wise I'm pretty confident that the airline industry is a cobbled together mess. A much bigger problem than COBOL that has been doing the rounds on HN lately. (mind you, there's probably some overlap in the venn diagram)
Honestly, the airline industry is quite fascinating in terms of how safe it is. But that safety is maintained by procedure, cross-checking, and (especially in the commercial space) aggressive investigation of any deviation from expectations.
This serious incident is a great example of that process in action. The initial issue they were investigating was that the flight gets computer-analyzed to compare the actual dynamics of the plane to the theoretical dynamics. That analysis revealed a 1kt difference between what the takeoff speed should have been and what it was measured to be (about a 0.76% deviation from expectation).
That <1% deviation led to an investigation and a 7-page report.
Such a level of scrutiny is expensive, but it's how commercial air travel has gotten to the "safer than cars" level it currently supports.
I would argue that even if it was developed in the UK it still might have occured. Most developers in London/UK come from abroad anyway and might not know this nuance.
Nothing to do with the Boeing 737, actually just an operator error. Doesn't even seem worthy of the title 'Serious Incident'. Interesting to see that title is used to give some kind of estimated weight to the passenger though.
This principle can conflict with Don't Repeat Yourself. If you can infer something from existing values, you're often better off than making it explicit and redundant.
In this case we seem to be talking about a heuristic for estimating weight, and heuristics are kind of a weird middle ground on that score. If all you need is an approximate value and can compensate for errors, it's reasonable to use a properly-designed heuristic rather than an explicit value.
That said, a lot about this story smells weird. They already had an explicit value in the age field, and this particular heuristic is completely useless for male passengers. So it's less about proper programming practice than the fact that somebody is just plain doing something stupid. So stupid that I'm not sure we're actually getting the story correct.
Avaition Clickbait: This one simple trick will fix your outsourced IT at minimal cost!
> The upgrade programmers adapted a piece of software, which changed the title of any adult
female from Miss to Ms automatically, and this was implemented on 17 July 2020. This
adaptation was only capable of changing bookings before check-in. Any passenger bookings
with the title Miss already checked in, including online up to 24 hours before departure,
would not be amended. On 20 July 2020, the programmer was making enhancements to
the program to improve its performance. This should not have stopped the program from
working, but as this was a ‘fix’, it could not be known for sure.
Because as @syberspace stated above, and I pointed out below, the ground crew needs a weight figure to plan some things prior to loading/boarding (at least cargo distribution in the cargo hold and amount of fuel to place into the fuel tanks).
To use actual weight when individual passengers weights are unavailable (as in this case) would require first boarding all passengers, then waiting at the gate while the fuel tanks are filled and the cargo in the hold is loaded and distributed based on the actual passenger weight. The passengers would not want to wait for this loading order, nor would the airlines as it would directly increase their turn around time for the aircraft.
they do. which is how they figured out the discrepancy between estimated and actual weight.
but they do need to estimate the weight to plan the loading of baggage and cargo, e.g. more male adults in the back of the plane means cargo will prefarably be put in the front of the hold and vice versa.
Simple data design flaw, or the absence of such. "Ms", "Miss", etc is only a title and that's about it. Want a flag child/adult, well, add it then. Or better yet, use age to determine average weight even more accurately.
Edit: It usually means a disaster when people try to read "between the lines". One favourite example is trying to infer purpose/role of the server based on its hostname. When hostname starts with "X" it means only one thing - the first character of the hostname is "X", no more, no less.
This story seems like a SJW or alt right set up to get normal people to argue about "Pronouns", with a heap of fat shaming thrown in for good measure.
If load weight is such an issue, why wouldn't they just have scales at the gates or somewhere alone the taxi route that weighs the entire loaded plane. In the trucking industry there are even certain trailers with scales built-in and portable enforcement units that the highway enforcement use to catch and fine overweight loads.
I have heard stories of helicopter passengers needed to be seated according to their weight to balance a load but would hope the margin of error in a 737 covers atleast 2X passenger weight, they made everything else double redundant on them.
Yes my wording was imperfect there, loading is and issue and there are many solutions to the problem. Other than my unfortunate turn of phrase, I feel the point I was trying to make was valid.
