All the airports that Singapore Airlines flights have come from See the airports that Singapore Airlines flight have traveled to / or see all the flights this airline has flown (in and out of SFO)

Honolulu International Airport. This airport in the United States is also referred to as HNL or sometimes PHNL
Hong Kong International Airport. This airport in Hong Kong S.A.R. is also referred to as HKG or sometimes VHHH
Boise Air Terminal. This airport in the United States is also referred to as BOI or sometimes KBOI
San Francisco International Airport. This airport in the United States is also referred to as SFO or sometimes KSFO