Flying thru London Heathrow to Madrid in September

Flying PE will allow you to deplane after first and business classes so not really much to gain from that. Making a connection will mean that you avoid immigration and customs, you will need to go through security again. The largest impact will be the number of flights that land at or around the same time as yours as this will affect the number of fellow passengers aiming to achieve the same objective at the same time.

I dislike BA, but I wouldn't do this. Won't you have a line even for automated, British Immigration? Everything at Heathrow takes forever, and often multiple security lines. Your second flight will be like a fresh arrival at the airport.

You can use the web to see the last departure gate of the second flight, i.e. yesterday. I assume it's a bus ride, outside security.

A 90-minute connection in LHR wouldn't be my preference, but if the ticket was booked more than 24 hours ago, and thusly, presumably, non-refundable, I wouldn't stress too much. You'll face transit security in LHR, but that has not been the greatest pain point. It's entering from "landside" where the problems have been.

IAG (BA and Iberia) has a ton of daily flights between LHR and MAD, and if you miss your connection I'd bet you'd be on another plane in less than an hour. If you'd like to take a look at that use google flights to look at the one-way on your day of travel. Filter for Airline/Alliance = OneWorld.

I think you will be fine.

The problems are not airside but when you enter the airport.

I have done a lot of transfers at LHR it's not hard and you won't be going through the mess in the terminal area!

The USA doesn't take on trust any other countries' security and neither does the UK. No need for immigration though.

By the time you are flying, your BA flight will arrive in T5 and your IB flight will leave from T3. Your 90 minutes connection is at the minimum for a terminal change in normal time so I would look at getting it lengthened even if retaining this routing. Switching to BA from T5 might help.

The secret is to make sure that your carryons match British security rules. You will need to have your liquids in a proper sized plastic bag that is easy to remove from your luggage and make sure that any water or liquids you collected on board your first flight are discarded prior to security.

A 90 minute connection is usually doable. I don’t think that anyone can accurately predict the situation 2 months from now. I would not stress or worry about something out of your control. Be prepared to get through security, move briskly, and know there will be another flight if you do for some reason miss the connection.

Go to this website:

http://www.heathrow.com/flight-connections

Fill in your flight information. It will give you step by step instructions. Follow them. You will basically follow the fight connections signs.

You do go through security again. You do not go through immigration. You do not go through customs. You do not pass "go" nor do you collect $200.

You will have to change terminals but that is done via a bus airside.. Do not listen to anyone who says you have to catch the train between terminals.

By the way, London is in Europe.

I am grateful that my AA flight departs from Charlotte to Madrid and then Bologna.
Lucky because BA is a major code share partner and the majority of flights to Europe transfer through Heathrow.
Regarding Bologna, this is my preferred Italian arrival city. Whether using my air miles or paying cash flying into Bologna the cost is significantly less.

If T5 to T3, here's a video of that.

https://www.youtube.com/watch?v=f-4sVZRpwow

Tim is incorrect. With a flight connection on one ticket, you do not go through immigration at Heathrow, even if the connection involves a transfer between terminals, such as Y5 to T3. The bus between terminals is an airside transfer. You do need to go through security in any case, even transferring between gates in the same terminal.

90 minutes is a “legal connection” time and in “normal” times would have been fine, even if your inbound flight was a bit late. Our last flight through Heathrow in 2019,, on our way to Barcelona, our plane from Seattle was so late we had only 35 minutes for the transfer from T5 to T3. There were 16 passengers on our plane who needed to make the Barcelona flight. BA provided a person to meet us as we got off the plane to escort us to a waiting bus they brought to the gate especially for the transfer to T3. The escort stayed with us and took us to the front of the security line at T3, then led us to the gate for our waiting flight. 👍

But things have changed post-covid, and Heathrow has had a lot of problems due to low staffing. There have been reports of impossibly long lines for security, and other problems. This is not unique to Heathrow—-other airports have similar troubles and have reduced the number of flights in and out to try to alleviate the problem.

FWIW, the morning hours have tended to have fewer congestion problems than the afternoon and early evening, but on any given day that could change. And hopefully the problems will be resolved by September. We have a flight with BA at that time ourselves.

Thanks everyone for your helpful replies on my post. I will see what additional flights from LHR to Madrid are available in case I miss my connection going there (return wise I have more time in LHR). I do have a changeable ticket so I might explore flying through Charlotte or Philadelphia and then onto Madrid. But I realize that these days travel delays and flight cancellations are fairly common, and I may just have to roll with it....

"I do have a changeable ticket so I might explore flying through Charlotte or Philadelphia and then onto Madrid. But I realize that these days travel delays and flight cancellations are fairly common, and I may just have to roll with it...."

Yes, there can now be significant delays at any airport. If there's a delay at Heathrow, as you said there are multiple other flights to Madrid that day. If there's a delay in Charlotte or Philadelphia, there's no other flight to Madrid until the next day - which may be full, so you may have to wait even longer.

Before Covid, my sister had flight from Baltimore through Heathrow to Madrid. Her plane was delayed 2 hours taking off from Baltimore (due to an issue at Heathrow), so she missed her original connection. She was met at Heathrow by a BA agent, with a new boarding pass for a new connecting flight. She had something like 20 or 25 minutes to get to the next gate (changing from T5 to T3 in the process), and made it!

Short version - keep your Heathrow connection.