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@sparky6086

8 ай бұрын

It should be noted, that the US was going to adopt the Metric System in the late 1700's even before France, where it was invented, but the standard weights & measures were lost in shipment, while on their way to the US, and because of the Napoleonic Wars & various turmoil in Europe, replacements were unable to be shipped to the US for decades. By the time, they were able to be shipped, the US had already Industrialized using what would become known as the US Customary System, so it was not cost effective to change all their machinery to Metric. Btw: People often reference the US using "Imperial" units, but it's not the same as "US Customary". For instance, an Imperal Gallon is larger than a US Gallon.

@sparky6086

8 ай бұрын

Petter, This is a great & accurate overview of the issue. Great work!

@Seriously_Unserious

8 ай бұрын

@MentorNow - I have a correction to give you about the Gimley Glider - I know you already know this, but slipped when introducing it. In the episode you said it was flying from Ottawa to Montreal, but this flight path makes no sense as that would be a short pond hopper flight that goes the opposite direction from Gimley, Manitoba. Montreal is East of Ottaway, while Gimley is WEST. The flight did make a short hop from either Toronto or Ottawa, to Montreal, but the incident flight was from Montreal to Edmonton, a flight path that would very much take it near both Winnipeg and Gimley. Maybe put in a caption correcting this statement.

@John-nc4bl

8 ай бұрын

What a mess. I wonder when we will smarten up and change altimetry numbers to metric-?

@alainkovacs2007

8 ай бұрын

Hi Peter & team, l.t.d.r. please consider also adding your videos to Nebula. I am a big fan, long time subscriber, patreon member and I greatly appreciate your videos. I have however grown sick of youtube lately as it is becoming worse and worse. I absolutely hate this new ad block blockade and their endless rush for more and more money. Don't get me wrong, I am more than happy to give that money to you(through nebula/patreon) and other creators i love, without youtube taking half or more from it, it is not fair to you or me. Therefore, I would like to ask whether you will consider also adding your videos to nebula. I no longer wish to use youtube, and I'm sure that I'm not the only one. I have no affiliation with nebula whatsoever, i just think that they provide a good service for a good price and also some competition to youtube, which at the end of the day is good for everyone.

As a Canadian trucker I get paid by the mile I drive kilometers, I buy diesel by the liter and calculate economy by MPG. I get load weights in pounds and the laws are in kilograms, I get personally paid in Canadian dollars but my load rates are in USD half the time… the struggle is real 😂

@bighammer3464

8 ай бұрын

Do you add air to your tires in pounds or bar but measure brake pressure in kpa? 😂

@georgejulien3286

8 ай бұрын

@@bighammer3464 that’s all psi lol

@georgejulien3286

8 ай бұрын

@thecritic8096 I don’t get bonus pay but I’m an absolute conversion machine hahaha

@danharold3087

8 ай бұрын

@@georgejulien3286 Keeps you sharp.

@bmxerkrantz

8 ай бұрын

​@@georgejulien3286gotta keep an eye on that exchange rate and post them usd invoices when the exchange is in your favor.

The funny thing about measurements is that once you get used to them, they feel normal. I am enjoying these unexpected videos about goings-on in aviation.

@MentourNow

8 ай бұрын

Thank you!

@joshlampe3458

8 ай бұрын

As an American I grew up with imperial, but learned metric from working on cars and much prefer it to imperial. If I find fasteners on any of my stuff that are imperial I replace them! :)

@sk3lly2023

8 ай бұрын

The only annoying part of metric measurements is cm, because every other unit goes up in tens but a cm is a hundreth of a metre.@@joshlampe3458

@ginbei711

8 ай бұрын

​@@sk3lly2023there's decimeter in-between but I never seen its use outside math test about that particular measurement

@livethefuture2492

8 ай бұрын

I don't belive in one over the other. It's Entirely dependent on context and the industry you're working in. The point is to have it all standardized and accepeted across the industry. And in aviation that is already the case. Everyone who has flown a plane knows knots and nautical miles and feet. So there is no need to change that just for the sake of using a different system.

It should be noted, that the US was going to adopt the Metric System in the late 1700's even before France, where it was invented, but the standard weights & measures were lost in shipment, while on their way to the US, and because of the Napoleonic Wars & various turmoil in Europe, replacements were unable to be shipped to the US for decades. By the time, they were able to be shipped, the US had already Industrialized using what would become known as the US Customary System, so it was not cost effective to change all their machinery to Metric. Btw: People often reference the US using "Imperial" units, but it's not the same as "US Customary". For instance, an Imperal Gallon is larger than a US Gallon.

@PhilippDebus

8 ай бұрын

If this is historically true, it explains a lot to me. I have always wondered why imperial units are used in the US at all. The imperial units were defined by law in 1825, hence at a time when the United States were no longer a part of the British Empire and politically more allied with France, the Empire's old rival.

@sparky6086

8 ай бұрын

@PhilippDebus Yes. It's true. Also, what would become known as the US Customary System was, what Britain used prior to the Imperial System. That's why the terminology & measurements between the two systems are often similar, if not the same. I don't remember, what the British called it? Probably something like, "HM King George III's Royal System of Weights & Measures". Btw: The shipment of Metric Standards to the fledgling United States, in the late 1700's which was lost in shipping, was lost due to a shipwreck or due to piracy (I've read both), not some mere dock or warehouse mixup. If not for that, what might have been!

@KCadbyRacing

8 ай бұрын

They aren't important like machinery measurements but several other US and UK liquid measurements are different as well. From Teaspoon, Tablespoon to Pints, Quarts and Fluid Ounces (Teaspoon, Tablespoon and Pint conversions are all US 1 to UK 0.8327) 🤷‍♂

@freeculture

8 ай бұрын

@@KCadbyRacing The "Gimli miracle" incident was the result of confusing litres with gallons. And certain Nasa probe to Mars was lost for this nonsense. The scientific community in the US is very metric, but as soon as you step out of it, there is the customary units nonsense.

@greentriumph1643

8 ай бұрын

The US has been on the metric system since about 1900. We have a standard kilogram, etc. Pounds, inches are all defined relative to the metric system. But industry and individuals are free to use whatever they want.

13:44 Yes, a lot could go wrong, but they didn't really need that kind of precision and accuracy in their sailing ships. A rope with knots in it did a good enought job, especially when you consider the fact that the ships speed varied as the winds changed. The statute mile comes to us from the Romans who paced out distances (pace is two steps) placing markers every thousand paces or mille (M is the Latin symbol for one thousand) which gave us mile. They placed stone markers along the roads every mille paces giving us milestones. When they said all roads lead to Rome it was literal because distance markers started at Rome. by the way, the statute mile was defined by the British Parliament in 1593, so the mile was defined by law, or statute, thus we have statute miles.

Verrry Interesting. :-) Thanks. I am 80yo electrical engineer still practicing part time. Even from day one, the EE and physics professors were very averse to using foot-pounds per 6.24x10^18 electrons per second so we used watts. Sometimes the physics professors made us calculate using slugs (mass), pounds (force) and foot-pounds (energy) so that we never again asked to use imperial units because almost no one got it right. (imperial sounds bad in American English anyway) . When I started college, an inch was 25.0001 cm (was supposed to change to 2.54 in 1959...so surprise! The length of a foot has changed during we geezer's lifetimes). I found that some states (the organization that defined weights and measures...not the Bureau of Standards who only recommended) had two widely different definitions of the pound which was something my mother had to beware at the grocery when I was little. Soon after I started working (50+ years ago), major US electrical and computer companies went dual dimension (they had a lot of people working outside the US so you could get a motor designed to be less than one kg when you wanted it less than one pound...didn't fit) saying only metric in 5 years but they went metric in 1 or 2 years. And that was 50 years ago. The last group in our business to go metric were the mechanical shop techs (who no doubt still have rusted 1/2 inch punches). In a review one day, a major Japanese company who distributed 60% of our product, all in Asia, flat out refused to go on with #6-32 screws and inches etc. (service parts problem) That would doom our group and there was no changing their mind or replacing them short order...so we retooled all the cabinets and moved to like M4 screws. You could get metric hardware in the US easy but getting English/Imperial hardware elsewhere involved delay. So the likes of me have lived our whole careers using metric in the US because of ...money. Slugs be dammed. We are the majority of those working in international companies.

@rainscratch

8 ай бұрын

Thank you for the detailed history. One correction: one inch = 25.4 mm (not cm as the first figure states)

@StringerNews1

8 ай бұрын

I'm still using the speed of light in furlongs per fortnight to make antenna calculations.

@terryrogers6232

8 ай бұрын

@@StringerNews1 love those farlongs...😁

@Markle2k

8 ай бұрын

You are misremembering that inch conversion. The US inch has been 25.4 mm since the late 1800s. The Imperial inch was very very close to that, just 2 um longer. 1959 is about the date that the British Empire switched to the International Yard of 0.9144 m. Industry had already begun to switch to a metrified inch in the 1930s in the Commonwealth and the US.

@erikthomsen4007

8 ай бұрын

If only the inch had been defined as 25.0 mm instead of 25.4 mm back in 1960, we would have avoided sooo many ugly conversion decimals...

1:10 In a whimsical move, the Pilot started the Gimli Glider Club. All passengers and flight crew were automatically members of the club with all priviliges, which meant attending reunions.

@sharoncassell9358

7 ай бұрын

They ttriied to convert USA to mettic measures but it didnot go well. People couldf not adjust so they went back to Imperial. Gallon of milk or booze instead of four.fout liters for liquor.gallons of gas or pettro.will it ever resolve?

@wayneyadams

7 ай бұрын

@@sharoncassell9358 I remember that debacle. We still have the remnants today where there are metric measurements printed directly below the Imperial measurements. Nobody pays attention to them except maybe people from foreign countries who use metric. LOL

@robnobert

4 ай бұрын

​@@wayneyadams there's even a 60mi~ish stretch of Interstate-19 in Arizona where the distance signs and "mile markers" are *exclusively* in metric, the one spot they didn't go back to customary or tack on customary to have both like they did for every other highway in the US built using metric only originally 🤷‍♂️

One point that often seems to be forgotten: It's not a choice between "metric" (SI) and "imperial" (US or UK). It's a choice between "metric" and 400 different national systems. The rest of the world didn't use "imperial" before they switched to "metric", each country had their own system, and sometimes more than one. Sweden also had "inches" (tum) and "feet" (fot), but they were different from the imperial ones. The same for all other countries.

@PhilippDebus

8 ай бұрын

However, due to the sheer extension and economic power of the British Empire, the imperial system could rival the SI system for quite some time.

@ChristofferETJ

8 ай бұрын

Sweden, and Norway, still use the mile (mil) as a unit of measurement. Only, it has been adjusted to be equal to 10000 metres.

