Airlines redesigned the way you choose your seat—and raked in $12.4 billion in the process

A new Senate report accuses airlines of using dark patterns to upsell customers.

Want extra legroom on your flight? There’s a fee for that. Care for a window or aisle seat? Pay up. There once was a time when airlines didn’t charge extra for certain seats, but over the past two decades, so-called ancillary fees have become a regular—and costly—part of modern air travel. In fact, they’ve been designed right into the buying process. And soon, airline executives will answer for that.