Regardless of wether "Miss" is a pronoun You understood what I was saying. And the fact that You argue the fact that it is not a pronoun just enforces my argument.
> This story seems like a SJW or alt right set up to get normal people to argue about "Pronouns", with a heap of fat shaming thrown in for good measure.
Lol wat?
> If load weight is such an issue, why wouldn't they just have scales at the gates or somewhere alone the taxi route that weighs the entire loaded plane. In the trucking industry there are even certain trailers with scales built-in and portable enforcement units that the highway enforcement use to catch and fine overweight loads.
Did you even read the report? They show the readout with the estimated vs actual weight. The captain was aware of the discrepancy, they knew the load sheet was off, but went with it anyway.
> I have heard stories of helicopter passengers needed to be seated according to their weight to balance a load but would hope the margin of error in a 737 covers atleast 2X passenger weight, they made everything else double redundant on them.
The plane didn't crash.. it was within safety factors. The captain decided it was a small enough error. Some random error is expected, but still, it's an issue if the estimates are systematically wrong.
"why wouldn't they just have scales at the gates or somewhere alone the taxi route that weighs the entire loaded plane."
Have you never flown on a passenger flight, or are you somehow unable to imagine how catastrophically inefficient it would be to have a flight delayed/canceled when an airplane has been boarded and is taxiing down the runway?
And if fat-shaming is a concern, how do you think forcing passengers to line up and have their weight recorded? Having an accurate-enough algorithm for estimating weight is obviously a desirable and achievable solution to satisfy safety and engineering requirements.
This looks like a systemic error in the software development process. If an individual programmer caused it, it should have been caught in review. If it came from a requirement, that requirement was broken and it should have been caught in review.
Either way, a bug that results in an aircraft weighing 1,244 kg more than expected is indeed deadly serious. I write plenty of bugs, but luckily worst case is usually a web page failing to load rather than hundreds of people falling out of the sky. Our development process is clearly not adequate to this domain.
An adequate process for this would necessarily slow down development greatly and make it far more expensive. It's so much easier and cheaper to cut corners.
Having spent some time in the industry, I can say there is a fair amount of scrutiny on the software that's used directly for weight and balance purposes.
This situation, though, where input data to those systems is bad before it even gets there, is a loophole of sorts.
Somewhat related, this makes me worry a bit about all the data privacy regulation that keeps you from testing (easily, at least) with real production data. Good testing from the W&B software might have unearthed the lower overall weights per aircraft.
The really scary part is that someone decided to use the output of the booking system as an input for deciding fuel levels, without auditing the entire chain.
Surely the real root cause here is that their systems are overloading the title field with age assumptions at all, rather than their heuristic being wrong? Given that the age information is safety-critical, it should be passed through as a separate field directly. Doing anything else is error prone, as demonstrated in this case.
I'm disappointed that the AAIB did not identify this.
If I recall from booking airline tickets (in the long, long ago), you always have to enter your birthdate to book the ticket in the first place. Why wouldn't that information just be used to determine child/adult?
187 comments
[ 2.7 ms ] story [ 185 ms ] threadSurprised this classifies as a serious incident.
> As part of the prestart procedure, the flight crew reviewed the flight plan, which gave an expected takeoff weight (TOW) of 66,495 kg (Figure 1), and the load sheet, which gave a TOW of 64,889 kg (Figure 2). They noticed that there was a discrepancy, with the load sheet showing 1,606 kg less than the flight plan. They noted that the number of children shown on the load sheet was higher than expected, at 65, compared to the 29 which were expected on the flight plan. The commander recalled thinking that the number was high but plausible; he had experienced changing loads on the run-up to the temporary grounding as passengers cancelled and altered trips at short notice.
If the weight estimate is too low, then it would be possible for the ground crew to load too little fuel, leading to a situation at the destination of nearly or actually running out of fuel.
So it may have been labeled "serious" due to the possibility of not loading enough fuel if the weight estimates are too low by too much.
For example if the aeroplane had been on a relatively short runway, and its passengers consisted entirely of overweight women who were miss-classified as much lighter children, perhaps it would have struggled to clear the runway at calculated power.
Flight crews are not trained to attempt to overrule the computer by explicitly commanding maximum thrust because humans are bad at figuring out if they're accelerating as much as expected - and so in the absence of a check that the plane is performing as anticipated † they are going to have a bad time if the calculations are badly enough wrong.
