Coming from the mouth of the pilot recuiter : Upgrade based on seniority and needs. EY seem to have stopped DEC hiring FOR NOW probably until the big expansion starting in 2011. A lot of very qualified FOs waiting in line. Airbus guys upgrade on the Airbus fleet, Boeing guys upgrade on the Boeing fleet. It will probably change depending on the needs. For a while EK allowed fleet transfer when they had too many FOs on the 330/340 and not enough captains on the 777. I could see EY doing the same thing when more Boeings come on the property.