I believe this should be filed under a) oops and b) Operations cockup
'An error in American Airlines' flight assignment app has resulted in all of American Airlines' pilots being assigned leave over the Christmas holiday week. That means over 15,000 flights will take off without an assigned pilot.
Unfortunately for the airline, this glitch comes at a time when the union has been trying to get increased holiday pay for their past few contracts. American Airlines has stood firm on not renegotiating holiday pay.'