I am scheduled to connect to IAD-SJU UA399 today from 5877 PIT-IAD. The PIT flight is delayed and isn't scheduled to land till 5pm, which means I miss connection to SJU (last flight of the day to SJU.) I have tried to figure out where the inbound SJU flight is coming from and am hopeful that it too is delayed, but so far it keeps showing on time. Is there any way to find out where this flight is coming from? I checked flightaware, but when I click on "check inbound flight it shows me a flight from MSP-ORD. Can anyone help? I am protected on the IAD-SJU departure tomorrow morning, but the really doesn't help me out a lot.