If you have multiple flights on one ticket, whose responsibility is it if one is delayed enough that you miss the next?

Question

I'm aware that if you have a single flight consisting of multiple legs on the same ticket, the airline is responsible if one is delayed enough that you miss the next. Is that also true if you have multiple flights booked together?

I was considering booking this itinerary:

... (SFO - NQY flights a week that are not relevant)
7/6 EI 3931 NQY - DUB
7/7 AA 6765 DUB - LHR (this is a codeshare of BA 831)
    AA 6996 LHR - SFO (this is a codeshare of BA 285)

Searching in ITA Matrix, I didn't find these three flights sold as legs of one flight from NQY - SFO, but if I searched for them as separate flights (NQY - DUB on 7/6 followed by DUB - SFO on 7/7 as part of a "multi-city itinerary") it showed up as something I could buy all as one itinerary.

There's only one NQY - DUB flight per day, so I'm worried about what might happen if it's cancelled / delayed by a day and I miss the DUB - SFO flight. Since they're all booked together would the airline still be responsible for getting me to SFO, or would that only be the case if it were booked as a single flight with multiple legs as opposed to multiple separate flights on the same itinerary?

(Leaving this up for posterity -- Aer Lingus decreased the price of their direct DUB - SFO flight so I am no longer considering buying this)

Answer 1

Yes, as long as you have a single ticket with a single confirmation number, the connection is "guaranteed" and the airlines involved have to get you to your destination, even if there are more than one involved.

In your case, I presume you're flying NQY-DUB-SFO on Aer Lingus, so they're responsible for getting you to SFO. This may involve putting you on the next available flight or rerouting you via another airline like BA via London, and they're generally also responsible for expenses caused by the delay: since Aer Lingus is an Irish airline, EU261 regulations apply.

Answer 2

If you have multiple flights on one ticket, whose responsibility is it if one is delayed enough that you miss the next?

EU regulation 261 is explicit about that: It's the operating carrier (of the flight that's delayed), even if your contract is not with them (code share, interlining, etc.). This is also the case for flights bought through a tour operator or as part of a package. The regulation goes on to say that the operating carrier can seek reimbursement from third parties but they still have to offer the traveller compensation, re-routing, and “care” (meals, hotels, etc. as appropriate).

Re-routing is explicitly to your final destination at the earliest opportunity or at a later date, at your convenience. In the EU, you also have the right to chose (partial) reimbursement and a return flight to the first point of departure instead of re-routing to your final destination.

If there is an issue on an itinerary like yours, I might try to approach staff for the airline operating the next flight in your itinerary (the one you missed) so BA. If you have issues in London, I would also ask at a BA counter, as you're transiting through their hub and they are in the same alliance. In the past, I have also requested and received compensation from the ticketing airline (not the operating carrier) for codeshare flights. But if for some reason it doesn't work, the law is clear: The operating airline is responsible, even if it wasn't the airline that sold the ticket.

The UK has similar legislation but as @lambshaanxy noted EU 261 applies since Aer Lingus is an EU airline. IATA rules are less comprehensive but they also put the responsibility squarely with the airline that caused the involuntary re-routing so the operating carrier of the flight that was delayed, see Who is officially responsible for rebooking a missed connection?