Why not just always use maximum thrust? Well if you're an aircraft carrier, or maybe even a military base you could definitely do that, but if you're a civilian airfield then the tremendous noise from jet engines at maximum performance is a constant problem and so you want jets to calculate a lower take off power that's still safe in order to reduce noise.
† [in some newer Airbus configurations the plane can work out its real acceleration and which runway you're on and conclude whether it will not successfully take off before it runs out of runway and so caution the pilots to abort before V1 when it's still practical - it doesn't matter why it isn't accelerating what matters is that you won't fly if you don't go fast enough, they can spend as long as they like to troubleshoot when they have stopped]
And...
"Whilst an incorrect takeoff weight was used for aircraft performance planning, the thrust required for the actual TOW and environmental conditions (88.2% N1) was marginally less than the thrust used for the takeoff (88.3% N1). This meant the safe operation of the aircraft was not compromised."
So it was a "something bad could have happened" situation that called for a change in procedure to avoid a future, real problem.
While my armchair opinion is that ~1500kg mis-calculation of payload on a Boeing 737 is minor - this is one of those problems you should treat pretty seriously as it might have repercussions on other flights.
Seen this a couple times in articles about Boeing.
Another article had a title about how an airline cancelled all their Boeing orders.
Reality, they cancelled all their Airbus orders too (clearly stated in the article) ... and the airline reiterated in the article would continue just flying Boeing planes and in the future planned to buy a different model of Boeing instead of the one they canceled.
But the title implied something different, and the comments were filled about how this was a big deal for Airbus... and the typical tribal riffing off the title.
Which means the weight is a ballpark anyhow. They aren't weighing anyone until totalled when on the plane.
Would they blame overweight people, if a bunch of over average people got on, and skewed that??
edit: just re-skimmed the article, I still don't get how a statistically averaged weight, which can be wildly variable for specific flights, causes issue because it was wrong.
Am I missing something? Is the average supposed to mostly be OK, thus not requiring fuel changes and delays for almost all flights, sav the outliers?
Just to pull some numbers out of, ah, thin air for an example, if you were using 110lbs as the average weight of a child and 160lbs as the average weight of an adult woman, your airplane seats about 200, and roughly one-third of your passengers are adult women, half of whom use "miss" as their title, that works out to 50 lbs difference * ~30 passengers = 1500lbs.
That's gonna make a big difference.
This seems to be in the UK, so what if an all female travel group, from the US, for the portly, showed up? When I visited the US, there seemed to be an inordinate amount of people in scooters that were quite.. large.
At least, this is what was in my head.
Then again, I just realised... do they have to buy two seats? Maybe I'm over analyzing all of this.
I would also point out, though, that it's just as likely that there would be something like a gymnastics or other sports team on a plane, which I think should be somewhat under the average weight (despite the extra muscle mass).
(The actual details of their architecture I'm not privy to).
If you have a flight which is performance-limited, they will limit baggage hold (checked) bags which are weighed and force you to carry that same bag into the cabin (where it is not weighed and added to the performance calculations).
I seem to recall that there are specific weights used for aircraft where the passengers are overwhelmingly different from typical adults (think of an NFL football team flying to/from a game), but that general variances among passengers do not need adjustments to performance.
To my knowledge no airline accounts for general variances among passengers leaving Mississippi as opposed to, say, Colorado. The standard passenger weights do change in the winter vs the summer to account for heavier clothing.
"As a result, the aircraft departed with a takeoff weight 1,244 kg more than stated on the load sheet."
If 50 women weigh 94 kg instead of the assumed 69 kg, that difference is also reached.
I'm surprised that the 737 has such a low error tolerance.
In a sense, it's not too terribly low; the end result here was that the plane took off outside of the correct flight envelope but well within a safe and controllable envelope (given a loading difference that - back of the napkin calculation - is 2% of its dry weight).
But AAIB pursues this sort of thing aggressively, under the principle of "Don't assume everything is safe because the O-rings didn't fail if the O-rings are showing not-understood ablation."
The performance calcs are done to ensure safety in a one-engine inoperative case.
