HR told our class that at first its all random on who can fill class dates. the only reason it could change is if you are applying for a FO position and have or are close to CA mins. then they might put you in the saab. this is only because of the fact that they need CAs. HR said that this dosen't happen all the time. but to answer your question, its based on when your're available and space available for training. minus the one exception. hope it helps... hope i'm right. if i'm wrong feel free to correct me anyone.