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A Tale of Two Feet (noaa.gov)
101 points by DarkContinent on Dec 30, 2022 | hide | past | favorite | 138 comments



So one type of foot is different than another type of foot.

Another difference: which is heavier, a pound of gold or a pound of feathers? The pound of feathers.

The feathers are weighed using a system called “avoirdupois”: this is how we weigh things like food, equipment and ourselves. Precious metals like gold and silver are measured using the “troy” system. If you normalize everything to mass a pound of feathers is 454 grams and a pound of gold is 373 grams, therefore the feathers are technically heavier

* https://www.suse.com/c/want-pound-feathers-pound-gold/

Now, which is heavier: an ounce of gold or an ounce of feathers? The ounce of gold.

> Precious metals such as gold and silver, and gemstones, are measured in troy ounces. Everyday measurements (food, copper, your body weight) are measured in avoirdupois ounces. A troy ounce (12 to a troy pound) is about 10 percent heavier than an avoirdupois ounce (16 to an avoirdupois pound). When converted metrically, a troy ounce weighs 31.1 grams and an avoirdupois ounce is equal to 28.35 grams.

* https://www.coinworld.com/news/us-coins/what-is-heavier.html

See:

* https://en.wikipedia.org/wiki/Avoirdupois_system

* https://en.wikipedia.org/wiki/Troy_weight


> which is heavier, a pound of gold or a pound of feathers?

I had presumed this would end with the classic joke: "the pound of feathers, because you have to live with what you did to those birds".


Yeah but that's cheating!

Obligatory Limmy: https://www.youtube.com/watch?v=-fC2oke5MFg


What's heavier, a pound of lead, or a pound of helium? (At standard temperature and pressure, ofc)


Lead, because lead is cheaper so you can buy more for a pound.


This was very fun to learn, thanks for posting


Huh. I thought that the pounds were the same, but the ounces were different. TIL.


LOL, USC never fails to amuse.


They don't really explain WHY.

So they already provide meters, which even according to them is real international standard, but also provide a "bad" foot definition for historical reasons. Instead of just scrapping sft and providing just meters like many other countries, they're shifting from sft to ift, even though ift too should be scrapped for the meter.

Not to mention during the transition from sft to ift it may result in errors and or costly updates, when these systems already support the meter, and it is less likely to result in type confusion.

NOAA needs to justify why they're ADDING ift in 2023 rather than just scrapping sft?


land surveys aren't just done for fun, they're done for legal compliance. and if the law you need to comply with requires something to be measured in feet, the surveyor needs to provide a measurement in feet.

until the NOAA and NIST have the power to rewrite all the zoning laws (at the federal, state, and local levels) that say roads must be X feet wide, or structures must be set back X feet from the property line, or utilities need to be buried X feet away from something, the reports that surveyors produce will need to include measurements in feet (or at the very least, there needs to be an official conversion factor between metres and feet, which is what is being discussed here).


This is just a guess, but it's possible that surveyors are so used to measurements in ft that the existing tools mostly use ft (like the GPS in the video), so completely deprecating it might leave surveyors without the tools they need to do their jobs.


In recent conversations i’ve had, plenty of surveyors are just plain old stuck in their ways and simply won’t change.

It’s a market we’re trying to break into, and coming from a European perspective it’s maddening, trying to build simpler apps is complicated enough when dealing with coordinate systems without the addition of multiple definitions of feet and trying to make sure the right one is selected by the user is especially important when dealing with cm accurate products


And here I was thinking posting something similar would be read as too pessimistic!


I’m pretty sure the GPS tool can be switched to meters by a toggle in the settings.


I'm sure any released in the last 10 years would, definitely. But don't forget that there are probably tons of underfunded rural outfits that are using old tech/out of support software etc. Meeting in the middle is going to make sure they don't get left behind.


The survey foot is, from what I could tell in the article, already officially defined in meters. It seems that the real complaint about how the US is backward is that we use fractions of whole numbers. The horror!


the inch changed in 1959 from exactly 1/39.37 m to exactly 2.54 cm; the survey foot is for compatibility with large-scale measurements based on old inches.


So that's why my windows are leaky! I knew there had to be a reason.


