Current Logistics Research.
The Air Force Materiel Command (AFMC) Studies and Analyses Office (SAO/XPS), a field operating agency under AFMC Plans and Programs (XP), conducts and sponsors studies and research of significant materiel issues. The research provides analytical solutions for improved business practices. Efforts focus on the development and enhancement of mathematical models that can relate materiel resource decisions to resultant impacts on business performance and weapon system availability, enabling AFMC to prioritize and justify its investments. The studies and analysis staff works closely with its customers to ensure a healthy balance between the rigorous application of operations research techniques and practical solutions.
The SAO/XPS senior staff consists of:
Visit the SAO web site to view the 1999 Annual Report: http://www.afmc-mil.wpafb.af.mil/organizations/HQ-AFMC/XP/sao/. A summary of recent studies follows.
Execution and Prioritization of Repair Support System (EXPRESS) Implementation Support is the Air Force depot repair and distribution prioritization system. SAO is the Air Force technical office of primary responsibility for the EXPRESS Prioritization of All Reparable Spares (PARS) math model, which is the primary EXPRESS prioritization mechanism. SAO provided EXPRESS support in a number of ways.
1. System Development. This included supporting the development, testing, and implementation of three separate EXPRESS releases:
* Version 3.1. The Air Force Logistics Board of Advisors (BOA) recommended changes to direct support to higher priority units. These were implemented in EXPRESS, but air logistics center (ALC) users questioned their impact. They felt the BOA priorities had unintended consequences that would degrade shop replaceable unit (SRU) support. An analysis confirmed these suspicions, and modifications were developed and approved. Efforts focused on testing these changes in the production system to ensure recommended modifications had the desired effects. Work on EXPRESS metrics demonstrated customer support for SRUs had improved as a result of these changes. The results were briefed to various audiences, including EQ AFMC Logistics (AFMC/LG) and the Air Force Supply Executive Board (AFSEB). This release was implemented at the ALCs in April 1999.
* Version 3.2. ALC users were concerned that long repair time and long flow time items do not receive sufficient repair priority when repair is very constrained. This release contained system changes that, based on a study of alternative methods, provide the best solution for AFMC customers. The release also included significant streamlining of the EXPRESS process, conceived and supported through the PARS model. These changes reduced system run times by several hours, which is significant since each ALC runs EXPRESS each day. This release was implemented at the ALCs in October 1999.
* Version 3.3. At the summer 1999 Corona meeting, the major command (MAJCOM) commanders devised the Spares Priority Release Sequence, which was a tweak of the BOA priorities, to provide increased support to project code 700 mission in-capable requisitions and broaden the category of customers who can use that project code. Appropriate changes were made to the PARS model, which was implemented in February 2000.
2. Demand Forecasting. Currently, EXPRESS offers three ways to forecast customer demands for parts: (a) historical daily demand rate (DDR), (b) historical demands per flying hour and projected flying hours, and (c) deepest holes. This study determined which forecasts most accurately predict demands.
3. Improving Support to Engine Items. The AFMC Propulsion Product Group manager felt engine items were not being supported properly in EXPRESS. The most significant concerns were that EXPRESS did not explicitly recognize war readiness engine (WRE) targets and engine items were not being treated equitably. Working with the Joint Engine Working Group, these concerns were evaluated, and it was determined (a) EXPRESS inherently supports engines to a level beyond their WRE target because it tries to support all parts causing existing and projected holes in engines, and (b) improvements could be made in EXPRESS forecast demands by considering the schedule for engine overhauls at the depot, instead of just looking at historical demands. Work continues with the AFMC Logistics Item Management Division and the development contractor to incorporate these changes.
4. EXPRESS Metrics. At the request of the AFSEB, an effort was initiated with AFMC/LGI to capture data that could be used to measure the supply performance of items being managed by EXPRESS. The data have been presented to the AFMC Commander, AFMC/LG, AFSEB, and other Air Force logistics managers. Study results show EXPRESS-managed items are generally healthier than non-EXPRESS managed items and changes to the EXPRESS logic are having a positive effect on customer support.
