Trying to get from SF-Paris as inexpensively as possible, and I am looking at an ideal United itinerary which gets me in to Heathrow at 6:55 connecting to BMI at 10:50.
The return via BMI puts me back at Heathrow at 10:50 to catch a 1:25 UA flight back to SF.

Now the catch. Booked together I can get a price of $790 booked separtely it comes in at $598 a savings of $400 between 2 tickets. Obviously very tempting, and I seem to have plenty of connecting time each way, but I am wondering if there are any serious downsides to this strategy?

The one concern I have is that BMI won't check my bags through to United, so I would have to pick them up and recheck them at LHR. I think UA WILL check them through to CDG on the outbound.

Anyone, have experience with this?
Are flights between LHR and CDG frequently delayed? Is 3 hours enough connecting time on the return to get my bags and recheck to United,etc. Am I missing anything here?

Appreciate any and all replies as I need to book today. Thanks in advance.

I would be wary of the separate tickets. One little delay will throw the whole schedule into a mess. I had a 2.5 hour difference between my arrival from SNN and my departure to MIA (in Heathrow) and barely made it, between going through customs, picking up luggage, dropping off luggage (this was an hour wait in line) and then getting to the gate. It is MUCH MUCH MUCH less of a pain to have your luggage checked through. Remember, Heathrow is big, and the gates are sometimes at different terminals, which means a long travel time - with luggage in tow, it's awful.

My advice, suck up the $400. I wish I had.

If the two airlines have a luggage agreement I don't see why the bags could not be checked all the way through even if you book the segments separately.

In those cases you can ask the originating check-in agent to check the bags all the way through (show them the other ticket if necessary) BUT make certain the two airlines have an agreement.

I don't know about checking your bags through with all the regulations changes. Someone can answer that, I'm sure. But both UA and BMI are part of the Star Alliance, so I think that this would help. You could easily call BMI about this.

Also though you bought the tickets separately, you could indicate that you've a connection to catch when you check in during the first leg. I did once with BMI also -- I forget what my carrier was -- AA, maybe? I think I flew AMS-LHR on BMI, and when I checked in, I pointed out my flight from LHR.

I don't know what would happen if you miss your connection given you bought your tickets separately, but I think that the airline would be happy to note that you've a connection and make things as easy for you.

Personally I'd be tempted to save $400. But everyone's risk tolerance is different.

I missed my final connection on that trip - from Miami to Orlando - and they basically said tough. I ended up renting a car and driving, since they couldn't get me on another flight that night. It cost me another $130 just for the rental car, and the flight was $120 - all because of no luggage agreement between the two airlines (and yes, I asked the gate agent if she would tag it through, and she said she could not).

The same with my other flights, between MIA, LHR and SNN/DUB - no agreement, no luggage through.

I interpreted it that scooterb had already checked and BMI wouldn't check the luggage through with UA. If they do have an agreement, by all means go for it and save the cash!

In contacting United it looks like they won't interline bags to BMI either if they are not booked on the same ticket. I just don't have a feel for how much time is needed to get bags, change terminals, get through immigration, etc. 3 hours seems like a long time to do all this...

Scooter, when are you going? I can usually get SFO-CDG in winter for $600 on one reservation. Of course, if you're looking at Christmas or New Year, it's probably a bit late for a cheap flight. Have you checked sidestep.com? I'm seeing flights for $595 by plugging in random, non-holiday December dates.

We do this all the time but I must note two things:

1. Each ticket is legally a point-to-point ticket, there is no 'connection' at Heathrow as far as the airlines listed on the separate tickets are concerned. So strictly speaking if you miss the onward flight, it will be your financial loss. You might be able to talk your way out of such a scenario, but don't count on it.

2. You have two ways to reduce the risk - spread it over several such trips, if you plan to do this often, or overnight in London between flights. A word of caution: flight schedules can change subsequent to booking, ours did and it narrowed the 'connection' time considerably (or would have had we not been overnighting in between flights.)

Best of luck in your decision.

Granted this was a once in a lifetime mess, but I had 2 tickets (once) where one was free Anchorage through Seattle to London, one was free Seattle to Dublin, and the other 2 segments were paid. So we were each on a partially free ticket. Then, Sept 11 happened when we were to leave Dublin. The ensueing mess and all the phone calls took us an extra week to get home. I swore I'd never do it again!

My advice: pay the extra $400 and book it as one ticket. If you book two separate tickets and anything goes wrong on the SF-Heathrow leg, there's a good chance you'll miss that BMI flight and have to purchase a new ticket (at full fare price) to get to your final destination. If you book it as one ticket and there's a delay, it's the responsibility of the airlines to get you there.

(My August 2005 flight from Chicago to Heathrow departed nearly 4 hours late due to mechanical problems with one of the engines. Long delays, though rare, do happen - and when you consider you'd have to clear Customs and recheck your bags with BMI, that long layover suddenly doesn't look nearly so long!)

Another thought for you -- a tip I learned here is to check flightstats.com for your flight. You get a sense for whether it's been on time over the past two months.

LHR (and CDG, probably) offers realtime flight arrival and departure times. A few years ago, I monitored a flight to Athens because I had a tight connection and I had to switch airlines also -- I had no trouble.

Another possibility: Try open-jaw SF-CDG, LHR-SF, and consider taking the train for one leg. If this saves you money, your risk of missing the connection is cut in half.

You can even take the train both legs. It will probably take longer, but I've done this in the past.

Of course you risk delays with trains also, but presumably they're better and present a smaller risk. Also it gives you some incentive to pad your schedule and spend a few hours in central London.

We checked our luggage through to our final destination even though using two separate tickets-Virgin Atlanticto Hathrow then British Midlands to Paris.
Virgin's agents had us book it this way since we were flying Vrigin's Premium Economy we would have had to fly Business Class on BMI and that segment would have cost more than Boston to London.We wanted economy to Paris. It worked fine.