Mathematically, both are fractions of whole numbers (or decimals - the notation makes no difference). The problem is that they're different - which is a problem if you confuse them.


Do you know why that’s popular in the US? I’m so used to the decimal point notation that when hear “the Dow Jones index dropped by one hundred thirty three or one-tenth of a percentage point” on NPR it just throws me off. “Point one percent” is just so much easier to visualize the number. It feels unnecessarily complicated to use the fractional system. Same with the “the time right now is three past five” vs “it’s oh-three-oh-five or three-oh-five pm”.


It's a tradition. The US is more traditional than most of Europe. Its political system did not change for nearly 250 years, and the last major war on its territory ended in 1865. Europe had many more wars during a comparable period, and much more political reorganization. It had many more chances to scrap an old system and enforce a new system. The US federal government won't enforce a metric system, or it would likely be overstepping its mandate.

So, if everyone from your grand-grandfather to your dad use measures like 3/8 and not 0.375, feet and inches instead of meters and centimeters, etc, you naturally use them, too. All the books have them. All the public displays have them. There is just too much inertia that makes everyone keep using them.

You of course can use metric units (most rulers in my home have both inches and mm, every bottle or carton has the volume in oz/gal and ml), 24-hour clock scale (call it "military time"), Celsius temperature scale, etc. If you do science, you most likely use metric units. The metric system coexists with the imperial system, but does not dominate over it.


I do think decimal measurements have become more popular over time, though, even in areas where we haven’t switched to metric. I’m more likely to say something weighs 1.5 pounds than one pound, eight ounces. (On the other hand, we absolutely still use feet and inches ubiquitously).


There are situations where fractions are easier and more importantly more accurate than decimals.

For example, measuring a third of something in decimals would be 0.333... while in fractions that would be 1/3. Fractions are particularly popular in the construction industries for this reason, where base 12 math will toss out anyone who tries to be metric and base 10.


When redefining traditional measuring units into metric, it is generally preferred that the traditional unit equals a terminating decimal number in metric. For example, 1 inch = 25.4 mm exactly. This helps with transitioning to metric because old specifications can be translated to metric without introducing fractions or repeating decimals. The fact that the survey inch is exactly 100/3937 metres violates this property and makes it more cumbersome to work with in metric.


> fractions of whole numbers. The horror!

I mean you have to either handle numerical error or rational numbers. In any case fron a numerical analysis pov, it's a pain


Not it's more you use body part names that sound funny as unit of measurement.

Like it sound backward to say stuff like "I'm 5 feet tall, but I can see as far as 20 inches! Maybe I can also count up to twenty teeth but I have only 5 toenails of time remaining".

Ok I exagerated a bit, but to the rest of the world that's how silly this all sound lol

Isnt it weird we all measure prices in USD between non US people when we need to compare price across countries, but the US cant use the meter, a unit so old and basic they re the one country left without it...


I hope the U.S. will adopt the metric system in day-to-day life (I used to be a member of the U.S. Metric Association), so I'm not disputing your larger point, but I can't think of anything but the foot that's named after a body part.

The commonly-used U.S. customary units are inch, foot, yard, mile (distance); ounce, pound, ton (mass); teaspoon, tablespoon, ounce, cup, pint, quart, gallon (volume). I only see the foot there as a body part.

(Also for time the hour, minute, day, week, month, and year are not based on powers of ten, but the U.S. does share these and the SI second with the rest of the world.)

There are lots more weird and obscure U.S. customary units that are rarely used by most people, like for length (link, chain, rod, furlong, league), but I'm still not thinking of anything else named after a body part!


hogshead?

Wikipedia-ing around, I knew about "hand" for measuring the height of horses, and had heard of "finger" in the context of "a finger of whiskey". It was apparently a unit of measurement too.

The "digit" Wikipedia entry mentions "finger (7/6 digit), palm (4 digits), hand (16/3 digits), shaftment (8 digits), span (12 digits), cubit (24 digits) and ell (60 digits)" as body-part-based measures - https://en.wikipedia.org/wiki/Digit_(unit)#Britain


That is definitely a fair list of body-based customary units; thanks for pointing those out!


