In Memoriam, FlyerTalk Evangelist
Join Date: Jun 2000
Location: Benicia CA
Programs: Alaska MVP Gold 75K, AA 3.8MM, UA 1.1MM, enjoying the retired life
Posts: 31,849
It's a pretty easy walk. You'll go down a set of escalators that connects you to the corridor that runs between the international terminal and T3. When you first come out on the T3 side you'll see the start of the counters for UA and eventually the security checkpoint. I regularly walk that coming on on BART and it's about 10 minutes as you do cover some distance. I never bother with AirTrain.