From my understanding, you're correct. Deny Boarding can be avoided by checking in early. These people had boarded and the plane was full before the mistake was realized.

EDIT: Still unsure as to the legality of this. IDB is well established, but the fact that everyone has boarded is a different matter. Reading the contract of carriage did not bring any more light to this point. And let's be clear, denying someone and removing someone are very different. At least one source says it does matter (unknown reputability) "This is important because involuntary denied boarding only applies when passengers have been fully checked in (including baggage) and are at the gate at a specified time, typically 30 minutes before scheduled departure." https://thepointsguy.com/2014/12/what-to-do-if-your-flight-i...

I believe your understanding is incorrect - someone can be denied boarding regardless of when they have checked into the flight. If there are 100 seats, they may sell 105 tickets and permit 105 people to check in - if they cannot find 5 volunteers they will have to IDB 5 passengers.

While the rules aren't printed very well (I just scanned United's Contract of Carriage, and the Federal Code), I believe it counts as an IDB even if you are physically on the airplane.

Reading through the rules, it would appear that you are correct, though it looks like checking in earlier should make it more unlikely "The priority of all other confirmed passengers may be determined based on a passenger’s fare class, itinerary, status of frequent flyer program membership, and the time in which the passenger presents him/herself for check-in without advanced seat assignment."

I'm not sure the United Conditions of Carriage are really relevant here anyway - if United were to decide to violate their own conditions of carriage, the worst penalty a court would likley invoke would be to consider the whole contract null and void, awarding that passenger a full refund, and maybe paying for a hotel (damages).

They could very well, unless otherwise restricted by law, apply punative damages as well as pain and suffering beyond that.

For reference, section 25 of their contract of carriage: https://www.united.com/web/en-US/content/contract-of-carriag...

The point is that if you're late at the gate (after the 30 minute cut-off, say), then they are under no obligation to let you on the plane, and do not have to compensate you under IDB rules.

Too bad, I say. If we're going by the exact letter of the law on what is/isn't acceptable then the mistake started and ended on the airline side.

If the airline makes a mistake and realizes that mistake too late, they should take the hit themselves, not punish an innocent passenger for their own mistake.

Airlines should make a better effort to avoid overbooking. If they can get away with this kind of despicable behaviour, they'll never improve.

> they should take the hit themselves, not punish an innocent passenger for their own mistake.

If they don't get their crew to the other airport, the next day a full plane load of people (or more, due to knock-on effects) might have been denied a flight.

That just means they should plan better. It's no excuse for intentionally screwing over their paying passengers.

Nobody disputes that better planning would be better, or that they should not have let everyone on board.

However, mistakes happen. For operational reasons, now the flight had a smaller capacity. Could have been that the seatbelt for a seat didn't work, or weight & balance issues.

At that point, it strikes me as perfectly legit to seek volunteers, and then, well, disembark pax involuntarily (while giving them all the help and compensation that they're entitled to, and more).

That's hardly "intentionally screwing over paying passengers".

What they're entitled to, is a seat on the plane that they booked and paid for. And whatever the problems that this airline might run into if they don't do this, they're not taking into account the problems they're causing for others by doing this. The guy was a doctor who had to be in a hospital the next morning. What if a patient dies because of this?

Sure, mistakes happen. But the real mistake here is that the airline punishes passengers for the airline's mistakes. They should be taking responsibility for their own mistakes, rather than take them out on their customers.

Given this situation with an overbooked plane due to their own stupid lack of planning, they could and should have offered more money until someone did volunteer. That would have been cheaper than this travesty, and not a single person would have complained about it. Instead, they short-sightedly try to save some money by having the police (who also don't work for free) drag a perfectly legitimate customer out of the plane.

It's a distressing rejection of responsibility for their own actions.

Thanks to overbooking, flying is cheaper and more efficient. I do not think there is a need to avoid it.