I'm looking at a flight from BOS to LIS with a 2 hour layover in LHR on BA. Don't know which terminals. I don't think this is enough time. The other option is an 8 hour layover. Should I go for the 2 hour?

If you go to the Heathrow Airport website and click on "Flight Information" then you will be given a screen that has "Which Terminal" as an option. BA flights from Boston arrive at T5 and BA flights for Lisbon depart from T3.

Transferring between terminals is a case of following the signs to "Flight Connections" and letting the staff there sort you out

If you click on "Airport Information" on the LHR website there is an option for "Flight Connections" which will tell you what will happen

And 2 hours is enough time for the connection. If you do miss the flight then it's BA's problem which as there several flights a day isn't much of a problem for you

Yes, 2 hours is enough.

As alanRow says, follow "Flight Connections to T3" when you get off the plane in T5. You'll get on a coach which connects you to T3, then you'll go thru security check, before you get into the departure hall.

Just be sure to double-check the terminals for both flights before your trip, to make sure BA hasn't changed the terminals for these flights.

If your connexion isn't what the airline calls 'legal' - in other words you will have sufficient time to make the onward flight - I do not believe that BA will permit you to make the booking anyway.

It sounds VERY tight to me, even if your transatlantic flight is not delayed (though, because of the normally prevailing tail winds across the Atlantic, flights from the East Coast of the US often arrive at LHR before their scheduled time - but you certainly should not bank on it).

Bearing in mind the distance between the two terminals, the frequency of the shuttle bus service, and the time required to pass through the strict security in Terminal 3 (which frequently has a very long line) I seriously doubt that you would make your proposed Lisbon flight - even IF BA will let you book your desired itinerary, which again I doubt.

I did a T5->T3 transfer last month. It took 40 minutes from the time my T5 flight landed (touched down; not parked at the gate) to the time I emerged into the T3 departure hall.

I'm not saying 40 minutes is the norm, I'm just saying that 2 hours for the T5->T3 transfer is possible.

yk was, in my experience, seriously lucky. I wonder if he/she had some sort of priority - First Class passenger / wheelchair / Diplomatic or similar - particularily at the T3 security.

Also, at what time of day was the ongoing flight - presumably not a rush hour departure. Otherwise I certainly would not reckon his/her experience to be typical by any means !

Surely, the fact is that IF the airline will sell you a ticket allowing this amount of transit time between terminals, they must feel confident that you CAN - in normal circumstances - connect with your ongoing flight. BA can answer this question far better than any of US.

Please let us know what they tell you. Their answer should be interesting for us all.

NOPE. Just a regular passenger sitting at the back of the plane.

It was a Tuesday afternoon when I did this transfer.

For the OP, the following link is the T5->T3 transfer instructions with visuals:

http://www.heathrowairport.com/porta...0357e120a____/

I've also done gate-to-gate T5>T3 transfers in under an hour; couple of times in fact.