@erikthomsen4007

8 ай бұрын

Indeed. This century-old inch conversion tool is a nice illustration of the chaos. upload.wikimedia.org/wikipedia/commons/4/4f/Inch_converter.jpg

@termitreter6545

8 ай бұрын

Even inside of the imperial systems theres different kinds of miles and knots, I think touched on in the video. On wikipedia I also see short and long tons sometimes, besides metric tons. And the main benefit of the metric system, or rather the SI system of units, is that its a condensed system. Theres just one measurement of length, the meter, and thousandth' (or tens) of it. Not Inch/Feet/Yard/Mile/etc. But they also translate: You can eg calculate the amount of energy it takes to boil a liter of water to the boiliing point much more directly, because those metrics are intersecting. (without super weird conversion formulas) Thats kinda the thing. The metric system is an improvement over the imperial system, and has been constantly improved to become better. The imperial system is just outdated.

@demopem

8 ай бұрын

@@termitreter6545 Yes, the imperial system isn't really one system, it's a collection of systems for baking, carpeting, surveying, etc. They each work fine within their domains, but it gets messy when you try to combine them. I don't think it's a coincidence that the metric system took over with the industrial revolution and emerging modern sciences. The mix of random, disconnected units just doesn't cut it there.

Errata: the Gimli Glider was AC143 from Montreal (C-YUL) to Edmonton (C-YEG), which is why it was flying through Winnipeg Centre airspace and was near Gimli in the first place. An Ottawa-to-Montreal flight would have only been a ~30min hop taking place nearly half a continent away from Gimli.

@morrij01

8 ай бұрын

I was just going to point out that Ottawa to Montreal via Gimli would have been the worse routing ever.

@lloydzilinski4401

8 ай бұрын

Yes, I was wondering why (and how) the AC 767 would fly the relatively short hop from Ottawa to Montreal, run out of fuel on the way, and then somehow magically glide several hundreds of kilometres out of the way far to the west to land at Gimli in Manitoba. I knew two of the passengers on the Gimli glider, they were from the town where I spent most of my adult life here in Alberta. The Gimli Glider bought them a new home in our town.😂. Still, a heck of a frightening way to get your house paid for. Don't think I'd want to do that.

@timothypirk9083

8 ай бұрын

I'm a little surprised that this mistake slipped through since he did an episode about this incident on Mentour Pilot around 2 years ago...

@CarbonKevin

8 ай бұрын

Came here to say this!

@bertblankenstein3738

8 ай бұрын

Yep, Gimli is no where near Ottawa-Montreal.

Something that alot of metric folks don't understand about imperial is that we don't use the wierd unit conversions that often. A prime example is the mile, we know 1 mi = 5280 ft, but we don't think about that. Instead we will keep the units the same and use fractions to measure. We will say something is 1/4 mi. instead of converting to 1320 ft.

@stephenj4937

8 ай бұрын

Yep. The only frequent conversions are from cups to pints/quarts when cooking.

@Rob2

8 ай бұрын

But when looking at subdivisions of units, it again is a mess. E.g. with an inch, you would use quarter, eighth and sixteenth of an inch to indicate subdivisions and they are by far not as easy to add as with metric where only decimal subdivisions are used (1 meter is 100 centimeter or 1000 millimeter). (in fact tenth of an inch is used in some technical areas like electronics, but I think not in the everyday world)

@mbvoelker8448

8 ай бұрын

When you're accustomed to it adding fractions is simple. You assemble them into whole units then add those. 🙂 Or, even simpler, pull out your tape measure and count them off. After all, you're not interested in getting x-hundred 32nds, you're after x inches to actually use.

@AaronOfMpls

7 ай бұрын

Yup, it's mainly feet-and-inches where we use both units together. But a.) we'll often go to just inches when doing actual math with them, and b.) if you know your 12s, the conversion isn't _that_ difficult. (Side note: I actually have a feet-and-inches calculator somewhere [that also does square feet for area], from when I took architectural drafting classes. No doubt there are apps that can easily do it too, from modern phone apps to the old command-line "units" program for Unix/Linux/etc.)

@jimm3205

5 ай бұрын

IDK - When I see "Next Exit .12 km" I immediately know it's 120 m. As far as feet, they're something I walk on, thats about it.

Im an ex process engineer, textbooks of old used units like dynes, slugs, etc. There's also pounds mass (lbm) and pounds force (lbf). We had a uni module on units alone. The three golden rules of process engineering: energy balance, mass balance, ensuring equations are dimensionally consistent. We had to master units and balancing equations from the outset. Great video, they are always interesting and enjoyable. Thanks Capt. Petter for sharing your knowledge.

@TheScotsalan

8 ай бұрын

Mechanical Engineer here. In Pnumatics, I dont think there is even a metric version of pipe threads ? Sure, there is M5, but everyone uses BSP or NPT. And just to confuse things, its based on bore.

@ericmintz8305

8 ай бұрын

A dyne is the cgs unit of force: centimeter-gram-second unit of force, equal to the force required to impart an acceleration of one centimeter per second per second to a mass of one gram.

@strehlow

8 ай бұрын

Unit analysis, regardless of what unit system is in use, is extremely useful, especially for unit conversions. You don't need to remember whether to multiply or divide by a conversion factor if it includes the units. For example when trying to convert miles to kilometers, your result better come out in km. If the answer you get is in miles squared, you immediately know you inverted the constant.

@johannesgutsmiedl366

8 ай бұрын

@@ericmintz8305 so basically a newton is just 100,000 dyne? Actually kinda funny I never heard of it, I guess it fits into this weird "no mans land" in the metric system where sometimes multiples of 10 or 100 are more useful than the usual 1000, similar to how we use bar and hPa for pressures because the "normal" kPa doesn't relate to atmospheric pressure very well

@ericmintz8305

8 ай бұрын

@@johannesgutsmiedl366 right. To elaborate: there are two main, equally valid conventions for metric units: MKS and CGS. MKS uses meters for length, kilograms for mass, and seconds for time. It appears to be used more often than CGS which uses centimeters for length, grams for mass, and seconds for time. When I was studying physics in the dim and distant past, my assigned textbooks used MKS. The Berkley Physics Course, which I read even though it was not required, was the only text to use CGS. Funny old world, this!

Petter did not mention it, but the cars manufactured in the USA by the American companies were all converted to metric parts in the 1980’s. Ford, GM, and Chrysler didn’t want to keep two completely separate sets of tools.

@kenoliver8913

8 ай бұрын

And also had a big export industry which was in the process of being smashed by the Japanese, for whom using the same measurements as their customers' mechanics was part of their "reliable, easy to maintain, spares available" schtick.

@JoshuaTootell

8 ай бұрын

Yep. Funny how my big 7.3 liter diesel is metric 😂

@z987k

8 ай бұрын

That's not true, I wish it were. At least with every Ford I've owned all the accessories used metric, but anything that bolted directly to the block was SAE. You need both sets to do major work. So for example the bolts holding the alternator on are metric, probably M10. The head bolts however are going to be 9/16 or 1/2.

@ericfielding2540

8 ай бұрын

@@z987k Bummer. I thought they had converted everything so they could sell a car made in Spain or whatever in the USA and vice versa.

@cr10001

8 ай бұрын

@@z987k My 1978 British Ford Escort, the gearbox and diff are metric (because they were made in ?Germany). But the engine bolts are all inch (UNF/UNC), with the exception of the bolts that go into the bell housing and the starter bolts, which are specials with 1/2" AF heads and M10 metric threads. I think the point is that you can thus do all work with one set of inch spanners. You only need metric if you're dismantling the gearbox or diff.

You mentioned (timestamp 20:24) the military using ‘a click instead of a kilometre’. Certainly it is a civilian colloquial expression these days. However, during my military days (admittedly mid last century) a ‘click’ was an artillery term when calling artillery gunfire down on a target. We infantry radioed back to our supporting gun battery, for example, to adjust their next round(s) to the left or right by a certain number of ‘clicks’. One ‘click’ was exactly one metre of deviation to the left or right at 1000 metres of distance for an artillery shell. Hence, with practice, adjusting fire onto a forward target became a straightforward calculation in the frantic chaos of a firefight to desperately radio back to friendly gunners sometimes many kilometres behind us. Apparently the term was originally derived from the mechanical click made when adjusting the artillery piece. Then, fire for effect! Incidentally, we never used degrees of arc (360 to a circle) and nor were our compasses or maps calibrated in degrees. Everything was in ‘mils’ … there are 6400 of them to a circle. Extremely accurate. (I have no idea if any of this applies today. Everything changes eventually.)

@Markle2k

8 ай бұрын

The mils, I believe, refers to milliradians of arc, or a close enough approximation, there are 3,141.59… milliradians in 180 degrees. Rounding up to a number divisible by a power of 2 (64) simplified the math.

Good video. The important difference is whether the units are used for measurement or for communication. In most aerospace examples it's communication: "climb to 20 000feet", or "visibility 3nm". In these cases, the use of different units actually makes communication easier to understand, and therefore better communication. There's a Canadian trucker who has commented here how mixing units is a pain if you rely on them for measurements. The Gimli glider is another example. But using a variety of units in day-to-day aviation is probably making everything safer. Horses for courses.

I think the last point about unit conversion being easier might be a bit off the mark. We Americans do have all these different units that have different conversions, but we don't usually need to convert from one to another. For very small things, you might measure in inches, and it would make no sense to use fractions/decimals of a foot. Likewise, you wouldn't measure long distances in feet, so there's little reason to remember that conversion. You might be aware of what those conversions are, but it's more likely you'll mentally switch between units depending on the scale, rather than convert between them.

When we flew Convair CV440s and Vicers Viscounts at Lufthansa, we had a lot to do when refueling. The Convair had fuel indication in the cockpit in LBS, under the wing US gallons and the tanker delivered liters...... At that time (1965) there were no calculators. We were all very good at mental arithmetic. The engine oil came in US gallons on Convair and Imp gallons on the Viscount. Then there was hydraulic fluid in pints and gallons. When refueling the 707, we had to measure how heavy the remaining fuel was because it was very cold from the long flight. The refueled fuel was not that heavy and all that then in liters and gallons. One had the indication in the Cockpi in Lbs, refueled in liters and to the security everything was measured again by Dripstick (not Dipstick, that had the L1049) in Inch. By the Way:With the dripstick you always had to look where the wind came from otherwise you had the JP1A in the face or it hit the flight engineer ......;o))

Hi Peter. Engineering software typically use Metric behind the scenes and then convert it to whatever the user likes. This could possibly be done in aviation as well. The main problem in future will therefore be risk of misunderstandings. This can be overcome with the development of computer systems that check if settings and pilot actions fit in with the flight plan and some information of these computer systems can be communicated to control towers to give them not only position and heading, but also what's planned for a specific plane for the next few minutes. Warnings can then sound if it seems like the plane is planning something different than the tower requested.

@COPKALA

8 ай бұрын

The problem is there yet, see the Canadian fly.

