To survive cold weather at home, you likely have a favored Big Coat. But whether it’s a flowy wool trench that grazes that ground or a bulbous puffer that makes you a dead-ringer for the Michelin Man, it’s probably unsuited for life in transit. When you’re traveling on a plane, a truly big coat can make getting yourself through security and squeezing yourself into ever-shrinking basic economy plane seats a real hassle.