KLM's 24-hour rule allows passengers to make changes or cancel their flight within 24 hours of booking without incurring any penalties. This policy applies to tickets booked directly with KLM for flights departing from the United States. If you book a flight and later realize you need to make a change, you can do so within the first 24 hours of booking without paying any change fees, ... https://www.giantbomb.com/forums/general-discussion-30/live-support-what-is-the-24-hour-rule-for-klm-1932528/