It's not very often Mentor pilot makes a mistake. But, we convert to mass, not for weight and balance, though that is a factor; but primarily because the energy of the fuel is in its mass, not volume. We cannot say an aeroplane has enough legal flight time by volume of fuel. Only by mass.

Some years ago, I used to fly a Jetstream 31 where the fuel indicators showed lbs. The loadsheet was in kg, and the fuel order was in liters. It took some time to get used to this, but after some time prectizing mental gymnastics, we got pretty good at it. For example, if we wanted to depart with 1,100 kg fuel, and the fuel indicators showed 700 lbs each (1,400 lbs in total), we had a total of 700 - 10 % = 630 kg total fuel onboard. The uplift would be 1,100 - 630 = 470 kg. With a specific gravity of 0.80, we added 1/4 to 470 kg = 590 liters. To be on the safe side, we would order 300 liters in each wing tank. It worked like a charm.

@petergamache5368

8 ай бұрын

Yes, you can see the Swiss cheese lining up though, can't you? Just add fatigue to that, and see what happens...

@user-lv7ph7hs7l

8 ай бұрын

​@@petergamache5368 Gliding is fun!

@bradrobinhancock8491

7 ай бұрын

I absolutely loved flying in the super 31's that American Eagle flew from PHF to BNA! Much more like a GA experience than the DH-8's of US Air back then.

I found this video quite amusing, as it is quite true for someone in my position. I am a 50 year old Canadian tradesman, doing things like carpentry and framing. When I began elementary school, Canada was just beginning to go Metric, so for the first few years, I was learning Imperial measures- then we switched. This absolutely led to some confusion on my part, like the time my mother sent me to a grocery store for a pound of butter, but all the butter was marked in grams! As I moved forward in life, I became very familiar with both systems and used whatever I felt was appropriate. For example, I enjoyed building customized scale car models, and by a great coincidence, one inch in 1/25 scale, rounds out very nicely to 1mm. Back in the here and now, all my tape measures are in Imperial, and I build things using feet, inches, and fractions of an inch. Hell, I don't even know if there is a metric term for 2x4 lumber- that would be really weird like 50.8x101.6. Doesn't roll off the tongue very well. The upside to all of this is that I can do a lot of conversions in my head, with neither system being foreign to me. Thanks for another informative video!

@bertblankenstein3738

8 ай бұрын

Don't forget to subtract 12.7mm from the width and depth for planing.

@lroke2947

8 ай бұрын

:: if there is a metric term for 2x4 lumber:: You'll find that the available material is 50x100 mm. Most carpenters will know what inch is, but you'll get 25, not 25.4, unless you specifically say you'll want a 30 planed down to 25.4.

@IN10THRC

8 ай бұрын

@@lroke2947 Where is that, anyway? Here in Canada, it's still all sold by traditional dimensions- 2x2, 2x, 2x6, etc. I've never actually seen it advertised in Metric dimensions. (None of this of course addresses the fact that a 2x4 is actually 1 1/2" x 3 1/2", but that's a whole other story.

@lroke2947

8 ай бұрын

@@IN10THRC Estonia. We've been on metric since 1929.

@AaronOfMpls

7 ай бұрын

I can imagine! As others have said, Canada's construction industry is highly integrated with the US's, so you guys haven't been able to get rid of feet and inches in your building supplies. Meanwhile, here in the US, when I was taking architectural drafting classes, I half-jokiningly asked my first day, "Can we just use metric?~" (instead of feet and inches in calculating dimensions)

I’m from the U.S. and I strongly support metrication. I learned the appreciation studying physics and chemistry in college. 1mL = 1 cc = 1 g = moles = this = that. Absolutely beautiful. That said, “freedom” (ugh) units seem a little bit more intuitional, especially in construction. For example, pipe diameters…but then again. I could probably get used to # cm = 7/8 inch. And two cups = a quarts X 4 = a gallon is just stupid…I’m not certain I even got that last sentence correct.

@ss-tx-rx2860

4 ай бұрын

You do have to be careful here in aviation, and he even mentioned this. 1mL = 1g only works for water at standard temperature, pressure, salinity, etc. Conversion is still necessary for calculating the mass of a specific volume of jet fuel, because it has a lower specific density than water. Whereas water weighs 1kg/L and makes the math easy, jet fuel weighs .81kg/L. So metric units offer quite literally no added convenience in this regard. Similarly, using meters as altitude would realistically result in more difficult math than feet, because 1km of vertical separation is entirely too much, whereas 1000’ (~300m) is just right. So we ensure separation by flying on either even or odd thousands depending on our direction of flight. Doing the same calculating using 300m results in some weird modular division that cryptographers may find convenient, but pilots doing mental math in the air would not. Standard adiabatic lapse rate is another example of where ft being more precise than meters results in nice round numbers (~2°C/1000ft) which is used the world over by pilots as a basis for where moisture may be expected to form. The same 2°C/600m again results in a fairly inconvenient modular arithmetic difficult to do in flight. So to Mentour’s point, it’s not as cut and dry as it seems and any hard line “just convert because my units are better” position is short-sighted and perhaps impractical.

@johnweb7055

4 ай бұрын

@@ss-tx-rx2860 Thanks for thought-out response.

@ss-tx-rx2860

4 ай бұрын

@@johnweb7055 Of course. I’m no unit apologist. I’m from the US but have spent about half my working career in Germany and N Africa. Americans inability to comprehend the units the rest of the world uses is inexcusable. But I’m also a realist. Flying is mentally demanding and for some reason the weird combination of nautical, US Customary, and metric units seems to work quite well.

The situation is further complicated by differences in old measurements such as British pints and gallons being different to US pints and gallons. The good thing about metric is it's universal throughout the world. British construction is now metric including plumbing pipes. In my younger days I was using feet and inches but now use metric and prefer it, especially small measurements. Using millimetres is more practical than using factions of an in such 3/64ths of an inch!

@rogerphelps9939

8 ай бұрын

You still order x metres of 4 by 2 from the timber merchant though.

@bradrobinhancock8491

7 ай бұрын

And yet they still use "stone" as a measure of weight at times. Or so I've heard. Can you still get a pint at the pub?

@KendalMike

7 ай бұрын

@@bradrobinhancock8491 Stones are pretty much only used for body weight now but more and more people are now using kilos. Pints at the pub was kept because it's a British tradition. Thankfully a British pint is bigger than an American pint. It would be be weird to go to the pub and ask: "Please can I have 568ml of your best bitter, Landlord"! 🤣

US is going to adopt the metric system…. Inch after inch!!

@bearcubdaycare

8 ай бұрын

Given that the inch is 25.4mm...it's getting there! 😅

The Gimli Glider was on route between Montréal and Edmonton. Not Ottawa and Montreal. 40 years later, Canada is still stuck in an awkward in-between position with the metric system being the only official system, but integrated industry with the US meaning we can’t get rid of US customary. Great video though!

@richardgoulden3572

8 ай бұрын

I was surprised he got that wrong From cruise you could almost glide to Ottawa after departing YUL 😅 He works with a ton of info so we will let it slide Now back to the video…..

Interesting fact when we "can't fathom something" it comes from using knots and a rope to test water depth which as recorded in fathoms, became "to fathom" - and if you didn't have enough rope, it was too deep to fathom.

@rainscratch

8 ай бұрын

Have always found it fascinating how far back and to what use a lot of our common systems, measurements and sayings, have their origins.

@andrewpinedo1883

8 ай бұрын

unonethousandthofanauticalmileable.

@kevinmobile

8 ай бұрын

And 'fathom' comes from Old English fæthm, meaning "outstretched arms." The noun fathom, which now commonly refers to a measure (especially of depth) of six feet, was originally used for the distance, fingertip to fingertip, created by stretching one's arms straight out from the sides of the body.

@ivorgotten2368

7 ай бұрын

@@kevinmobile I'm an ex merchant seaman, and to this day ships deck crews measure rope by the fathom. So if the Bosun asked me to make 3 heaving lines, I would measure the required rope by running it through my outstretched arms and counting 20 fathoms.

I am always fond of explanations in the kind of "Well, it's not that simple"!

I think the volume-to-weight conversion also becomes more intuitive with full metrification. Since a liter is basically the volume of 1kg of water, it's easy enough to remember and makes for easy math if you apply the specific gravity of fuels (generally a bit less than one) and should be an easy gut-check for using the right conversion.

@ianinscotland6358

8 ай бұрын

Unfortunately planes don’t get very far running on water.

@jeromethiel4323

8 ай бұрын

Indeed. This is what an instructor i had at one time call "engineering math." I.E. simplified calculations that told you if the numbers you were getting were close to what you needed. Or a "gut check." For example, if i need 500Kg of something, and i have to order it in Lbs, i know that a kilo is roughly 2.2 Lbs. So if the order says i am getting 150lbs, that is not even close to what i need. 150Lbs is only 330Kg or so. Also called napkin math, estimations, or whatever. I actually had a class in this in college, as it's something a real engineer should know how to do, just as a backup check to actually doing a full calculation of values. Because sometimes this has to be done spur of the moment, and in your head. So simplifying the calculations such that you can do the mental arithmetic is valuable. Less so, since the cell phone came out, because all of them have a calculator now, and everybody has a cell phone. But when i was in school, cell phones didn't exist yet. It's funny how often people remark on my ability to do simple math in my head. Which i think is a shame.

@aykutylmaz2745

8 ай бұрын

@@ianinscotland6358 strange that with all the videos on KZread of engines running on water, no one has put one on a plane yet

@csabamagyar3244

8 ай бұрын

Even at car gas stations we have a problematic situation with liters. The density of gas is lower than the density of diesel. Therefore buying a liter of diesel gives you significantly more "material"...

@bradrobinhancock8491

7 ай бұрын

@@csabamagyar3244 I thought that fuels were sold by volume. Sure, diesel (or even Jet A) weighs more than AvGas (100LL), but the volumetric equivalent is the same. Your one will always occupy the same space, but will have a different weight for the same volume. Now if we're talking BTU's per unit volume, that's true.

The history of measurements has me thinking about how many modern engineering feats and systems have been constrained by building over existing infrastructure. To a degree even the rockets on the space shuttle were limited due to decisions made from the ancient romans. The Romans were the first to set a standard for horse cart widths. The paths they set were then converted to the first train tracks. Those tracks then became a standard and when the US built it’s first railway it continued using those standards. This lead to the tunnels around the tracks being built around those fairly narrow paths. When it came time to build the rockets for the space shuttle, they realized the only way to ship them from the manufacturer to the blast pad would be by train. Because of that the engineers were forced to build them to fit through the existing railway tunnels. So yeah, some cart builder that’s been dead for a couple thousand years in a sense restricted how we started our space exploration.

