Vietnam Airlines' cancellation policy varies based on the fare class and ticket type. Generally, passengers may cancel and request a refund within 24 hours of booking without incurring fees. After this period, cancellation fees may apply, with the amount depending on the specific fare conditions. Some tickets may be non-refundable. Passengers are encouraged to review the airline's cancellation terms on their official website or contact customer service for detailed information. In cases of flight cancellations by the airline, passengers may be eligible for refunds or rebooking. It's advisable to check the latest policy updates and terms for accurate information.