There’s nothing worse than turning up for a global flight only to discover you don’t have the right visa or onward flight data, you’re a day late, or your baggage is over the limit and it’s important to pay $a hundred on the spot! Usually the gate agent will make an announcement asking for volunteers to test their carry-ons, but I’ve requested and been given the OK. I just ensure the things I would like on the airplane can slot in a bag underneath my seat, and I have one much less bag to carry around — significantly useful when …