San Francisco

Examining the History Behind San Francisco International Airport's ‘SFO' Code

The airport’s name has ties as far back as 1945

What is the deal with SFO? No, we are not referring to delays that can ruin flight schedules. Rather, we are talking about the Air Code: SFO. Obviously, SF is the city’s initials, but it seems that very little is known about the ‘O.’

KQED podcast Bay Curious covered the topic and spoke to SFO Museum Assistant Director John H. Hill.

Hill pointed out that some may assume that the ‘O’ represents Oakland. He debunked this theory though by pointing out that Oakland’s airport opened around the same time as its Bay Area neighbor. This deemed the reference obsolete. Instead, the airport’s name has ties as far back as 1945.

To fully explain the airport’s name, Hill elaborated into the history of the International Air Transport Association.

Prior to the association’s formation in 1945, many airports went by a two letter initial. After the International Air Transport Association opened, the company required each destination to have three letters. This was due to the increase of new airports across the country.

This led some airports to just attaching an ‘X’ at the end or even coming up with a more unique three letter code based on surrounding locations, explained Hill. For SFO, the most apparent fix was to add on an ‘O.’

Hill resolved the mystery in his statement to Bay Curious: “So with SF, they simply took an ‘O,’ which we can assume was convenient to the fact that San Francisco has an ‘O’ at the end of it.”

Now, go forth to pub trivia and impress friends with your newfound knowledge.

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