It would be interesting to hear from UA Insider whether this flight had any upgraded passengers in the front cabin (obviously there were no nonrevs) and whether it's UA policy to involuntarily downgrade the last person who checked in, rather than prioritizing full-fare pax over upgraded pax.

KPhill: If you send UA Insider a message with your flight number & travel date you might be able to get a good answer about whether this is SOP.

I am somewhat reminded of http://www.flyertalk.com/forum/unite...le-agents.html where the computer got to decide who was IDB'd -- "they had economy board...and if the gate scanner buzzed, you were denied boarding and put into a long line to be dealt with."