Changing airlines at Heathrow

What airline from US? If BA or partner look at the multi city ticket option so you would get a through ticket to Nice on inward trip and LHR - to SFO for return. This way checked bags will be taken care of. You stay in secured area even if changing terminals so just follow signs. No customs/immigration as you are not staying in UK. Check the Heathrow website for latest and up to dates info on transiting as it has been a few years since I did it.

Thanks. It would be United from SFO-LHR. This option is at least $400 pp cheaper than booking open jaw, which adds up quite a bit with 4 people.

https://www.heathrow.com/at-the-airport/airport-maps/travel-between-terminals

This will be a start for a separate ticket transfer.

Can you not book SFO-Nice as a single ticket? Would make life much simpler.

Otherwise anything less than 4 hours is the proverbial 'engraved invitation to disaster'.

Go to the Heathrow Flight Connections, fill in the flight information and it will tell you what you need to do.

However, note, it also says:

PLEASE NOTE
If you’ve booked two flights separately, in most cases you’ll need to pick up your checked bags and check-in for your connecting flight. If so, simply exit through Arrivals and check-in at Departures. Be sure to keep a keen eye on the time.

Uniited and British Airways are at separate terminals at Heathrow.

Have you tried booking multi-city:

SFO to LHR

LHR-NCE

LHR-SFO

The separate tickets is a bit of an issue here and a checked bag is the time waster/possible problem. You will need to give yourself plenty of time if you check a bag. Someone will correct me if I am wrong, but I believe you will have to go through UK immigration prior to baggage pickup.

Here is a link to FAQs about flight connections at Heathrow
https://www.heathrow.com/customer-support/faq/faq-connections

I don't know your actual dates, but I did put a multi-city routing from SFO to nice and then LHR to SFO in Google flights for May. Five different options came up at about $850.

I understand that the price difference X4 could make a huge budget difference. However, give yourself hours of extra time to do what you are describing. It will take time.

That sounds like a really bad idea in my opinion. An open jaw ticket would be a much better idea, if an open jaw ticket to Nice is too expensive, look up the cost of flying to Marseilles or Milan, or even Paris or Frankfurt would be a better idea than arriving in London.

The process needed at Heathrow is you will go through immigration, pick up any checked in luggage, go through customs, change terminal and then check in again.

Sara,
I understand trying to take the savings on 4 SFO-LHR tickets. I have done this myself, but the problem with buying a separate ticket is that you have no recourse if you miss the connecting flight. United only has an obligation to get you to London. BA would essentially have you as a "no-show" if your fail to turn up on time. Then it is very likely you would have to re-book at walk-up fee prices.

With flight delays, cancellations, re-routing, etc these days, I would be more hesitant to do this unless I was planning on spending the night at LHR. I have done several trips this way. For example, I have taken a flight from the midwest into London, stayed at the Premier Inn at Terminal 4, (Very reasonable if booked ahead), and then got up early in the morning for a BA flight into Zurich (leaving from BA's Terminal 5). It is very easy to do and you feel quite refreshed after a good night's sleep at LHR. You would obviously have to go Landside for this to happen. Other than that, my suggestion would be to select the multi-city and pay the extra for peace of mind or build in at least a 6-hour layover and hope it works out. And yes, you would have to re-check your bags with BA in Terminal 5 which tends to be busy. You would then waste time getting in line to check luggage again. Best to do this with carry-ons only.

Margaret

Thanks to all for the advice. I'll keep ironing out the plan before making any reservations.

I actually misspoke in my initial post as Marseille (not Nice) is the final air destination, but that's not the critical bit of info. We have kids in school so we won't be traveling in May, and the cost between open jaw/multi-destination and a less expensive workaround is the difference between being able to take the trip or not.

Look at potentially flying into Paris (CDG) and out of London. You can take the train from Paris to Marseille. Would save the connection faf at LHR.

We are looking at the separate ticket option as well for our E. Africa safari in July.

I have over 500,000 sky miles on Delta, but cannot acquire a miles award for the entire journey. However, I can get an award flight to Heathrow or Amsterdam then purchase a separate ticket to get to and from Africa.

Things to consider:

1) How much time to schedule between arrival of transatlantic flight from the USA until flight to Africa. TA flights into Heathrow usually arrive in the early morning hours, whereas flights to Africa are either mid afternoon or late PM, which gives us a day and a half between flights. Even if our flight to Heathrow was a day late, we could make the Africa flight.

2) COVID19 tests are usually available at major airports, so I suppose if we needed another test that would not be right. Anyone have information counter to that?

3) For a stay of one night, I would be tempted to just stay at or near the airport, however, on the way back home to the USA could schedule some days to visit London or Amsterdam.

Not doing the checked bag would be difficult for us.