Airport by airport: which connections stay inside security, where you need a train or a bus, and where you clear security again.
Connecting at Nashville (BNA)? Most gates are a walk apart, but gates C4–C11 are a bus ride across the apron. How to plan it, from a pilot.
Connecting at Denver (DEN)? You never clear security twice, but the train, long concourse walks and the weather decide your margin. A pilot's guide.
Connecting at Detroit (DTW)? Delta connections stay in the McNamara Terminal. Switching to Evans means a shuttle and security again. Here's how to plan it.
Connecting at Newark (EWR)? United's airside shuttle links Terminals A and C. Other terminal changes often mean the AirTrain and TSA again. Here's how it works.
Connecting at New York JFK? Changing terminals means the free AirTrain and a second TSA check. How to plan it, and the Delta Terminal 4 exception.
Connecting at LaGuardia (LGA)? Delta is in Terminal C and most other airlines are in B. Switching between them means leaving security. Here's how to plan it.
Connecting at Phoenix (PHX)? Most connections stay in one terminal. Switching between Terminals 3 and 4 means the Sky Train and TSA again.