An Airline Provisioning Problem

The authors describe a method of computing the number of spare parts of each kind to have at each field station in a maintenance system. One-at-a-time replenishment is used and the variables considered are: (1) the replenishment time from a central warehouse to field stations, (2) a specified protection level (maximum number of shortages per year), and (3) the predicted usage rate for each part-station combination. The method employs multi-channel queuing theory in a routine programmed for Univac I. Of basic interest is the technique of predicting part-station usage from the number of landings per time period, rather than from hours flown, a modification of usual airline practice that allows usage predictions to be tied directly to a given station, and, furthermore, allows allocations of parts to stations to be revised as schedules change. Thus, the procedure bases inventory levels at each station on future needs, rather than on past history--a poor predictor as plane types and schedules are revised. The method is also applicable to field inventory planning for non-airline use, particularly if part usage is low, if one-at-a-time replenishment is used, and if the number of part-station combinations serviced is large. "Management Technology", ISSN 0542-4917, was published as a separate journal from 1960 to 1964. In 1965 it was merged into Management Science.