5. EXPRESS Assessment Tool. SAO developed a tool, based on earlier recomputations, that supports forecasting the impact of changes of weapon systems analysis. The tool was instrumental in completing the long flow study and helping convince Oklahoma City ALC (OCALC) management an alternative prioritization scheme gave inferior results to the EXPRESS prioritization approach. (Analysts: Rich Moore, Captain Michel Lefebvre, Karen Kilager, Lieutenant Jason Vinson, Freddie Riggins)
Retail and Wholesale Stockage Levels for the Air Force.
The readiness-based leveling system (RBL) integrates retail (base) and wholesale (depot) environments while determining the best base stockage levels and depot working levels to achieve the lowest expected worldwide base back orders. SAC provided technical support in the following areas:
1. Reviewing the adjusted stock levels (ASL) in RBL for all commelectronic items. Under stockage policy, these Air Force Communication Agency (AFCA) items receive certain minimum stockage levels based on a single-point failure code. Currently, ASLs for these items are fed directly to RBL from the bases via AFCA. In the future, the only source of ASLs will be from AFCA through a direct pass from AFCA to RBL. SAO analyzed the ASLs from both sources, notifying AFCA
of any differences. Using the results, AFCA asked the using commands to verify or delete their ASLs. This enables the correct levels of these critical items to be loaded at the bases.
2. Identifying and providing data to RBL for about 10,000 items not available during normal RBL processing due to system interface issues. It was able to provide the data, enabling the MAJCOMs to receive the benefits of RBL processing.
3. Analyzing how RBL handles items with high condemnations. The investigation revealed RBL logic does not properly treat depot condemnations. A solution is under development.
4. Many of the issues associated with RBL surround the data that it is fed, so SAO initiated a study that looks at the two-way interfaces between RBL and D041. Other data that comes into the system prior to RBL processing will also be examined. (Analyst: William Morgan)
PSBA Minimums and Standards Resource Baselines
The AFMC Product Support Business Area (PSBA) needed a method to estimate the minimum and standard budget and manpower requirements to use as input for the program objective memorandum process.
To support this requirement, program data provided by the AFMC Acquisition Support Team, Product Line Division, and DRS, along with manpower data provided by AFMC Manpower and Organization, were used to compute manpower requirements for 23 categories of system program offices (SPO). SAO computed minimum manpower requirements using data from SPOs identified as benchmark SPOs or SPOs that operated most efficiently as a result of acquisition reform practices. The remaining program data were used to compute standard manpower requirements. The AFMC Business Area Operations Division used the results to calculate air logistics center resource requirements to use in the POM process. (Analysts: Thomas Stafford, Rich Moore)
AFMC Logistics Response Time
This effort involves providing a way for AFMC and the major commands to monitor base supply wait times associated with orders for AFMC-managed items. This facilitates identification of supply chain bottlenecks. Trend analysis may indicate developing problems or improvements.
SAO built the monthly Logistics Response Time (LRT) databases and incorporated new business rules to improve its tool. This system uses data on closed requisitions to monitor wait time by ALC inventory control point, product directorate, weapon system, requisition priority group, item, base, and major command for both recoverable and consumable supply management activity group items. The source of the data is the monthly Logistics Metric Analysis Reporting System (LMARS) files from the Defense Automated Addressing System. A special version of AFMC LRT focuses on Contract Repair Enhancement Program (CREP)/organic/dual repair items. Versions that focus on two-level maintenance items and one that focused on support for the Kosovo crisis were also developed. In addition, SAO worked with the Air Staff to address AFMC LRT and LMARS differences. Trend information, charts, and data are available via a web site: http://www.afmc-mil.wpafb.af.mil/HQ-AFMC/LG/LSO/lot/. Senior AFMC management regularly reviews the results from the tool to monitor AFMC supply chain performance. (Analysts: Captain Thuan Tran, Mike Niklas, Curt Neumann)
Wholesale Back Order Targets
The wholesale back order targets study determines the planned number of wholesale back orders inherent in the AFMC requirements computation system; that is, how many back orders can be expected based on the aircraft availability targets supplied by Air Staff and the forecasted pipeline times and demand rates?
