[brewdad]

>>There's no scenario where they don't know exactly who is sitting in what seat for every seat on every plane when it takes off, it's all just data in the computer they can reference.

I would amend that slightly. They know exactly how many people have boarded the plane and presumably who they are. People move seats to allow families to sit together or trade a window for an aisle on many flights. The airlines aren't modifying their seat assignments after you walk down the jetway.

[jki275]

Actually they track that now. The flight attendants are absolutely brutal about enforcing and knowing exactly who sits in what seat to the point that if you get up and move without asking they will come up to you and tell you to go back to your seat. I'm sure people do occasionally get away with moving without being noticed, but that's not the norm anymore.