What are "code-share" flights?
In a code-sharing agreement, two or more airlines share a flight.
In this way, one airline can book a seat on a flight that is actually operated by another airline under a different flight number or code. If Company XX has a code-sharing agreement with Company YY, your ticket from XX will probably say "operated by YY".
All major airlines are party to one or more code-sharing agreements. There are very well-known codeshare alliances, for example the "Star Alliance" with (currently) 27 member airlines, including Lufthansa, SAS, Singapore Airlines and Swiss, among others.
Codesharing agreements are an important detail for flights to the EU when it comes to a refund claim under EU Regulation 261/2004.
Flights to the EU are only refundable under this EU regulation (for example, in the event of delays of more than three hours) if they are operated by an EU airline.
So does the ticket have to be from an EU airline?
No. - And this is where code sharing comes in:
Let's say you're flying from the US to the EU. You have a ticket from Delta Air Lines and the flight number on the ticket is DL1234.
Let's also assume that your flight has a delay of more than three hours. Are you entitled to a refund?
That depends on the following: If the flight was actually operated by Delta, then you have no claim - Delta is not an EU airline. But Delta has a code-sharing agreement with Air France, an EU airline. If your ticket says "operated by Air France", then it is a code-sharing ticket and you may be entitled to a refund.
That's good news for you as an air traveler!
You can fly to the EU with your favorite airline (in the USA for example: Delta, AA, UA, US Airways). You book your ticket with this airline, but you must make sure that it is a code-sharing flight operated by one of the EU partners. In the event of a delay, you then have the option of requesting a refund in accordance with EU Regulation 261/2004.
The small code-sharing addition on the ticket "operated by..." can be worth up to 600 euros. It is therefore worth paying attention to this.
Of course, refund.me takes care of the verification of these flight data details: