We have a 70 minute layover in Chicago on our return to Los Angeles from Dublin, Ireland. Is that enough time to go through customs and get from Term #5 to our LAX flight in Term #3?
I seriously doubt it. The last time I came through terminal 5 (May) it took a full hour just to get my bag and go through immigration check. You will have to claim your bags and recheck them at terminal 3 since you are coming in from outside the country. Then security again. Can you change your connection?
The US immigration check for flights from Dublin to the US is conducted at the airport in Dublin. That's right the US Immigration check is in Dublin. Thus you won't have to wait in line to have your passport stamped when you arrive in Chicago. When you de-board the plane look out for signs that point passengers from Dublin to a special exit the bypasses the immigration hall. I say you will make your connecting flight; but if you were taking a flight from any other city in Europe you probably wouldn't make it.
The immigration check does take place in Dublin, but you still have to claim your luggage (if any was checked) and clear customs. There is a convenient place to re-check your bag just past customs. Customs in Chicago is pretty efficient. Then you board a train to the domestic terminal, where you must go through security. It takes only a few minutes get to to the domestic terminal.
A 70 minute connection at O'Hare going international to domestic is tight. We are travelling DUB/ORD/DFW later this year and I am allowing two hours. And we don't check bags.
It would be very close "IF"your flight from Dublin was on time and that is seldom. Go to the American web site every day for a week or so and check to see if the Dub-Ord flight is on time. I flew this route,Dub-Ord, in June and we were six hours late leaving Dublin. Also the amount of time required between planes in Chicago depends on home many flights arrive at about the same time as yours.
It might be a push but since you are flying to LAX if you do miss your connection you'll likely be able to get on a later one (since I assume there are many many nonstops from ORD-LAX). I wouldn't worry.
The US immigration check IS in Dublin (also in Shannon), but you still must claim and recheck your bag, as well as pass through the final passport check (just a glance to see if it's stamped) before leaving Terminal 5. Depending on how many international flights come in at once and how many passport check stations are open, this can add quite some time to your wait once you get your bag. On my most recent reentry, there were three flights in at once so the line was 700 or so people with one station open.
I just checked on todays flight from Dublin. It arrived in Chicago one hour and 19 minutes late.
How you booked could make a difference. You didn't mention if you purchased the itinerary as one ticket or separately. It's been my experience that the airline will either hold the connecting flight or put you on the next one if it was one ticket. If you booked each leg separately, you are on your own if your first flight is late as the airline is not responsible for the connection.
Todays flight from Dublin will arrive approx. two hours late.