Originally Posted by
docbert
There's an air-side bus. The trip itself is maybe 5 minutes, although the total time will depend on how long you need to wait for the bus to arrive.
There are signs within Terminal A directing you to the bus - it's hard to miss.
Just note that the shuttle bus operates from two of the three "piers" in Terminal A, basically A10-A28. If you come into A30-A39 you have to exit security and take the AirTrain. But all UAX flights in Terminal A come into 10-28.