An obscure one is the fingertip unit (https://en.wikipedia.org/wiki/Finger_tip_unit)

I wouldn’t call that a unit, though, as it is scales with the size of the patient’s fingertip (https://dermnetnz.org/topics/fingertip-unit).


Ton ? Long ton or short ton ?


Or metric tonne? Don't worry, the spelling is different, so you can count on that to encode your unit information. Authors of scientific papers always pay attention to proper spelling/ grammar so you'll never have to worry! /s

I once read a paper that had mixed units (unfortunately common in my field), and the author was very lazy about throwing the words ton and tonne around with zero care. I had to carefully examine every instance of the word with it's context to make sure I was getting the right information. I still haven't quite recovered from that experience.


While we're listing weird American units, don't forget the American tendency to measure any distance greater than about a mile in units of "minutes" or "hours", because of our compulsive car culture.


This is how distance is measured in cities with public transit…

“It’s about 30 mins on the subway, etc”

Giving miles for distance between things in dense metros is worthless for people who want to know how long it will take to get somewhere.

What is car centric is giving distances between far apart cities in miles. That’s only meaningful for someone with a car who knows how fast they can drive roughly on the highway.


Generally 60 to 80mph, though for reasons of objectivity we usually just use the legal speed limits (which is generally 65mph).

So if someone were to say the next big town over is 4 hours away, I can do some simple mental math and understand it's 260 miles away give or take.


Alpine hiking trails are also so measured. Once you know how many hours it takes you to walk an hour, you are good to go.


there are other countries that still use imperial. Britain officially uses metric, but there’s a lot of imperial in common use. most people will tell you their height in feet and inches and their weight in stones and pounds. you buy pints at the pub and older generations will probably give you estimates of distance in miles

apparently also Liberia - a country set up by Americans - and Myanmar still use imperial


Pfft, who names a currency after a German valley?? Those hilarious idiots...


Not sure how its relevat anyway, but that doesn't sound silly to me. Why would have a concrete, relatable equivalent be a bad thing?


It's a bad thing because as it turns out, feet are all kinds of sizes, vary over time both in individuals and in groups, and may have different sizes or averages in different geographical areas. Even the unit foot is different between Indian survey feet, US survey feet, and apparently the international foot. To add extra confusion, there's the ISO 2848's "metric foot" which is exactly 30 cm, which supercedes former "metric feet" of different lengths. If you take old feet into account, a feet can be anywhere between 25 cm and 33.5 cm. What a mess!

A standard foot corresponds to EU shoe size 48 - woe be upon the person who goes shoe-shopping with thus Goliath feet.

Then there's the randomness on how super- and subunits seem to be randomly defined (1 foot apparently is a third of a yard (which is a stupid unit name in itself, because otherwise, yard defines an area, which is much larger than around a meter), but 12 inches.

This being a stupid situation is something Europe has understood already in the 18th century, which led to unifying to rational - metric and eventually SI - units.


> yard (which is a stupid unit name in itself, because otherwise, yard defines an area

I assume you're referring to an enclosed plot of land. That has a different etymology than the unit, which comes from a word meaning stick or staff.


Those are problems that have nothing to do with having measurements that can be imagined with concrete analogies. Nobody uses "feet" to mean literally their personal feet. A foot is a standardized unit of measure about the size of a foot. I have no problem with that, that's not an absurd thing to do.


Yes, the US should move to the metric system. There are many reasons, but etymology isn't one of them.



> NOAA needs to justify why they're ADDING ift in 2023 rather than just scrapping sft?

The reason is well known.

American exceptionalism.

Personally I've just given up on the USA dropping anything legacy for international standards.

Things will only get worse, as this example clearly shows.


This is needlessly pessimistic. The US has been, ahem, inching its way towards metrication for decades. It's not a particularly sexy or urgent topic, and it's staunchly opposed by a certain vocal segment of the populace, but industry, academia, and the government (including the military) have been making metric the default (and sometimes the only option) in more and more places. Previously the big win was in requiring consumer packaging to label in both customary and metric; nowadays the big win is that goods themselves are increasingly sold in nice round metric numbers with a customary conversion rather than the other way around. Give it another generation or so and we'll be in no worse a position than Canada or the UK is today.


