Join Date: Feb 2008
Location: Auckland, NZ/New York, NY/ATL
Programs: DL DM MM, BIS 2.5MM, EK Gold, SQ Gold, Marriott Gold, HH Gold, OW Emerald, HY Globalist
Posts: 5,506
Its been this way for as long as I can remember. Its a myriad of different reasons. High traffic combined with low priority, fog in SFO, overpadding of the scheduled flight time, and also very tight schedules for the aircraft's that serve these rotations. Often a delay sustained in the morning will stick with the aircraft's rotation all day and will slowly grow.