Probabilistic Treatment of Airlift Delivery
Final rept. Jan-Sep 2009
INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA
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Traditionally, a deterministic simulation is used to estimate airborne cargo and passenger delivery in wartime scenarios. Deterministic models address reliability by removing the number of non-mission capable aircraft from the total possessed numbers at the very beginning of the delivery process. Only mission capable MC aircraft, minus any special mission withholds, are used in the model. Most important, once an aircraft is deemed to be MC, it never fails anywhere along the delivery and return routes in the deterministic models. This has long been recognized to be a vulnerable feature of such models. How inaccurate is this What problems can arise from its assumption In this paper we present a set of equations that provide quantitative, rapid, but simple first-order observations on how uncertain the results from deterministic model runs can be, once stochastic critical part failures are incorporated in the analyses. In particular, we find that the standard deviation of delivery rates, a measure of the uncertainty in the expected results, can be substantial for particularly unreliable air transport aircraft such as the C-5A and even noticeable for the most reliable ones, such as the C-17. The simple results found here should serve as an incentive for further research into this important area.
- Military Aircraft Operations
- Transport Aircraft
- Statistics and Probability