In understanding of the Sustainment Key Performance Parameter (KPP) for Materiel Availability (Am), the Key System Attribute (KSA) for Materiel Reliability (Rm) and how both of these relate to requirements for Operational Availability (Ao) it is important for program managers to focus on reliable system designs, effective life cycle support strategies, and adequate testing of these system parameters and attributes. Since testing alone cannot insure that these system parameters, attributes and requirements will be met by any given system design and support strategy, it is important for program managers to understand how system analysis, modeling and simulation can be used to help insure the goals of these parameters, attributes and requirements are satisfied.
CJCSI 3170.01I establishes a mandate for programs to develop a Sustainment KPP and for all programs of JROC interest to develop a Sustainment KPP and supporting KSAs. Definitions of the Materiel Availability KPP and supporting Materiel Reliability and Ownership Cost KSAs were provided in the DoDi 5000.02 of November 2013, Encl 6, Page 113.
Materiel Availability (Am) – Definitions and Methods of Assessing. The OSD definition of Materiel Availability includes two different formulas for expressing Am. The first is shown below and represents a point (instantaneous) estimate for Materiel Availability as a measure expressed as a percentage of systems (end items).
The key elements that must be incorporated in any assessment of Am are: any measure of Am must include the total population of systems (end items) to be fielded; any measure of Am must consider the total life cycle timeframe of the system (end item); and any measure of Am must include all major categories of downtime, both planned and unplanned. These are the distinguishing features of the Materiel Availability metric that differentiate it from the more familiar Operational Availability metric (uptime/uptime downtime).
Given that the definition of Materiel Availability mandates that it consider the entire fielded population of systems, the entire system life cycle, and all categories of downtime it is not possible to obtain a comprehensive estimate of Am from system testing during the Engineering and Manufacturing Development or Production and Deployment phases of system development. System testing, both Developmental and Operational Testing, can be used to obtain data on some of the variables that make up Am; e.g. MTBF and MTTR. Only after a system has completed fielding and is in the Operations and Support phase of its life cycle can data be collected to produce estimates of actual Am. During earlier phases, Am goals and the assessment of a given system's ability to meet those goals must be estimated through analysis. The Maintenance Division of the Logistics Directorate of the Joint Staff has published a guide to the Sustainment KPP that outlines criteria that the Joint Staff will use to determine if a program has done an adequate job of implementing the requirements for the Sustainment KPP (Am). Those criteria are:
- Is there evidence of a comprehensive analysis of the system and its planned use, including the planned operating environment, operating tempo, reliability alternatives, maintenance approaches, and supply chain solutions leading to the determination of the KPP value?
- Does the program account for the total population of end items being acquired for operational use?
- Are specific definitions provided for failures, mission-critical systems, criteria for counting assets as "up" or "down"?
- Does the metric clearly define and account for the intended service life, from initial placement into service through the planned removal from service? (A graphic representation (timeline) of the life-cycle profile is an effective way to present the data.)
- What is the overall sustainment CONOPS? Is it consistent with other CONOPS, design reference missions, scenarios, etc. being used? Is it traceable to the ICD, CDD, other JCIDS analysis, or agreement with the warfighting community? What alternatives were considered? Have surge/deployment acceleration requirements been identified?
- Is planned downtime (all causes) identified and included? Does the analysis package support the downtime? Are sources of data cited? How does the downtime value compare with that experienced by analogous systems?
- Is downtime caused by failure addressed? Are the values used for failure rates supported by the analysis? Is there a specific definition established for failure?
- Are sources of data identified? What models are being used to establish and track the KPP?
Guidance from OSD and the Joint Staff do not mandate particular methods for developing estimates of Am but they do make clear the need for programs to demonstrate that the Sustainment KPP goal has been developed after comprehensive and thorough analysis that considers all factors impacting the Sustainment KPP. A number of different methods can be used to perform analysis of Materiel Availability. For low density systems with simple supply and maintenance concepts, closed-form analytical solutions could be used to develop estimates of Am. For more complex systems with higher densities simulation modeling may provide a better analytical method of estimating Am. Stochastic simulation modeling helps overcome some of the problems inherent in making assumptions about the nature of the variables that contribute to Am. Simulation modeling also allows the program to test various alternative support strategies and, once developed, can continue to be updated and used throughout the system life cycle to provide estimates of Am as fielding plans, operational environments and deployment requirements change. Even complex, high density systems can be assessed with simulation models and these models can often be developed in a reasonable period of time, even with limited resources.
Relationship of Operational Availability (Ao) to Materiel Availability (Am). The Materiel Availability is not interchangeable with the Operational Availability metric that is a KPP requirement for many DoD systems. The Materiel Availability KPP must apply to the entire fielded inventory of systems, the entire life cycle of the system and incorporate all categories of downtime such as depot-level and scheduled maintenance. Operational Availability requirements always apply to a limited number of systems fielded to a particular echelon of operational units and frequently incorporate only unscheduled maintenance downtime due to reliability failures. The fact that the same formula (Uptime / Uptime Downtime) is included in the definitions for both Materiel Availability and Operational Availability should not be mistaken for an indication that the two metrics are identical.
This does not mean, however, that these two metrics are unrelated. A good way to look at the relationship between Am and Ao is to view Am as a function, (together with many other variables), of Ao. An adequate Ao is one of the essential building blocks to achieving a high level of availability of total fielded inventory throughout the life cycle of a fielded system. A poor Ao will have a negative impact on Am that will be difficult to overcome regardless of strategies for operational readiness floats and national maintenance. Since Am can be viewed as a function of Ao, programs need to carefully assess how they establish goals for Am and how these goals relate to program requirements for Ao. Simply using their Ao requirement as their Sustainment KPP Am objective might result in an Am goal that is impossible to achieve for some programs. Since Am includes the entire system inventory and life-cycle and all categories of downtime it will usually be difficult for a system to achieve an Am goal that is equal to or higher than an Am requirement defined for a smaller group of systems, shorter time period and limited categories of downtime. In some cases, however, systems that are very low density may be able to establish Am goals that are equal to Ao requirements.
Relationship of Materiel Reliability (Rm) and Other Variables to Operational Availability (Ao) and Materiel Availability (Am). Higher materiel reliability will result in higher Operational Availability and Materiel Availability since both Ao and Am are a function of Rm. The inherent reliability of a system is, by far, the biggest contributor to high Operational Availability.
By far, the biggest impact on Ao comes from increasing reliability. Doubling MTBF has the effect of increasing average Ao far greater than any of the other variables tested. The second biggest impact is made by increasing the availability of repair parts. MTTR and ALDT have relatively little impact on Ao compared with MTBF. Unless the inherent reliability of the system is sufficiently high it is very difficult to meet an Ao requirement by reducing MTTR and ALDT.
Summary. Materiel Availability has been defined in OSD and JCS documentation in a way that makes it clear how it differs from Ao; i.e., it must apply to the entire fielded inventory of systems, over the entire life-cycle of the system and incorporate all categories of downtime. The best way to view the relationship between Am and Ao is to see Am as a function of Ao, together with many other variables. The best way to assess both Am and Ao is through comprehensive modeling and simulation. Materiel Reliability is the cornerstone that insures both Am and Ao requirements can be met. Rm is far more important in determining the level of availability that is achievable than any other component of logistics system.