There is another situation where you can go anywhere your seniority can hold, and that's long term disability. After being out on LTD, when one is ready to return to work, he calls flight management and they look at his standing bid. If he's senior enough to hold a particular jet and seat, and there's someone junior to him in that jet/seat, and it's on his standing bid, then a training date is set and he goes immediately back to school (if this is a new jet or seat). The only other requirement is that there has to have been a bid between the time the guy went out and the time he returned. At least that's how I understand the process.

JJ