Using input data and results from the March 1999 D041 cycle and the October 1999 RBL leveling process, the planned number of wholesale back orders was determined. Planned back orders are a function of the depot pipeline requirement and the amount of stock placed at the depot. According to the requirements process, there are 18,421 planned wholesale back orders for Air Force recoverable items. For consumable items, the planned number is 8,460 back orders. Planned wholesale back orders were compared with actual back orders on an item-by-item basis, and more than 90 percent of the nearly 28,000 active national stock numbers (NSN) were within ten back orders. In other words, the planned and actual back orders differed by less than ten units. On the other end of the spectrum, there were 177 NSNs where the difference was more than 100 units, including 10 items with a difference of more than 1,000 back orders. The total number of actual back orders for this group of 28,000 NSNs was 142,054. A sensitivity analysis r evealed the effect of executing the computed stock levels with unanticipated pipeline increases (for example, repair constraints, excessive demand variation). Planned back orders increased significantly when the expected pipelines were doubled or tripled. Results were briefed to AFMC/LG and the Logistics Business Board Tier 2. At the request of AFMC/LG, the planned wholesale back orders by supply chain manager were identified and rolled up to each ALC. The next step is to work with the customer to transform these measures to actual targets that can be used to measure SCM performance. (Analyst: William Morgan)
SAO provided a quantitative methodology for determining issue effectiveness (LE) and stockage effectiveness (SE) targets for recoverable items. IE is measured for all items and represents the percent of time a customer receives a part immediately upon request. SE has the same definition as IE but is only measured for items authorized to be stocked.
A method for determining IE/SE objectives for each item using an approach similar to that employed in the Wholesale Back Order Targets project was developed. RBL data, expected pipeline times, and base stock levels from the AFMC requirements system were used to compute the inherent IE/SE values. The command-wide values were 81 percent for IE and 89 percent for SE. SAO also decomposed these into values for each ALC and supply chain manager and briefed the results of the study to AFMC/LG and the Center executive directors at the Logistics Business Board. Work continues with AFMC/LG to refine the values into achievable targets. (Analyst: Michelle Judson, William Morgan, Rich Moore)
Excess Awaiting Parts Management
The AFSEB has been concerned about the proliferation of items that are excess awaiting parts (AWP)at base level. The purpose of the study was to first quantify the extent of the problem, then to recommend business rules to reduce it.
In August 1999, SAO briefed the AFSEB to quantify the extent of the problem. Only 15 percent of the AWP that existed at that time were within the authorized stockage requirement for the base. These items are adequately supported by EXPRESS version 3.1. The remaining 85 percent of the AWP exceeded the bases' authorized stockage requirements. Of these, the vast majority--71 percent--exceeded the total worldwide-authorized stockage requirement.
Working with the Air Force Logistics Management Agency, SAO recommended to the AFSEB business rules intended to mitigate these problems. These recommended rules had the following effects:
* Parts excess to the worldwide level should he returned to the depots for storage.
* Parts not excess worldwide, but excess at a given base, should be redistributed to the bases that need them.
Work also continues with the Standard Systems Group and the D035 system representatives to improve the reporting of AWP to AFMC. (Analysts: Rich Moore, Captain Michel Lefebvre)
Supply Chain Operational Performance Evaluator
The Supply Chain Operational Performance Evaluator (SCOPE) is used to address a variety of supply chain issues. The software, formerly the Supply Chain Simulation Model, is a stochastic event simulation that quantifies the impact on weapon system availability due to changes in logistics policies and procedures. SCOPE was used in several studies.
* BOA Priority Analysis. SAO analyzed the impact on aircraft availability from applying BOA priorities to JCS-coded units. The BOA priorities allowed the Joint Chief of Staff units to improve their requisition priorities in EXPRESS, resulting in increased spares support. Conclusions were (a) as spares become scarce, EXPRESS with BOA priorities provide more support to JCS-coded bases compared to the non-JCS bases, (b) EXPRESS without BOA priorities always resulted in fewer total not mission capable rate due to supply aircraft, and (c) spares have to be scarce before EXPRESS with BOA priorities has a noticeable impact on JCS units. The information was presented to the AFMC/LG and MAJCOMs as a baseline for understanding the impacts of the Spares Priority Release Sequence.
* EXPRESS versus the Uniform Materiel Movement and Issue Priority System (UMMIPS). OC-ALC had developed an alternative to EXPRESS prioritization that relied on UMMIPS priorities. SAO quantified the differences between using availability-based (for example, EXPRESS) and UMMIPS-based business rules for repair and distribution prioritization and found that customer support (as measured by available aircraft, MICAPS, and stockage effectiveness rate) was better when EXPRESS distribution and repair policies were used. Results were briefed to the AFMC/LG and OC-ALC/LG, which directly led to OC-ALC reverting back to EXPRESS for its entire center workload.
