[HPsquared]

1 knot is about 100 ft/min which is very convenient for descent at a specific glide slope (i.e. for 100 knots ground speed at 5% slope you want 500 ft/min descent rate). Standard is 3° which is about 5%.

Knots are also handy for navigation as 1 nautical mile equals 1 minute of latitude. And of course a knot is 1 nautical mile per hour. So if you're doing 300 knots, that's 5 degrees of latitude per hour.

The units fit together nicely as a system.

[Ringz]

The calculation in the metric system would not necessarily be more complicated, but it would be different because the reference points in the metric system are not directly aligned with the geography of the Earth.

"1 knot is about 100 ft/min which is very convenient for descent at a specific glide slope (i.e. for 100 knots ground speed at 5% slope you want 500 ft/min descent rate). Standard is 3° which is about 5%."

You are right. It's an easy calculation. But I would say its easy because its historically based on imperial units. Its easy to think about easy calculations like this in metric units like:

A 5% slope means descending 1 meter vertically for every 20 meters horizontally.

[HPsquared]

The gradient thing would work if ground speed and vertical speed were both in m/s, but km/h is more common in metric for a ground speed. You don't usually think in terms of hours during a climb/descent!

Glide slope of 3.6% would fit nicely though. Then, 100 km/h ground speed goes with vertical speed 1 m/s.

Metric navigation would use the fact 90 degrees of latitude is 10,000 km.

[jaggederest]

I suspect that the math is even easier using meters, meters, and meters per second than nautical miles, feet, and knots. I'll eat my hat if you can tell me the conversion from feet or inches to nautical miles without looking it up

[dullcrisp]

Well if what they say is true then 100ft/min = 1 nautical mile/60min, so one nautical mile is 6000ft. Or I guess I missed the about so not exactly.

[HPsquared]

It's within about 1%

[rmu09]

who is flying exactly north/south?

[Dalewyn]

This sums it up. Metric is nice and clean tenths, but the real world is seldomly easily expressed in clean tenths.

Another example: The feet is cleanly divisible in thirds, quarters, and twelfths, which is greatly appreciated in industry and particularly construction.

Also to be bluntly mundane, almost everyone can just look down and have a rough measure of a foot which is good enough for daily use.

Also, the "sterility" of metric doesn't do it any sentimental favours. Japan loves measuring size/volume in Tokyo Domes, for example.

[NotEvil]

Not really, I have no idea what a foot is. But I can just look at yhe tiles and know they are 1*1 meter

[throw5959]

Who cares? It's what the indicator says, I don't need to visualize feet to do calculations and talk to the tower about them.

If you can see a 1x1m tile from the cockpit, you're dead.

[Dalewyn]

If you're an amputee I truly am sorry for you and hope the handicap hasn't disrupted your life too much.

Jokes(...?) aside though, your absolute deference to precision is an example of why metric flies over people's heads. Feets, Tokyo Domes, arguably even nautical miles and so on are relatable at a human level unlike metric which is too nice and clean.

[notahacker]

This sort of argument is odd to someone in a country which uses both, where a yard is intuitively "a bit smaller than a metre", a pint corresponds to a pint glass or "about half a litre" rather than anything meaningful and I'm aware that a rod and a furlong are things but have absolutely no idea what they correspond to. A foot is comfortably bigger than the average foot size, and an inch really isn't an easier unit to approximate than a centimeter

[avmich]

The SI was specially aimed to reduce such meaningless discussions, yet we steel have big endians and little endians comparisons, long after the dust settled.

[HPsquared]

Now I'm wondering if right-to-left languages (e.g. funnily enough, Arabic) write the least significant digits at the left or the right.

EDIT: numbers in those languages are the same way as in English, the "ones" are at the right. Kinda strange!

[Thlom]

One meter is about one long step for an adult. To approximate the length of a field, you just walk along it with big steps and count. It will not be correct, but pretty close. A cm is a little bit smaller than the width of your index finger. It's all bout what you are used to. Metric doesn't "fly over people's head" where metric is the standard way to measure things, but inches, feet, gallons, pounds, miles fly over our head because we are not used to it so don't have any frame of reference.

[HPsquared]

A foot is about 1 sheet of metric A4 paper :)

[avmich]

A meter is _exactly_ square root of area of A0 paper.

[HPsquared]

Yes and a blank 80 gsm A4 sheet weighs exactly 5g, if you need a weight reference!