Safety Stock Estimation of Unit Load Devices for International Airline Operations

Unit load devices (ULDs) are used to load air cargo and passengers’ checked baggage for wide-bodied aircraft operations. Since ULDs are reusable at the destination, airlines can invest in an appropriate fleet size for their requirements. The estimation of safety stock levels for every operating airport is a premeditated task because airlines must prepare enough devices for the outbound consignments of each flight. The variance of the number of used devices for each arrival and departure flight will influence the stock level of an airport. For scheduled international services, this study proposes an analytic method based on a cyclically time-sequenced network that can be used to express ULDs moving in and out of an airport. The safety stock level is defined as the minimum quantity that can support the utilization for the entire next cycle at the period end. The results of a case study on one company reveal that the airline normally establishes a high safety stock level.