There was a plane that dang near crashed because of the differences between pounds and kilos of fuel. A plane headed to the US refueled in Canada, had problems with changes in fuel measurements, ran out of fuel. Had to glide in, was diverted to an abandoned airfield used for car racing, etc. people on the ground barely avoided getting hit as they couldn’t hear the p,and coming in.
Yes, these things happen.
The Gimli Glider.
Fuel loading was miscalculated due to a misunderstanding of the recently adopted metric system which replaced the imperial system.
http://en.wikipedia.org/wiki/Gimli_Glider