Originally Posted by
emcampbe
Believe sweeps also run a couple of times on the day of flight, with the last 3 hours prior, and then upgrades go to the gate.
On the day of, EUA runs every time a customer on said flight checks-in. I believe this is designed primarily to clear eligible elites on B/M fares (and those on all other fares if RN>0) before CO.com offers Day of Departure/'ToD' upgrades.
After checkin closes, the upgrade list as displayed on the United app/mobile.united.com is used by the GA to manually process all remaining upgrades.