Who knew that "knots" could be so fascinating to talk about and understand

As a draftsman I can only say the SI system is the best which limits conversion mistakes. When miles are used I never know for sure which one they mean. M/s gives a clear indication which ballpark you’re in. I read a book Theory of flight, written at the end of the 40’s, to learn that they used Stokes as a measurement to define viscosity. It is in itself already a difficult concept, but this doesn’t make it easier. Pa and seconds give a better indication what this is about. In short I will stick with SI system because it simply is a better system

You presented this argument with great humor.😀 In my job I work in both imperial and metric measurement. People are astounded when I can convert without even thinking about it.

Very fairly handled. One thing that you didn’t touch on is the near correspondence between nautical miles and degrees and time being in units divisible by 60, is that it facilitates dead heading navigation and estimating time to a waypoint simpler to calculate in your head.

American here. Grew up in the '70s and remember the attempt at "metrification" well. I liked it because base10 just made so much more sense (how fast can you divide by 12?). Auto manufacturers jumped all over it. Other trades, not so much. Construction/HVAC will probably never convert because there is so much tooling that would need to change. I'm just glad they didn't mess with time units. Can you imagine changing the definition of the Hertz? 🙃

@freeculture

8 ай бұрын

The scientific community did adopt it, common folk, no so much. It is one of the barriers for entering Science, the schools have failed. Truth be told anything can be changed, its a matter of definition, so yes even time. But it seems humans prefer 12 instead of 10, and its not like they didn't try... Even the soviets tried 5 day weeks. The original Roman calendar was 10 months (which is the meaning of December = the 10th month) but they left a void until spring.

@sharoncassell9358

7 ай бұрын

Metric system???. ? ? ? .

@sharoncassell9358

7 ай бұрын

@@freeculture inhey..se

You make an excellent point about the potential ambiguity of using the same unit for different things (such as altitude vs horizontal distance). I'm a programmer--to a computer, they're all just numbers, so we invent "units" like altitude-meters and horizontal-metets, so we can avoid mixing them.

Petter, you forgot that gliders in your native country uses metric fully, even for blocking air space in TMA's, when contacting the controllers. :)

@ivansemanco6976

8 ай бұрын

Also it was not mentioned enough that in some Eastern countries we was pushed to switch to feets for altitude in the past. We still have a metric altimeters in the older aiplanes and its sometimes realy funny to recalculate altitudes given by ATC... And we was told, that reason why we are moving from metric to feets and NM is that its easier for us than for the rest of the world. I like NM for navigation exercises but the rest is bad. But its life, we need to handle it as pilots.

@philipsmith1990

8 ай бұрын

@@ivansemanco6976 I flew for 30 years in places where metric altitudes were used We had a simple card that gave the conversions. It was not a problem so I doubt that it is a problem the other way.

@Norenius7988

8 ай бұрын

As a former airline pilot i think we still should use Nautical Mils for distans because it fits in vite the grid system on the maps, and Feet for altitude because if we use Meter we have to use decimal meters to be ackurat enough and that is in practical. Every thing else should be in SI units.@@ivansemanco6976

@ivansemanco6976

8 ай бұрын

@@philipsmith1990 Its not a problem, its only old habit. We are also using conversion cards sticked near altimeters.

I did my early training at a flight school with old 172s. Half of them had MPH airspeed indicators and half were in KTS. It was maddening.

@bradrobinhancock8491

7 ай бұрын

The 172's I train in have MPH on the outer ring, and KTS inner ring. The one that is *not* an H model has that reversed. Gotta pay attention when you draw that unit!

When switching a cockpit instrument field to different units, sometimes the indicator is limited to a certain number of digits. If the new units require more digits than available, then the actual indicator may need to be switched out. Also, in software, the problem doesn't always go away either. The screen space may already be allocated to make everything fit together. So adding an extra digit, may make one indicator interfere with another indicator. These issues can be solved but it may require making significant changes to the entire screen.

@ChrischenL

8 ай бұрын

Without having deep knowledge in aviation, this should only be relevant for “large” distances as km is smaller than miles with switches to the the next meter digit at ~ 6, 62 and 621 miles. With ft to meters, it shouldn’t matter, as m is ~3x larger and I don’t think you need the precision of 1ft / 0,3m. Same with 2.2 pound to 1 kg.

@freeculture

8 ай бұрын

Its easier now in the glass cockpit era. Just imagine trying changing those in the past, its no wonder the customary units (because the US led aviation) prevailed to this day.

@COPKALA

8 ай бұрын

Luckily engineers are clever, these are NOT issues.

@atzuras

8 ай бұрын

Same digits of precision can be used without losing accuracy. You only need to adjust to the most suitable 10th power as base unit.

@termitreter6545

8 ай бұрын

On digital displays its not really a problem. And the nice thing with metric system is that you got modifiers like mili, centi, dezi, kilo, mega, etc.

It's fascinating how we measure things. I graduated from school in 1981 so I missed out on learning metric system. I could not tell you my weight and height in metric but temperatures and speed I understand. One thing about Canada is that our country is so large that in the larger provinces we measure distance in time. It takes me one and a half hours to drive to the city my kids live in, 1/2 an hour to work. 🙂🇨🇦

@JimAllen-Persona

8 ай бұрын

That last statement is so true. What amazes me about Canadians is their willingness to drive long times to events. Canada: concert is 12 hours away? No problem. The States, especially the Northeast: 4 hours? Damn, why don’t they just have it on the west coast if I have to drive that damn far 😂😂

@jeanmkaufmann

8 ай бұрын

@@JimAllen-Persona 🤣🤣

@mbvoelker8448

8 ай бұрын

Distance measured in time is normal in rural parts of the US as well.

@georgegilbert7347

8 ай бұрын

Actually measuring distance in time has also become common in urban areas also. This is because traffic makes distance alone insufficient information.

@2ndfloorsongs

7 ай бұрын

We measure trips by hours down here in Texas as well. I bet they do in Australia too. My sister lives in Houston (big city) and measures trips in time units as well only she uses minutes... though considering how rush hours are getting nowadays, maybe she's going to join us and switch to hours.

As a middle-aged 'Murican, and from working in IT, I have 0 problems with metric. I

@ARockRaider

8 ай бұрын

i have no problem with people using metric. but i dont think its any better then using the mesurements that are more specialised. people can mess up what prefix just as easy as they can mess up a conversion between systems.

@user-lv7ph7hs7l

8 ай бұрын

Me as a European I'm just too bad at math to use fractions. American engineering would give me a headache. Fractions of inches, psi, kg, m, °F and Newtons in one equation. Also why are fractions not the same base? 1/4 inch and 1/32 in the same sentence, it should all be 1/32 or 1/64 or whatever, at least that would give me a chance. And 5280 feet to a mile. That's just not pretty. SI? How much is a 1000 kg of water? 1000 L. How many m in a km? 1000. How many mm in a m? 1000... it's way more idiot proof. And inches are too big for precision work so you end up with fractions. Or the classic American 3 inches and 2 mm lol... I get a headache just thinking about it. Physics must be a nightmare too. In SI as long as you always use seconds, meters, kg, etc... your result will always automatically have the correct unit be it Newtons, Pascals or etc... once the equations get longer imperial units become a nightmare and half the time is spent figuring out what unit the result is in.

@ARockRaider

8 ай бұрын

@@user-lv7ph7hs7l the fractions of an inch are always half the larger size. 2,4,8,16,32. but nothing stops you from using 10ths or 100ths if you really wanted to, infact in machining they DO use those and 1000ths. there is nothing metric can do that imperial can't do. most of your easy conversations between volume and mass are only going to work with a single fluid at a single temperature. imperial isn't so much a single saytem as it is several systems that have worked together for so long that the rounding errors have been filed off, unlike metric that needs several decimal places to work with any imperial measurement for it fit nicely.

@user-lv7ph7hs7l

8 ай бұрын

@@ARockRaider Did I say metric can do things inperial can't? No I said its painful and gives me a headache and no one who uses math in their job would seriously argue imperial is more conveniant. It leads to more mistakes. There's a reason you get 0 points in physics if the result is correct but the unit is off. 2.5 what? Apples? Atom bombs? The unit is important and that is easily messed up in imperial. SI which is what I'm talking about (no one calls it metric that's outdated it SI) the units always line up. Go do a differential physics equation abd try figure out the units. It's an absolute nightmare. You end up with psi/lbs/s/inch etc... and spend an hour figuring out if you end up with a force or a weight or whatever. In SI it's always blindingly obvious like m/s/s bingo acceleration, kg*m/s? Yep that's Newtons. Ir always lines up. I'm not talking about everyday use for that it's irrelevant. Use furlongs per fortnight if it amuses you. You need to use SI to truly appreciate it. No one cares how you measure weight in day to day life, SI is about science and engineering and for that it's a system so beautiful it almost brings a tear to your eye. It all libes up, every unit can be boiled down to m, s, kg. All units are expressed as those. The system is specifically designed to make scientific calculations as easy an error free as possible. I really don't give a sh*t what you prefer to weigh apples or easure the speed of your car. SI isn't about day to day use and no one is stopping you from using stone or yards.

@ARockRaider

8 ай бұрын

@@user-lv7ph7hs7l I guess counting distance of travel and checking how much my load weighs doesn't count as "math". all measurements are arbitrary, so why not get your "scientific" units to be something that can work neatly with more units? I actually find keeping track of the prefix in metric easy to mistake, in fact i know of a medical mistake where someone had a kidney stone that was 10x the size they thought when reading the paperwork because they were used MM and it was listed in CM. these are the kind of mistakes that could happen to any system in some way, but i personally don't know of any task where a meter is a better unit then any of the options i have. it's to big of a unit for the tasks done by inches, feet or yards, and it's to small a unit to replace miles. it's only 'benefit' that i know of is something that can be done with any of the imperial units, what's stopping anyone form using a kilo-inch? or a centi-yard? you wouldn't even get funny looks in construction if you ask for something cut to 48 inches! even if you could just as easily say 4 feet.

I love the Gimli Glider story. Such an amazing outcome. But I think it was flying from Montreal to Edmonton, not Ottowa to Montreal. That's quite a short distance.

@1486230

8 ай бұрын

I was just checking if anyone else commented. Gimli is in Manitoba, so the complete opposite direction.

@JimAllen-Persona

8 ай бұрын

Yeah I was thinking something sounded wrong with that too.

@danuttall

8 ай бұрын

The airplane started the day in Montreal. Captain Pearson ordered 22300 kg of fuel to be loaded on the airplane to make it to Edmonton, with a short stop-over in Ottawa. Unfortunately, the fuelling technician used the wrong conversion rate so the plane was loaded with 22300 pounds of fuel instead of 22300 kg of fuel, less than half the required amount. Pearson had not been trained on using the metric system for aviation fuel so did not notice the mistake when he signed off on the fuelling report. With less than half the fuel needed, they ran out of fuel just past the Ontario-Manitoba border and made an emergency landing on a former Royal Canadian Air Force runway, which had been converted to a drag race strip.

