It’s not unheard of that some passengers who are not familiar with codeshares would arrive at the airport expecting to fly with one airline, when in fact they’ll be flying with another.
Show me an example
Codeshares are an agreement between airlines to market each other’s flights.
In this codeshare example, Finnair is marketing the non-stop flights between New York and London, however, the flights are actually operated by British Airways.
If you were to book this flight, your ticket will have a Finnair flight number, despite Finnair having nothing to do with the operation of this flight. This is what you would call a codeshare.
Although codesharing is extremely common within alliances, airlines that are not part of the same alliance can still be codeshare partners (e.g. Emirates and Bangkok Airways).
How can I know if a flight is a codeshare?
Look out for anything that says “Operated by _______” when making your booking. Usually the Online Travel Agent will mention if the marketing airline is not the same as the operating carrier.
You can also use common sense when looking at the flight details. We all know that Finnair do not operate non-stop flights between New York and London.
Another thing you can look out for is the flight number (although this is not a very reliable method). Many codeshare flight numbers have a four-digit number, such as KL7990.
Should I book a codeshare flight?
There’s no reason why not. You’re still getting the exact same flight as if you booked a non-codeshare flight.
The only difference is that frequent flyer members can also earn miles with the marketed airline.