This situation is not that. This situation is "We f***ed up with booking the flight, our plane is perfectly functional, but we're going to force paying customers off of the flight for our own employees and cause a great inconvenience to them."
Actually it isn't a mess up of booking. It has to do with crew availability. This wife of a pilot explain it to us people who don't know much about it:
3: “So what’s this ‘must ride’ nonsense anyway? They shouldn’t bump a paying customer for a free employee ride!” I’m afraid you’re going to have to take this up with the federal government, not United. And it’s actually pretty important to you as an airline traveler anyway. They were not ‘freeloading home’. That’s called non-rev and they have to wait in line behind your checkbook and often don’t make it home to their families if flights are booked (believe me, I know). No, this was a must fly, a positive space situation. In layman terms, it means that a crew must be flown to an airport to man a flight in order to avoid cancellation of said flight due to crew unavailability. This is a federal DOT regulation, not an airline one. The airlines are required to do so to avoid disruption of air traffic. In other words, if there are no willing volunteers and they need seats to get a crew somewhere to avoid disruption of aviation flow, they can, will, must by federal regulation bump people for the better good of the 1000’s. Why? Because one cancelled flight has a serious domino affect in the delicate, complicated world of connections and aviation law.
apparently it is literally federal law to bump people off the flight in this case
It's a blogger's word vs numerous lawyers that have said United breached their contract. ---