Checking in

If you a book a single trip Charlotte -> Atlanta -> LHR (as 1 transaction) then you'll only check your bags once at CLT. If you buy a ticket CLT -> ATL and then another ticket ATL -> LHR then yes, you'll have to check your bag in CLT, claim in ATL, recheck in ATL and back through security.

If you have no bags then you don't have to enter baggage claim and exit to the non secured area. You won't leave the secured area when you reach ATL which means you will NOT have to go back through security.

2 hours is enough time...if you actually get the whole 2 hours and your flight from CLT -> ATL isn't late. That's a big "if".

So will I go thru passport security in Charlotte or Atlanta?

There is no such thing as passport security so not sure what you mean or are asking. If you have a single ticket, then the check in deck in Charlotte will check the validity of your passport. If two tickets as implied, then the check-in desk in Atlanta will check your passport. But there is no immigrations or customs leaving the US.

If you fly from Charlotte to Atlanta you will land at one of the domestic terminals. If your flight from ATL to LHR is a direct one with no other stops in the U.S. you will leave Atlanta from the International Terminal. If you don’t have checked bags you will not have a problem. If you have checked bags and your flight legs are all on one ticket, you still will not have a problem as your bags should be checked through all the way to London. You SHOULD be able to go from your arrival terminal to the International Terminal using the "plane train" without going through security again and a layover in of 2 hours should be enough time. You MAY have to do something with customs at the International Terminal but I'm really not sure since we never transfer from a domestic terminal. The Atlanta Airport had a pretty good web site that may be able to provide some better information about you particular situation.

....You MAY have to do something with customs at the International Terminal......

Let me repeat so there is no misunderstanding. Immigrations and especially customs is ONLY on ENTRY to a country. It has nothing to do with leaving a country. On leaving the US, the only passport check you will face is the check in counter for the airlines as they check that you have a valid, date wise, passport.

bb,

As the others have mentioned, if your tickets were purchased on a code share arrangement between the airlines, your checked luggage will be loaded in Charlotte and you won't see it again until it appears on the carousel at LHR. When the agent attaches the luggage tag, have a look at it to make sure that the last airport listed is LHR. Which airline are you using from Charlottte to Atlanta?

In order to enter the departures area at Charlotte, you will have to go through TSA security, and they'll want to see your boarding pass so keep that close at hand. If you've flown in the past, you'll know the usual security routine of taking belts off, placing Laptop computers in the Bin and the 3-1-1 liquids rule. When you pass through the gate to actually board your flight, you'll have to present your Passport and Boarding pass (have the Passport open to the photo page to speed things up).

I'm not too familiar with ATL, but it's possible you'll be arriving at the domestic terminal and will then have to transfer to the international terminal for your next flight. If that's the case, it's highly likely that you'll have to go through TSA security again as you'll be transiting from a secured area to unsecured and then back to the secured departures area of the international terminal, so be prepared to go through the "dog & pony show" again. Again, when you board your flight to London, you'll have to present your boarding pass and Passport to the agent.

Hopefully one of the group here can provide more specific details on the process at ATL.

All of the ATL- domestic and international- is within the same security area. There are not separate TSA zones for foreign and domestic flights. (Inbound international passengers get routed to US Immigration & Customs underneath the E&F boarding lounges via a 'cattle gate' system as you get off the plane from London or Paris.)

For as stupidly huge as the place is, it's really nicely laid out and once you're 'airside' ( aka. past the TSA checkpoint) you can roam by foot or plane train from Terminal T to Terminal F and back again. Even when I'm making a domestic connection there, I like to hang out in E or F between flights because the food is better, the terminal is nicer, and it's generally less crowded than the A-B-C domestic zoo.

Agree with Selkie about the food being better in E and F than in the International Terminal. Lots of Americanized "international" food there that is a bit on the rich and spicy side. The "chili dog" at the Varsity in the International Terminal is NOT what you want to eat just before a long flight. Trust me.

Just to clarify some points the other posts have (correctly) made.

Security, passport control, and customs are three different things. (My mother still mixes them up, despite have taken several trips with me and seeing them in action). Passport control is about people; customs is about goods; and security can be about both. What you have to go through and when depends on your exact ticketing.

The US has no passport control on exit; the airline will want to see your passport when you check in for your international flight, but there's nothing more "official" than that. European countries do have passport control on exit (no big deal, as they just scan it and stamp you out, and there's rarely a big line). All countries have passport control on entry ("immigration") and this can take time, depending on how many other flights arrive and how many agents are on duty.

As said above, what you will have to do depends on whether you are all on one ticket from Charlotte to London, or on two separate tickets (CLT to ATL, and another ticket ATL to LHR). If you let us know which is your situation, people can give very exact directions on what to expect. But in general, don't stress about it too much. You just follow the crowds, and remember you won't be allowed to "skip" a mandatory step. For instance, if you have to go through passport control, you can't get to your gate without passing through it; you won't be allowed to "forget" or "get lost" on the way to your plane.

So, EXACTLY which flights are you on, and are they on one ticket or two? While you're at it, post the details of your return tickets as well, so we can give you specifics on what to expect on that end.