San Francisco - Wikipedia.
Though located 13 miles 21km south of downtown in unincorporated San Mateo County, San Francisco International Airport SFO is under the jurisdiction of the City and County of San Francisco. SFO is a hub for United Airlines 342 and Alaska Airlines.
San Francisco International Airport - Wikipedia.
In 1961 the airport had helicopter service on San Francisco and Oakland Helicopter Airlines known as SFO Helicopter Airlines, and as SFO Helicopter with 68 flights a day. Helicopters flew from SFO to downtown heliports in San Francisco and Oakland, to a new heliport near the Berkeley Marina and to Oakland Airport OAK.