What airport is SFO?

Why the code is SFO

San FranciscO — the first two letters plus the last.

The airport authority or a contemporaneous record states this directly.

The airport

IATA code

SFO

ICAO code

KSFO

Airport

San Francisco International Airport

City

San Francisco, United States

Opened

1927

Code origin

Documented

It is built on fill in San Francisco Bay and sits about four metres above sea level, which makes it one of the most sea-level-exposed major airports in the United States. Its two pairs of parallel runways are only 230 m apart, too close for simultaneous approaches in poor visibility, which is why SFO delays cascade through the entire domestic network whenever the fog comes in.

The other code, KSFO

Every airport has two codes. The three-letter IATA code, SFO, is the one on your boarding pass and your luggage tag, and it is assigned for commercial use. The four-letter ICAO code, KSFO, is the one pilots and controllers use, and it is assigned geographically: the first letter or two identify the region, so every airport in the same part of the world shares a prefix. That is why KSFO looks nothing like SFO.