The performance calculations for all multi-engine turbojets require at least a balanced field (simplified meaning: that you can experience an engine failure at the most adverse moment in the takeoff sequence and either bring the aircraft to a halt on the runway surface [including EMAS or other stopway surface] or you can continue the takeoff and meet initial obstacle clearance and second stage climb requirements with the most adverse engine inoperative and maximum thrust from the working engine).
That's why this is a serious deviation, even though turbofan engines rarely fail. 737s do reduced power takeoffs as a matter of economic optimization. The error here caused too little power to be commanded during the takeoff.
A few overweight passengers can't do that, but a combo of too many passengers and etc can have an impact.
TLDR: 5481 crashed because the figure used as the average weight of a person for the purposes of calculating the planes centre of gravity was from before America got fat.
Surely the solution is to fix the software? Miss is the 'appropriate' title for an unmarried woman or girl. Why not have a person select 'adult' or 'child' when booking (I'm pretty sure most airlines I fly with do this already).
Pure speculation on my part, but it may be a data-hiding issue - if they realized late in design that the passenger manifest system had to feed into the weight estimator, but the passenger manifest (for privacy reasons, or simple "Don't access more data than you need" coding best-practices reasons) only had access to passenger names, surnames, prefixes, and IDs.
It shouldn't have happened (clearly, that's the point an engineer should be pulling the red lever on schedule and doing the work to get the data that's needed to the service that needs it, including clearing legal hurdles for privacy, if necessary), but I can easily imagine it happening if quality took a back-seat to deadlines.
"The incident occurred due to a simple flaw in the programming of the IT system, which was due to the meaning of the title ‘Miss’ being interpreted by the system as a child and not an adult female. This was because in the country where the system was programmed, Miss is a child and Ms is an adult female."
Not sure what the country in question is - the report doesn't name it.
> The system programming was not carried out in the UK, and in the country where it was performed the title Miss was used for a child, and Ms for an adult female, hence the error.
"Cultural differences" is an easy scapegoat.
So if you’re presented with Ms. and Miss as options in a form, and neither has to do with marriage status, it’s natural that Miss will refer to the young.
She used "Miss" to say unmarried female. Her ticket was for unaccompanied minor.
Miss is the one specific to unmarried women.
I also never said we should or shouldn't use the terms. I don't have an opinion on that and it's not a debate or argument I'm going to waste my time on. I was simply explaining how they are conventionally used. This kind of thing was taught in schools as recently as 20 years ago as part of explanations on how to write and format letters.
Edit:
It seems using it until the age of 12 is a convention in the US. Using it until 18 is the convention in the UK. Another argument for why software shouldn't make decisions using terms that can mean different things to different people :)
Not anymore, that is. It used to be an abbreviation for two appellations, one of which was associated with an unmarried gentleman. It's rarely used outside of the British Commonwealth, anymore. Except on Fresh Prince, of course.
I got this impression from my father. When I was little I would help stamp and address sales mailers he would send out, and he always used Ms. When I asked him, he said start with Ms. and let them correct you if they want something different. But, some divorced women get angry at being referred to as Mrs.
[0] https://www.grammarly.com/blog/ms-mrs-miss-difference/
Not since decades in the US at least. Women are not titled according to their marital status.
https://www.theguardian.com/world/2007/jun/29/gender.uk
> Miss and Mrs are marks of the old world, reminders of women's second-class status as wives-to-be (Miss) or simply wives (Mrs). If you are a woman who doesn't use Ms - particularly a woman under 30 who has never even thought of it - then ponder this: how do you want to present yourself to the world? Are you an appendage or an appendage-in-waiting? Don't be branded and marked by old-world convention. Let's kick against those fools at companies such as Atlantic Data. Let's put two fingers up to employers and bureaucrats who want to define us by our marital status. Choose Miss and you are condemned to childish immaturity. Choose Mrs and be condemned as some guy's chattel. Choose Ms and you become an adult woman in charge of your whole life.
However, HN is overwhelmingly male (and threads like these illustrate why it is likely to stay that way), so what is obvious elsewhere may not be obvious here.
It seems to me that the passengers themselves were selecting their own title.
I still say sir, mam, mister, and miss (Mrs is generally considered unneeded and overly formal) because I come from a culture that finds them not only to be appropriate but pretty standard, especially when dealing with strangers. You find that declaring them universally acceptable is wrong, but if you came to my state you'd also be equally wrong, and maybe rude.
