What is the 24-hour rule for KLM? KLM's 24-hour rule permits travellers to make changes to their bookings or cancel their f????ights by phone at "???????????????????????????????????????????????????????????? OR ????????????????????????????????????????????????????????????? (US)" inside 24 hours of buy without causing any punishments (Charges) or expenses. What is the 24-hour rule for KLM? f????ights KLM's 24-hour rule allows you to cancel your=???????????????????????????????????????????????????????????? . F????ight reservation or make changes to your booking ???????????????????????????????????????????????????????????? within the first 24 hours of purchase without any penalty fees, as long as your F????ight is at least 7 days away. To cancel or change your reservation, call KLM at ???????????????????????????????????????????????????????????? OR ????????????????????????????????????????????????????????????