[Ronsenshi]

Can you give an example? I can't imagine calculating conversions between inches and feet to be easier than using millimeters/centimeters/meters. Or using mostly millimeters in construction in Europe. You have one unit to deal with that generally tends to be integer value. No need to fractions.

[bluGill]

You don't convert. Airplanes are designed in mm and you never need meters. Houses are in inches - we say 92 5/8. Or sometimes 2 feet 3 inches. Our measurement tools have both marks so we can do it without coversion.

[iggldiggl]

Airplanes might be designed in mm, but airports are most likely designed in metres, and whoops, suddenly you need to convert between the two.

Actually civil engineering as a whole is probably a relatively mixed bunch – vehicles drawings (when you need to design the infrastructure to fit specific vehicles for example) and other small-scale details might be dimensioned in mm, the standard curbstone naming system in Germany is based on centimetres, while infrastructure design itself (definitely including the CAD drawings) usually works in metres.

[ecommerceguy]

Imperial’s base-12 (inches) is more factor-rich than base-10:

12 divides cleanly by 2, 3, 4, 6

10 divides cleanly only by 2 and 5

Obviously downvoters who've never used a speed square nor tape measure before.