For an upcoming trip I am gong to have to transfer between American and Alaska. I can either make the transfers in Los Angles and/or San Francisco.

I know that at LAX there is a bus that runs between Terminal 3 and Terminal 4. I also know that the bus is in the secure area so that I will not have to re-clear security. What I do not know is how often the bus runs and how long it takes.

I know less about SFO, other than the two airlines are at opposite ends of the airport. What are my options, how long will they take, and can they be done within security or will I have to reclear?

Many thanks for everyone’s help and suggestions