i acidentally shot one of my squaddies in the last bob setup. i was diving on a ju88, and just as i opened up, my squad co flew across in front of me. thankfully i didn't kill him......but i can see how it happens.
that all said, personally, i think that the loss of the plane, the loss of the safe landing bonus, and the loss of any possible kills, or assists that that downed pilot may have scored is punishment enough for friendly fire. that's just my opinion though. it is however a VERY good topic of discussion.