First-class fliers have a code. It’s subtle and usually comes with a glass of champagne. If you want fit in before you fall flat in a sea of stares, learn the unspoken rules—lest you mistake the amuse ...

First-time flight upgraders should be aware of business and first-class etiquette. A flight expert shared his top tips for blending in with passengers who often book premium cabins. He said not to ask ...