With the peak summer travel season winding down, it's time for National Cheap Flight Day. "There's no specific day where flights are going to be at their cheapest," Katy Nastro, a travel expert at Going, tells CNBC Make. Instead, Nastro says that the best time to book air travel will always be in relation to when you're planning on flying. Here are three travel expert-approved tips for National Cheap Flights Day. They're watching data, they're watching traveler behavior and they're mapping out these pockets where they can be super competitive," she says.

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Persons: Katy Nastro, That's, Nastro, it's, Gemma Jamieson, Skyscanner's, we're Organizations: CNBC, Google, Airlines