@improvised_hominin

8 ай бұрын

yeah was about to say, Gimli Manitoba is very much not on the route between Ottowa and Montreal haha@@1486230

Even though the USA is looked down on as still using the imperial system, our kids are taught metric system from the beginning in school (my teens are comfortable in Metric system) and those of us with higher education use metric system all day. I.e. as a physician i measure with cm, mm, cc/ml, L, etc.

@RS-ls7mm

8 ай бұрын

The US is bi-lingual in measurement so we are better than those snobby Europeans who only know one system. Almost everyone I know can use both interchangeably.

@nomore6167

8 ай бұрын

"Even though the USA is looked down on as still using the imperial system, our kids are taught metric system from the beginning in school" - When did that start? It must have been after I graduated from high school. For most people in the U.S., I think the closest they'll get to using the metric system is checking sale flyers for a 2L bottle of soda.

@stevehuffman7453

8 ай бұрын

they are??? The only "metrics" I was taught was cents and dollars. (I attended school in the 1960' and 1970's. College mid 1970's and again in the mid-late 1980's.) ALL measurements were in inches/feed/yards/rods/acres/miles/squares/cups/quarts/gallons, etc. When I was an OTR trucker (retired 2017), the ONLY state that had "mile markers" in Kilometers was Southern New Mexico,near the Old Mexico boarder, and ONLY on that one road. The Interstates, US, and State Highways (other tan that single one, inside 50 miles of the border) in NM were in miles. IF the Us ever converts to metric system, I hope it is AFTER I have left for the next life. I understand the imperial measurements and can visualize them; Not so the metric system.

@bernadetteP9999

7 ай бұрын

So you all aren't like Agent Booth in episodes of Bones requesting "tell me in American" lol

@jakob_z

5 ай бұрын

​@@bernadetteP9999I think it depends. We may get taught both and can use both, but do we have intuition for both? For me I still have my intuition in imperial, I don't instinctually know how far 10km is, or how much a 100kg box weighs, and for the ones I do. Though for smaller amounts I still have it since 1 meter ≈ 1 yard, 1 inch ≈ 2½ cm, 1L ≈ 1 quart, 1g ≈ a normal paper clip. (2L bottles of sodas are also really common)

A decade or so ago, I was sitting in the waiting room at a doctor's office. One of the available magazines was a sort of Danish aviation magazine. When I read a story about a private pilot that made an emergency landing, a came across the unit "nm". At the time, I was working with lasers, and immediately interpreted this unit as nanometer. "Nanometers??? That doesn't seem right. Aaaahhh... nautical miles!"

@james-p

8 ай бұрын

Funny, my first thought was Newton-meters lol (although they are correctly abbreviated N•m).

@erikthomsen4007

8 ай бұрын

@@james-p Yeah, Newton is abbreviated with a capital N. Nano with lower case.

The only issue I have with "mixed" units is that usually you don't get to understand how one unit relates to the other. In metric (SI) it's easy to understand the relation between distance, speed and acceleration. In imperial it's almost as easy too. In a mixed situation though, you have miles/feet/knots, feet per minute and G's (m/s2). You cannot easily understand the direct link between these units. While the attributes they measure are all interlinked, they become a bunch of meaningless numbers that don't seem to be linked to each other. Using a single system (instead of a mixed one, whether it's metric or imperial) makes you understand how changing one attribute affects others.

@kueflies

8 ай бұрын

You could adapt G though couldn't you? Since it's used practically as more of a scalar G could be the gravitational acceleration in whatever units you prefer.

@greentriumph1643

8 ай бұрын

32.2 ft/s2

@Norenius7988

8 ай бұрын

"G could be the gravitational acceleration on earth in whatever units you prefer." to be korrekt. @@kueflies

@TrimeshSZ

8 ай бұрын

The problem is that imperial/US customary units were never coherent systems in the first place - the biggest problem was that they were defined before there was really a distinction made between mass and force, so a lot of units effectively have the earth's gravitational constant baked into them. There is also the unit diversity problem where in many cases things that are measuring the same fundamental quantity have different units depending on the application area. So a boiler might be rated in BTU per hour, an air conditioner in tons, and a car engine in horsepower - but they are all just different representations of power, with wildly different (and unrelated) scaling factors. In SI, you would just use Watts for all of them, and the scaling factor issue immediately goes away. SI was designed from the outset with the specific idea that it would be a coherent system of measurement, so this issue never arises in the first place. In fact, there were some attempts to make coherent systems based on imperial units with the base units being foot-pound-second. Unfortunately, there were several of them and they were defined in somewhat disjoint ways. Most notably, there was disagreement about if mass or weight was the primary unit, which tended to make the entirely consistent MKS system look a lot more attractive.

@atzuras

8 ай бұрын

But 'g' is a base unit in aviation. it is not used to measure linear acceleration, not even vertical acceleration, but the load factor of the wings. it is rarely used in speed calculations without a computer or calculus tables. Same happens with N1 or N2, it could be Newtons but it would not help at all to understand if your engine is performing well.

And we do use the metric system in the US, just sporadically. Like nutrition labels, pharmaceuticals, science, and for some reason beverages

You mentioned the story of Knots. I believe, because the wood on the rope was called the log (as you mentioned), when the speed was recorded it was referred to as the "Log Book".

"... took off from Ottawa heading towards Montreal..." No. The flight was from Montreal to Edmonton. That's a pretty big mistake. Ottawa and Montreal are relatively close (under 200km), while Montreal to Edmonton is most of the width of the country (3500km).

@MentourNow

8 ай бұрын

Yes this is an error. That particular leg was from Ottawa to Edmonton.

@firefly4f4

8 ай бұрын

I already know from other videos that even degrees in a heading aren't universal. A heading requires a reference for 0 degrees. I understand that most of the world uses magnetic north as zero. However, as magnetic north isn't actually fixed, the more north you are the more noticeable it is that it moves, so more northern counties (ie Canada) give headings based on geographic/true north. This would be particularly noticeable on runway numbers, as Canada got fed up hwith renumbering them every few years as magnetic north moved.

@kevinsbikingadventures278

8 ай бұрын

I noticed that too but it was just a slight error in naming the cities involved. The flight was from Montréal to Edmonton with a stop in Ottawa.

One thing I'd be curious about is whether aviation today is more similar to nautical travel (where non-metric units dominate), or to space travel (where metric units dominate). Perhaps there's some benefit in going metric for the sake of those boundary-blurring vehicles like aircraft that air-launch spacecraft?

For the record, Ottawa and Montreal are quite close to each other. The actual flight was between Edmonton, Alberta and Ottawa, Ontario. It ran out of fuel over Gimli, Manitoba. Also, we converted to Metric in 1975, not 1983. The The 767 was one of the first American-built aircraft to use metric for it's flight computer whereas the ground refueling equipment was older and used imperial.

Bring back cubits! 🤣😉 Great overview of units in aviation Petter. As glass instruments become more ubiquitous, computers can adjust primary display measurements in whatever is desired. People are going to be the gating factor because a mind needs to judge distances at landing and takeoff whatever the system used.

In the sailing Navy every hour the midshipman of the watch threw the log which was attached to a rope with knots at regular intervals. They would flip a sand glass over then count the knots as the rope played over…I think it was a 30 second glass. They would convert the count to knots per hour and mark it on the traverse board. They did this every hour. They marked the course every half hour. The sailing master (navigator) then could plot positions on the chart by dead reckoning, not as accurate as celestial navigation but a quick estimate of their position.

I had a 20 year career with Pan Am … American company but we were metric for everything but fuel. It’s just so easy to work with.

I have only recently found Mentours channels but have been binging on them. I feel like I am getting an entire education in each one, I came to find about knots and ended up getting a politics, geography, measurements and aviation lesson too. The man is a legend, I really enjoy understanding the complexities of other people's industries/jobs.

I'm a metric fan and I'm nobody to judge aviation for the units they use... But why inches of mercury? 😭

@SeekingTheLoveThatGodMeans7648

7 ай бұрын

old weather barometers, i guess

Gliders in Germany have metric instruments: km/h for speed and meters for elevation.

@julienhoffmeyer2597

8 ай бұрын

I fly glider in metric in Switzerland, too. In fact, all gliders are german 😂

When I started school, up until I was about 15 (my memory's a bit hazy) we used only Imperial units. Then we changed to metric. I'm 71 now and prefer Imperial units for some measurements and metric for others. Metric isn't inherently superior to the Imperial system but it makes some calculations easier. I prefer large distances in miles, smaller distances in feet and inches, but even smaller distances in millimetres! Heights and weights of people - Imperial. By the way, the Imperial system is identical to the US Customary system apart from pints, gallons etc. I believe a US pint is 16 fluid ounces and Imperial pint is 20 fluid ounces, making a US gallon 128 fl ounces and a UK gallon 160 fl ounces - in other words a US gallon of water weighs 8 lbs and a UK gallon of water weighs 10 lbs!

@cigmorfil4101

4 ай бұрын

Almost: the US fl Oz is a slightly different size to the imperial fl Oz - it is about 4% larger (29.5735...ml compared to 28 4130... ml)

@stumccabe

4 ай бұрын

@@cigmorfil4101 Thanks, I was unaware of that difference.

That’s a really cool thumbnail. I love the detail you go into regarding the history of units like the ‘knot’. It is bizarre that in countries (like Canada) that have officially converted to the metric system, there are plenty of remnants of the imperial system that are definitely dying hard in day to day use, even for professionals in many industries….

@user-lv7ph7hs7l

8 ай бұрын

Even Europe still has some of it. Bread used to be in pounds at the baker for a long time. I still remember that. But the rest is always kg. Jewelers often still use ounces.

@WillSmith63957

8 ай бұрын

@@user-lv7ph7hs7l yup that reminds me, the royal canadian mint still produces and sells in ounces as their most common denomination ( though they do have metric portions in large bars). Most people express their own weight in pounds and height in feet/inches. Small measurements are almost always in inches (whether you’re talking about the size of your TV or you’re framing the wall of a wooden framed house). When Mountour said old habits die hard, he wasn’t kidding. Even the governments themselves haven’t fully adopted the metric system. Sure, our speed limits and distances are expressed in killmetres, but maximum vehicle height for low overhead bridges etc are often expressed in feet. Maximum vehicle height overall in most jurisdictions is simply 13’6”.

@user-lv7ph7hs7l

8 ай бұрын

@@WillSmith63957 Screens are inches globally for some reason. I know what a 27 inch monitor is. I have no idea what that is in cm but if you asked me to show you what 10 inches looks like absolutely no idea... Plumbing too, though Mentour mentioned that. But plumbing isn't too bad it's either half inch or 3/4 gor almost everything. It would be expensive to change and there isn't really a good reason. If plumbers want to keep doing inches that's fine. I rarely have to deal with it.

@AaronOfMpls

7 ай бұрын

Re: Canada -- Their building supply industry is heavily integrated with the US's, so much of their building trades are likely to stick with feet-and-inches for as long as the US does.

