LMI’s Aircraft Sustainability Model® (ASM®) helps managers determine the specific requirements for the myriad spare parts of a system by balancing each part’s cost with its explicit contribution to overall performance. To do this, the ASM sparing model employs advanced business analytics to rank spare parts purchases in the order of their benefit-to-cost ratios. It then incrementally adds spares to the sparing solution until a target budget or desired system availability is reached. Because the ASM sparing model is system oriented, it produces a far more efficient and effective sparing solution than traditional item-oriented inventory approaches. The ASM sparing model gives managers insight into the impact of individual parts on overall system performance, which is far more useful for resource allocation decisions than knowing the inventory performance for that part alone.