System design adequacy is the probability that a system will successfully accomplish its mission, given that the system is operating within design specifications.

Misapplication of a system is entirely excluded from measurements of system effectiveness. As an example, the differences between 75mm and 90mm tank guns in range, accuracy, and penetrating power against enemy tanks have a significant bearing on measurements of system effectiveness but are irrelevant to evaluations of their operational readiness and availability.

The characteristic discussed in the preceding paragraph can be identified by the term “system design adequacy.” System design adequacy is the probability that a system will successfully accomplish its mission, given that the system is operating within design specifications.

The design may include alternative modes of operation, which are equivalent to built-in automatic repair, usually with allowable degradation in performance. These alternative modes of operation are, of course included in the definition of system design adequacy. The probability itself is a function of such variables as system accuracy under the conditions of use, the mission to be accomplished, the design limits, system inputs, and the influence of the operator.

References:

1. MIL-HDBK-338, Electronic Reliability Design Handbook, 15 Oct 84
2. MIL-STD-721, Definitions of Terms for Reliability and Maintainability, 23 Oct 91