Funny: as a musical instrument guy, I use inches quite a lot for speaker diameters and the scale length of guitars. As a car guy, I immediately thought about car tyres, reading the title of this video, and it was nice to hear you about it. A car tyre measurent like 185/65/15 is mm/ratio/inch.

The ship's log you mentioned for measuring speed had a book to record the speed. Ship's log book. With how long that was, people just called the book the log.

I absolutely love your channel! The care and detail you put into every episode is fantastic!

@MentourNow

8 ай бұрын

Thank you very much!

I like how much fun you had with this one Petter!

There is also the fun problem where attempting to simplify an overly complicated system winds up with it being more complicated because the simplification merely becomes an expansion pack to the existing system, rather than a replacement.

I'm a mechanical engineer who got a BS and MS from Purdue University in the late 1970s and early 1980s. As such, I not only use US Customary Units (taught to us as British Engineering Units), but also use Rankine for my absolute temperature scale. It doesn't matter, because I can convert between that system and SI or CGS (for nuclear work) in my sleep. My career was in missiles and space, and the ICBM development programs I worked on all used US Customary Units. It made a lot more sense, given that the astrodynamic calculations we used all employed celestial navigation frames of reference. Range of an ICBM was given in nautical miles, which instantly converted to 60 minutes of arc. And velocity was in feet per second, a unit having much finer resolution than meters per second, and one other advantage: the largest contributor to ICBM target errors is the cutoff velocity, and out of about 24,000 feet per second, everyone knew that a velocity error of 1 foot per second would translate into a range error of 1 nautical mile. That's more than an order of magnitude greater miss distance than we could tolerate, so having that one simple metric in hand always kept us focused on the important things.

@MrSigmatico

8 ай бұрын

Yes that is all well an fine but you could have gone to cm pr second for a much finer like you put it calculation by simply moving a decimal which is why the metric system is far superior to the imperial or any other system you care to produce.

@LadyPelikan

8 ай бұрын

Interesting

@Dyson_Cyberdynesystems

8 ай бұрын

I did my B.Eng (Mech) in metric since I grew up in a metric country but then moved to the US and work in Aerospace. Everyone wants to claim conversions are so much easier, and if I'm going to be doing some thermodynamic calculation sure, but from a manufacturing and fabrication standpoint, Imperial units make so much more sense. The ability to quickly mentally calculate stackups (especially with sheet-metal), EDs, bending allowances is a 100 times easier with fractions than metric decimal points. And as I stated in another post NM/KTS to me do not even count as either because that has more to do Spherical-coordinate system vs Cartesian which is again considerably easier in the former when it comes to navigation, for pilots or apparently missiles. Imperial/US Customary/Standard whatever you want to call it is a much more practical system and unless you have worked with it you really do not know. I will also mention that having been tough that ISO was the holy grail of just about everything I was pretty disappointed to learn that in reality every country still does its own thing, e.g. DIN, JIS, BSI ect..

@SkyhawkSteve

8 ай бұрын

as an electrical engineer, these discussions make me appreciate the universality of volts, amperes, ohms, etc! We do have to deal with metric vs imperial when it comes to the dimensions of the parts, though.

@RWBHere

8 ай бұрын

​@@Dyson_Cyberdynesystems I've worked with both systems in various jobs, sometimes using both in one job, and don't mind which was used, so long as everyone understood the units. For instance, we bought semiconductor Silicon in BS diameters, often used BS sizes for the coarser geometry of devices, but always used SI for fine details and doping depths, along with Celsius for temperatures. When aligning screening masks, back in the early 1980's, we did the alignment by eye in near UV light through microscopes. The alignment marks on the smaller devices which I was making were squares. The squares on the Silicon were 4 microns smaller on a side than the ones on the masks. This was deliberate because when aligned perfectly there was a 2 micron space all around the squares, but three concentric squares were visible. This was because of the interference patterns with the light used. The additive interference fringing produced the third square exactly 1 micron away from either real edge. It so happens that a micron is about the limit of resolution which can be obtained using visible light at the extreme blue end of the spectrum. A l micron wide feature becomes a somewhat fuzzy line, in other words. We could equally well have used 0.00004" in CGI for the same job, but who wants to have to write down or talk about a 6 digit number when 1 digit can be used in SI? Even using '0.04 thou(sandths of an inch)' is cumbersome. So the micron automatically became the standard unit to use for that application. Curiously, Angstroms were used for doping depths, even though it's not an SI unit, but it had the advantage that one less decimal point could be used than if using microns. My point is that in many instances the units used are the ones which are the easiest for the application. But in most instances SI is much simpler to use because of the easy calculations. An example: How much does one hectare of water which is 3.25 metres deep weigh? Simply, using mental arithmetic, 100 x 100 x 3.25 tonnes = 32,500 tonnes, or 32.5 million kilograms. Now try doing a similar thing in BS units: How much does one acre of water 10.25 feet deep weigh in tons? What is that in pounds? In ounces? It's no longer mental arithmetic, and unless you know the figures off by heart it's a process which is very prone to errors.

I've been both an certified aircraft mechanic and I also have worked as vehicle mechanic. Work in metric units is fine just as working in imperial units is also fine. There's nothing worse than working on a vehicle that uses both metric and imperial hardware as many US cars often have. One might think that this problem only exists on American cars but no. The KingAir aircraft have 1 metric bolt. This bolt attaches the air-conditioning compressor to the engine. This is because the KingAir uses a General Motors air conditioner compressor. At least it's only 1 bolt on the whole aircraft.

As a U.S. medical professional I've been using the metric system for 30 years and I'm a complete fan of it. Will the U.S. convert? I doubt it.

Interesting aspect regarding the unit mix. It reminds me of the phonetic alphabets in different languages. Something most people don't know is that these words/names used have been carefully chosen to avoid errors when used over a "bad line". Those who don't know them tend to use other, more common names, instead of the correct ones when spelling something. A typical, very common error in Swedish - where not even names are used - is to use "etta" for the number 1. Most other numbers have two syllables and end in '-a', but using "etta" instead of the correct "ett" makes it susceptible to mix up with the number 8, "åtta".

@michiyl

8 ай бұрын

There's a similar thing in German when you want to really distinguish between 2 ("Zwei") and 3 ("Drei") - when you want to make sure the other side has the correct number, you say "Zwo" instead of "Zwei".

@kkfoto

8 ай бұрын

The ICAO phonetic alphabet also has some adaptations in Portuguese to avoid confusion. As a side note, Atlanta International Airport (ATL) uses “Dixie” instead of “Delta” for the letter "D" to prevent any confusion with Delta, the airline.

Flight 143 was not flying from Ottawa to Montreal, it was flying from Montreal, known as Dorval at the time, to Edmonton, with a stopover in Ottawa. Gimli is in Manitoba, on the shores of Lake Winnipeg, almost on a direct line between Ottawa and Edmonton, but nowhere near Montreal, which is in the opposite direction, east of Ottawa.

The US Metric Board recommended switching from gallons to liters in 1979. Some gas stations, like my local Shell station, did switch. But in the face of massive public resistance the whole idea quietly went away and my station eventually switched back to gallons. Of course it's worth mentioning that a US gallon is smaller to a UK Imperial gallon.

@rainscratch

8 ай бұрын

Which goes to show an ingrained habit is hard to change. It is easy to be bemused by the origins of Imperial measures but metric measures have somewhat more grounded origins based on meridians etc

@effyleven

8 ай бұрын

That's because the eight pints that make an American gallon, are smaller than Imperial ones. There are 16 fluid ounces in an American pint, while the Imperial pint has 20 fl.oz. Therefore, in America, a pint of water weighs a pound... whereas, in the UK, "A pint of water weighs a pound and a quarter." PS. Don't tell anybody, but the American and Imperial fluid onces are not *exactly* the same size.... (sigh)

@M1903a4

8 ай бұрын

@@effyleven The actual reason US and UK gallons are different is a side effect of that fact that the UK had a great many sizes of gallons, both liquid and dry, historically. The US officially adopted the wine gallon in 1834. When the UK initially standardized they used a slightly upsized version of the Corn gallon (33/32) which was actually a dry measure as the Imperial gallon. The US gallon remains unchanged, albeit officially defined in metric terms. The UK gallon's size has be tweaked several times before it got redefined in metric terms.

@effyleven

8 ай бұрын

​@@M1903a4Thank you for your in-depth response. I am not sure I deserved it! 😅

18:34 my favorite clip of the FO cranking the flap handle.

Being an American Southerner myself, I do find the metric system easier to use and convert, but I have no problem with the imperial system and can convert very easily. I am used to it and do not think about it. I do not know about being superior, but the metric system is easier since everything is based on the power of ten. Also, the U.S. had tried to go metric for centuries. Joe Scott has a video about it.

As an American I am often at odds with others because I am in full support of using the metric system and try to use it as often as I can (especially for body weight because it sounds like I weigh less than I do 😂). As usual, Petter, watching your videos often teach me that things are often more complicated than they seem in aviation and I can see where going 100% metric may not make the most sense.

@erikthomsen4007

8 ай бұрын

When I was an exchange student in Florida in the late eighties, the high school students seemed to be divided regarding units of measure. Those that had an interest in science were fans of the metric system. Others were not, and some would make the gruff statement "Y'all should switch to *our* system!" Yeah... good luck with that.

@user-lv7ph7hs7l

8 ай бұрын

The most confusing for me coming from metric is height. Feet and inches?? If someone says he's 5 feet 7 inches I'm completely lost. 5 x 3.3 + 7 x 2.5?? If it was 5.5 feet or 70 inches I'd have a chance bit two different units with different conversions. I just know what six feet is and then I can figure ok it's about 180 cm - 5 inches. Of course sometimes you see lbs and ounces. But I didn't see that too often when I was in the US. Reminds me of the old English money with pounds, shillings and pence. Somehow knots don't annoy me, that's universal. Boats and plabes do knots... but it's 1.9 km so relativemy easy to guesstimate.

@aliyousuf2342

7 ай бұрын

The American/Imperial system has such staying power because the primary units are on very human scales. A foot is roughly the length of your forearm, an inch roughly from your second knuckle to pointer finger tip, a 1 lbs water bottle feels just right in the hand, 100ºF is dangerously hot and 0ºF is dangerously cold, everything in between doesn't require extraordinary measures. It takes 15 minutes to walk a mile, i.e. 4 an hour, or a 9 1/2 minutes to walk a kilometer. An acre is the amount of land one man and a team of oxen can plow in a day. If you gave me a compressor that measured in atm's and I had to inflate my tire to 2.28 atm I'd throw the thing at you. But 35 PSI is a lot easier to understand.

