This topic has been gone over, in length, before. But from someone who has traveled under both systems, TWA (IAM) senority, and AA (TWU) first come, first serve,------- AA's system seems to work best. I think this is one of the few things they got right!----- But no matter which system your under, it's getting harder everyday to get on an airplane! Now if that will change with the merger,------ I guess we'll have to wait and see!