Operations and Support (O&S) Phase
The fifth phase of the Defense Acquisition System as defined and established by DoDI 5000.02 after Materiel Solution Analysis (MSA), Technology Maturation and Risk Reduction (TMRR), Engineering and Manufacturing Development (EMD), and Production and Deployment (P&D). The purpose of the O&S phase is to execute the Product Support Strategy, satisfy materiel readiness and operational performance requirements, and sustain the system over its life cycle (to include disposal). This phase has two major efforts: Life Cycle Sustainment and Disposal. The phase is not initiated by a formal milestone, but instead begins with the deployment of the first system to the field, an act that initiates the Life Cycle Sustainment effort of this phase. The Life Cycle Sustainment Plan (LCSP), prepared, by the Program Manager and approved by the Milestone Decision Authority (MDA), is the basis for activities during this part of the phase. The Life Cycle Sustainment effort overlaps the Full-Rate Production (FRP) or Full Deployment part of the P&D phase. At the end of its useful life, a system will be demilitarized and disposed of in accordance with all legal and regulatory requirements and policy relating to safety (including explosives safety), security, and the environment.
Source: DoDI 5000.02