A good question.

Today I saw on "The Seattle Times" a very interesting new "Travel Q&A: Who rules on airline seats?" Have you ever been on this situation? What should we do?
The post, please comment:

Q: I recently traveled round trip to Philadelphia on Southwest. On the return flight, just as the plane was ready to depart, a woman boarded with two children. First, the person near the window was asked to move to a middle seat, and later I was asked to move to a middle seat. I declined because I'm not comfortable in anything but an aisle seat. Eventually, this very late boarder got to sit with her kids. Could the crew have forced me to move?

— T. Byrnes, Lompoc, Calif.

A: Probably not.

Although preflight safety announcements note that it's a violation of federal regulations to fail to comply with a crew member's instructions, airline representatives said the flight attendant probably made a request and wasn't issuing an order.

"We have an open-seating policy that in some instances could cause difficulty for a late-boarding family," Marilee McInnis of Southwest said in an email. "In those rare instances, we will ask for volunteers so that family members can sit together. As the term volunteer implies, it is voluntary!"

But — and when it comes to seats, there's always a but — circumstances alter cases. "If a person is seated in an exit row and is not willing or able to comply with those responsibilities, we do ask them to move," Alison Croyle, manager of corporate communications for JetBlue, said in an email. "Additionally, we have 'Even More Legroom' seats that customers can select for an additional charge, and if a customer moves to one of these seats without purchasing one, we offer them the opportunity to buy at that time or request they move back to their originally assigned seat.

"If they do not comply in either situation, for example, this could be considered interfering with an in-flight crew member's duties."

"Crew members" also include the PIC, or pilot in command, said Ian Gregor, a Federal Aviation Administration representative. "We have a rule that says that the PIC has ultimate authority over everything."

So if the pilot tells you to do it, you'd better do it. Add him or her to the list of people you should never cross (a list that presumably also includes any nun or your mother). No buts about it.

Catharine Hamm / Los Angeles Times