I think it's rather random. You're most likely to get the 777, a few will get the A310 or A330.
[edit - I mean the sim]
If you get through the selection process they will ask you what your preference is Boeing or Airbus (777 or A330). Ultimately though it's the company's call which aircraft they assign to you (im sure it depends on lots of factors)
Last edited by stealthpilot; 14th Sep 2011 at 09:49.