The only one I’m going to be sad about is going from Fahrenheit to Celsius, outside of the slightly harder to remember water freezing and boiling points, Fahrenheit seems like it has a better UX for weather comfort. Because the scale is spread out more, each 10 degrees corresponds pretty well to a type of dress, whereas a 10 degree swing in Celsius is pretty drastic.

I’m sure Celsius users have their own mental mapping for that, but it‘s not going to be simple 10 degree bands.


> Because the scale is spread out more, each 10 degrees corresponds pretty well to a type of dress, whereas a 10 degree swing in Celsius is pretty drastic.

On the level of comfort and dress, looking at a ±10°F as a change of clothing type corresponds reasonably closely to viewing ±5°C in the same way. Seems like, while there is a familiarization period, its not likely to be any less convenient long term.


Yeah, that’s roughly what I was guessing based on the conversion, so just slightly worse on that front. There’s also something aesthetically pleasing about having a normal temperature range that’s essentially 0 to 100, rather than -20 to 40.


Why is -10F not as normal as 0F? Seems arbitrary.


On the flip side, Celsius is well suited to measure weather, because I can actually feel a 1~2°C shift in air temperature whereas 1~2°F is more faint


> Give it another generation or so and we'll be in no worse a position than Canada or the UK is today.

On the other hand, give it another generation and the UK will be in a worse position than the US’ today…


Unfortunately, this will make things even more confusing due to the amount of existing data in various state plane projections (almost all of which use us feet).

Then again, feet vs US feet is something you get very aware of very quickly as soon as you're working with geographic data. It's just that sometimes folks garble metadata and you're left with something that claims to be one, but is therefore offset from it's real location by large distances, and if you don't have things to compare it too, it can be very hard to detect incorrect metadata.

Either way, us feet are going to be with us for a long time. E.g. we still have (rare) things like "German meters" too. (Edit: I was thinking of vertical datums and Swiss maps, not German.)

The core issue is that when you are working with coordinates with absolute values in the millions, tiny differences in basically identical standards really accumulate.


My physics teacher used to joke that the standard horsepower was James Watt's horse, forever preserved in a vacuum in France.


That doesn't make sense because 1 horse has a maximum power output of approximately 15 horsepower.


1 HP was meant to represent the average amount of power a horse could sustain for a work shift. A horse can’t sustain 15 HP for more than a few seconds at a time.


Peak horsepower is not that relevant to the sorts of applications that horses were performing that they proposed to use engines for. In that case they wanted sustained power, and a horse can only produce about 1 horsepower sustained.


Not in a vacuum.


What if it's a spherical horse?


Well, it's scientific in the same way that an accused witch and a duck look the same weight on the scale then. Besides, after a few minutes sous vide, I wouldn't be able to pull with all my usual strength, would you?


> that minor difference can reach a few to several feet

That's... an interesting way of stating a range in an article about precision and units of measurement.


American here, what is that in football fields (the one true measurement)?


> football fields

FYI, the NFL and the NCAA agree on the dimensions of the “inbounds” area, but not on the dimensions of the “field”

https://operations.nfl.com/the-rules/2022-nfl-rulebook/#plan...

http://www.ncaapublications.com/p-4648-2022-ncaa-football-ru...


That’s about a tenth of a double-decker, FWIW.


about 123/1234 of a football field.


Ah, about two washing machines then.


Which side of washing machine? And what type of washing machine?


Postulate a spherical washing machine.


No physics, please.


Why is it called the international survey foot if it’s just used in the US as well?


I think NIST has a better explanation of the history: https://www.nist.gov/pml/us-surveyfoot

But basically, the "international foot" IS the foot. It's the foot you use everywhere, except in US surveying. Calling it the "international" foot in a sense is just picking an arbitrary way to explicitly disambiguate against "US survey foot".


Infuriating that we still use the foot but it is legally defined based on the meter!


The US foot has always been defined by the meter. Originally, Thomas Jefferson set the foot to be exactly .3 meter. The science of surveying and measurement weren't great in the late 18th and early 19th c, so the definition of the meter changed; by then, the US surveys were too far along to change.

