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Unformatted text preview: needed to
achieve a particular level of availability, holding other
logistics resources fixed. The line between availability
models and logistics supportability models can be
inexact. Some logistics supportability models may deal
with a single resource; others may deal with several
resources simultaneously. They may take the form of a
simple spreadsheet or a large computer simulation.
Greater capability from these types of models is generally achieved only at greater expense in time and
effort. The system engineer must determine what
availability and logistics supportability models are
needed for each new system, taking into account the
unique operations and logistics concepts and
environment of that system. Generally both types of
models are needed in the trade study process to
transform specialty engineering data into forms more
useful to the system engineer. Which availability and
logistics supportability models are used during each
phase of the protect life cycle should be identified in the
Another role for these models is to provide
quantitative requirements for incorporation into the
system's formal Integrated Logistics Support (ILS) Plan. Figure 27 shows the role of availability and logistics
supportability models in the trade study process.
Essential to obtaining useful products from any
availability and/or logistics supportability model is the
collection of high quality specialty engineering data for
each alternative system design. (Some of these data are
also used in probabilistic risk assessments performed in
risk management activities.) The system engineer must
coordinate efforts to collect and maintain these data in a
format suitable to the trade studies being performed.
This task is made considerably easier by using digital
databases in relational table formats such as the one
currently under development for MIL-STD- 1388-2B.
supportability modeling and data collection through the
operations phase permits operations trend analysis and
assessment on the system (e.g., is system availability
declining or improving?) In general, this kind of analysis
and assessment is extremely useful in identifying
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