LM Otero/AP

The first sign that the massive weather front menacing the East Coast may impact air travel just pinged on the Federal Aviation Administration map.  Alas, it is the world’s busiest airport — Hartsfield-Jackson in Atlanta — that is showing 30-minute delays as weather puts a cloud lid low overhead. Too soon to tell if the weather in Atlanta will impose its will long enough to send a ripple effect through the nation’s aviation system on the day before the biggest holiday travel day of the year. But when Atlanta and the New York airports get backed up for any extended period of time, travelers throughout the system usually suffer.