My family has been involved with surveying on-and-off for ~100 years. I hated grabbing measuring tapes as a kid, because the "foot" or the "inch" was always sone batshit crazy thing. Like: decimal foot based on a 30cm foot; the "inch" is 3cm.


No, until shortly before the convention of the meter (1875) the US used imperial prototypes provided by the UK. There was some divergence after the fire in the Palace of Westminster destroyed the originals, and the replacements were not very high quality, wrt the rapidly improving manufacturing tech of the time. I can’t remember if the US got a copy of the mètre des archives during this time, but both the US and UK defined (different) official conversions between metric and imperial / US customary. After the new BIPM prototypes were made in the 1890s, they became the standards for high precision purposes in the US and UK. The imperial / US customary conversion factors reconverged over the next few decades, except for the US survey foot.


That makes more sense, thank you.


Wait until you learn about shrink rules, used in patternmaking!

Cast metal shrinks when it cools and solidifies. To make patternmaking tolerable, shrink rules are scaled up by the shrinkage allowance so that 5" in the pattern doesn't have to be scaled by the patternmaker to some random measurement. Unfortunately, the shrink allowance varies among metals...

A steel framing square also has some completely cursed scales. I'm not a carpenter, and I won't even pretend to know why anyone needs inches graduated into 10ths or 12ths.


Same reason why is it called World Series when only parts of North America compete.


If there is ever a baseball team somewhere else in the world that is remotely similar in quality to top MLB teams, I’ll happily admit that “World Series” is a dumb name. (This would most likely happen in Japan if it happens anywhere). Until then, I’ll continue using it.


In this case the USA is in the same club as Myanmar and Liberia.


The name dates back to the 1800s, when most countries were still on customary measurements (the meter existed at this point, and indeed the "international foot" has been defined in terms of the meter since 1893, but SI was still 70 years away).


Because it was agreed to by six nations in the International Yard and Pound Agreement of 1959.


Oh, just wait until you read ISO 2848, which defines a "metric foot", which is exactly 30 cm, and which is an international norm...


Canada had used it too prior to 1970, and probably some time after as they made the metric switch.

I wish we’d just switch too already.


When we invade other countries we need to survey there. So it is international.


A lot of places do business with the United States.

Consider it an international standard used for working with the United States.


One of my favorite things about doing sone surveying years ago was that we used the foot but not the inch. The foot was broken into 10 units named “tenths”.


> That’s a difference of only one one-hundredth of a foot per mile.

Well if we're being pedantic, it's 5280/499999 feet per mile, or 1/499999 feet per foot.


Non-native speaker being curious: do we need to use plural with fractions less than one?

Is it 1/2 foot or 1/2 feet?


Half a foot (or a half foot), but 0.5 feet


Why are we still using foot (US or international) as a unit of measurement?


Someone should really tell these guys about the metric system


If you're hosting video on the internet and don't have a team of 50 engineers to make sure it streams smoothly on every type of device and internet connection speed on every continent, then please just embed YouTube or another streaming site who do have the necessary resources to make sure it plays properly.

That video explanation pauses for 10 seconds every 5 seconds of playback for me, which makes the content almost useless.


Using YouTube is legally not an option here due to Privacy Act of 1974.


This is not true. It’s perfectly possible for the US government to use YouTube in a privacy act compliant manner.

https://www.dhs.gov/youtube-privacy-policy-and-notice


This is why the U.S. government needs a dedicated digital team like the Obama administration had setup.

The entire government can be their clients, so they can efficiently reuse stuff they’ve developed.

The UK government has done this I believe (I’m not entirely sure how it’s setup, but I do remember them publishing a UI toolkit that didn’t just look good but covered accessibility properly), and I think every govt should be doing it going forward.


It's still around: https://www.usds.gov/, and similar to the UK system, there's a US Gov equivalent: https://designsystem.digital.gov/

The UK one: https://www.gov.uk/government/organisations/government-digit...


There's even https://cloud.gov/

But parent's comment doesn't make sense. The video file is only 1.2mb in size and it's already being hosted on a Azure's object storage: https://aambpublicoceanservice.blob.core.windows.net/oceanse...

I think the native HTML5 video player just doesn't preload as much video and maybe his connection was spotty.


