You can't. The best you can hope for is to look at ticket availability on their website (I am assuming you can do this like you can a US carrier) and base your decision on IF they are still selling tickets. I put my folks on Alitalia a few years back, and I couldn't get ANY information about whether they were even on the flight or not. If you do figure out a way, it would be nice to post the results though.

Good luck