If your plane isn't full enough you lose money. You want to be able to predict when to cancel flights early enough you don't have to refund too many customers w

If your plane isn't full enough you lose money. You want to be able to predict when to cancel flights early enough you don't have to refund too many customers without wasting money on empty routes. You also need to manage how much you're overbooked to allow for full flights when people miss their flights or cancel at the last minute. You also need customer support for all sorts of actions. These are just a few of the many hard problems they face.