Azure


A U.S. survey foot is expressed as a fraction — 1200/3937 meters — while an international foot is expressed as a decimal, exactly 0.3048 meters.

A decimal is an alternative notation for a fraction.


They are still not the same value.


Who has the kind of money to quibble over that fifth decimal place? Oh yeah, national governments.


Assuming the question is serious: Owners of land near the US west coast.

Not near the east coast. US property is measured from a line of reference points near the east coast, so if you use the wrong foot there, your property boundaries will be less than 1mm wrong, and you and your neighbour are unlikely to notice. But near the west coast you may be building your house/fence/whatever 0.5m into your neighbour's land.


Near part of the west coast, there are fairly large effects due to plate tectonics (centimeters per year). I would think western California must have a measurement system whose position relative to points on the east coast gets adjusted periodically, with various deeds recording positions relative to ‘fixed’ points near the west coast.


I wasn't serious, but this is good information. I assume some of that is a holdover from mineral or oil rights being life-and-death.


No, it's about cities, and it's as old as street networks.

Suppose your neighbour has a 30×30m corner plot and you build a five-story building 50cm onto your neighbour's plot. The street isn't going to move, so you've just reduced the size of his possible six-story building by about 2%, and 2% of the value of a six-story downtown building is worth a lawsuit.


It's the result of how the US handed out land to settlers using survey to hand out square blocks largely sight unseen. However California has grants from the Spanish crown at the root of many of its property deed chains, so the mess will be different.


It can still be very life-and-death if your survey says that the natural gas line is half a meter from where it actually is.


But when they dig it up and it was really half a yard, they're just going to scratch their heads, nobody dies.


Only for rational numbers. Decimal -> fraction is a surjection. Irractional numbers, notionally representable as decimals, are uncountably infinite, and do not map 1:1 to fractions.


It is literally a ratio of integers, therefore rational.


Correct, rational numbers are those numbers that can be represented as a ratio of integers (excluding zero as denominator). Our points agree.


It is rational: 391/1250


(Note: this was a mistyping of 381/1250)


This particular value is, certainly.


I think you’re technically equating non terminating to irrational but the looser point seems fair to me— it’s hard to codify precise decimals.


Close. Many non-terminating can be mapped to fractions (e.g. 0.88888... = 8/9), which is equivalent to rational, but non-terminating and non-repeating are irrational (e.g. π or e).


I guess I’m just making the point all nonterninating are hard to codify in non mathematical fonts formatting etc. For instance using that 0.88888 example, that decimal very much does not precisely equal 8/9. you’d either have to keep writing 8s into infinity or hope everybody who copies/Padres your writing has a way to preserve the indicator of repeating digits.


They could just cop on and use the meter.


I like how they gently say "this is a step in the right direction".


Chances are the tools they use are working in meters and convert to feet either in their front end display, or it's a manual process that the surveyers perform.

But changing the definition of the unit whilst keeping it the same is a very pragmatic solution if they want to converge on the 'normal' foot. Software displays stuff with the right units, values which are old are probably close enough to be correct if just used directly, and anything large enough for the transformation to need to be applied will be hopefully rare enough that it can be calculated and applied with ease.


I’m not sure this is a pragmatic solution at all.

You’ve now raised the possibility that someone who starts being educated in the field a few years down the line, and never used the old foot at all, will look at old data with SFT measurements and assume they are IFT and introduce all sorts of errors in their analyses and calculations.

You’ve gone from 2 distinctly named standards with a 3x difference in value, which meansa mental sanity check should be sufficient to identify errors in most cases, to introducing a 3rd that is named very much like 1 of those and is close enough in value that a mental sanity check will not get you anywhere in most cases.


All other countries had to transition but the US is sadly stuck as long as they perceive themselves as leading and modern.

Once they get left behind maybe a politician will finally propose to "modernize" the whole thing but feh... the US will drag this crap for centuries like we still have a completely special keyboard layout in France for reasons no one seem to remember lol


You are making the common mistake of assuming that the US political system works similarly to the standard modern democracy found in Europe and parts of Asia.

It doesn’t. It is infinitely more deadlocked and slow-moving, mostly by design. Switching to metric wouldn’t be a matter of “a politician” proposing it and 50%+1 of the parliament agreeing. It would be a massive, years-long all-consuming struggle.


