We are using a PBS Preference Bidding System. You can only opt to DO something and cannot opt to NOT DO something. Apparently this is deemed to promote a "positive lifestyle choice" on the behalf of the crew member. We cannot request specific flights only very general patterns of work and time off at specific locations (i.e. night stops at your mistresses Home airport perhaps).
You assign an ascending points value to your bids and then Carmen does its thing.
How many of your preferences are honoured is the Satisfaction Ratio and the minimum ratio each crew memeber should acheive is set dependant on Rank and then Seniority within the rank. i.e. all Captains should acheive 60% satisfied with those with higher seniority acheiveing maybe a little more 65% thats my guess.
Although what those ratios are exactly is a State Secret on pain of Death me'thinks...... though I've probably said too much already. :P
The system before....
We were for all intents and purposes manually rostered as far as I'm aware any systems were used as support tools to acheive the roster. However we had no influence over our rosters. The only biddable items were Longhaul and Standbys/Reserve. So in theory Carmen should be a positive change.
Carmen was introduced by the management with a fairly in-depth co-operation of BALPA. I believe they were in on it from the early stages of development to ensure it actually provided some benefit to the employee as well as the employer.