@erikthomsen4007

7 ай бұрын

@@aliyousuf2342 This is really weird... 100°F is dangerously hot? It is just about your standard body temperature, not even running a fever. 9.5 minutes to walk 1 km? That is quite a brisk pace. I suspect that you have just, somewhat inaccurately, converted your 4 mph to metric, and set that as a standard. I typically estimate roughly 6 km/h, or 10 minutes per kilometer. As people walk at different speeds, adding decimals is unnecessary accuracy. "An acre is the amount of land a man and a team of oxen can plow in day." How is this even remotely relatable to modern-day people? And how is PSI easier to understand? It is only because _you are used to it,_ nothing else. Besides, when you inflate a tire, you just need a number and a gauge. As long as the number has the same unit as the gauge, it doesn't matter what the unit actually is. The pressure gauges I have used, have scales for both PSI and bar, so it is just a question of looking at the right scale. By the way: Atm is NOT a metric unit, and I've never seen it used on modern pressure gauges. But 1 atm is close to 1 bar, which is equivalent to 1 kg per cm². No, aviation aside, I see two main reasons that the US clings to its customary units. 1. A complete switch to metric is costly. A vast amount of technical equipment and road signs would cost a fortune to change. 2. The impressive US stubbornness stands in the way of virtually any change. Not only regarding units of measure.

Great video. I think you did a great job of outlining the usage of various units as someone who used to have a bit of an interest in metrology when I was studying my mechanical engineering degree. In terms of changing altimeters, it is possible to recalibrate them rather than simply scrapping them and getting new units (I know the altimeter isn't necessarily the only thing that aircraft have with imperial units, but it's arguably the most important). If we were to impose a transition period to using metric for aviation, it would then be possible to manufacture altimeters for new aircraft that can be switched to use either metres or feet during that time period so we can carry on using feet during that time and then switch to metres without having to kit every aircraft out at the same time. What I would suggest about potential confusion between different units for visibility and cloud base is simply just to either use metres or kilometres and not mix the two, in the same way we only currently use feet for altitude and not miles as well. That way, you don't even have to specify the unit, in the same way that ATC doesn't say "15 000 feet," they just say "flight level 150." In terms of giving units snappier names, that's something that goes on a lot for complex multi-dimensional units. For example, the unit of force in its base dimensions in SI is kilogram metres per second squared (kg m/s²), but no one wants to say that all the time, so we simply call it the newton instead. However, I don't think calling a simple base unit like the metre by a different name depending on the situation is necessarily a good idea, as it imo defeats the idea of having a universal system of units that is intended to be clear and free of ambiguity. I understand what you mean about the use of imperial units making you think about unit conversions in more depth, but ultimately I think it's something that becomes fairly simple with a decent knowledge of basic algebra and sufficient training in fuel weight/volume calculations. Ultimately, the accidents and incidents that have happened over the years such as the Gimli Glider and the crash of the Soviet aircraft in Singapore due to the mix-up of feet and metres are because we don't have universal standards in terms of units and I do think it's something we do need to unify at some point. Edit: if we did switch to metres for altitude, it might open up an opportunity to perhaps narrow flight level separation from 1000 feet (305 m) to say 200 m (656 ft) or even as low as 100 m (328 ft) given how much more accurate things like autopilots are these days and things like TCAS compared to when that 1000 foot rule was first introduced. That would obviously increase the possible traffic through busy air corridors but at the expense of potential safety margins. Do you think it would be a possibility?

I'm in my 60s. Twice now I have seen gas stations offer fuel in liters. Everyone went "Oh! Wow! Gas is SO cheap!!" in liters. Only to have the ACTUAL price, when converted back to gallons, turn out to have been jacked higher. People would then pull into a station, seen the "Price per Liter" on the pumps and drive off. (On a personal note: I like being comfortable with fractions. It helps keep my brain working. And to ad to that, I often find myself get information in metric units. No problem, they are easy to use. I can even convert them, if needed.)

The military has been using meters, kilometers for a long time, especially in land navigation. I served before cell phones, home computers, and every day GPS. When I needed to go somewhere, I used a map, a protractor, and a compass. And my distance was done by a pace count. It's way easier using a pace count in a kilometer, which is 1000 meters, as compared to a mile, which is 5,280 ft.

@billelkins994

8 ай бұрын

True, you don't have to walk as far.

Re. knots : this is also, of course, why Captains of both ships and aircraft maintain logbooks - originally they were literally a record of the knots recorded via the knot log.

@danielbarreiro8228

8 ай бұрын

To clarify, you mean "log" like in "timber", like fuel for the stove. And the reason for using knots is that they were counted by touch, not visually. The sailor would let the knotted twine slip by his hand and feel the knots passing by, something handy by night or under poor lighting conditions. Over time, the British Admiralty standardized the hourglass used to measure time so that it matched the speed measured in nautical miles per hour. The distance in between knots was already more or less standardized by custom for no particular reason. It is the standard hourglass that made the match possible. BTW, notice also that the same relation in between nautical miles and minutes of a degree also holds for kilometers if you use units based on multiples of ten, which are called or "grads" or "gons", that is, if you divide the right angle not into 90 degrees but a hundred "grads". If you further divide a "grad" in decimal fractions, you eventually get the kilometer, as a matter of fact, a "centigrad" or "centigon" of latitude at the Equator is a kilometer.

@thomasm1964

8 ай бұрын

@@danielbarreiro8228 Paragraph 1 : yes. Rest of your reply: I've learned something new. Cheers!

@filanfyretracker

8 ай бұрын

@@danielbarreiro8228 and of course eventually the hour glass gave way to a proper clock I am guessing. As I have read the accurate marine clock or chronometer as they like to call it was one of the most important inventions for navigation.

@joeyvanostrand3655

8 ай бұрын

What was found floating in the toilet of the Starship Enterprise? The Captains Log.

@danielbarreiro8228

8 ай бұрын

@@filanfyretracker Not really, no relation. The hourglass would remain in service long after the marine chronometer was commonplace. The chronometer was meant to determine the longitude. The 28 second hourglass used for reading the speed was only used for that because even the most illiterate sailor could handle it. The marine chronometer was a very delicate and valuable piece that would not be handled by anyone but the senior officers on board. And it wasn't a stopwatch, as its name might lead you to believe. While a "clock" would tell the local time, a "chronometer" was meant to literally "measure time", specifically Greenwich time, with utmost precision, so as to determine the longitude. It would not necessarily reflect the local time of day, not when far east or west of Greenwich. As a matter of fact, a separate half-hour hourglass would be used to measure each of the 8 "bells" (an actual bell was struck for each) that made a 4 hour watch on board. It didn't really matter that the half-hour hourglass wasn't precise as local noon was determined each day by direct observation of the sun crossing the zenit. Anyway, when going east or west a day would not last 24 hours either so, who cared. As long as the watches were spread evenly enough for the crew, the half-hour hourglass didn't need much precision.

Petter, This is a great & accurate overview of the issue. Great work!

@MentourNow

8 ай бұрын

Glad you liked it!

This was fascinating! One thing you didn't mention is the "We invented it" effect; for example the U.S. invented the modern roller coasters and still has the best coaster collection on earth, (and the 2nd most after China which is both new an irrelevant, so I digress) so as a result: coaster enthusiasts the world over are aware of coaster stats in feet instead of metres, even if they live in a country that exclusively uses metric for all of their measurements. I'm also pretty sure elevation stats on airliners are usually in feet too, as a non pilot and as a GP person (member of the general public) that's what I'm used to too, even though I'm Canadian. Also: the Narrator of the mostly aviation disaster TV show "Mayday" is Canadian, and all of altitude stats on that show are in feet. Please correct me if I'm wrong about measurements used for altitude pilots announce on any domestic Canadian flights or any within the EU. Thanks for posting!

Mentour's being polite not calling people like myself old. Americans still grow up in "imperial" units but I have the added advantage of being a baby boomer having lived my entire life in Canada. In school we had "yardsticks" but my daughter schooled with "metresticks" or, for the Americans out there, "metersticks". As a child on the farm I lived with pounds, feet, miles, and fahrenheit degrees. In school chemistry and physics classes I lived and learned in foot-pounds (now pound-feet) and Nt/m. The outside temperature was 70°F but in chem. class we cooled the solution to 10°C while the lab where we did our chem class was 74°F (our school didn't have A.C. back then). Normal human body temperature was 98.6°F (there was even a hit song on the radio in 1967) but in many hospitals, even back then, the doctor was looking for 37°C. Also, in Canada a gallon was 4 quarts 160 fl.oz. but in the U.S. a gallon was (and still is) 4 quarts or 128 fl.oz. An imperial (Canada and UK) quart is 40 fl.oz. or 5 cups while in the U.S. the quart is 32 fl.oz. or 4 cups. This makes quantity baking from a recipe book that may use quarts and gallons very tricky. Was the cookbook American or Canadian. The ridiculousness of the variety of measurements is mind-boggling but for people like myself this is what we grew up with. I'm now used to temperatures in °C but when I travel to the U.S. I still easily understand their weather forecasts in °F. I can travel to the U.S. in my km/h car and easily follow their m.p.h. speed limits. The conversions are done unconsciously in my head and are completely second nature to me and most Canadians my age. As for should the airlines and aviation convert to one set of standard measurements? I think that would be very expensive, quite possibly unworkable, and probably fraught with multiple dangers to passenger and crew safety, as the Gimli Glider illustrated. At the very least, it would probably make numerous aircraft all over the world obsolete and mostly unusable. A bit of a parallel can be drawn to driving vehicles with a standard versus an automatic transmission. Most young people in Canada and the U.S. no longer have the ability to drive a vehicle with a standard transmission thus rendering these vehicles unusable for a large and growing segment of the vehicle market.

I am equally comfortable in SI and US measures. I've had a complete set of SAE and metric tools since 1972 (except for a metric monkey wrench), and find it a lot easier to think in millimeters than fractions of an inch. I'm a yank born and bred, and would love to see the US go completely metric. I'm no longer young, so the sooner, the better.

@KendalMike

8 ай бұрын

I'm a Brit and fractions of an inch drive me crazy! Metric is more practical, especially when it come to small units. I always find it amusing that Americans seem to love big numbers/small units, example: measuring weight in hundreds of thousands of pounds instead of using tons! I wish Americans would use tons more often because they're almost the same as a metric tonne.

@utha2665

8 ай бұрын

​@@KendalMikeBut oddly enough, for a metric country you still use miles and mph. But, I shouldn't complain as we in Australia have kept imperial units for certain things too, although most have the metric conversion as well. Tyre pressures most still use PSI, certain industries still use acre, printers still use DPI, some of us still use feet and inches when referring to height, although GenZ are using m/cm. I like to wind up our American friends with their "freedom" units and how backwards they are, but we can't claim any moral high ground due to our reluctance to let go of some imperial units. But, I just can't get why Americans insist on using hundreds of thousands of pounds when 2000 lbs is one US ton. They also don't use stones as weight like we did here in Australia or over your way in the UK, but I guess with their fascination of pounds they just didn't think it necessary.

