I guess we can be involuntarily assigned while on days off in theory, but as a practical matter, it just doesn't happen. For one, they almost never junior man far enough in advance for commuters to get to CVG in time for the assignment. Especially with the new contract where open time gets offered with increasing value (150%, 175%, 200%) as the day of the trip gets closer, it's usually the day before or day of by the time they get to junior manning. At worst, you just tell them "unable". Your days off are your days off and you are in no way required to be able to get to CVG before your next scheduled work day.