codeshare flights are flights operated by a specific airline, but seats are also sold by another, usually partner-airline. codeshare flights do have different flight numbers shown. Example: British Airways flight Denver – London BA218 is also labelled as American Airlines AA6169, Finnair AY5418, Iberia IB7406 and Aer Lingus EI8918. The flight is operated by British Airways, so you will find a British Airways airplane and crew.