How do the Nepal airlines charge a cancelation fees?

The normal cancellation charge is 10% of the airfare, however, if the flight gets canceled due to weather or other reasons by the airline the fare is fully refundable. In the case of bad weather, the airlines often do not officially declare the flight canceled till late in the day 1 or 2 pm. If you decide to take a helicopter in the meantime and cancel your flight ticket the cancelation charge is still charged even if it is a near certainty that the flight will eventually be formally canceled.