The Proposal of Demand Estimation of Repairable Items for the Weapon Systems During the Initial Provisioning Period: F-16 Case Study

  • Bahtiyar Eren
  • Serpil Erol
Part of the Operations Research/Computer Science Interfaces Series book series (ORCS, volume 56)


Every country that has military systems such as aircraft, radar, warship or tank has to meet the operational needs of those military systems in order to keep them ready for military operations . Logistics support needs are defined basically either before or after acquisition. If they are defined before acquisition, they are called “initial support requirement” , otherwise called “sustainment support requirement”. Our study is focused on the initial support requirement phase since the new weapon systems will be added into the Turkish military inventory . In addition to that, it is focused on repairable items since most of the material acquisition cost within the initial support budget is allocated to repairable items. The flight hour parameter is used for computing the initial support requirements of repairable items in the United States of Air Force (USAF) whereas the usage parameter is used in that of repairable items in Turkey. Based on these calculations, a new parameter called SORTIE, which is the one cycle of take-off and landing, is generated. Taking the consideration of flight hour, usage and SORTIE parameters, 24 scenarios (eight for each parameter) have been created by using real data set of F-16 with a quantity of 894 repairable items. Each scenario is named according to the usage of past data in years. The data set which covers the last 11 years (44 quarters) is divided into two parts: the first 8 years data is used for running the scenarios, and the last 3 years data is used for comparing the results of scenarios with the actual values. While evaluating the effectiveness of scenarios, parameters of mean absolute error and mean percentage error are used. In addition to the traditional approach that tries to find the best parameter common for all data, two new approaches are formed up. The first approach requires grouping the repairable items according to the supply group corresponding to the first two digits of NATO Stock Number (NSN). The other approach treats each NSN independent from each other. Each scenario is run under the three approaches including the traditional one and results are recorded. The Friedman and Wilcoxon Sign Test are applied for determining whether the results are significantly different from each other at the confidence level of 95 %. The approaches that decrease mean absolute error down to the level of 55 % can provide significant cost savings. On the other hand, repairable items whose mean absolute error and standard error values are higher than 3 and 5 respectively are recommended for future detailed studies.


Inventory Weapon systems Repairable parts Initial support requirement Item based approach Flight-hour based approach SORTIE-based approach 





Application Percentage


Daily Demand Rate


Doctrine, Organization, Training, Material, Personnel, Leadership and Facilities


Expected Failures


Failures per sortie


Item Based Approach


Multi-Echelon Technique for Recoverable Item Control


Not Repairable at This Station


NATO Supply Group


NATO Stock Number


OIM Annual Demand


Organizational or Intermediate Maintenance


Program Forecast Period


Quantity Per End Item


Requirement Distribution System


Repairable at This Station


Total Organizational or Intermediate Maintenance Demand Rate


Turkish Air Force


United States of Air Force


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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  1. 1.Hv.K.K.ligi Karargahi Harekat BaskanligiBakanliklar-AnkaraTurkey
  2. 2.Gazi Universitesi Endustri Muhendisligi BolumuAnkaraTurkey

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