How can I know if a flight number is codeshared, and if so, what other flight codes the flight have?

Question

https://en.wikipedia.org/wiki/Codeshare_agreement:

A codeshare agreement, also known as codeshare, is a business arrangement, common in the aviation industry, in which two or more airlines publish and market the same flight under their own airline designator and flight number (the “airline flight code”) as part of their published timetable or schedule.

How can I know if a flight number is codeshared, and if so, what other flight codes the flight have?

Answer 1

Since you did not specify at what time you wanted to know this as in before or after buying tickets etc.

One way to know is to look at the departure boards in the airport as they will rotate through all the code share flights for that particular flight.

If you need this information before you buy the ticket it depends on the airline or agent you use but normally they will not publish all the code shares they will simply state their own and the operating airline if that’s is different from their own. They will not specify all other airlines who also code share

Answer 2

I have not been on too many codeshared flights, so my personal experience is not massive there, but you have two options:

1. Look at the online departure board. Here's example for Heathrow:

Bunch of flights departing to basically two locations: Glasgow and Zagreb - most likely codeshares. In case of Glasgow we can be sure it's codeshare because it's departing from T5, and that terminal is used only by British Airways. Obviously just relying on time that flight departs might raise some false positives. There actually might be two flights at exactly the same time to the same location, but it's pretty unlikely.

2. Check on Flightradar24 - when searching for codeshared flight it will actually tell you how it maps to code of airline that operates it. Then after actually searching for it, it will show you information for the operating airline.