Predicting Wartime Demand for Aircraft Spares.

Abstract : U. S. fighter aircraft demanded surprisingly few spare parts in Desert Storm despite flying long hours. Although the sorties flown were much longer than their peacetime counterparts, demands per sortie remained about the same. This simple observation raised suspicions that parts fail on the basis of sorties flown, not hours flown, even though Air Force planning systems forecast demands on the basis of projected flying hours. This method of forecasting demands proved inadequate in 1993 when the war plans were modified to include the longer sorties that typify regional conflict scenarios. We found that demands are, for most aircraft, much more closely related to sorties flown than to flying hours. We developed a demand forecasting method that incorporates our results into the wartime spares requirements computation Called Decelerated Demand Forecasting, this method has been implemented by the Air Force for fighters and bombers, avoiding a $ 1.1 billion overstatement in the gross requirement.