Most currently used keyboard layouts (like qwerty, azerty..) were made for one reason: to avoid jamming typewriters.

They are old legacy that is clearly suboptimal, but no one wants to change it because it still works and the transition would be costly

A bit like the imperial system


That would be communism.

I've actually seen an old ex-NASA engineer claim that.

He was not joking.


What ? They still dont use the meter at NASA ? So they ll drag this silly foot for millions of years if they colonize space ?

I root for the chinese communist to be there first then lol


According to this article[1] they do, but Lockheed Martin uses feet because America! Missiles! Eagles! etc.

[1]: http://www.cnn.com/TECH/space/9909/30/mars.metric.02/


It's even more subtle than that: Lockheed Martin did use metric in the design department that communicated with NASA, but its manufacturing department used imperial units.

I had a friend (in Europe) who worked as a mechanic on Apache helicopters in Afghanistan; all of that is in imperial too. He worked as a contractor so had to provide his own tools, but those are all in imperial and essentially useless outside of the US. So he now has an expensive high-quality useless toolset.

Switching manufacturing from imperial to metric is the real challenge. Nuts, bolt, things that have to fit exactly: it's all very banal, but there's a lot of it and switching it all over isn't easy or cheap.


This was one person who allegedly said that.


There is the old joke: “there’s 2 types of countries on this planet - those that use metric and those that put man on the moon.”


I agree, the Liberian space program simply doesn’t get the respect it’s due.


... and pissed away $193M when they missed/crashed into Mars because a US made spacecraft was using metric units while US-ground control was using Imperial (ironic because I thought we fought a Revolution to get out from under the Empire). By the 1990s when that loss occurred, there was no scientific or business reason for the US space program to be using Imperial units: except maybe in press releases that no one read. Generations of machine tools, dies, moulds and instruments have come and gone since the 1970s push for metrification. It's all about as rational as people insisting on only buying incandescent light bulbs. Oh wait.


The primary cause of this discrepancy was that one piece of ground software supplied by Lockheed Martin produced results in a United States customary unit, contrary to its Software Interface Specification (SIS), while a second system, supplied by NASA, expected those results to be in SI units, in accordance with the SIS. . . .

. . . The discrepancy between calculated and measured position, resulting in the discrepancy between desired and actual orbit insertion altitude, had been noticed earlier by at least two navigators, whose concerns were dismissed because they "did not follow the rules about filling out [the] form to document their concerns".

https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_...


> whose concerns were dismissed because they "did not follow the rules about filling out [the] form to document their concerns".

Typical government bureaucracy.


Communication within large groups of humans is difficult. I think the examples that NASA provides are enlightening and occur occluded in many places but NASA bares all. Below are examples from the Challenger and Columbia disasters.

It was not the Morton Thiokol engineers who made the decision to go ahead with the ill-fated launch. It was NASA. The engineers, meeting in Utah, communicated two messages from their meeting to their local managers. First, they produced the a formal, abstract result: "With the data available to them, and with NASA knowing as well as they that the design was flawed and that temperature might be a causal factor, the engineers argued that the Challenger ought not to fly so far out of the field database, the firmest evidence available." --Robison, et. al.

https://www.asktog.com/books/challengerExerpt.html

This fourth-level bullet concluding the slide says that, by the way, the debris that struck the Columbia is estimated to be 1920/3 = 640 times larger than data used in the tests of the model! Thus a better headline would be "Review of Test Data Indicates Irrelevance of Two Models." There is an interesting dynamic to this slide: the headline is an exercise in misdirection, which the text then awkwardly and slowly eviscerates.

https://www.inf.ed.ac.uk/teaching/courses/pi/2016_2017/phil/...


I think they do now, but this guy was a retired engineer and he did NOT like the change.


Seems kind of pointless. The entirety of the US is already surveyed using survey units. Land plots are divided using survey units. People buy and sell land using survey units.

100 links per chain, 10 links per furlong, 8 furlongs per mile. 1 acre = 1 chain x 1 furlong


I took surveying class. And while I am familiar with the terms of links, chain, and furlong, I have never used it in studies or practice (between 2005 and now).




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