China has conducted what provincial officials describe as the world’s first flight of a megawatt-class liquid-hydrogen turboprop engine, sending a 7.5‑ton unmanned transport aircraft on a short ...

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 ...