Cancellation of booked flights depends on the policy of each airline and the type of ticket you purchased. Here are some things to keep in mind:

1. Cancellation policy by ticket type

• Flexible/Fully Refundable: Usually allows cancellation with low or no cancellation fees, and you can get a refund or change your ticket to another flight.
• Standard: Can be cancelled but usually incurs a cancellation fee. The refund amount may not include these fees.
• Non-Refundable: Usually cannot be cancelled or refunded. In some cases, you can change your ticket for a certain fee.

2. Cancellation Time

• Before Departure Date: You usually have to cancel your ticket at least a few hours before your flight departs. If you cancel late, you may lose the full value of your ticket.
• Cancel within 24 hours: Some airlines allow free cancellation within 24 hours of booking.

3. Cancellation Fees

• Cancellation fees are usually applied to non-refundable or low-cost tickets. These fees can range from a few hundred thousand to several million VND depending on the airline and ticket type.

4. Cancellation of tickets due to force majeure

• In case of flight cancellation due to force majeure factors such as weather, epidemics, or airline decisions, passengers are usually supported to cancel their tickets without having to pay a fee or change to another flight.

5. Contact the airline or agent

• To cancel your ticket, you will need to contact the airline or agent directly for assistance.

Before booking, carefully review the airline's cancellation policy to ensure you understand the terms and conditions and fees involved.