You won't be responsible for Jetstar flight cancellation fees if you cancel within 24 hours of making the reservation; and you may obtain a full refund. Under the Jetstar flight cancellation rules, you will be required to pay the flight cancellation fee if you submit your cancellation request after the 24-hour window for free. You can cancel a flight without incurring any fees if you become ill after booking it, but you will need to submit valid documentation to Jetblue staff. If the reservations were made using coupons or vouchers, you will receive the coupon back as a refund after paying the flight cancellation cost. If a delay occurs, the traveler has the option to reschedule the flight or cancel it without incurring any fees. https://sites.google.com/view/jetstarcancellationpolicy/home