Originally Posted by
narvik
I suspect UA (and most other airlines) have a pretty good idea which flights they can overbook and to what extent, based on past experience. This will likely vary from route to route, depend on time of day and time of year, etc.
Having worked in that department (and not speaking on behalf of them), I can tell you it's amazing how accurate the predictability is and how high the no-show rate is on certain markets on certain times/days!