Yes, it's geeky, we know, but double checking flight codes can mean you can get the same flight at a much lower price. Some flights have multiple flight numbers thanks to ‘codesharing’, where airlines assign their own flight numbers to a flight flown by another company. We found on one flight from London to New York – operated by British Airways but shared by American Airways and Iberia – that it cost £1,788.20 ($2,303.33) to fly with BA or AA and £981.94 ($1,264.76) to fly with Iberia. Same economy flight, just a £806.26 ($1,038.57) price difference...

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