Q. I'm planning a trip to Europe this summer, starting in Rome and ending in London. The thing is, a multi-destination ticket is way more expensive than a round-trip ticket to London I have found I can save $220 if I purchase a round-trip to London-Heathrow, and then just a one-way from Heathrow to Rome on the afternoon I arrive. It's even the same airline and same flight numbers as the connecting flight, yet it's cheaper to book them separately! My question is, since it's the same airline, will they transfer my bag or will I have to go through passport control/customs, get my bag, and go back through security? Will the airline frown on this, since I didn't buy the through ticket?
A. You are perfectly well within your rights as a consumer to purchase these tickets separately, and as long as you use both the outbound and return portions of your round-trip to London, the airline will have nothing to complain about.
That said, we'd like you to consider the following and weigh the savings versus the potential hassle.
One issue is baggage limits may be vary on trans-Atlantic flights vs. intra-European flights. You may have to pay additional baggage fees, or check your carry-on if it's too big in size for flight number two.
Also, if your incoming flight to London is delayed or cancelled, the airline is in no way obligated to get you to Rome. Whereas if it's all one itinerary, they'll put you on the next connecting flight for free, or put you on another airline. Otherwise, should you enounter some little snafu, you'd be on your own. If you do purchase these tickets separately, it would be a good idea to leave as much connecting time as possible, just to be safe. And yep, you may indeed have to go through security and collect your bags and re-check in, if you purchase separately.
There's a reason why they charge more for a through ticket. Because they know it's more trouble to do it the other way!