Yeah, I should have mentioned that there used to be direct airside busses. I wasn't aware of the specific reason, but had a general idea that it was some sort of construction project. The fact remains: don't try airside connections between T5 and T4 if you can go groundside fairly easily.

Connecting @ LHR
 

Hello,
I'm planning a trip with my 77 yr old mother.
Will be connecting @ LHR. PRG-LRH-CLT
Flight from PRG-LHR AA 6632 arrives in Terminal 3, and flight leaving LHR-CLT AA 733 also leaves from Term 3.
Will we have to go through security?
Given same terminals, is 2hr connection easily doable? we'll be walking slowly.

Thanks in advance!

2 hours is plenty of time.

You will go through security. Follow the purple signs to flight connections

I concur depending on when you arrive and what the security lines are like but with a lot more people now able to use the automated passport lanes you should have plenty of time to spare. Just be advised it will likely be quite along walk to the gates in T3, you might want to hop a ride on one of the buggies.

There is no passport control on this connection

and you will still have time to stop at one of the lounges...
and remember to take out your liquids..

ALL liquids. And make sure to place it in a clear plastic bag (TSA approved clear bag from Target will work).

Thanks everyone!

This is especially good advice in regard to liquids. About a year ago we were connecting at LHR to BA from AA. My companion keeps a hotel room sized bottle of hand lotion in her jacket pocket, and has done so for years without being stopped, domestically or internationally. On this occasion she was stopped at the security checkpoint in T-5, and was detained for 25 +/- minutes, where her carry on and jacket were given something akin to the TSA’s SSSS treatment.

Fortunately we had ample time, so we were still able to visit the Galleries lounge before boarding our BA flight.

What lounges are open to us at LHR terminal 3? 3 of us are in J on AA metal to DFW. 1 platinum, 1 gold and 1 with no status.

T3 in LHR has AA, BA, CX, QF lounges. CX is the best, make sure to check out noodles bar ( I usually don’t eat noodles but it was really good).
And if you don’t have AA security stamp on your boarding pass - stop by at AA lounge 10 min before you Ned’s time head to the gate.

Much appreciated. Need to learn how to use the advanced search tool.

In my experience, LHR security is the most aggressive in the world at sending bags for secondary screening for anything that looks at all unusual to the X-ray person. My advice is to look at everything you bring to see if anything might possibly seem dense or electronic or potentially sharp or liquidy. For example, packages of wipes (surface, baby, hand, butt), electric razors, electric toothbrushes, charging adapters, battery packs, empty bottles, nail clippers. Put everything like that in a plastic zippy bag, as large as needed (e.g., gallon or 2.5 gallon), and when you get to the security belt, take that bag out along with your liquids bag and all electronic devices larger than a cell phone (laptops, tablets, readers, video players), and put all this in bins. If the belt person asks you what the large bag is, explain that it does not contain liquids but has everything that might look unusual on an X-ray.

In my experience, having anything unusual or electronicy or liquidy or potentially sharp in your bag can cause that bag to get marked for secondary, which is usually a time-consuming and unpleasant process at LHR. There is often a lengthly wait for secondary inspection agents to get to your bag due to the large number of bags being so selected, and depending on the agents and what the issue is, your bag may be slowly and meticulously unpacked, with an agent pawing each and every item (one even stuck her (gloved) fingers into each a boxed piece of chocolate handed out on my flight just before landing), often sending many of them for additional X-ray checks as well. In my own experience, it is well avoided.

Of course, YMMV, and I have had bags zip through LHR security unmolested even with liquids left inside, but far too many times I had bags sent to secondary because of something minor that the X-ray person didn't like the looks of.

Yes I would say the opposite tbh in my experience. I will take my liquids out along with laptop and ipad, but other than that everything remains in the bags and 90% of the time there is no problem. To be honest the remaining 10% of the time it is just a random swab of electronics or liquids anyway. I can't remember the last time I had a bag pulled for a problem inside.

What remains in my bags are laptop cable, wash bag full of cables/adaptors/spare batteries, small power pack (bit bigger than a lighter), small camera (canon M100), and dslr when I have that too. These don't seem to cause an issue.