The purpose of Reliability and Maintainability (R&M) engineering is to influence system design in order to increase mission capability and availability, and decrease logistics burden and cost over a system's life cycle. Properly planned, R&M engineering reduces cost and schedule risks by preventing or identifying R&M deficiencies early in development. This early action results in increased acquisition efficiency and higher success rates during operational testing and the development process.

R&M parameters (e.g., mission and logistics reliability, corrective maintenance, built-in test) are important characteristics used in measuring the operational suitability and effectiveness of Department of Defense (DoD) weapon systems. R&M parameters also relate to other system parameters, primarily those that characterize the system performance, readiness, logistics supportability, and total ownership cost. The R&M parameters and particular levels of performance support other system parameters essential to the success of the mission.

Results of R&M engineering activities are essential for programmatic decision and control functions. The R&M design methods and procedures are not new, but the challenge occurs in the diligent management of these methods and procedures to achieve reliable and maintainable systems. Effective management control of the R&M program, using the policies and guidance set forth by DoD, are intended to ensure timely performance of the necessary R&M activities to achieve the requirements and the development of adequate data to assess R&M at major milestones.