Fuel measurement is the biggest pain in the @rse.
Could be bought in L or US Gal, weighed in lbs or Kg, consumed in Kg, L, US Gal or Imp. gal.
Next is horizontal measurement.
Navigate in Nm (usually), vis. measured in Km or m. , runways in m or ft. Except USA where it's navigate in Nm or Sm, vis in Sm & fractions, runways in ft.