The flight returns to a different city to where your trip began e.g. New York to Paris, France, but returning to Miami.
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The outgoing destination is different to the incoming origin e.g. London, UK to Singapore, but returning from Bangkok Thailand back to London.
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All cities in the itinerary are different e.g. Los Angeles to Sydney, Australia, returning from Auckland, New Zealand to San Francisco.
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We call this a double open-jaw flight.