This paper deals with an estimation method of the airfield capacity for the airlift operation. In the US Air Force, airfield capacities has been estimated using MOG(Maximum -On-the-Ground) concept, which is known to having several weaknesses. Recently, RAND suggests a personal-computer- based model called the Airfield Capacity Estimator(ACE), which is a more advanced and realistic technique compared to the MOG. This paper attempts to modify the ACE appropriate to the Korean airlift operation. While ACE is developed on the basis of strategic mobilization, Korean airlift operation is done on the tactical basis. A designed mdel is tested with simulation technique.