There was a sudden plane change from an old 777 to a new 777 on UA 653 LAX-IAD on sunday Jan 15.
It caught everyone by surprise (including the United staff) as seat numbers were all over the place --many people asked to check in at the gate for new boarding passes but the new business class was really good...a big change from the old 777 layout.
Many had to get new boarding passes...or had a surprise when checking in.
As there a lot fewer seats people were worried about their confirmed upgrades---
I guess the moral is if you book a 777 flight; be prepared for an equipment change.