* Spares Priority Release Sequence Analysis. This is a follow-on project to the BOA priorities analysis that uses a Corona-modified version of the priorities. Analysis continues, using the latest version of SCOPE, which allows the use of actual assets. (Analyst: Thomas Stafford)
Requisition Objective Holes Versus Back Orders
MAJCOM and ALC customers have identified a disconnect between the number of outstanding wholesale back orders and the number of requisition objective (RO) holes reported to AFMC. Each of these values can be viewed as a statement of customer needs. They should be similar. HQ AFMC/LG tasked SAO to run a comparison of the two to determine if there was a real disconnect and to quantify the magnitude of the problem.
There was, indeed, a problem. Only 64 percent of the back orders from depot customers could be tied to an RO hole, and only 75 percent of the RO holes from depot customers could be tied to a back order. For base customers, only 77 percent of back orders could be tied to an RO hole, and only 71 percent of the RO holes could be tied to a back order. Looking at specific item/ base combinations, more than 95 percent of the differences were within two units. The results were presented to the AFMC/LGI and AFLMA. Potential reasons for the disconnect include data system timing, workload transfers between the depots, and items that are ordered in batches rather than one for one. (Analysts: Karen Klinger, Captain Michel Lefebvre, Rich Moore)
CREP Cost-Benefit Analysis
SAO provided a tool to help decide whether to pay for improvements in contract repair responsiveness. The CREP is developing processes to improve contract repair responsiveness. Depot personnel have the responsibility for evaluating cost-benefit ratios associated with asking contractors to shorten their repair cycle times.
SAO enhanced the prototype CREP cost-benefit analysis by converting it to a relational database and adding more information regarding status of the items. This helps contract repair managers gather information that can aid in making decisions affecting the responsiveness of contract repair. If there were a plan to buy additional spare parts, perhaps it would be cheaper to work with the contractor to reduce the repair time, thereby reducing or eliminating the buy requirement. The tool also provides supply indicators to determine the effectiveness of the support currently being provided. (Analysts: Mike Niklas, Jenny Woodrum, William Morgan)
The Defense Logistics Agency (DLA) provides cataloging, acquisition, stockage, and distribution support for most Air Force-consumable items. The Air Force Weapon System Support Program (WSSP) is a process to register identification and prioritization data with DLA for consumable Air Force weapon system parts that DLA manages. DLA uses this information to prioritize its acquisition and stockage actions. AFMC Logistics Item Management is the functional manager for the WSSP. Their customers at the ALCs and MAJCOMs report that inaccuracies in WSSP data are impacting the Air Force's ability to perform its flying missions, since these deficiencies can lead to consumable item delivery shortfalls.
A report was developed that documents Air Force and DLA registration and support processes and major problems. It covered many of the high-level requirements for markedly improving the WSSP registration process and looks at ways for implementation. After analyzing alternatives, a recommendation was made to rehost the registration data and several WSSP functions in D200F, an existing data system. The recommendation was approved, and requirements are being refined. (Analysts: Steve Bankey, Raj Srivastava, Mike Niklas)
The Program for 2000
Current plans are to continue devoting a major portion of the effort toward implementing new methods for improving the management of materiel spares. This will include methods to determine requirements, allocate resources, execute support actions, and assess impact.
Some specific areas of focus are:
* Evaluating the impact of alternative supply policies on customer support. Some of these policies relate to providing premium support for certain squadrons, considering centralized intermediate-level maintenance facilities, support for major end item overhaul maintenance at depots, and improving the execution of contract repair.
* Formalizing and implementing a methodology for determining supply chain manager performance targets by incorporating the impact of uncontrollable factors.
* Defining strategies to improve piece parts support for depot repair.
* Finalizing a methodology for readiness-based contract repair management.
* Conducting studies of interest to Air Expeditionary Forces, such as minimization of deployment footprint (shipping weight) for a squadron, given an operational flying requirement.
* Providing valuable information for weapon system management by integrating databases that depict asset status and constraints.
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|Publication:||Air Force Journal of Logistics|
|Date:||Sep 22, 2000|
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