The air ticket policy is very flexible in nature and totaly depends on HR policy of the company.
It is generally a non cash benefit; and it should not be encashed.
Annual airticket is attached with annual leave; and the person has to take leave; but only in case of business reason one can be stopped from taking leave; and in such cases the ticket encashment policy should apply.
The company can be flexible and formulate the policy for encahsment it can be in the following way-
-Reimbursement basis( on actual cost of ticket by producing original bills); this need to be checked with the provision made for the ticket and should not exceed the accounting provision.
-Monthly value of ticket to be attached with the salary pay out
-Yearly lumpsum payout.