Comment by Tankenstein
2 days ago
Just a guess, but aerospace generally works with feet for altitude and knots/mph for airspeed, internationally. I’m doing a PPL in Europe and we, like everybody, use feet and knots/mph. I believe this is because the US have been on the forefront of aerospace regulation (a set of rules called the chicago convention is the basis of all air law) and aircraft manufacturing.
Not for aerospace no
And knots are not mph, they're "nautical miles per hour" which are a different measure (1nm is 1.8km, not 1.6km as the regular mile")
Sorry, not a native speaker, I was under the impression that aerospace means air and space. I guess i meant aviation.
I didn’t imply knots are mph, I used the slash to signify “or”. They are completely different units, but both are used. Sometimes the airspeed indicator even has two scales, one for kt and one for mph.
Can confirm, all aviation worldwide deals in feet and knots. It's also because it's much easier to do calculations on the fly (literally) - in your head. Metric is precise and logical but harder to use in stressful situations.
Can you please give some real-world example of why it's easier to do calculations? Not disputing what you say, just hard for me to imagine why it would be so.
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.
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Certainly not "worldwide". China uses metres. Recreational aircraft in Europe often use metres (almost all sailplanes).
No glider I have ever stepped in used metres. It doesn't make any sense, the tower wants to hear feet and knots and will communicate using that.
Thank you, I wasn't aware of China using metres. It turns out Russia uses them as well, confusingly below the transition level.
You can be just as precise with either system.
"Metric is precise and logical but harder to use in stressful situations."
That fully depends on your cultural background. Feet, miles etc. are so foreign to me that I would be unable to calculate with them under stress.
But I am not a pilot nor a navigator, so...
No, it doesn't. I'm European, never used imperial before I became a pilot, and it's easier. Check it out, the formulas are much simpler to do in your head. Intuition doesn't matter, all that matters is that I can do the calculations quickly so I know I'm within parameter limits.
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