I do understand that peoples attitudes over generations will change about words. That seems to be the natural evolution of languages, but it also seems we've never overtly adopted a system that deprecates language outside of outrage, which seems inappropriate in itself if you're getting angry with someone who is going out of their way, in their mind, to treat you with respect.
My family has an interesting habit of addressing mail to my children by these titles. I don't know why or when they started it, but I myself, was never addressed as Master, yet my son is.
> Definition of miss (Entry 3 of 4) 1 capitalized a —used as a title prefixed to the name of an unmarried woman or girl
https://www.merriam-webster.com/dictionary/miss
"There was a fault in the system which, when a female passenger checked in for the flight and used or was given the title ‘Miss’, caused the system checked her in as a child. The system allocated them a child’s standard weight of 35 kg as opposed to the correct female standard weight of 69 kg."
So titling it "Root cause: adult females checked in as 'Miss'" is wrong. The linked article does not even have the word "root".
The mistake was how their software reasoned poorly about passengers with "miss" as their honorific.
So it's more appropriate to say that checking in as "miss" was what exposed the problem, not that it was the root cause.
> UTC AAIB Bulletin: 4/2021 - G-TAWG - AAIB-26814
So creating a title to describe it would have always been required.
I also assumed that the the title had been editorialized/was click-bait until I read the pdf and the incident was filed and issued by the AAIB as a 'Serious Incident'.
Which is understandable given that the flight was 1,244 kg overweight at take off due to a programming error that assumed a 'Miss' = 35 kg / passenger instead of the correct average weight of an adult female of 69 kg.
True that the actual incident was a lot different than the title suggested (and I assumed) but taking off a ton heavier than what the manifest stated is a ‘bit of a problem’ to use the English art of understatement.
The root cause was that the system assumed "miss" = "child". So it's a case of a mislabelled category.
The real root cause was a mistranslation: "in the country [India?] where [system programming] was performed the title Miss was used for a child, and Ms for an adult female".
a) the assumption that country in question was likely English-speaking (which increases the risk of translation mistakes, due to the "false friend" effect)
b) the fact that India is a powerhouse when it comes to offshoring software development.
If it's not the case, well, I wonder if someone is able to identify the country? Out of sheer linguistic curiosity
The whole thing is just bizarre - I guess it was outsourced to some chopshop.
The reason that the mislabeled category was a problem was that the system used those cultural honorifics to estimate takeoff weight.
The reason takeoff weight was estimated using those categories, rather than from more accurate birthdate data, or calculated from actual weight data, was...
I thought that given the complexity of trim in modern airliners with massive fuel-tanks on long hauls, etc. that aircraft would include integrated weight / balance sensors.
https://en.m.wikipedia.org/wiki/Gimli_Glider
> The system programming was not carried out in the UK, and in the country where it was performed the title Miss was used for a child, and Ms for an adult female, hence the error. A manual solution for correcting the problem was quickly identified that involved a team identifying upcoming flights, checking each booking, and changing all adult females with the title ‘Miss’ to ‘Ms’, which overcame the problem. Subsequently, this work was shared between two teams, and the process was completed every afternoon and evening for the next day’s flights. It was checked again every morning, where possible, before flights departed...
> The upgrade programmers adapted a piece of software, which changed the title of any adult female from Miss to Ms automatically, and this was implemented on 17 July 2020. This adaptation was only capable of changing bookings before check-in. Any passenger bookings with the title Miss already checked in, including online up to 24 hours before departure, would not be amended. On 20 July 2020, the programmer was making enhancements to the program to improve its performance. This should not have stopped the program from working, but as this was a ‘fix’, it could not be known for sure.
This serious incident is a great example of that process in action. The initial issue they were investigating was that the flight gets computer-analyzed to compare the actual dynamics of the plane to the theoretical dynamics. That analysis revealed a 1kt difference between what the takeoff speed should have been and what it was measured to be (about a 0.76% deviation from expectation).
That <1% deviation led to an investigation and a 7-page report.
Such a level of scrutiny is expensive, but it's how commercial air travel has gotten to the "safer than cars" level it currently supports.
