This is the part that still makes no sense to me. This situation started with offers of compensation for people to give up their seat voluntarily. The airline can still raise the compensation amount until someone bites
But is this the rule applicable only to when a flight is overbooked because, as I have read, United have admitted that the flight wasn't overbooked and we all know the truth, that United were utilising the flight as a means of crew transport.
Now, as an ex crew scheduler there are a few possible scenarios of when that crew became scheduled to position from A to B:
1. It was a regular weekly crew rotation but a cock-up prevented the seats from being blocked-off, or:
2. There had been an operational problem, perhaps a crew going out-of-hours or a change of aircraft type, and this positioning crew had been called out from standby at their homes some hours before this flight was departing, or:
3. As per 2. except this positioning crew had been on airport standby duty and were called, quite literally, minutes before this flight was departing and with passengers already boarding.
I don't favour 1. or 3., my favoured is 2., that the crew had been called out from standby at home, I'd guesstimate at least 2 hours before STD, and somebody forgot, didn't bother, couldn't care, to notify passenger handling that their flight was going to be 4 seats short.
And would I be right in presuming that this happened over a weekend when no management may have been on duty to authorise a King Air or whatever?