The use of imperial units in aviation is lamentable. AFAIK, Russia and China use metric, the rest of the world uses a wild mix (feet for altitude, nautical miles for horizontal distance, statute miles for visibility, metres for runway visible range, etc.)
Quite obviously, switching units is complicated, but the current patchwork is a nightmare, and has lead to accidents (like the famous Gimli glider, where kg/pound confusion lead to insufficient fuel).