In this case we seem to be talking about a heuristic for estimating weight, and heuristics are kind of a weird middle ground on that score. If all you need is an approximate value and can compensate for errors, it's reasonable to use a properly-designed heuristic rather than an explicit value.
That said, a lot about this story smells weird. They already had an explicit value in the age field, and this particular heuristic is completely useless for male passengers. So it's less about proper programming practice than the fact that somebody is just plain doing something stupid. So stupid that I'm not sure we're actually getting the story correct.
> The upgrade programmers adapted a piece of software, which changed the title of any adult female from Miss to Ms automatically, and this was implemented on 17 July 2020. This adaptation was only capable of changing bookings before check-in. Any passenger bookings with the title Miss already checked in, including online up to 24 hours before departure, would not be amended. On 20 July 2020, the programmer was making enhancements to the program to improve its performance. This should not have stopped the program from working, but as this was a ‘fix’, it could not be known for sure.
Which make you wonder why they still use the estimated weight when they can have the actual one.
To use actual weight when individual passengers weights are unavailable (as in this case) would require first boarding all passengers, then waiting at the gate while the fuel tanks are filled and the cargo in the hold is loaded and distributed based on the actual passenger weight. The passengers would not want to wait for this loading order, nor would the airlines as it would directly increase their turn around time for the aircraft.
Edit: It usually means a disaster when people try to read "between the lines". One favourite example is trying to infer purpose/role of the server based on its hostname. When hostname starts with "X" it means only one thing - the first character of the hostname is "X", no more, no less.
If load weight is such an issue, why wouldn't they just have scales at the gates or somewhere alone the taxi route that weighs the entire loaded plane. In the trucking industry there are even certain trailers with scales built-in and portable enforcement units that the highway enforcement use to catch and fine overweight loads.
I have heard stories of helicopter passengers needed to be seated according to their weight to balance a load but would hope the margin of error in a 737 covers atleast 2X passenger weight, they made everything else double redundant on them.
It is an issue, passenger weight is included in calculations, but you don't have to weight everyone.
Huh? "Miss" is not a pronoun.
This is terrible system design regardless, as "Miss" can refer to an adult woman. Per Wikipedia:
> Miss is an honorific for addressing a woman who is not married
Lol wat?
> If load weight is such an issue, why wouldn't they just have scales at the gates or somewhere alone the taxi route that weighs the entire loaded plane. In the trucking industry there are even certain trailers with scales built-in and portable enforcement units that the highway enforcement use to catch and fine overweight loads.
Did you even read the report? They show the readout with the estimated vs actual weight. The captain was aware of the discrepancy, they knew the load sheet was off, but went with it anyway.
> I have heard stories of helicopter passengers needed to be seated according to their weight to balance a load but would hope the margin of error in a 737 covers atleast 2X passenger weight, they made everything else double redundant on them.
The plane didn't crash.. it was within safety factors. The captain decided it was a small enough error. Some random error is expected, but still, it's an issue if the estimates are systematically wrong.
Have you never flown on a passenger flight, or are you somehow unable to imagine how catastrophically inefficient it would be to have a flight delayed/canceled when an airplane has been boarded and is taxiing down the runway?
And if fat-shaming is a concern, how do you think forcing passengers to line up and have their weight recorded? Having an accurate-enough algorithm for estimating weight is obviously a desirable and achievable solution to satisfy safety and engineering requirements.
Either way, a bug that results in an aircraft weighing 1,244 kg more than expected is indeed deadly serious. I write plenty of bugs, but luckily worst case is usually a web page failing to load rather than hundreds of people falling out of the sky. Our development process is clearly not adequate to this domain.
An adequate process for this would necessarily slow down development greatly and make it far more expensive. It's so much easier and cheaper to cut corners.
This situation, though, where input data to those systems is bad before it even gets there, is a loophole of sorts.
Somewhat related, this makes me worry a bit about all the data privacy regulation that keeps you from testing (easily, at least) with real production data. Good testing from the W&B software might have unearthed the lower overall weights per aircraft.
I'm disappointed that the AAIB did not identify this.
If you need to identify the passenger as child/adult (especially for something as safety critical as this) then it should be its own field.
It feels like something is missing from this story.
It sounds terribly old fashioned though.