@termitreter6545

8 ай бұрын

Honestly yeah, the fractions of an inch thing is where things go mad. That doesnt even feel like an imperial system thing, but just a really old way to measure tooling.

Really great video! I would just love it if you could also give us speeds in km/h in addition to knots because I have no feel for knots at all since I am not a pilot :)

Volume measurements are based on binary numbers. In other words, you divide by two. 1-gallon = 2-half gallons = 4-quarts = 8 pints = 16-cups = 128-ounces (8-ounces to a cup). 1-ounce = 2-tablespoons. Conversion from one volume unit to another involves division or multiplication by two. The only place it breaks down is with teaspoons. For some strange reason there are three teaspoons in a tablespoon. 1-Gallon = 128 ounces 1/2-Gallon = 64=ounces 1-Quart = 32-ounces 1-Pint = 16 ounces 1-Cup = 8-ounces 1-Tablespoon = 1/2-ounce

Definitely a great and thoughtful exposition on these measurement systems. Thanks

Being a child of the 70's in Canada I was fortunate (IMO) to be around many of my elders that still used US & Imperial systems, and because of that, I can quickly convert many of the commonly used measures in my head. US Gal 3.785L / Imp Gal 4.54L - 1Kg / 2.2lbs and km/h - MPH and relate them to one another. One conversion / relation I struggle with to this day is L/100km to MPG which is the default 'mileage' calculation in our vehicles and used by the Government. I have always used US MPG (our vehicles use the US Gal in its computers when set to miles) and can conceptualize what that means, maybe if they used km/L then I could then do the quick conversion and be able to relate to it.

@strehlow

8 ай бұрын

Yes, the auto efficiency rating is baffling. MPG makes more sense because a bigger number indicates a better condition. L/100km is backward. km/L would be more relatable.

@frank7353

8 ай бұрын

@@strehlow I assume you say this from a commonwealth country, but no it is not baffling. The lower the number the more efficent. To the rest of the world it is MPG that is baffling.

I was still in primary school when we converted to metric here in South Africa. As such I got used to it. However, when I have an interest in tracking a plane on one of the plane trackers (like when a family member travels), I tend to switch to the "aviation standard" of the old imperial system. I somehow relate to 32000 feet in altitude more than say 8000 meters. I understand driving at 120 km/h more than 75mph. I guess it is what one gets used to. I think that it might make pilots check their calculations more carefully if the metric system were enforced. A kilogram is 2.2 pounds and a mile 1.6 km. Don't ask me to convert yeards or feet to meters. I have no idea. 🤣

Great video! If you think it's bad on the aviation industry, the mess they make with the units in the oil and gas industry will blow your mind off!

My mother was a mathematics teacher throughout the metrication of the UK (still incomplete, with distances and speeds in MPH and Miles and beer sold in pints - imperial 20fl.oz. ones, not the short measures of the US, which are 80% of the volume, like its gallons. This does, of course, allow for a mixed system to have ten pints per gallon, which in the case of fresh water, would convert pints to pounds at 1:1 as well, finally making the US saying "A pint's a pound the world around" a statement that did not limit the world to the US. Back to the point, my mother was absolutely certain that metrication and decimalisation of currency had been the ruin of numeracy in the UK, and had mathematics examination results to prove it. Numeracy after decimalisation fell over two full years behind what it had been before. You simply could not afford to be innumerate under pounds shillings and pence, and inches, feet, yards, and miles, ounces, pounds, stones, hundredweight (which is NOT pluralised with an s but in the same way as sheep!) and tons. Once it was all decimalised, mathematics became something only engineers and scientists needed to know, and most people forgot how to do if they had ever known. Sad but true. It still amazes me that businesses ever agreed to convert from the nice regular packaging of items in dozens and gross to wastefully shared packaging necessary to sell things in tens. A dozen can be split many ways evenly - between two, three, four or six people. Ten only into five or two equal measures. Cartons of 12 can be a very regular 2x3 with 2 layers, which also pack neatly into another box of a dozen cartons, and interlock evenly onto a pallet, so that they don't slide around without being strapped so tight the outer boxes get damaged. And as every storekeeper, trucker, warehousman and tradesman was used to counting in dozens, it was very easy to count up and make sure the right amount was in whatever had been delivered without wrecking the stack and making it almost impossible for the forklift driver to fit closely with its neighbours on high shelving, leading to a sharp increase in injuries from falling objects in warehousing. Everything decimal also makes it very easy to misplace the decimal point without it being obvious. At least in aviation outside the US we are used to saying decimal instead of point, which does save us on one potential for miscommunication. But it is still horribly frequent to find that people have miscalculated by some power of ten. Pre-decimal that error screamed at you from the page. And if you ever need to do navigation by sextant, compass and chart, without electronics to help, you will be very thankful for nautical miles and knots, which is all by itself a good justification for keeping them. And yes, I knew the origin of knots and the fact that it merely forms a convenient shorthand for "nautical miles per hour" is just a handy coincidence. I wonder if French sailors put wooden pegs in the cordage instead of knots (easy in the days when even an ordinary seaman could splice rope), and so counted the "clicks" as they went over the rail?

I remember Hawaii pricing gasoline in liters in the late 1970s/early 1980s before switching to gallons. The biggest thing I noticed was how the numbers changed from something like 45 cents/liter to $1.80/gallon.

I am not sure if anyone had mentioned this, but unit conversion also played a part in the failure of one of the unmanned Mars mission in which Jet Propulsion Laboratory (JPL) was the primary contractor. Someone devised a program for a soft landing on Mars, but that program used United States Customary Units (feet, pounds, etc.) and caused the spacecraft to crash onto the Martian surface. It is hard for us oldtimers to make the switch.

@EnergyUni

8 ай бұрын

I heard a different version - that it missed Mars altogether. When (a few years back) I tried to track this down on the Internet I came to the conclusion it was probably apocryphal. I would certainly be very interested if you have a reliable primary source for this story.

@se-kmg355

8 ай бұрын

Was it not because NASA used (as a scientific organisation ) SI units, while Lockheed Martin, the manufacturer was using imperial?

@csabamagyar3244

8 ай бұрын

@@se-kmg355 Yes. (Mars Climate Orbiter + Mars Polar Lander)

@bethhentges

8 ай бұрын

It crashed into Mars. Yes, along the way someone used US Customary units. IIRC, the problem was not that two different units were used; the problem was the conversion factor used did not have enough significant digits. By the time the probe reached Mars the accumulated round-off error was much bigger than the tolerance needed.

The question is not really about metric or non-metric measurements. It is about improving communications between the tower and the pilots through all of the computational and communications aids that are available now. Instead of an ATIS message of some 200 characters or so, pilots could receive in their tablets a full set of radar images, the position and speed of all aircraft in the region, warnings about important changes, and so much more. And they would be able to see all of the above in metric or non-metric units so everybody can comfortably make calculations in their heads. Also, instructions would not be sent by talking to everybody and hoping that other people using the same frequency are not scrambling the message, the ATC could send messages to a specific plane or to everybody at their discretion, with the messages managed in text and in the preferred units of the receiver. A lot can be done when communications are digital and computers are used as tools, but almost nothing is being done.

@chriscran2003

8 ай бұрын

Learning to fly at the moment, I realize how far the aeronautical world is behind on this point. The time spent programming and having to change frequencies at the right time, listening to useless conversations (not all of them are useless), having to collate orally; different equipment depending on the aircraft (radio, transponder, ADS); the transponder to be adjusted... With a secure cellular system (e.g. GSM-R in the railway), all this becomes unnecessary: unique identification number for each aircraft, real-time transmission of the GPS position (which allows an anti-collision system) , written sending (SMS) of orders, technical collation by CRS and human with a simple button, possibility of being called by different control sites... All this is additional piloting time, and therefore added security.

My friend Petra had her first job as the 'Eye in the sky', reporting traffic conditions in the Jo'burg area. The first day on the job, she made the headlines as 'Nose on the ground '. Cessna 172. Tanks dipped, but read in litres, not gallons...

When studying surveying we used metric measurement of degrees where one circle is 400 grads or gons. If that is used to calculates a “ metric nautical mile” 24900 freedom miles / (400 grads x 100 minutes) = 0,622 miles. This is equal to 1 km. Would be interesting to change all time zones according to that, to be fully metric, and have one day have 20 metric hours.

@zromo8994

8 ай бұрын

Would be interesting? In the sense that every single piece of technology that currently exists would immediately be obsolete. That would be pretty interesting, alright.

@joeldumas5861

8 ай бұрын

In fact in the decimal time in use during the French revolution, the day was divided into *10* decimal hours of 100 decimal minutes of 100 decimal seconds. So 1 decimal second = 0.864 s exactly.

@bethhentges

8 ай бұрын

Most surveying historically in the USA used degrees, minutes, and seconds for angle measures, not grads.

It’s interesting that the time measures you mentioned WRT unified use are minutes and hours because nav lat and long post chronometer is how we now navigate when with aviate and communicate 😅

Ah, I didn't know there was this much history behind "knots" Very informative

I really love the way you explain things. It’s very easy to follow and understand. Has really helped me in my aviation knowledge and training. Thanks Petter!!

Differences exist everywhere between units, it's just that the US is the most obvious place this happens. For example, as with the screen sizes, here in Greece we go with inches (which probably is only one of two things we count in inches, other one being wheel/tire sizes). Which was confusing with my Hungarian wife, as there screens there are measured in cm, so you can imagine my confusion first time I was in a store in Hungary 😁

@csabamagyar3244

8 ай бұрын

In Hungary we measure flat TV screens in inches -- just because the manufacturers write these data on the cardboard box... But long ago CRT televisions were in centimeters. CRT computer displays in inches.

@Unclekase

8 ай бұрын

@@csabamagyar3244 Really? Mostly when I went to places like Tesco they were in cm, but I'm talking about the store cards where they write the info, perhaps I happened to get in specific stores. I'm travelling back on Monday, I'll try to check 😁

Gimli Glider was flying between Edmonton, Alberta and Montreal, Quebec. Ottawa, Ontario and Montreal are only a 2hrs DRIVE apart.

@anthonyx916

8 ай бұрын

I noticed the error too. For reference: en.wikipedia.org/wiki/Gimli_Glider

Holy cow the Tucker “we have no reason to be ashamed for using FEET” bit had me rolling. Keep up the amazing content!

Having refuelled aircraft for 20 odd years I always did it by weight. Initially pounds and then kilos never ever by volume.

SI units are supposed to be international , it’s in the name ‘System Internationale’

The UK is also still a partial exception to metrification, like with their speed limits. "Speed limits throughout most of the world are set in kilometres per hour (km/h). The UK remains the only country in Europe, and the Commonwealth, that still defines speed limits in miles per hour (mph)."

Using metric, or one system, helps with mental visualization of distance, e.g. you can judge with your eyes how far is 3 metres. A phase of dual instruments will be useful to switch over to metric.