This flight left SFO late today due supposedly to ATC delays at EWR. The FLIFO shows it diverted to PIT and seemed to terminate.. However, all UA flights out of SFO to EWR had no significant problems. Looking at LAX-EWR flights today, all AS flights had delays or were cancelled but UA had minor problems on this route. This is not the first day this has happened with AS on this route. We are flying with them at the end of April SFO-EWR in F. So far I'm not impressed with their reliability. I wonder what they did with the passengers who were left in PIT this evening?