In addition to the presentation of airfares and freight invoices for future flights, the adjustment of air traffic liability includes estimates of any refunds made on previous flights, during which passengers ultimately did not fly for one reason or another. Of course, this aspect of revenue adjustment is largely a subjective judgment of the airline, as it is not sure for anyone to know for sure how many tickets will be refunded in relation to the tickets exchanged. For this reason, estimates are often based on the historical experience of an airline, combined with seasonal models. Airfares or freight bills are usually sold and issued in a timely manner prior to the flight date. As a result, the money received at the time of the sale is technically considered undeserved income. For this reason, it is a common accounting practice for airlines to defer these revenues and characterize them as liabilities on their balance sheets. Finally, when air service is provided, the company`s profit and loss account revenues will be reclassified into earned revenues and the liability for air travel will be reduced accordingly. Taxes and royalties are also taken into account in the traffic liability equation. In particular, airfares charge on-board transportation taxes, airport taxes, security charges and foreign travel expenses. Since airlines only act as collection agents for these expenses and do not collect them themselves, they do not record them as revenue. Instead, this money is first recognized as a liability when selling tickets and, if the airline subsequently makes payments to the relevant agency, the debts will be reduced accordingly in its accounting documents.
Depending on the policy of a single airline, unused tickets may be rebalanced for different periods. However, in all cases, the revenue collected for these notes must remain part of the calculation of air traffic liability until a given exchange window expires. At this point, the airline can determine the number of tickets that have finally expired and the number of tickets exchanged. With regard to the adjustment of liability revenues in the air transport sector, estimates should be made based on previous models. Airline revenue corrections with respect to air traffic liability will be incorporated into the accrual accounting method that almost all airlines observe when recording passenger and freight revenues. This is because the aviation industry uses relatively low margins, so revenue detection is an important step in ensuring that airlines remain profitable. Simply put, revenues are only accounted for when the airline`s service is actually provided and revenues must be classified accordingly.