Just looking at KSEA and see that it is already Dec. 2 !!! (actually Dec 1 @ 13:11 PST. And the same at SFO, I guess your clock is wrong somewhere!!!
Check the “Display Options” section in your profile to make sure they reflect your preferred timezone.
All is correct at my end.
Aircraft do use GMT which for Seattle Dec 2 would start at 4PM or 1600, Dec 1st PST. Schedules may be in local time but all Air Traffic Control is GMT.