Just one word about this topic: International standards set the coherent metric system as the only one to be used on international engineering, in the early 50! and to day he doesn't still come true! and I am always reading in 2012 about BTU (British Thermal Units) instead of Joules, PSI (pound per square inches) instead of Pascal (Newton per square meters) etc.. And when you write about Newton as a force and kilogramme as a mass, there is always some stupefaction with common people, but it must be write in that way, or you will not understand why you jump so far on the moon!
In the same way, an interplanetary US drone miss Mars because the soft was made in metric system, and the users thinks at first that all was set in feet. And they enter bad orders to correct the trajectory.
But, the US won the second world war and had imposed to Europe, then to the world, their units for flying.
All continental European planes (commercial, military, glider etc..) before the world war II were set with metric system.
Funny isn't it