Why do they use Knots and Feet instead of Km/H and Metres?

I am asking this because of one main reason: The entire SI system uses constants derived from Physics and to get the value in a different unit we just multiply or divide the number by 10 to the power some number. Compared to Knots and Feet this is simple. But why do they use Knots and Feet instead of Km/H and Metres?

4 Likes

I think it’s because the first planes were made in the us but I’m not 100% sure

1 Like

That explains the feet part but not the knots part.

Knots are used because aviation originates from the ship industry, and they have been using knots since the 1500’s. And it’s easier to universally calculate distance when using knots

15 Likes

But still, has there ever been some sort of proposal to use SI units for aviation?

Im pretty sure its just because some people in the world use metric and some imperial my guess is it is for simplicity (I am just guessing)

Knots stands for nautical miles, which means a mile that is just straight in one direction, instead of on the ground making turns and what not. Aircraft and marine vessels use knots for that reason.

http://oceanservice.noaa.gov/facts/nauticalmile_knot.html

http://www.convert-me.com/en/convert/length/nmile.html?u=nmile&v=1

Why is speed at sea measured in knots?

http://engineering.mit.edu/ask/why-speed-sea-measured-knots

Why is a ship’s speed measured in knots?
MAY 14, 2014 By Elizabeth Nix

knot

The number of knots let out in a given period of time (measured, usually, by a small hourglass) would allow them to calculate the distance and consequently the speed at which the boat was moving. One knot is one nautical mile (about 1.15 statute miles) per hour.
The Nautical Knot - Infoplease The nautical knot finds its origin in a …

It’s a legacy thing. The aviation industry is more based off of airspeed rather than ground speed. Airspeed plays better with knots than km/h. Metres doesn’t play nice with established spacing procedures, 333.3 metres doesn’t work as well as 1000 feet.

I suppose that’s it’s because of the reasons listed above.
I do think that suddenly changing it to metric would be very difficult.
I don’t know about you, but when someone asks me for the landing speed of a plane, I can’t answer in km/h

1 Like

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.