We had 15 cadets, and 50 DECs in our class. They split it up, staggering everyone by seniority into 3 groups each separated by 2 weeks. Bidding will be done on day one of Indoc, where you'll state what base and seat you want. DECs are expected to bid CA, but they can bid FO if they want...however they'll still be trained as CAs, checked out as CAs, expected to perform within the training enviornment to CA standards. They'll also get a reduced pay amount during training if they bid FO (standard training pay, vs I believe 70 hours CA pay if they bid CA.) They'll assign seniority at Orientation, and let you know when you'll be coming back. If the FOs in the class are Cadets, they get seniority ahead of the DECs, but it only impacts sim time bids during training. Once out of training, even though the FOs may be senior, they'll still be bidding on the FO list, while DECs bid on the CA list.