Originally Posted by
guv1976
If the OP already has his AA boarding pass, couldn't he just go through security at T5, and then take the airside transfer bus from T5 to T3? If it looks like the security lines at T5 are light, that's probably what I would do.
Theoretically, I believe yes, but that bus is IME often unreliable and for a while did not run at all. Personally, I would not take the risk of queueing for T5 security and potentially having to come back out to get the train to T3. T3 security is also mostly far quicker, though bear in mind that the TSA pre lanes at checkpoints 7A and 8 only open until 7:00 or 7:30 pm and that for some reason these days on Thursdays the TSA pre lines are often longer than the normal lines.