Not that I can do much about the situation but here 'tis. My wife and I will be flying from San Francisco to Vienna via London, taking British Airways all the way. The flight schedule is such that we will have one hour 40 minutes to get from Terminal 5 to our connection in Terminal 3. Assuming the flights are on schedule, does that sound doable?
If you're getting short on time, don't be shy about asking for help. More than once British Airways has been very good about helping us with tight connections at Heathrow (like getting us in the Fast Track line), and we've seen others being helped along as well.
Heathrow has been better on the last two times I've flown through, but it still is one of the slowest major airports in Europe for flight transfers. If your flight is on time, one hour and 40 minutes sounds more than adequate. I would get nervous for anything under an hour.
We had a similar connection a couple of months ago - 1 hr 30 minutes - between arrival in Terminal 1 (or 3, don't remember which) and departure from Terminal 5. We barely made it. Had to run long distances, and airport staff routed us through "express" lines at two locations. Would not have made it otherwise. Heathrow is a madhouse. I will avoid it whenever possible from now on.
If the original flight is on time, you should be able to make the connection. The good thing about your travel plans is that you are using BA for both flights; if you should miss the flight, BA is responsible for getting you to Vienna and since you are in Heathrow, there should be no problem finding a later flight.
I don't understand why you are going to T3 at Heathrow because BA usually only use T5 for their Heathrow flights. Is it a codeshare?
Linda.....FYI......BA still operates a few intra-European flights out of T3.
. . . And for some BA fllights you even have to transfer to Gatwick!!!
I know BA fly out of Gatwick, it's the airport we use more often than not when flying BA. It was just that I was under the impression that when T5 opened, BA shifted their operations at Heathrow to the new teminal. Especially since they have exclusive use. Well you live and learn!