3 ms·

It says ‘metric’. Good.

tialaramex 2y ago
Indeed. There are plenty of things in aviation where they care so much about compatibility that something survives decades after it should reasonably be obsolete and replaced. Inches of mercury, magnetic bearings (the magnetic poles move! but they put up with that) and gallons of fuel, all just accepted. Got a safety-of-life emergency on an ocean liner, oil tanker or whatever? Everywhere in the entire world mandates GMDSS which includes Digital Selective Calling, the boring but complicated problems with radio communication are solved by a machine, you just need to know who you want to talk to (for Mayday calls it's everyone) and what you want to tell them (where you are, that you need urgent assistance and maybe the nature of the emergency) On an big plane? Well good luck, they only have analogue radio and it's your problem to cope with the extensive troubles as a result. I'm actually impressed that COSPAS/SARSAT wasn't obliged to keep the analogue plane transmitters working, despite obsoleting (and no longer providing rescue for) analogue boat or personal transmitters. But on that, at least, they were able to say no, if you don't want to spend a few grand on the upgrade for your million dollar plane we don't plan to spend billions of dollars to maintain the satellites just so you can keep your worse system limping along.
- mnw21cam 2y ago
  Air pressure is reported in hectopascals and fuel quantity in kilograms (or tons). It's only in America where this isn't the case. We're still using feet for altitude in most places though (it's mainly Russia that uses metres).
  - p_l 2y ago
    Feet are "optionally accepted" due to USA being China of aviation and flooding the market with feet-marked hardware
- rounce 2y ago
  > Inches of mercury, magnetic bearings (the magnetic poles move! but they put up with that) and gallons of fuel, all just accepted. Here in Europe we use hectopascals for pressure, as does pretty much everywhere else. It’s important to have a magnetic bearing in case your glass dies and you’re reliant on a paper map and compass, if you didn’t plan with magnetic bearings you’d be screwed if this happened in an area of high magnetic variation.
jp57 2y ago
Though one could argue that the (original) definition of a meter and the definition of a nautical mile are equally arbitrary and yet similarly based. Originally 1 meter was one ten-millionth of the distance over the surface of the earth from the equator to the pole. One nautical mile is the length one arc-minute of latitude along a meridian. (About 1.85km).
- lmm 2y ago
  They were. The difference is one is part of a standard system of units with sensible relations between different units in the system, and the other isn't; the specifics aren't what's important, the relations are.
- eru 2y ago
  Yes, the nautical mile is actually les arbitrary than the 'normal' mile. > Originally 1 meter was one ten-millionth of the distance over the surface of the earth from the equator to the pole. Even more originally, they wanted to use the length of a pendulum that takes one second to swing. But they discovered that this varies from place to place. So they came up with the newer definition based on the size of the earth. And just like with all the subsequent redefinitions (like the one based on the speed of light etc), the new length of the metre matches the old length of the metre: > [The] length of the string will be approximately 993.6 millimetres, i.e. less than a centimetre short of one metre everywhere on Earth. This is because the value of g, expressed in m/s^2, is very close to π^2. The definitions matching is by design, not an accident. See https://en.wikipedia.org/wiki/History_of_the_metre https://en.wikipedia.org/wiki/History_of_the_metre and https://en.wikipedia.org/wiki/Seconds_pendulum https://en.wikipedia.org/wiki/Seconds_pendulum If you want something less arbitrary, you can pick 'Natural Units': https://en.wikipedia.org/wiki/Natural_units https://en.wikipedia.org/wiki/Natural_units
- water-data-dude 2y ago
  1 foot is allllllllmost the distance light travels in a nanosecond. If we’d just adjusted the length a tiny bit it would be an excellent unit of measurement

Indeed. There are plenty of things in aviation where they care so much about compatibility that something survives decades after it should reasonably be obsolete and replaced. Inches of mercury, magnetic bearings (the magnetic poles move! but they put up with that) and gallons of fuel, all just accepted. Got a safety-of-life emergency on an ocean liner, oil tanker or whatever? Everywhere in the entire world mandates GMDSS which includes Digital Selective Calling, the boring but complicated problems with radio communication are solved by a machine, you just need to know who you want to talk to (for Mayday calls it's everyone) and what you want to tell them (where you are, that you need urgent assistance and maybe the nature of the emergency) On an big plane? Well good luck, they only have analogue radio and it's your problem to cope with the extensive troubles as a result. I'm actually impressed that COSPAS/SARSAT wasn't obliged to keep the analogue plane transmitters working, despite obsoleting (and no longer providing rescue for) analogue boat or personal transmitters. But on that, at least, they were able to say no, if you don't want to spend a few grand on the upgrade for your million dollar plane we don't plan to spend billions of dollars to maintain the satellites just so you can keep your worse system limping along.

mnw21cam 2y ago
Air pressure is reported in hectopascals and fuel quantity in kilograms (or tons). It's only in America where this isn't the case. We're still using feet for altitude in most places though (it's mainly Russia that uses metres).
- p_l 2y ago
  Feet are "optionally accepted" due to USA being China of aviation and flooding the market with feet-marked hardware
rounce 2y ago
> Inches of mercury, magnetic bearings (the magnetic poles move! but they put up with that) and gallons of fuel, all just accepted. Here in Europe we use hectopascals for pressure, as does pretty much everywhere else. It’s important to have a magnetic bearing in case your glass dies and you’re reliant on a paper map and compass, if you didn’t plan with magnetic bearings you’d be screwed if this happened in an area of high magnetic variation.

jp57 2y ago

Though one could argue that the (original) definition of a meter and the definition of a nautical mile are equally arbitrary and yet similarly based. Originally 1 meter was one ten-millionth of the distance over the surface of the earth from the equator to the pole. One nautical mile is the length one arc-minute of latitude along a meridian. (About 1.85km).

lmm 2y ago
They were. The difference is one is part of a standard system of units with sensible relations between different units in the system, and the other isn't; the specifics aren't what's important, the relations are.
eru 2y ago
Yes, the nautical mile is actually les arbitrary than the 'normal' mile. > Originally 1 meter was one ten-millionth of the distance over the surface of the earth from the equator to the pole. Even more originally, they wanted to use the length of a pendulum that takes one second to swing. But they discovered that this varies from place to place. So they came up with the newer definition based on the size of the earth. And just like with all the subsequent redefinitions (like the one based on the speed of light etc), the new length of the metre matches the old length of the metre: > [The] length of the string will be approximately 993.6 millimetres, i.e. less than a centimetre short of one metre everywhere on Earth. This is because the value of g, expressed in m/s^2, is very close to π^2. The definitions matching is by design, not an accident. See https://en.wikipedia.org/wiki/History_of_the_metre https://en.wikipedia.org/wiki/History_of_the_metre and https://en.wikipedia.org/wiki/Seconds_pendulum https://en.wikipedia.org/wiki/Seconds_pendulum If you want something less arbitrary, you can pick 'Natural Units': https://en.wikipedia.org/wiki/Natural_units https://en.wikipedia.org/wiki/Natural_units
water-data-dude 2y ago
1 foot is allllllllmost the distance light travels in a nanosecond. If we’d just adjusted the length a tiny bit it would be an excellent unit of measurement