Originally Posted by
linglingfool
Head straight for the exit doors of T3 on the concourse level; don't go down the escalators to baggage claim. Up the stairs or elevator to the ATS (Airport Transit System)
I've flown in and out of ORD for 20+ years. I've never know of ANY way to exit the concourse level 2 except by going down the escalators to baggage claim (level 1). I'd love to be educated on an alternate route out of the concourse level that doesn't require going down to baggage claim. To get to the ATS from baggage claim, you must take an elevator or escalator up 2 levels.
Originally Posted by
linglingfool
... T3-T5,.... outbound international flights don't require any additional processing besides a document check upon boarding.
An ORD terminal change, T3 to T5, requires leaving the secure area at T3. When you arrive at T5 via the ATS, I'm almost certain you have to pass through a full security checkpoint.