On what is one of its busiest travel days, San Francisco International Airport reported scattered delays of up to an hour Saturday. The airport has had some delays — mostly arriving flights — of about 30 to 60 minutes, said Joe Walsh, a spokesman for the airport. Due to a low cloud ceiling, SFO is on a ground delay program — when flights cannot arrive and depart as frequently as under ideal conditions — that will last until 11 p.m.