connection at Heathrow

Not sure if you mean on arrival or departure??
Most of the time it is. I would recom you be the one of the first ones off the plane with hopefully only carry on luggage. As far as departures again carry on luggage only and have all your documents in order.

Sorry, what I mean is we are flying to Vienna and have a connection in London. Is two and a half hours enough time? Is it going to be hard if we have checked baggage. I am going to try to have only carryon but not sure yet.

If you do end up having to check baggage, will you be flying on the same airline or on a code share partner airline so your baggage will be checked through?

I booked everything through American Airlines but when we get to London the flight will be with British Airways. Does that make a difference?

AA and BA are partners so your checked luggage will be automatically sent to your connecting flight wit BA.

Ok, so it won't make a difference if we check baggage or only have carry on? We are going to try to only bring carry on but we may end up checking just one bag total.

You will be able to check luggage through to your final destination so you won't have to worry about it at LHR. As far as the time is concerned you should have more than enough. They wouldn't have sold you the ticket if the connection wasn't possible. When you arrive look for signs saying something like "Connecting Flights" and you should be fine. If you can find out in advance which terminals you will be arriving at and departing from it might things a bit easier.

When is your flight?

Your AA flight should arrive at Terminal 3. Your BA flight may leave from Terminal 4 or if it's after March 27th, Terminal 5.

Terminal 5 opens on March 27th and its only occupant will be British Airways. You can read about it here:

http://www.msnbc.msn.com/id/23117153/

our flight is April 18th.

Then your BA flight will probably be out of Terminal 5. It's best to check with the airline before you leave. BA has a toll free number in the U.S. Or you can check their website which will tell you. You don't have to do this until a day or two before.

It's best to just have carry-on. If you do decide to check luggage, just make sure, when you check in for the AA flight, that the computer strip they attach to it has both flights on it.

On current flight information displays AA will still be using T3 on 18 April.

18 April is a Friday and things can get very crowded on Fridays at LHR. Therefore queues at passport control can get very long. I certainly don't want to cause alarm but I've known it take well over an hour to clear passport control at T3 on a Friday, particularly Friday afternoon.

Current flight information displays show that BA WILL be using T5 on 18 April.

This could be a very tight squeeze. I suggest you contact AA directly in order to establish what the procedure will be for a missed connection.

Our flight leaves from Los Angeles on April 18th in the evening. It will be noon on Saturday when we arrive in London.

Al, do you need to go through passport control when connecting between T3 and T5? I've never had to go through pass control when transferring at Heathrow to a flight outside of the UK. I've only gone through the security check. It has been a few years since I have taken a connecting flight.

I am very interested in Laura's question, too. I hope a reply will come from someone "in the know." Thank you!