Unfortunately, there WERE american losses due to friendly fire in 1991. As for more recently, Canada lost serveral troops in Afghanistan due to some doped up American pilots (and who said flying while under the influence isn't fun?).
As for SFC, well, I remember one case of friendly fire. It was an SL match with me flying wingman to the best pilot in our fleet (Sharky old boy!). We took 2 fed BCF (SFC1) against a Gorn/Lyran combo (those damned iCoP pilots - wait, I was in that fleet for a while too). We made a pass and separated, then flew around to regroup. As we were approaching, I targeted my wingman and hit the 'z' key by mistake (meant to hit 's'). To my surprise phasers fired through his downed forward shield causing minor damage. We had forgotten to team up in spacedock. I laughed so hard I fell out of my chair.
If memory serves we still won.