Hi! I've already booked a flight to LHR, via EWR on United, arriving at 9:30am on a Thursday. I need to book a same-day flight from LHR onwards to VIE. Since i'll have to pick up baggage, go through passport control, drop baggage/check-in, and continue through security again - how much time do you suggest I leave in between? From my understanding, my flight in will arrive into Terminal 2 and my best departing flight options will likely leave from Terminal 3 (British Airways).
You're coming in at a bit of a rush hour and on an american flight which will probably have a lot of other non-European passports coming off ..... so you can expect a long wait to get through passport check (whether or not you've got an e-passport). looking on the bright side, your luggage will probably already be wating for you once you get to luggage pick up. Depending on where you sit on the plane (cos you can add 30 minutes dis-embarcation time if you're in teh wrong part of the plane) I'm thinking 2 hours before you're even out of the terminal. then to get to the next terminal - a bit of a walk so say 30 minutes (with a loo break etc.).
Presumably as you've got luggage you'll have to check back in.......depends who you are flying with (budget airlines are a bit quicker as they positively discourage having any hold luggage) but this is now a lunchtime flight (popular because you get into the destination at a good time). Give it two hours for that and security.
smart move of course would be to limit your luggage to handluggage which will at least give you flexibility on the transfer in case flight into LHR runs late...... ah the challenges!
enjoy your trip
LHR is a miserable airport to transfer through, their website says you need a minimum of 75 minutes from T2 to T3 but that is assuming no luggage pickup and a through ticket. You may have to pick up your bags as you are not on a through ticket and you are also not using the same alliance if you book United and BA. If I couldn't confirm that they would check my luggage all the way through I'd probably not feel comfortable unless I had 4 hours