In Oct. we are scheduled to fly British Airways from ORD to LHR into Terminal 5. Carry on luggage only. If all goes well, we have 3.5 hrs to catch an Aer Lingus flight out of T2 to Shannon, Ireland. Separate tickets. 1-Upon arrival at T5, do we follow the purple signs to connecting flights? 2-Do we need to go through immigration and customs upon arrival at T5? 3-Which option is best to transfer between terminals: Heathrow Express or the interterminal bus? 4-Is a 3.5 hr layover time adequate? I’ve been searching everywhere but can’t seem to get straight answers. I also tried https://www.heathrow.com/connecting-flights but am still unclear. Any help and any additional tips will be greatly appreciated.
It is a compliced answer.
IF you can check in online and have your Aer Lingus boarding passes, you can try to follow the purple signs to use the Flight Connections bus to take you from Terminal 5 to Terminal 2. There you will go through security. I can't remember if you go through passport control due to the CTA. Even if you do, it's a separate area and you get to use the egates.
If you can't use the Flight Connections bus, you will go through Passport Control at T5, take either the Heathrow Express or tube to Terminal 2/3, go through security and then to your gate.
You should have plenty of time either way if your arriving flight isn't too late.
You will go through immigration at LHR due to the Common Travel Area between the UK and Ireland.
....for self-connecting flight, ( "if you have booked two separate flights (self-connecting)") please follow arrival and departure procedure, see ....https://www.heathrow.com/at-the-airport/airport-maps/travel-between-terminals
My reading of the info is you cannot take the "Flight Connections" Frank describes.
The key is your first flight being on time, or nearly so.
The only times I connected at LHR I was on a single ticket booking with BA, so have no first had experience with your situation.
My reading of the info is you cannot take the "Flight Connections" Frank describes.
If you have your boarding passes for the second flight, and no checked luggage, they sometimes let you connect by staying airside.
The Heathrow Airport Flight Connections site assumes everyone has checked luggage.
Thanks to all for taking the time to reply. Any additional information is always welcome.