I will be flying back from Barcelona to Boston in July. The only flights I can take (as I need to fly in the afternoon) are BA with LHR connection time 1 hr 55 min (terminal 3 to terminal 5) or AF with CDG connection time 1 hr 20 min (terminal 2F to 2E) and the BCN-CDG flight has only 66% ontime performance. Which is better (or less bad)? Thanks!

The answer is in your post.

I just looked up the BA flight (475) from BCN to LHR, and it has only 59% on time performance, with average delay 35 min. i.e. same problem at both sites! Is it hard to get from terminal 3 to terminal 5 at LHR? It is necessary to go through customs or security?

It isn't difficult to move between terminals at LHR, but it can be time-consuming. You don't go through Customs because you aren't entering the UK, but you must go through security, and that just takes time.

I've always found lines at LHR to be long but well organized. I can't say the same at CDG.

However, there's one additional issue you may need to consider: price. It is generally considerably more expensive to connect through the UK on any itinerary because of their regressive carbon taxes. Just something to think about. But if the prices are similar, I find LHR a better run airport than CDG and subject to fewer work actions, too.

Your options suck, but we've made a scheduled 55-minute connection at CDG (thankfully it was actually 75 min because the plane arrived early). And going from t3 to t5 at Heathrow can be a hike (no, you won't walk it, you'll take the tube or airside shuttle).

You won't have to go through security at CDG, you will at Heathrow.

We did a connection on BA from Madrid via LHR to US in November with about the same amount of layover time.. It was so well organized with buses waiting for our transfers. No problems at all. There is a place on tne Heathrow website for connections where you enter both of your flight numbers and it clarifies what you have to do. Good luck!

Assuming you are booking one ticket meaning BA or AF will get you to Boston one way or the other . . . I'd do the LHR connection. Reasons being there are more flights out of LHR (just in case you do miss the connection) and IF I had to be delayed I'd rather it be a T-5 than at CDG.

Very helpful -- thanks! I booked with BA through LHR. Rude surprise (to me, at least): after paying extra for premium economy, I had to pay still more to choose seats ($65 each)! As even the premium economy section on the 777 has a 2-4-2 arrangement, waiting until the day of the flight could have left us in the middle of a 4-seat row in "premium."

I realize it's too late for you now, but people really worry way too much about the seat selection issue. If you check in as soon as check in becomes available, you'll find almost all the seat configurations available. It's extremely rare that a couple would have to sit in the middle seats of the 4-row. I've never experience that before, and I have never paid for seat assignments on a BA flight.

>>I realize it's too late for you now, but people really worry way too much about the seat selection issue. <<

Ditto that . . .

>>I have never paid for seat assignments on a BA flight.<<

double ditto that . . .

What do you mean Doug by the term "regressive carbon taxes" ? Isn't that what all airlines should be doing?