It makes good sense using different units for different functions (altitide in feet, speed in knots, visibility in metres, etc) to avoid confusion. Similarly why do you climb and descend? Because you are less likely to confuse climb rather than ascend with descend.
On a separate issue, its just as well that tons aren't used (long, or short, a 12% difference).
Incidently do US airlines still use US gallons? They can be confused with imperial gals. Luckily I am not aware of imperial gallons being used anywhere.
Last edited by Peter47; 23rd Feb 2019 at 15:08.